first international symposium on avian …

CONVENER AND ORGANISER: ASOK GHOSH - CALCUTTA
EDITOR OF ABSTRACTS: BRIAN K, FOLLETT- U,K,
PRINTED: UNIVERSITY COLLEGE OF NORTH WALESJ BANGORJ U,K,
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ACKNOWLEDGEMENTS
The Symp:>sium was sponsored by the Government of India, the University Grants Commission of India, the University of Calcutta and the Ramakrishna Mission Institute of Culture. The meetings were held at the Birla Industrial & Technological Museum in Calcutta. Grants-in-aid are gratefully acknowledged from the Directorate of Education, Government of West Bengal, the Indian National Academy of Science, the Kothari Scientific and Research Institute and Organon (India) Ltd.
The local organising committee (Professor Asok Ghosh) are indebted to the International Advisory Committee for their advice and encouragement.
All the foreign participants are grateful to their respective Governments and Scientific Councils for financial support.
EDITOR'S COMMENTS
The volume records, in the form of slightly extended abstracts, the presentations given at the First International Symp:>sium on Avian Endocrinology held in Calcutta during January, 1977. Approximately 200 persons from 12 countries attended the meeting and fifty-six papers were read covering most aspects of avian endocrinology. Lectures which were intended to review a particular field, and which lasted for 30 min., have been condensed into 3-5 pages while shorter communications have been limited to a single page. Reprints have been provided to each author.
Many of the abstracts have been edited slightly and retyped to improve their clarity. Any errors are the responsibility of the editor.
INTERNATIONAL COMMITTEE ON AVIAN ENDOCRINOLOGY
During the meeting in Calcutta it was decided to form a small Committee whose function would be to try and coordinate efforts in avian endocrinology and possibly arrange future Symp:>sia. It should be emphasised, however, that this informal committee has not been set up in competition with more established organisations but solely to help and I ink together !hose persons with an interest in the hormones of birds. It includes the following persons: Chairman - B. K. Follett (Department of Zoology, University College of North Wales, Bangor, Gwynedd, U.K.), I. Assenmacher (Montpellier, France), A. Epple (Philadelphia, U.S.A.), A. Ghosh (Calcutta, India), E. Gwinner (Erling Andechs, Federal Republic of Germany), S. Ishii (Tokyo, Japan), B. Lofts (Hong Kong), A. Oksche (Federal Republic of Germany) and E. Skadhauge (Denmark). Should any person require further information please do not hesitate to contact either the Chairman or one of the Committee.
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CONTENTS
Presidential address: Time measurement in photoperiodic birds D. S. Farner
Session I - General Organisation of the Avian Endocrine Syste_m
Phylogenetic peculiarities of the avian endocrine system A. Epple
Hormonal regulation of the uropygial gland S.P. Bhattacharyya, B.R. Maiti &Asok Ghosh
Field investigations in avian endocrinology-methods and some results John C. Wingfield & D.S. Farner
Histomorphology of the avian thymus S. Banerjee
Effects of hypercalcaemia on the ultimobranchial gland of pigeon, Columba I ivia -- V. K~ Das & S. Das
Session II - Neuroendocrine Mechanisms
The neuroanatomical basis of avian neuroendocrine mechanisms A. O~sche
The neuroendocrinology of photoperiodism in birds B. K. Follett
Hypophyseal portal vessels in birds : A comparative study C.J. Dominic
Potential sites and action spectra for encephalic photoreception in the Japanese quail.
K. Homma, K. Sakakibara & Y. Ohta
Effect of hydrocortisone on the hypertonic saline-induced changes in the hypothalamic neurosecretory system of the spotted owlet, Athene bromo, Temminck --- --
K.B. Singh
Sess1on Ill - Physiology of the Pineal Body
Role of the pineal in the control of circadian and circannual rhythms in European starlings
E. Gwinner
Pineal and the neuroendocrine basis of reproduction in birds R.N. Saxena
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Role of pineal and photoperiodism in the hypothalamo-hypophyseal gonadal axis of weaver bird
K.S. Balasubramaian
Pancreatic control of avian carbohydrate metabolism R.l. Hazelwood
The role of glucagon in birds P. Mialhe, G. Sitbon, C. Foltzer, E. Krug, R. Gross & F. Laurent
Effect of two oral hypoglycaemics on the blood sugar level, adrenal medulla and cytology of the endocrine pancreas of pigeons
B. Guha
Cholinergic assistance to the release and action of insulin in pigeons B. Pilo, P. V. Patel & R. V. Shah
Evidence for a non-pancreatic source of chicken insulin R.l. Hazelwood & J.R. Colca
~':ssion V - Developmental Endocrinology
Ontogeny of corticosteroid receptors in chick embryonic kidney J.G. Lehoux, C. Beaudry & D. Bellabarba
Aminoglutethimide phosphate-induced inhibition of cortical tissue in chick embryonic gonads
J.S. Knight
Influence of hypothyroidism on histophysiology of feather development R.V. Shah, G.K. Menon & B.M. Jani
Effect of methyl-thiouracil and T 3 on the CNS of chick embryo K. Chandrasekhar, G.N. lv10skovkin & M.S. Mitskevich
Transformation of the female right gonad of the fowl into a fertile testis M. T. Frankenhuis
Session VI -Mechanisms of Honnone Action
Gonadotropin receptors in the avian testis S. Ishii
Corticosteroid receptors in avian tissue L. Charest-Soule, A.Z. Mehdi & T. Sandor
The action of avian LH on androgen secretion from the interstitium of the avian testis
Z.W. Maung, S.L. Maung & B.K. Follett
Hormonal regulation of certain enzymes of L-ascorbic acid metabolism in chicks
A. Bhattacharyya
Proc. First lnternatl. Symp. Avian Endocrinolo•Jy, Calcutta, Jan. 1977
iv Session VII - Reproduction
Endocrine aspects of ovulatory cycle of the domestic fowl. K. Tanaka
Photoperiodic responses of Indian birds A. Chandola & J.P. Thapliyal
Adrenal sex-steroidogenesis in caponised domestic pigeon, Columba Iivia ----
--R.N. Mukherjee & A. K. Sarkar
Effect of ext ern a I gamma irradiation on the testis of the house sparrow, Passer domesticus (Linn.). --O.K. Vyas & D. Jacob
Endocrinology of avian Sertol i cells B. Lofts
Differences in the endocrine mechanism of ovulation of the domestic fowl and the Japanese quail.
Y. Tanabe
Effects of avian and mammal ian pituitary materials on ovarian function in the hen.
K. lmoi
M. Wodo, K. Wakabayashi, T. Adachi & S. Ishii
Steroid synthesizing cellular sites in the developing gonads of the domestic pigeon, Columba Iivia.
B. V. Bhujle & V~B.No::lkarni
Photoperiodic induction of gonadotrophin release in quail on the first long day.
B. K. Follett & D. T. Davies
Effect of Sodium malonate, on inhibitor of TCA cycle on spermato genesis in hens.
C. Deb, G. Mojumder, P. Koul & N. Mollik
Some observations on steroid dehydrogenoses in the avian ovary. P.M. Ambodkor & V. C. Kotok
Polysaccharide cytochemistry of the duck oviduct. D. Pol
Session VIII - Salt G1ond Function
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Pituitary control of avian adrenal function W.N. Holmes
Adrenocortical functions in birds T. Sandor & A.Z. Mehdi
Mechanism of release of catecholamines from the adrenal medulla of fowls.
S. Subrahmanyam & M. Quadir
Relationship between adrenal and gonadal cycles. C.M. Chaturvedi & J.P. Thapliyol
A comp:::~rative survey of the interrenal tissues of some avian species. C.K. Manna
Adrenal response to crowding in parakeet, Psittacula kromari. J. Banerjee --------
Cytochemical study of odrenomedullary mucopolysocchorides in an avian species, Pholacrocorax niger.
D. Bhakta---------
_5essio~ X - Thyroi~ and Paro!~rr..?~~~lond~
Role of parathyroid hormone on renal excretion of calcium and phosphate in the European starling.
N.B. Clark & R. F. Wideman
Effect of thyroidectomy on the premigratory adaptive hyperlipogenesis in the migratory starling Sturnus roseus.
R.V. Shah, S.T. PoteT&B.Pi1o
~essi~~-~:_nal Endo~rinologr_
Drinking induced by angiotensin in birds. H. Kobayashi, Y. Takei, H. Uemura & M. Woda
The avian renin-angiotensin system H. Sokabe
Hormonal control of avian osmoregulation. E . Skadhauge
A biochemical-histochemical investigation on the effect of vasopressin on the avian kidney.
D.N. Kamat, M.M. Kothari, P.V. Deshponde, S.D. Sontakke, R. P. Athalye & K. G. Chacko
Cytology of the avian juxtaglomerular apparatus. D. Ghosh
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Proc. First lnternatl. Symp. Avian Endocrinology, Calcutta, Jan. 1977 ?roc. First lnternatl. Symp. Avian Endocrinology, Calcutta, Jan. 1977
Vote of thanks A. Oksche
Author Index
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University of Calcutta, India.
Avian endocrinology concerns the study of endocrine glands in diverse
species of birds, including poultry, game and wild. The prime academic objective of this subject is to reconstruct evolutionary pathways by the study of living avian species. Apart from contributing to the over all phyletic study, we also aspire to rebuild the lines of evolution
within the endocrine system itself taking both morphological and functional criteria in our account. We can concern ourselves with the molecular evolution of hormones, with the prcbable acquisition
of new active sites conveying new properties and finally explaining the mechanism of hormone action in terms of receptor protein and
consequent genetic effects.
The provision of the academic aims is not however, sufficient justifi cation for the men with a more materialistic outlook. The applied avian endocrinology is the answer to them. The process of reproduc tion in birds, like other group of vertebrates, is dependent on the
hormonal secretion and an understanding of this relationship can provide information that may be usefully applied when, for economic reasons, vve may wish to increase, or control, the fecundity of a species. Aithough there is a respectable endocrinology of the poultry birds
(particularly the chicken and not so much on the duck) there has been but rather restricted concern with potentially egg and meat producing
wild birds. Regarding the birds of agricultural importance, we must attempt to prepare an inventory, to determine which birds does harm, which is beneficial, and which is of neutral status ; thus as to which
species should be encouraged near the agriculture and which should be discouraged. In near future, we hope a full fledged discipline of 'Economic Ornithological Endocrinology' will emerge out and would
prove particular significance to the cause of developing countries.
The first international seminar on a somewhat specialized aspect of
avian endocrinology (hypothalamic function and avian reproduction) was held in -.Japan sometime in 1 969, under the able leadership of Professors Farner and Kobayashi. After the great success of this seminar, some of us started thinking whether holding an international
symposium is possible encompassing multiple aspects of the avian endocrinology. -.Just about two years ago from now I had the fortune of meeting here in Calcutta three topmost avian endocrinologists like Professors Farner, Kobayashi and Assenmacher. They all enthusias
tically agreed to the proposal and with their approval we approached
other distinguished scientists of the field and their response was also tremendous. With this decision we started organising which resulted in the present symposium. This, in brief, is the genesis of the First International Symposium on Avian Endocrinology.
Proc. First lnternatl. Symp. Avian Endocrinology, Calcutta, Jan. 1977
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FARNER, D.S.
Department of Zoology, University of Washington, Seattle, U.S.A.
More than a half century has now elapsed since the first experimental demonstration by Rowan of the use of day length as information in the control of annual cycles. It is now clear that the use of some part of the annual photocycle as information for control systems is widespread among species of mid- and high latitudes. The extensive investigations on avian photoperiodism have had at least three basic often overlapping motivations: (1) To understand the basis of the temporal adjustment of reproductive and related functions of birds to the most favorable phases of annual environmental cycles. (2) To increase knowledge of the temporal organization of life in terms of the interaction of endogenous periodicities with both periodic and aperiodic changes in environmental conditions, (3) To provide a basis for under standing better the general scheme of control of reproduction in higher vertebrates. The rationale for the last is simple since the organs and hormones involved are very similar among these classes of vertebrates. The photoperiodic species of birds offer unique research opportunities since there are quantitatively predictable relationships between input into the system, day length, and output, plasma levels of gonadotropins and sex hormones, and gonadal growth and function, The important experimental opportunity of setting precisely the rates of gonadotropic functions by simple manipulation of day length remains relatively unexploited.
The literature on avian photoperiodism, at least superficially, presents elements of confusion. In part this confusion has been generated by differences among the conceptual frameworks in which investigators have designed experiments. Further confusion has resulted from a failure to recognize substantial specific differences in control systems, doubtless due, in part, to multiple evolutionary origins.
Among the photoperiodic species that have been subjected to careful quantitative investigation growth of testes under constant stimulatory day lengths closely approximates a logarithmic function of time until about half of maximum size is attained; furthermore, the logarithmic growth-rate constant is a positive function of the duration of the daily photophase although this function differs among species. Although information is somewhat fragmentary it seems clear that there are quantitative relationships between day length and the plasma level of gonadotropic hormones.
These quantitative relationships indicate that the control system must have a chronometric function, The basis for this chronometric function in at least some photoperiodic birds appears to be an external coincidence timer, the concept of which was first proposed by BUnning in 1936 and subsequently refined by
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Pittendrigh and Minis in 1964. Simply stated, the hypothesis proposes the occurrence in the control system of a circadian periodicity in photosensitivity that is entrained by the daily environmental photocycle. The rate of the photoperiodic response is a positive function of the time during which the environmental photo phase is coincident with the photosensitive phase of the oscillation in photosensitivity.
This hypothesis has been tested in photoperiodic species by three general types of experiments: (1) Scotophase-scan experiments. In such experiments birds have usually been subjected to a basic daily photophase of six or eight hours, in itself non-stimulatory. Each experimental group receives each night, at a different time for each group, a short photophase. The response has been measured in terms of increase in gonadal weight. The results have generally shown that the short photophases become increasingly effective through the course of the first part of the scotophase and then decreasingly effective during the latter part. These results have in general been interpretable as demonstrating an entrained oscillation in photosensitivity that accounts basically for the increase in the logarithmic growth rate as a function of the length of the daily photophase, However, because the experimental birds must be subjected to many cycles there are problems of entrainment and questions about the precision and interpretation of the results. (2) Resonance experiments. In its most common form groups have been subjected to lighting regimes of (a) sL (24-s)D, sl (48-s)D, sL (72-s)D ... and (b) sL (36-s)D, sl (60-s)D, sL (84-s)D ... , where the photophase s is non-stimulatory, i.e.' 8 hours or-less, in a 24-hour cycle. -The external coincidenc~ model predicts that repetition of the regimes in series b should be s~imulatory whereas those in series a should be non-stimulatory. This has been generally confir~ed by experiments on at least five species. However, as the duration of the scotophase is increased, the gonad weights in a and b tend to converge suggesting problems of entrainment~ (3)-Single-stimulus experiments. The development of a microradioimmunoassay for avian luteinizing hormone by Professor B.K. Follett and his colleagues permits experiments that avoid the difficulties of entrainment encountered in the scotophase-scan and resonance experiments. In Zonotrichia leucophrys gambelii a single photophase coincident with the photosensitive phase causes a three to five-fold increase in the level of luteinizing hormone in the plasma (Follett, B.K., Mattocks, P.W., and Farner, D.S., Proc. Nat. Acad. Sci. 71, 1666. 1974); similar results have been obtained-- with CotUrnix coturnix (Follett, B.K., and Davis, D.T., ~· Zool. Soc., London 35, 199. 1975). This has permitted experiments in which a single photophase applied at selected intervals to individual birds held in continuous darkness for 12 to 108 hours (Follett et al., ibid,). The results indeed show an approximately 24-hour osciTTation between photosensitive and non-photosensitive phases. However, this kind of experiment cannot define rigidly photosensitivity as a function of time.
An interesting further test is provided by the unusual relationship
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between day length and the rate of testicular growth in Passer domesticus in which day lengths longer or shorter than 6~ours cause growth of the testes. Dolnik (In "Fotoperiodizm zhivotnik rasteni i ," O.A. Scarlato, ed., Akademia Nauk SSSR, p. 47. 1976) has proposed an explanation for both the long-day and very-short day responses on the basis of a two-oscillator {internal coincidence) model. This model assumes that one oscillator is entrained by "lights on" and the other by "lights off." Photoperiodic responses occur when the phase angle between the two is relatively great. Recently we {Farner, D.S., Donham, R.S., Mattocks, P.W., Lewis, R.A., Darden, T.R., and Smith, J.P., Physiol. Zoo!., in press) have demonstrated that the very short-day responses are consistent with a simpler external coincidence model. On very short daily photo phases the phase of the photosensitivity oscillator apparently advances so that the photosensitive phase becomes coincident with the environmental photophase.
Internal coincidence models as the basis for photoperiodic control systems in birds have been discussed in a general sense by Gwinner {~. Repr. Fertil. ~. 19, 51. 1973). Schwab and Rutledge {Cong. Intern., "Le Solei! au Service de !'Homme." UNESCO. p. B. 15-1. 1973) have suggested that such a system may be involved in gonadal development in Sturnus vulgaris in continuous darkness. It is clear that the photoperiodic control system of this species differs conspicuously from that of most photoperiodic avian species. I find it difficult, at the present state of our knowledge, to rationalize it in terms of mechanisms established for other species although the existence of a circennial cycle appears to be established {Schwab, R.G., in "Biochronometry," M. Menaker, ed. p. 428. Nat. Acad. Sci. 1971; Gwinner, E., cited above). The available data argue strongly in support of a hypothesis of multiple origin of photoperiodic controls of gonadal function among birds.
Professor A.H. Meier and his colleagues (~·.9.·• Meier, A.H. In "Proc. XVI Int. Ornithol. Congr. ," H.J. Frith and J.H. Calaby, eds, p. 355. Austral ian Acad. Sci. 1976) have developed a complex model to rationalize the annual cycle of the photoperiodic White-throated Sparrow, z. albicollis. Basically, this model depends on seasonal changes i;:;- the phase angle between "circadian rhythms" in the plasma levels of corticosterone and prolactin, the latter inferred from assays of pituitary prolactin and experiments involving injections of mammalian prolactin. It involves inferences concerning photo-inducible phases in secretion of LH, FSH and prolactin without direct measurement of the plasma levels of the hormones, and a "circannual" rhythm of change of phase of a circadian oscillator. In our more conservative approach to the system of the closely related I· leucophrys we have been unable to confirm the assumptions on which the Meier model is based. However, we in no sense at this time argue for its rejection but urge that it be rigidly tested.
Another possible mechanism in the chronobiological basis of photoperiodic controls is the hourglass timer. Although I have
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often considered this type of mechanism in a model for z. leucophrys, I have set it aside because of the evidence-for, and attractiveness of, a relatively simple external coincidence model. However, the possibility that both may occur in an avian control system should not be overlooked.
Following the impetus of the important review of Aschoff (Stud. Gen. 8, 742. 1955) substantial evidence for the occurrence of endogenous circennial periodicities among birds has been accumulated (~·.9.·• Berthold, P., Voaelwarte 28, in press, 1977; Gwinner, E., ibid.). There is for no less than ten species acceptable evidence for such cycles in molt, migratory behavior or gonadal development. Such periodicities must be regarded as real or potential components of temporal organization although further information is needed to assess their nature, general occurrence and role in natural annual cycles. Like endogenous circadian periodicities, endogenous circennial cycles have periods, that differ from the period of the annual environmental cycle, usually being shorter. Thus, whatever role such periodicities may have in the temporal organization of natural annual cycles requires a Zeitgeber with a precise annual frequency. This raises the question as to whether photoperiodic systems drive annual cycles or serve an entraining mechanism for endogenous cycles and Gwinner (1973, cited above) argued.
I agree that for at least some species a hypothesis, that annual cycles are endogenous circennial periodicities entrained by environmental Zeitgebers with annual periods. It provides an easier rationalization for annual cycles in which day length has no obvious role and perhaps also for the annual cycles of trans equatorial migrants. What must have been learned about photo periodic control systems is, in general, whether these systems function as drivers as synchronizers. Nevertheless, beyond the precarious assumption that the annual cycles of all species that have such, conform to a single system, there are other reasons for caution, at least in the present state of our knowledge.
With the exception of the irregular cycles in domestic mallards held in continuous light or dark demonstrated in by Professor Jacques Benoit and his colleagues, the demonstrationsof endogenous circennial cycles have been effected under conditions involving 24-hour light-dark cycles. Although I agree that continuous light and continuous darkness are very unnatural conditions, this does remove certain doubts about the nature of these cycles since the recurrence of light in a 24-hour cycle may be, in itself, a source of environmental information. Indeed, at least in Zonotrichia leucophrys this seems to be the case.
As demonstrated by Gwinner (1973, cited above) for Sturnus vulgaris and by Wolfson (1. ~· Zool. 125, 353. 1954) for Junco hyemalis and I· albicollis, manipulation of the photoperiodic environment can result in several cycles within the course of a year. Jf these are entrained endogenous circennial cycles one is forced to assume that the basic oscillator has an unusually labile
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period, so unusual as to raise the question as to whether it indeed has the characteristics of an oscillator. These comments are made not to challenge the existence of endogenous circennial periodicities. Rather, they are intanded to serve as a reminder that adaptations of control systems for the exploitation of an annually periodic environment may •,o~ell be too diverse and of too many origins to fit a general hypothesis that requires an endogenous circennial oscillator. Many phenomena ascribable to an endogenous circennial periodicity can be explained by assuming that the control system has a natural period of about one year (King, J.R., and Farner, D.S. In "Chronobiology" L.E. Scheving, F. Halberg, J. E. Pauly, eds. p. 625. lgaku Shoin, Tokyo. 1974) just as a motionless pendulum has a fixed period. External information, such as some phase of the-annual photocycle, ~·~· vernal increase in day length, or the "constant conditions" of continuous 12L 120 could release internal energy that causes oscillation in accordance with the natural period of the system. The performance of the system subsequently would depend in part on its damping characteristics. If the damping constant is high the system would appear to be one in which the photoperiodic control scheme has a driving function; if it is low it would be one that would characterize the endogenous circennial cycles in the several species of warblers investigated by Bertho I d and his co II eagues ( 1977, cited above). As I have argued earlier, and as expressed much more eloquently, and with much more data, by Dolnik (1976, cited above), the use of day length as environmental information in the photoperiodic species is confined to one, or at most two, restricted components of the annual cycle. The remaining components appear to be natural sequelae of those controlled by the photoperiodic system. Thus the question of the role of day length, as a driver or synchronizer may become a matter of interpretation or even of semantics. I urge that we not attempt prematurely to force our fragmentary information into a single
"comprehensive hypothesis. Selection in evolution has been on systems that enhance survival, not on their origins and prior histories.
Proc. First lnternatl. Symp. Avian Endocrinology, Cal~utta, Jan. 1977
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Phylogenetic peculiarities of the avian endocrine system
Introduction. It appears a tacit assumption that a high rate of intermediary metabolism should be accompanied by sophisticated neuro-endocrine control mechanisms. Along this line of reasoning, one would expect the birds to possess a particularly well-developed endocrine system. In the following it will be tried to test this assumption, paying particular attention to three endocrine systems which show obvious phylogenetic variations: the pineal complex, the hypothalamo-hypophysial system and the islet organ.
Phylogenetic Distribution of Vertebrate Endocrines. The attempt to correlate the total number of endocrines with the rate of metabo lism, particularly with homeothermia shows that neither birds nor mammals have the largest number of endocrines. The largest number of endocrines is actually found in the teleosts. This group pos sess~ all classical endocrine glands ever developed in vertebrates with the exception of the parathyroid, which is restricted to the tetrapodes. On the other hand, we find in birds a reduction of the components of both the pineal complex and of the hypothalamo hypophysial system, and a s.implification of the control mechanism of the pancreatic islets. Thus, the conclusion is inevitable that phylogenetically a high rate of intermediary metabolism and a sophisticated endocrine control system are by no means connected. The simple endocrine system of the Myxinidae shows that there is no connection between a low rate of intermediary metabolism and a well-developed endocrine-sjstem either.
The Pineal Complex. As a derivative of a pair of frontal eyes (Eakin, R.t1. (1973): The third eye. University of California Press Berkeley) this structure shows a phylogenetic trend to develop into a receptor-secretor complex which transfers light stimuli into endocrine secretion. Along this way the anterior eye (Parietal organ, Parapineal organ) retains its photoreceptor function while the posterior eye {Epiphysis cerebri, Pineal gland) seems to specialize increasingly in endocrine secretion. Quite frequently, the parapineal organ disappears completely. However, since it is still a rather well-developed frontal eye in certain lizards and in Sph~noion, it must have persisted in the ancestors of the birds "up" to the reptilian level. At this stage, the parietal organ controls the deeper situated and mainly endocrine pineal gland via its Nervus pinealis, though the pinealocytes themselves can still respond to light stimuli. In addition, the pineal is innervated by sympathetic fibers, arising from the superior cervical ganglion, and humoral stimuli may also have an effect. Furthermore, the pineal gland conveys nervous messages to the CNS via its Tractus inealis, thus possessing both nervous and endocrine function Ueck, M. (1974): Fortschr. Zool. 22:167-203). In summary then,
the reptilian ancestors of the birds must have had a well-developed
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pineal complex whose endocrine component, the pineal gland, was under dual nervous control (Nervus pinealis and Sympathicus); in addition direct photic and humoral stimuli may have had an effect on its function, which was exerted via hormonal and nervous signals.
In birds, the parietal organ has disappeared, and even the pineal gland may be absent in some species (Ralph, C.L. (1970): Amer. Zool. 10:217-235). The outer photosensitive segment of the pinealocytes is almost as strongly reduced as in mammals, and the Tractus pinealis shows no response to phototimulation of the pineal gland. This leaves us only with one clearly established control mechanism, i.e., the sympathetic innervation. However, one might speculate that humoral factors (hormones?) and perhaps still some direct light stimuli have an effect on the avian pineal. Physio logically, the avian pineal gland remains largely an enigma. Neither pinealectomy nor interruption of its possible neural photo periodic control system (via pineal transplantation, denervation or removal of the eyes) seem to have an effect on gonadal activity, though all of these procedures strongly influence the gonads of mammals. So far, the only clear physiological effect of the avian pineal was shown by Menaker and coworkers (Menaker and Zimmerman, 1976) who found that the gland is essential for the maintenance of the circadian motor activity of Passer domesticus. Though the poor development or even complete absence in various vertebrates suggest that the pineal complex is phylogenetically one of the most "disposable" endocrine structures, its poor development in the generally very photosensitive birds is remarkable. The most plausible explanation we could come up with was that it was already reduced in the archosaurian ancestors of the birds {Epple, A. and M.H. Stetson (1976): J. Ormithol. DI.:257-278).
The Hypothalamo-Hypophysial System. The activities of the adeno hypophysis are largely controlled by two central nervous mechanisms: (1) Neurohormones, released into the hypophysial portal'·· circulation, and (2) direct innervation. Neurohormonal control is the prevailing mechanism controlling the Pars distalis, while direct innervation seems to be important for the function of the Pars intermedia (in almost all species). A control of the Pars distalis (via direct innervation) occurs in the teleosts, and to some extent also in lungfishes. Obviously, this indicntes the need for fast and/or private signals (For lit., see Epple, A. and J.E. Brinn (1975): Gen. Comp. Endocrinol. 27:320-349). A Pars inter media seems to exist in all gnathostomes below the ammiotes. In the latter group its size varies greatly even between close relatives, and it is even absent in some species (Wingstrand, K.D. (1966): In: The Pituitary Gland (eds. G.W. Harris & B. T. Donovan, Butterworths, London), Vol. 1:58-126.). The birds are the only larger phylogenetic group in which a Pars intermedia is totally lacking. Thus, at a first glance, the hypothalamo-hypophysial system of the birds appears rather simple. However, one feature of the avian hypothalamo-hypophysial system seems to be unique: the subdivision of the Median eminence into an anterior and a posterior portion. Each of these port1ons 1s largely drained into a
9
corresponding portion of the Pars distalis, the cephalic and caudal lobe, respectively. The evolution of this system from the general reptilian type is difficult to understand as long as one assumes that specific neurohormones control specific target cells scattered throughout the Pars distalis. However, if one assumes that a single neurohormone controls two topographically separated cell types with different secretory patterns, then this system makes sense. We have therefore suggested that it may reflect the control of two types of gonadotropes (each of which is restricted to a particular lobe only) by a single releasing factor {Epple & Stetson, 1976). Clearly, this hypothesis requires further support from data which confirm (a) the presence of two types of gonadotropes in birds, and (b) the presence of a single releasing factor controlling both of them. However, since the avian pattern of egg laying requires a highly sophisticated tempor·al coordination of hormonal secretions, and since this pattern must have developed from the simple simul taneous oviposition of the reptiles, our hypothesis appears reasonable.
Pancreatic Islets. The i ;let organ of all gnathostomes produces at least 4 different substa~cPs, of which insulin, glucagon, and pan creatic polypeptide are generally recognized as true hormones. The hormonal status of Somatostatin, (found in the D-cells) may yet require further studies (Fpple, A. & J.E. Brinn (1976): In: The Evolution of the Pancreatic Islets (Grillo et al., eds.) Pergamon Press, Oxford). The parti ':ular features connected wi tl1 the avian islet organ are (Hazelwood, R.L. (1976) and Epple, A. & J.E. Brinn (1976): In: The Evolution of the Pancreatic Islets (Grillo et al., eds). Pergamon Press, Oxford): ( 1) a very high percentage of glucagon-producing A-cells end D-cells, {2) a strong separation of A- and B- cells which occur largely in different types of islets, (3) the virtual absence of a secretomotor islet innervation, (4) the insulin-insensitivity of the avian adipose tissue (which, however, also occurs in the eel and probably other teleosts). The evolutionary significance of these features, which are in contrast to those of the mammals, is difficult to explain with respect to homeothermia. However, it is noteworthy that, as in the case of the adenohypophysis, the islet innervation reaches its peak in the teleosts (Epple & Brinn, 1975).
Conclusions. From the preceeding it is clear that the high rate of intermediary metabolism of the birds is by no means accompanied by a sophisticated endocrine system. The probably most remarkable endocrine peculiarity of the birds, i.e., dualism of the adena hypophysial blood supply, may be related to the reproductive function, particularly of the female bird. The reasons for the morphological and physiological peculiarities of the avian islet organ are unclear. The poor development of the avian pineal complex may be an irreversible heritage from reptilian ancestors.
10
* ** ** BHATTACHARYYA, S.P. , MAITI, B.R. AND GHOSH, ASOK
* Department of Zoology, University of Kalyani, Kalyani, India and ** Histophysiology Laboratory, Department of Zoology, University of Calcutta, Calcutta 700019, India.
This review attempts to point out the role of endocrine factors in the regulation of the uropygial gland, an organ whose exact fUnctions are not known. Earlier reports concerning its role in plumage maintenance, its assistance in buoyancy in water, in growth and in vitamin D production have yet to be confirmed (Elder, W.H., The Wilson Bulletin, 66, 6, 1954).
From histomorphological and cytochemical standpoints there exist basic similarities between the uropygial gland and the mammalian sebaceous gland (Das, M. and Ghosh, Asok, Anat. Anz., 1Ql, 75, 1959; Bhattacharyya, S.P. and Ghosh, Asok, Acta histochem., .Ji, 318, 1971; Bhattacharyya, S.P., La Cellule, &i, 111, 1972). Maintenance of both these holocrine structures is accomplished by a reciprocally synchronized balance between constant cell supply through mitotic division, and cell elimination (Maiti, B., Folia Biol., 1£, 49, 1968). The secretions from the uropygial gland are a complex mixture of different lipid classes, in which wax esters constitute the major component. The glands of Galliform birds, which have been examined so far, secrete diester waxes with long chain 2,3-n-alkane diols (uropygiols), which are of rare occurrence in animal tissues (Haahti, E. and Fales, H.M., J. Lipid Res.,~. 131, 1967; Saito, K. and Gamo, M., J. Biochem., £1, 841, 1970; Nikkari, T., J. Invest. Dermatol., 62, 257, 1974.
The structure and the secretory activity of the uropygial gland are influenced by endocrine factors and our knowledge at this stage is limited only to sex hormones and corticosteroids. Androgens are potent stimulatory agents for this gland. Hyper secretory conditions of the gland in the male house sparrow (Passer domesticus) coincides with the enhanced testicular activity during the breeding phase of the gonadal cycle of this bird (Maiti, B., Proc. Zool. Soc. Calcutta, 22, 87, 1969). Although chronic administration of testosterone caused a mild depression in the weight of the uropygial gland in cockerels (Selye, H., J. Morph., ll• 401, 1943; Kar, A.B., Anat. Rec., ~. 75, 1947), this steroid elicited a marked stimulation in the alveoli of the gland in adult pigeons (Maiti, B.R. and Ghosh, Asok, Gen. Comp. Endocrinol., 12.. 527, 1972). This effect resulted from an acceleration in cell renewal, cell differentiation and cellular desquamation, as well as by an increase in lipid production. Bilateral castration in pigeons and ducks resulted in atrophy of the uropygial gland by a decrease in the rate of cell multiplication and cell growth. Castration in pigeons also impeded release of the secretory materials from the gland. In ducklings and prepubertal pigeons the effect of castration was found to be more severe than that in adult specimens.,, Testosterone therapy of the castrates restored normal physiological conditions in the uropygial gland.
11
Like the preputial gland and the skin of 1111U11118.ls, the uropygial gland tissue of the domestic duck is capable of binding testo sterone. Experiments using 3H-testosterone have revealed the presence of an androgen-specific receptor protein in the nuclear fraction of the gland. Further, it has been shown that the uropygial gland of dude and chick can convert testosterone into the tissue-active androgen, 5o( -dihydrotestosterone, at a fairly high rate like other androgen-sensitive organs. These findings not only furnish another line of evidence for the positive in fluence of testosterone on the uropygial gland but also indicate some of the early metabolic events of androgen action within this organ (Loeb, P.M. and Wilson, J.D., Clin. Res., jl, 45, 1965; Wilson, J.D. and Gloyna, R.E., Res. Progr. Hormone Res., 26, 309, 1970).
The influence of oestrogens on the uropygial gland is not clear. Diethylstilboestrol tre:ttment was found to be ineffective in in ducing any alteration in the gland of intact or castrated white Leghorn cockerels (Kar, A.B., Anat. Rec., ~. 75, 1947), while administration of oestr3diol to male pigeons provoked weight loss of the gland and regression of the alveoli (Maiti, B.R., Arch. histol. jap., ,ll, 371, 1971). Alveolar atrophy was shown by excessive cell loss (with a concomitant fall in the cell renewal rate), decreased output of lipids and augmented levels of acid phosphatase. In contrast, in female juvenile spotted munia (Lonchura punctulata, L.) exogenous oestradiol brought about hypertrophy of the uropygial gland (Kar, A.B., Nature, ~. 495, 1949). In adult fe'lla.le pigeons this steroid caused pronounced alveolar hyperplasia associated with increased cell loss. These results indicate rather a sex-specific action of oestrogens. Since spaying either prepubertal ducks ~~d pigeons or postpubertal pigeons could not induce any recognizable effect on the glandular activity, it is assumed that oestrogen is not involved in the maintenance of the uropygial gland (Maiti, B.R., Arch. histol. jap., ,ll, 371, 1971).
Similarly, any direct action of progesterone on this gland can be ignored, as the luteoid, when administered to castrated pigeons at a dose of 1.0 mg daily for 15 days, failed to prevent the glandular atrophy which resulted from castration (Maiti, B.R., Monitore Zool. Ital. (N.S.), ~. 11, 1972). The observed simulatory action of a low dose of progesterone on the gland of intact adult male pigeons (Bhattacharyya, S.P. and Ghosh, Asok, Folia Bioi.,~. 89, 196o) might have been mediated through en hanced androgen release.
A direct role for the adrenals in the maintenance of the uro pygial gland has not yet been fully elucidated. Cortisone loading in male pigeons induces consistent hyperactivity of the gland. This has been assessed from cytodynamic and histochemical findings (Maiti, B. and Ghosh, Asok, Acta anat., ]k, 97, 1969}.
12
Inhibition of endogenous corticosteroid production by metopirone (SU 4885) led to degeneration of the alveoli (Bhattacbaryya, T.K. and Ghosh, Asok, J. Morph., jjQ, 257, 1970). These studies indicate a possible involvement of glucocorticoids in the regu lation of the uropygial gland.
It appears that the response of the uropygial gland to male and female sex hormones is identical to that of the sebaceous gland but the role of other (extra-gonadal) hormones on its function is still unknown.
13
WINGFIELD, J.C. AND FARNER, D.S.
Department of Zoology, University of Washington, Seattle, U.S.A.
Methods have been developed (Wingfield and Farner, Condor 78, 570. 1976) for collection of blood samples, and preparation and transport of plasma from feral populations of White-crowned Sparrows, Zonotrichia leucophrys. Adults of both sexes as well as birds of the year were captured in Potter traps or mist nets, color-banded, blood samples taken and then released for subsequent observation and recapture. Tape-recorded song was used to lure birds into mist nets. Notations of body weight, fat depot, brood patch and molt were also made. Laparotomy was performed in most cases to determine the state of development of the reproductive system. Blood samples were centrifuged in the field and plasma stored and transported frozen on dry ice. Our data and observa tions indicate that the capture and processing procedures were not sufficiently stressful to delay or otherwise disrupt the breeding cycle.
A fraction of each plasma sample was used for measurement of luteinizing hormone (LH) by a double-antibody radioimmunoassay (Follett, B.K., Scanes, C.G., and Cunningham, F.J., J. Endocrinol. 52, 359. 1972; Follett, B.K., Farner, D,S,, and Mattocks:-Py-; Gen. Comp. Endocrinol. 26, 126. 1975). The remainder was used for the simultaneous measurement of 171f-hydroxy-5ot-androstan-3-one (DHT), testosterone, estrone, and estradiol-17~ by radioimmunoassay (Wingfield and Farner, Steroids 26, 311. 1975) and corticosterone by a competitive protein-binding assay (ibid,) after chromatography on Celite microcolumns. ----
Plasma levels of these hormones were correlated with the reproductive cycle of a multiple-brooded, short-distance migrant, I·l· pugetensis, that breeds in the Puget Sound area at 48°N,
Plasma immunoreactive LH (irLH) and testosterone reached the highest levels in males in spring during courtship and nesting preceding the first clutch. A smaller second maximum in irLH was observed in males at the time of the second brood, but there was no increase in testosterone, In contrast, the females showed equal maxima in plasma irLH, DHT and estrone during ovulation and ovi position for both broods, Plasma testosterone was lower during the second brood and estradiol-17p increased to a maximum during vitellogenesis in the first brood but not the second.
The gonads and secondary reproductive organs of both sexes during the second breeding period recrudesce to the same level of development as attained during the first. Plasma corticosterone increased gradually throughout the breeding season reaching a maximum in both sexes during the time of the second brood. Titers of all hormones measured decreased to basal levels during
14
post-nuptial molt.
The maximum level of testosterone in both sexes occurred at the time of territorial defense before the laying of the first clutch. The maximum level in males was approximately seven times as great as that in the females. The latter defend territory during this period but less extensively than do the males. In both sexes there was an increase in the ratio of irLH to testosterone throughout the season. This relationship has been observed in ~·l· gamb~ during an experimentally induced testicular cycle (Lam, F., and Farner, D.S., Cell Tiss. Res. 169, 93. 1976) and in a breeding population in Alsaka (Wingfield and Farner, unpublished data).
Assuming that the plasma concentration of corticosterone is an indicator of the level of physiological stress, neither territorial defense nor post-nuptial molt are stressful. We have, at this time, no explanation for the elevated levels during the time of the second brood.
In birds of the year the plasma level of corticosterone was relatively high at fledging, about half the ~aximum level attained by adults during the course of the breeding season. By the time that adult body weight was attained during the post-juvenal molt it had declined to about one-third of the level at fledging. The level of plasma irLH was low at fledging. At about the time of attainment of adult weight there was a transiant three-fold increase, the significance of which is unclear.
Experience with our field system indicates that it is now feasible to perform field experiments involving such manipulations as implants of hormones, addition or removal of eggs from clutches, and removal of competing territorial males, and to correlate endocrine and behavioral changes induced thereby.
15
BANERJEE, SEliMA
Endocrinology Laboratory, Department of Zoology, University of Kalyani, Kalyani, India.
This report is concerned with the gross comparative anatomy and cytomorphology of the thymus in male juvenile and adult Indian birds: namely, fowl (Gallus domesticus), duck (Anas poecilorhyncha, Foster), common pigeon {Columba livia, Gmelin), parrot (Psittacula krameri), common myna (Acridotheres tristis, Linnaeus), house sparrow (Passer domesticus, Linn,), crow (Corvus splendens, Viellot) and red-vented bulbul (?ycnonotus cafer, Linn.). The thymus is a paired organ. Each half consists of 8-11 separate lobes occurring in the form of a chain on either side in the cer vical region.
The cytomorphology of the thymus in all eight avian species reveals a striking uniformity. In .juvenile birds the thymus is well de veloped. Lobes are divided into lobules ~xcept in the duck and sparrow). The lobular cortex is fairly extensive and exhibits a high population density of thymocytes, along with a relatively smaller number of medium and large lymphncytes, plasma cells and reticular cells. The medullary region is characterized by a low population of thymocytes and the frequent occurrence of blood sinusoids, lymph channels and islands or cords of nonlymphocytic c:ells. Besides typical mature reticular cells, six other cell types have been histologically distinguished in the medulla. They exist in the free state or as cellular elements of the cord. Morphologically, some of these types disclose their identity as degenerated and phagocytic reticulocytes, while others reveal the presence of intracellular masses of <J.cidophilic and PAS-positive material. In juvenile species Ha.ssall 1 s corpuscles of thymus are formed from two to three layers of lanceolated cells with a small c0re of central amorphous material.
In adult birds, there is a remarkable regression in the size of the thymus lobes. Notable anatomical and cytomorphological changes encountered in the involuted thymus are: (1) absence of lobulation (except in the parrot and crow), (2) loss of corticomedullary de marcation, (3) sharp fall in the population density of small lympho cytes in the cortical region, (4) increase in the size and number of non-lymphocytic cell types, (5) frequent occurrence of the epi thelial cell-cords in some cases (duck, parrot and sparrow) towards the periphery and (6) enlargement and maturation of Hassall's corpuscles by cellular stratification and accumulation of material in the central core.
Cellular architecture of the thymus in birds and the pattern of the cytomorphological changes during age-involution are grossly similar to those of mammalian thymus.
I am grateful to Dr. S.P. Bhattacharyya of Zoology Department, K.U. for his supervision.
Proc. First lnternatl. Symp. Avian fndocrinology, Calcutta, Jan. 1977
16
Effects of hypercalcaemia on the ultimobranchial gland of pigeon, Columba livia
* ** DAS, V.K. AND DAS, SOBHA
* Department of Zoology, Kamla Nehru Institute of Science & Technology, Sultanpur, India, ** Department of Zoology, University of Gorakhpur, Gorakhpur, India.
The present investigation deals with histophysiological observa tions on ultimobranchial glands (UBG) of pigeons in relation to plasma calcium. The experimental birds were subjected to hyp(:r calcaemia by alternate daily intramuscular injections of vitamin D2 (25000 IU) and by providing them 1% CaC12 solution for drinking. After 2, 6, 10, 15, 20 and 30 days of such treatment the serum calcium rose relative to that in the controls.
The UBG of the control birds exhibits two main features: (i) the glandular parenchyma consists of clustars of epithelial cells embedded in connective tissue stroma, (ii) there are duct-like follicles containing lHtle colloid and lined •,ti th a single-layered cuboidal epithelium, Hypertrophy and hyperplasia of the glandular parenchymatous cells have been noticed in hypercalcaemic birds. Mitotic figures have also been encountered after 10 days of treat ment. Hypertrophied calls lose their staining capacity, perhaps due to removal of their secretory product. After 25 days treat ment the UBG cells show degenerative changes indicating that they become exhausted after continous hyperactivity. No appreciable change was recorded in the follicles and their luminal content.
These results suggest that hypercalcaemia induces the UBG to secrete larger quanti ties of its prodnct (calcitonin) to counter act experimental hypercalcaemia.
17
OKSCHE,A.
Department of Anatomy and Cytobiology, Justus Liebig University of Giessen, Giessen, Federal Republic of Germany
Phylogenetically, the avian hypothalamo-hypophysial system has
attained a very high degree of morphological differentiation and
functional specialization, by no means inferior to that observed 1n
mammals. From extensive neurohistological investigations (Oksche,A.,
Farner,D.S., Adv.Anat.48/4, 1-136,1974; see also references), it was
concluded that the hypophysiotropic nuclei of birds consist of
cluster-like aggregations of differing neuroendocrine elements. In
further studies our concept of anatomical subunits was extended to
the parvocellular and magnocellular nuclei of the anterior hypothala
mus. In birds, numerous parvo- and magnocellular perikarya producing
different types of elementary granules were observed outside the
hypophysiotropic zone of the tuber and the classical neurosecretory
nuclei of the rostral hypothalamus. Not all of the secretory parvo
and magnocellular neurons are connpcted to one of the neurohemal
areas. Apparently, the avian hypothalamus produces not only hypo
physiotropic and posterior lobe hormones but also other, to date
only partly identified, peptides with a wide range of biological
properties.
In an attempt to elucidate the intrinsic organization of hypo
thalamic cell clusters, our most recent studies in Passer domesticus
were concentrated on the periventricular aggregations of nerve cells
at the level of the suprachiasmatic nucleus. According to micro
fluorimetric analyses by H.G.Hartwig, this phylogenetically archaic
region is unusually rich in noradrenergic afferents (see Oksche,A.,
Gen.Comp.Endocrinol. 29,225, 1976). Not all of the secretory peri
karya are separated by thin glial lamellae. The areas of direct
somata-somatic apposition show specialized junctional zones which
may play a role in cellular communication and electrotonic coupling.
In addition, axon terminals containing vesicles can be occasionally
situated between two neuronal somata. Perikarya containing secretory
granules approximately 100 nm, ISO nm and 180 nm in diameter can be
found in close proximity to the third ventricle. The larger-sized
granules are produced in very conspicuous neurons which topographi-
18 cally correspond to the scattered aldehyde-fuchsin stainable elements
of this region. Immunocytochemically, these cells appear to contain
arginine vasotocin. All types of periventricular secretory neurons
are embedded in a neuropil unusually rich in axodendritic synapses
of different types and different degrees of complexity. In contrast,
axosomatic synapses are relatively rare in the avian hypothalamus.
The neuronal perikarya and the afferents of the avian hypothalamus
are arranged in a patterned manner. The cluster-like subunits of the
avian hypothalamic nuclei consist not only of cells elaborating
different types of neurohormones and transmitter-like substances, but
also of steroid-binding neurons, interneurons, intrinsic collaterals
and afferents of differing origin, including ascending aminergic
elements. Specialized zones of neuropil located between cell clusters
and displaying numerous synapses may be essential for the propagation
of excitation along certain channels and circuits. Specific patterns
of intrahypothalamic synapses may be regarded as the anatomical basis
for functional isolation or interaction, convergence or divergence,
and integration of external and internal information. This neuro
anatomical interpretation appears to be con3istent with modern
functional concepts of neuronal networks. In the hypothalamus, this
type of neuronal arrangement could explain the isolated co-existence
of various functional systems within very circumscribed areas and
also some spectacular signs of functional interaction. The newly
acquired anatomical concepts will also aid in promoting discussion
on the hypothalamic components of 'circadian oscillators' or 'bio
logical clocks' and on the character of the 'deep hypothalamic photo
receptors'. It should be kept in mind that circadian oscillators and
neuroendocrine effectors may be located in different hypothalamic
areas. This spatial arrangement would require a complex wiring
diagram including longitudinal fiber connections. Using a wide spec
trum of combined electrophysiological and neurohistological tech
niques, reciprocal connections have been demonstrated between the
rostral and tuberal regions of the mammalian hypothalamus. Exact
anatomical data in the avian system are urgently required.
In birds, the hypothalamic projections to the median eminence are
characterized by tuberoinfundibular and anterior hypothalamic path
ways. The latter consist of 'Gomori-negative' and 'Gomori-positive'
Proc. First lnternoti. Symp. Avian Endocrinology, Calcutta, Jon. 1977
19
component of the palisade layer in the anterior median eminence.
Immunohistochemistry has opened up new prospects for the selective
identification and mapping of secretory neurons producing protein
neurohormones. Recently, BHihser (unpublished) has surcessfully
visualized the arginine vasotocin-containing neurons of the Zebra
Finch (PAP-method). Immunoreactive perikarya appear in all subdivi-
s1ons of the magnocellular nuclei displaying aldehyde-fuchsin stain-
able material, In addition to the main neurosecretory pathway, the
external zone of the median eminence and the neural lobe are rich in
heavily stained reaction produ,·t. There is an increasing body of
electron microscopic evidence indicating that thP 'Gomori-positive'
elementary granules of the palisade layer are considerably smaller
in diameter than those of the neural lobe: 130-150 nm versus 200-
250 nm. In analogy to mammals this mate rial may be closely rorrelated
to the CRF. In an Attempt to complete the analysis,LHRH antibody was
administered to hypothalamic sections of the Japanese quail.Innnuno-
rf-""aetive ;~xn:l81 rer~.-·in.:-'ls ~·.t~=>rp nb3Prv;·d in t~lt' p:::~lisn.::ir· 1: yPr r,r th0
anterior and posterior divisions of the medicm eminence.Unfortunate- ------ ly, to date all investigators have failed to map irmnunocytochemiral-
ly the LHRH-producing perikarya in the avian hypothalamus. An
immunocytochemiral proof of the TRH-system in birds is lacking.
As birds phylogenetically descended from archosaurian reptiles and
mammals from mammal-like reptiles, the r<"ptilian brain prnvidPs the>
key for the comparison of avian and mammalian hypothalami. From ex
tensive neuroanatomical studies wirh chelonian, crocodilian. lac~r
tilian and ophidian species we were able to conclude that very pr0-
nnunced di ffprPnt·es exist between these main systematic groups
(Oksche,A.,Gen.Comp.Endocrinol.29, 225, 1976; Prasada Rdo,P.D. et a!.,
Cell Tiss.Res._]_?Q, 63, 1976). The evolution of the hypothalamus
depends greatly on the rearrangement of the structural relationships
of the basic neuroendocrine units which already existed in primirive
nervous systems (Lentz). The proliferation of cPll clusters and
differentiation of specific synaptic patterns appear to hP respons
ible for the increasing functional complexity ot the hypnthCJlamus.
Proc. First lnternotl. Symp. Avian Endocrinology, Calcutta, Jon. 1977
20
FOLLETT, B.K.
Department of Zoology, University College of North Wales, Bangor, Gwynedd, UK.
Since many of the recent advances in avian neuroendocrinology have been published in the literature during the past three years it might be useful to try and draw together this knowledge and see whether a coherent model might be drawn therefrom. Let me first list some of the various findings: 1. Long daylengths act by stimulating increased LH and FSH secre tion. Radioimmunoassays are now available to measure both avian LH and FSH and these have been used to follow the changes in hor mone secretion under both artificial photoperiods and natural day lengths. On transfer to 20L/4D LH and FSH concentrations rise rapidly (within one day - see Follett & Davies, this volume) to reach peak values after 6-10 days. The 1H levels then remain relatively stable but FSH falls away rapidly as the testes reach maturity (Follett, J. Endocrinol. &2, 117, 1976). Thus, there is an asynchrony between 1H and FSH secretion during the latter stages of gonadal maturation. Since the metabolic clearance of 1H is identical under short days, long days and in castrates it appears that the enhanced plasma levels are indeed a result of increased pituitary secretion. 2. Gonadotrophin secretion during the first couple of long days is rhythmic but this soon disappears and secretion becomes con tinuous at all times of day and night (Gledhill, B. & Follett, J. Endocrinol. ]1, 245, 1976). In other words, there is no evi dence for a diurnal rhythm of secretion mirroring the circadian processes underlying photoperiodic time-measurement. This not only applies to the quail but also to the duck, the white crowned sparrow and the starling. 3. In contrast with mammals episodic secretion of LH and FSH is less marked in quail. Gonadotrophin secretion - even of LH - appears to be made up of a tonic component upon which is super imposed some pulsatile hormone release. Long daylengths seem to act primarily by increasing the tonic output rather than by altering the amplitude/frequency of episodic secretion (c.f. sheep; Lincoln, G.A. ~., J. Endocrinol. in press, 1977). 4. Once begun, LH & FSH secretion may continue for anything up to a week without further photostimulation. This so-called "carry-over" phenomenon seems to be a characteristic property of the photoneuroendocrine system. Since hypothalamic deafferen tation stops "carry-over" & leads to an immediate fall in LH secretion it would appear to be of hypothalamic origin. Put simply it appears that long days cause a semi-permanent change in the neuroendocrine machinery and elicit a prolonged period of enhanced gonadotrophin secretion. 5. Sex steroid feedback. Sex steroids have a strongly negative feedback action on LH and FSH secretion. Castration coupled with long days leads to quite enormous increases in hormone levels which often reach many hundred fold that seen in intact animals.
21
Normally, therefore, ovarian and testicular steroids greatly attentuate the photoperiodic response. Indeed, small increases in exogenously administered androgens easily override the effect of long days. Feedback resides at the level of both the pituitary and the hypothalamus.
During the photoinduced sexual cycle there are some changes in hypothalamic sex steroid sensitivity (e.g. Davies, D.T. et al., Gen. comp. Endocrinol. JQ, 477, 1976) but it seems certain (c.f. sheep) that long days do not act by simply altering the sensitivity of some "gonadostat" in the hypothalamus. This is shown by the fact that gonadectomized quail are completely photoperiodic (Gibson, W. et al., J. Endocrinol. ~. 87, 1975).
Davies, D.T. & Bicknell, R.J. (Gen. comp. Endocrinol. JQ, 487, 1976) have shown that the responsiveness of the quail's pituitary to LH-RF increases slightly during the early phases of testicular growth. It would seem, therefore, that this change, together with that in sex steroid sensitivity, may serve to amplify the pituitary's response to LH-RF but they are not the primary cause of increased gonadotrophin secretion. Enhanced LH-RF secretion from the median eminence under long days is extremely probable.
6. Within the hypothalamus are a number of discrete areas essential for the photoperiodic response. Lesions in either the ventral or dorsal regions of the infundibular nuclear complex ( posterior hypothalamus) totally block the capacity of the quail to grow its gonads under long daylengths. More recently, it has become clear that areas in the anterior hypothalamus are also involved. Lesions in the pre-optic region also block photoinduced testicular and ovarian growth (see Davies & Follett, Proc. Roy. Soc. B, J21, 285 & 303, 1975). The converse experiments of stimulating the hypothalamus with small electrical currents and then measuring changes in LH secretion confirm the importance of the infundibular nucleus and of the pre-optic region (Davies & Follett, J. Endocrinol. £1, 431, 1975).
The obvious question then arises as play in the photoperiodic response. to speculate that they are involved four functions:
to what functions these areas It seems not unreasonable
in one or more of the following
(a) The biological clock. Birds measure daylength using a cir cadian clock but the location of this time-measuring device remains unknown. Menaker and his colleagues have demonstrated that the pineal may be one clock in the bird (see Gwinner, E., this volume) but the removal of this organ seems to have little effect upon photoinduced gonadal growth in most bird species so far tested (although see Saxena, R.N., this volume). In rodents there is now strong evidence that a clock, or at least an essential com ponent of the clock, resides in the anterior hypothalamus and it is tempting to wonder if the lesions in the pre-optic region of the quail block testicular development by interfer ing with the bird's daylength-measuring system. Recently, we (Davies and Jimpson, S.M.) have found that preoptic lesions do interfere with some clock-driven functions in the quail but the matter is still
22
far from resolved.
(b) Location of the LH-RF producing cell bodies. The resolution of this problem seems important since their location in either the infundibular nucleus and/or the pre-optic region would clearly reduce the number of potential neuroendocrine models. Un fortunately, while it has proved possible to demonstrate LH-RF nerve terminals in the median eminence by histochemical methods (see Oksche, this volume) no-one has yet visualised the cell bodies. Evidence from experiments where pituitary implants have been placed in the quail's hypothalamus (Sharp, P.J., J. Endocrinol. 5}, 329, 1973),or where LH-RF activity has been measured following various hypothalamic lesions,have given equivocal results, sugges ting that LH-RF might be manufactured both in the anterior and posterior hypothalamus.
(c) There is good evidence that adrenergic nervous pathways are somehow involved in photoperiodism. Intraventricular 6-0H dopamine can block testicular growth (e.g. Davies & Follett, J. Endocrinol. 60, 277, 1974) while reserpine stops the photoinduced LH rise (Follett et al., J. Endocrinol, in press, 1977).
(d) The photoreceptor. There is unequivocal evidence (Benoit, J., p 121 in "La Photoregulation de la Reproduction chez les Oiseaux et les Mammiferes", CNRS, 1970; Menaker, M. Biol. Reprodn • .!!, 295, 1971) that an extraretinal receptor exists in birds. Recently, Bayle et al. (C.R. Acad. Sci.~. 1501, 1975) appear to have located the receptor in the infundibular nuclear region of the quail's hypothalamus - a finding which would accord well with our lesioning findings. Possibly then, one function of the posterior hypothalamus is as the photoreceptor for the photoperiodic response (but see also Homma, K. and Sakakibara, Y., this volume).
It may still be premature to speculate how these various components might be linked together into a system which regulates the photo neuroendocrine response in birds. However, one does wonder if the "clock" might not turn out to be some type of pulse generator whose output is circadian. The photoreceptor could act as a gating mechanism such that if the generator fired during lights-on then signals might pass into the circuits regulating LH-RF sec retion. At this point I suspect that this daily rhythmic input (under long days) must somehow be converted into a continuous output in order to allow for the sustained and continuous release of the gonadotrophins. Whatever circuit might be involved at this stage may have the property of remaining switched on for a number of days, even in the absence of further input, thus ex plaining the carry-over phenomenon. These ideas might well be totally incorrect but if they serve as a stimulus for further experiments then perhaps they are worth making!
23
DOMINIC, C.J.
Department of Zoology, Banaras Hindu University, Varanasi, India.
The hypophysial vascularisation in birds is reviewed with special reference to the hypothalamo-hypophysial portal vessels. The median eminence and the neural lobe are supplied by the infundi bular artery which originates from the anterior ramus. The median eminence is covered by a dense capillary plexus that is supplied by the branches of the infundibular arteries. The capillaries that form the plexus are generally distributed only on the outer surface of the median eminence and do not penetrate the palisade layer. Occasionally, capillaries from the primary plexus pene trate deeply into the hypothalamus. The primary capillary plexus is usually covered by the cells of the pars tuberalis. The primary capillary plexus in the median eminence is either single or is sometimes divided into an anterior and a posterior plexus. When the plexus is divided, the two divisions are more or less interconnected. However, in the White-crowned sparrow (Vitums, A., Mikami, S., Oksche, A. and Farner, D.S., Z. Zellforsch. ~. 541, 1964) and the Japanese quail (Sharp, P.J. and Follett, B.K., J. Anat. lQ.!!, 227, 1969) the two divisions of the primary capillary plexus do not appear to have any interconnections. The posterior plexus is smaller than the anterior one and usually reaches up to the ventral border of the infundibular stem. Irrespective of whether the primary capillary plexus is single or divided, in al most all species of birds investigated, there are separate anterior and posterior groups of portal vessels. The anterior and posterior groups of vessels originate from the anterior and posterior plexus, or from the anterior and posterior regions of the undivided capillary plexus. The anterior group of portal vessels traverses the anterior margin of the porto-tuberal zone and breaks up into capillaries in the sinusoids of the cephalic lobe of the pars distalis. Likewise, the posterior group of portal vessels traverses the posterior margin of the porto-tuberal zone and breaks up into capillaries in the sinusoids of the caudal lobe. Each group of portal vessels is formed from a few major vessels and several minor vessels. There are no important interconnections between the two groups of portal vessels. In some species the two groups of portal vessels converge below the median eminence before entering the pars distalis over a rela tively restricted area. However, in others individual portal vessels may pass directly into the pars distalis from the broad capillary plexus. In certain species additional caudal portal vessels which do not belong to the posterior group of portal vessels occur, These "accessory" portal vessels pass from the infundibular stem to the pars distalis without traversing the porto-tuberal zone and supply blood only to a circumscribed region in the caudal lobe.
The incidence of distinct anterior and posterior groups of hypo physial portal vessels was first convincingly demonstrated in the
24
White-crowned sparrow (Vitums et al., 1964). C.J. Dominic and R.M. Singh (Gen. Comp. Endocrinol. 11, 22, 1969; J. Endocrinol. .!£l., 3.5.5, 1971) and K.B. Singh and Dominic (Arch. Anat. micr. Morph. exper. ~. 3.59, 197.5) demonstrated the existence of distinct anterior and posterior groups of portal vessels in eighty four species of birds belonging to several orders and thus emphasised the generality of this phenomenon. A similar demonstration of the separation of portal vessels into anterior and posterior groups in the Japanese quail (Sharp, P.J. and Follett, B.K., J. Anat. 1Qk, 227, 1969) and in a number of other avian species (Assenmacher, I., Arch. Anat. micr. Morph. exper. hl_, 69, 1952; Duvernoy, H., Gainet, F. and Koritke, J.G., J. Neuro-Visc. Rel. ]1, 109, 1969) again emphasises the widespread occurrence of the regional distri bution of portal vessels in the avian pituitary.
It has been suggested that the existence of two separate groups of portal vessels in the avian pituitary may be correlated with the histological bipartition of the median eminence and of the pars distalis, and provides morphological evidence for the existence of two separate hypothalamic mechanisms regulating the secretory activity of the avian pars distalis. Light microscopic studies show that the anterior median eminence is rich in Gomori-positive fibres of the supraoptico-paraventricular tract, whereas the posterior median eminence is mostly composed of Gomori-negative fibres of the tubero-infundibular tract (Oksche, A., Mem. Soc. Endocrinol. 12, 199, 1962). It is well established that the avian pars distalis-is divided into cytologically distinct cephalic and caudal lobes (Wingstrand, K.G., The Structure and Development of the Avian Pituitary, C.W.K. Gleerup, Lund, 1951) and there exists a functional differentiation between the two lobes. Hence, it appears that the secretory activity of the cephalic lobe cells is regulated primarily by the neuro-hormones from the supraoptic and paraventricular nuclei travelling via the anterior group of portal vessels, and that of the caudal lobe cells primarily by neuro hormones from the tuberal nuclei travelling via the posterior group of portal vessels. Even though on morphological grounds there is a great attraction in the regional distribution of the portal vessels having physiological significance, the experimental in vestigations carried out to date (cf Stetson, M.H., Z. Zellforsch. 21, 369, 1969; ibid, 1JQ, 389, 1972; Sharp, P.J. and Follett, B.K., Neuroendocrinology, 2, 205, 1969) do not yet support the idea.
25
Potential sites and action spectra for encephalic photoreception in the Japanese quail
KAZUTAKA HOMMA, YOSHIKAZU SAKAKIBARA AND MITSUAKI OHTA
Department of Veterinary Physiology, Faculty of Agriculture, University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo, Japan 113.
This paper considers the important role of encephalic photo reception in the photo-gonadal reflex of the Japanese quail. Preliminary work on this subject has been reported in Biochrono metry (M. Menaker ed., 333-341, NAS Pub., 1971).
Sites of encephalic photoreception: Sites of encephalic photore ceptionforthe photo-gonadal reflex were extensively examined by chronically implanting small beads of radioluminoue paints for 21 days into various regions of the brain of young Japanese quail reared under environmental 8:16 LD cycles. Some beads were de signed eo as to illuminate one side only. Localized illumination by this means in any one of the following locations brought about unequivocal gonadal growth; 1) an extra-hypothalamic area facing towards the mid-sagittal plane, 1 mm above the anterior commissure, 2) the anterior and the posterior hypothalamus, and J) small areas of the midbrain, 2 mm lateral to the midsagittal plane on each side and adjacent to the tractus occipitio-mescencephalicue. Illumi nation in other locations of the brain gave no reproducible results or any positive responses. Correlations between the effective sites and the rate of gonadal growth supports the view that en cephalic photosensitive neural structures for gonadal stimulation are distributed within or close to the basal hypothalamus.
Action spectra and circadian rh.vthms: The action spectra of the photoperiodic response as well as cyclic changes in encephalic photosensitivity were investigated by employing light emitting diodes (LED). Birds for these experiments had various LEDs sur gically secured on to the skull (Figure). They were then sub jected to continuous encephalic lighting for 14 days. The results showed (Figure) that in the visible spectrum range, red light was most stimulatory. Infrared light (949 nm) was neither stimulatory nor inhibitory at the energy levels tested.
Using these data, night interruption experiments were carried out with red LEDs (.535 nm). Different photoperiods were allotted to groups of birds housed in the same chamber and lit with 8: 16 LD cycles. Plasma testosterone and LH levels were markedly elevated within 3 days in the group which received LED lights during the second quarter of the 16 hr environmental dark period. The photo periodic inducible phase assessed with LED lighting either by the rate of gonadal growth, or by hormone levels agreed well with that obtained by manipulating the on-off time of the room lights. It was concluded that the effectiveness of direct light stimulation to the brain is under the control of circadian mechanism and that the light intensity necessary to induce maximum gonadal growth was far below that needed for entrainment.
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27
Effect of hydrocortisone on the hypertonic saline-induced changes in the hypothalamic neurosecretory system of the spotted owlet, Athene brama, Temminck
* SINGH, K.B.
Department of Zoology, Banaraa Hindu University, Varanaai 221005, India •
Administration of a J% NaCl solution (1 ml/day) for 3 to 5 days induced characteristic histological changes in the hypothalamic neurosecretory system (HNS) of the spotted owlet. These changes included a reduction in the quantity of neurosecretory material (NSM) in all parts of the HNS, viz., the supraoptic nucleus (SON), the paraventricular nucleus (PVN), the hypothalamo-hypophyaial tract (TR) and the neural lobe (NL), as well as in a hypertrophy of the neurosecretory neurons in the SON and PVN. During the initial period (up to the third day) of hypertonic saline adminis tration, the quantity of NSM in the zona externa of the median eminence (ME) remained unchanged. However, when the treatment was continued beyond 3 days, there was a marked reduction in the quantity of NSM in the ME. The histological changes that occurred in the HNS following hypertonic saline administration were completel~ blocked by concurrent treatment with hydrocortisone (Efcorlin, BDH) (6 mg/animal/day).
Even tholl8h it is known that the histologically demonstrable NSM is not the ADH (arginine vasotocin in birds) the close functional relationship between the two is indicated by the depletion of both from the HNS following water deprivation or NaCl adminis tration. Hence, the hypertonic saline-induced histological changes in the HNS are presumably indicative of augmented sec retion of ADH (see Farner, D.S., Wilson, F.E. and Okache, A., In: Neuroendocrinology, Vol. II, eda. 1. Martini and W.F. Ganong, Academic Preas, New York, pp 529-582, 1967). The inhibition by hydrocortisone of these changes in the spotted owlet is therefore suggestive of an inhibition of ADH secretion. The mechanism of hydrocortisone inhibition of anti-diuresis, however, is not clearly understood.
* Present Address: Department of Zoology, Kamla Nehru Institute of Science and Technology, Sultanpur-228oo1, India.
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Role of the pineal in the control of circadian and cir cannual rhythms in European Starlings
GWINNER, E. Max-Planck-Institut flir VerhaltensphY-siologie, D-8131 Erling-Andechs, Germany
Within the last years it has become clear that the pineal organ plays an important role in the control of biologi cal rhythms in higher vertebrates. In mammals the pineal has been shown to be involved in the regulation of annual rhythms, but for birds, it appears that primarily daily rhythms are under pineal control. Menaker and his cowor kers have found that pinealectomy has no profound effects on the circadian rhythms of locomotor activity and other functions of house sparrows as long as they were kept in 24-hour light-dark (LD) cycles. However, when pineal ectomized birds were kept in constant darkness (DD) , these rhythms disappeared. Implantation of pineals into the anterior chamber of the eye restored the rhythms. On the basis of these and other results Menaker proposed that the sparrow's pineal was the seat of a circadian master oscillator. Its removal resulted in the loss of selfsustainment in the circadian system and, hence, dampened the overt circadian rhythms when no external Zeitgebers were present. - Photoperiodic reactions were not impaired by pinealectomy (e.g., Menaker, M. and Zimmerman, N., Amer. Zool. 16, 45 (1976)-
Our own investigations on starlings have revealed that as in the sparrow pinealectomy resulted in drastic dis turbances of the circadian locomotor activity rhythms in birds kept in DD or in constant light (LL). However, in contrast with the sparrow results, pinealectomy in the starling did not usually lead to complete and permanent arrhythmicity. In several cases arrhythmicity was only temporary and many pinealectomized birds remained rhyth mic throughout the 3 to 20 week experiments. The circa dian rhythms of those birds that remained rhythmic, were altered in at least one of the following aspects: (1) the circadian period was shortened, (2) the circadian period was subject to sudden and apparently spontaneous changes or (3) the separation between activity and rest periods was less clear and the time of activity onset became more variable. - Pinealectomy in the starling then leads to a general loss of stability in the circa dian system but does not necessarily abolish all self sustained circadian rhythmicity. The results are con sistent with the assumption that the pineal organ is a circadian master clock; however, the pineal does not seem to be the only selfsustaining circadian oscillator involved in the control of locomotor activity rhythms in that species.
Proc. First lnternotl. Symp. Avian Endocrinology, Ccl.:ul:·n, Jon. 1977
29
Since in the starling, as in other bird species, a cir cadian rhythmicity is involved in photoperiodic time measurement it was of interest to examine whether pineal ectomy would interfere with photoperiodic reactions. In three types of experiments the testicular reactions of pinealectomized, sham-operated and unoperated birds were investigated: (1) birds were exposed to sinusoidal chan ges of photoperiod, simulating the natural ones, but with periods of only 6, 4 and 3 months, (2) photosen sitive birds were exposed in midwinter to stimulatory long days or (3) to continuous light. In none of these experiments did the pinealectomized birds differ in any clear and consistent way from the respecitve controls. The fact that this was true for the birds exposed to LL is consistent with the proposition that a circadian rhythmicity persists in pinealectomized birds even in the absence of external Zeitgebers.
Proc. First lnternotl. Symp. Avian Endocrinology, Calcutta, Jon. 1977
30
SAXENA, R.N.
Department of Zoology, University of Delhi, Delhi, India.
There is no unanimity of opinion regarding the role of the pineal in avian reproduction. While some workers have failed to demon strate any relationship between the pineal and reproduction, others have assigned pro- or anti-gonadotropic functions. In the present review an attempt was made to reconcile these seemingly diverse observations on the basis of the work done in our laborator.y on the male Indian weaver bird, Ploceus philippinus. This bird is a seasonal breeder with a reproductive cycle which can be divided into breeding (June to July), regressive (August to October), nonbreeding (November to Februar.y) and progressive phases (March to May). It is known that these birds are highly photo sensitive but a refractor.y period typical of most other seasonally breeding birds is absent.
During the breeding phase of the male bird hypothalamic LHRH and plasma LH levels were high whereas pi tui tar.y LH was low. LH concentrations were measured by radioimmunoassay. The reverse was true for the nonbreeding phase. Exposure of the birds to long photoperiods (18L-6D) or pinealecto~ in winter (nonbreeding phase) caused precocious testicular recrudescence along with changes in the other secondar.y sexual characters typical of the breeding phase within eight to ten weeks of light treatment. Corresponding changes in the hormone levels were also observed. A combination of pinealecto~ and long photoperiods advanced the attainment of the breeding state as compared to a single treatment, suggesting that the effects of long photoperiod and pinealecto~ on testicular growth are additive. Gonadal regression and the chara cteristic changes in the hormonal levels were blocked in birds pinealectomised during the breeding phase and observed through the nonbreeding phase. Pinealecto~ of birds exposed to nonstimu latory short photoperiods (9L-15D) also caused gonadal recrudes cence and parallel changes in the hormonal levels but the response was late as compared to the birds under natural or long days.
To compare the antireproductive properties of the gland during different phases of reproductive cycle, injections of partially purified extracts of the pineal,obtained from birds throughout the year, were given to photostimulated birds, unilaterally ovariec tomized mice and pregnant rats. The pineal extracts from non breeding birds had maximal inhibitor.y effects on the breeding characteristics and hormonal levels in birds and also significantly inhibited compensatory ovarian hypertrophy in mice and pregnancy in rats. Pineal extracts from breeding birds had no such effects. The inhibitor.y effects of pineal extracts from birds in other phases (progressive and regressive) were also tested but were not as significant as those from the nonbreeding phase.
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In vitro incubations of partially purified extracts of pineal with pituitar.y isolated cells from male rats revealed significant LH releasing potency during the breeding phase as well as in the pineal of photostimulated birds. No such activity was detected during the nonbreeding phase or in the pineah of birds kept in short photoperiods. Corresponding changes in LH-releasing potency were also observed in birds transferred from long to short photoperiods or vice ~·
On the basis o

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