fisiologi reproduksi
Post on 08-Nov-2015
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ENDOCRINOLOGY OFTHE REPRODUCTIVE SYSTEM
INTRODUCTION
M. Djauhari WidjajakusumahFakultas Kedokteran Universitas Indonesia
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REPRODUCTIVE SYSTEM
Maintaining the continuity of the species
Asexual reproduction:forming new offspring that does not involve the union of two gameteslower animals, microorganisms, plants
Sexual reproduction:involves fundamental processes: gametogenesis & fertilizationgametes have half the normal chromosomes
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GONADS
Dual function:GametogenesisSex hormones: androgens and estrogensInhibin: inhibition of FSH secretion
TestesLarge amounts of androgens (testosterone)Small amounts of estrogens
OvariesLarge amounts of estrogens Small amounts of androgensProgesteroneRelaxin (particularly in pregnancy)
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Figure 46-2 Development of the human male reproductive organs and tract. Note the dependence on SRY, a gene on the Y chromosome that expresses the testis-determing factor, and on hormone products of the gonad (testosterone , dihydrotestosterone, and anti-Mllerian hormone [AMH]). 20072007Testis Determining Factor
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SEX DIFFERENTIATION
Determined genetically by sex chromosomes (X & Y)
Y chromosome:necessary for the production of testestestis-determining gene product: Sex-determining Region of Y chromosome testicular differentiation fetal testis: testosterone (Leydig) mullerian inhibiting substance / MIS (Sertoli) under the influence of hCG
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DEVELOPMENT OF THE GONADS
Primitive gonad --> indifferent gonad (cortex and medulla)
Genetic males (7th week):the medulla of indifferent gonad --> testis Leydig and Sertoli cells appearTestosterone and MIS secretedcortex regresses
Genetic femalesthe cortex of indifferent gonad --> ovaryembryonic ovary does not secrete hormonesmedulla regresses
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Pseudo-hermaphroditism: Hormonal Abnormalities
Pseudohermaphrodite
individual with the genetic constitution and gonad of one sex, and the genitalia of the other
Female pseudohermaphroditism
male genital development in genetic femaleandrogens exposure during 8th-13th week of gestationcongenital virilizing adrenal hyperplasiaandrogens administered to the mother
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Pseudo-hermaphroditism: Hormonal Abnormalities
Male pseudohermaphroditism
The embryonic testes are defective
development of female external genitalia in genetic malesdeficient in MIS female internal genitalia
Androgen resistance
male hormones can not exert their full effects on the tissue5alpha-reductase deficiency dihydrotestosterone decreased female external genitaliamutation in the androgen receptor gene
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