EAR

EARInternal Ear (sound wave to nerve impulse)Middle Ear (sound Conductor)External Ear (sound Collecting)Internal EarEctodermOtic PlacodeOtic/ Auditory VesicleSacculeCochlear ductUtricleSemicircular canalEndolymphatic ductventraldorsalOrgan of Corti

Middle EarEndoderm1st Pharyngeal PouchTympanic CavityAuditory TubeMalleus Incus2nd Pharyngeal PouchStapes

External Ear1ST pharyngeal cleft(Dorsal)External Auditory MeatusEar drum : 1. ectodermal epithelial lining at bottom of auditory meatus 2. endodermal epithelial lining tympanic cavity 3. intermediate layer of CT1ST and 2nd Pharyngeal ArchesAuricular hillock fuseAuricle

EYESOPTIC CUP and LENS VESICLE

Optic nerve

Optic Nerve Optic NerveHyaloid Artery Central Artery of RetinaLENS

Choroid, Sclera

Mesenchyme: inner layer CHOROID outer layer SCLERA

CORNEA

formed by (1) an epithelial layer derived from the ectoderm(2) the substantia propria or Stroma(3) an epithelial layer, which borders the anterior chamberVitreous Body-transparent gelatinous substance accumulateINTEGUMENTARY SYSTEMSkin origin: (1) Epidermis FROM surface ectoderm.(2) Dermis FROM underlying mesenchyme.Epidermis

EctodermPeriderm, or epitrichiumProliferation of cells in the basal Layer4. Intermediate zone 5. Four layers can be distinguished How is the hair and pigmentation acquired?First 3 months the epidermis is invaded by cells arising from the neural crest.

2. These cells synthesize melanin pigment in melanosomes.

3. As melanosomes accumulate, they are transported down dendritic processes of melanocytes and are transferred intercellularly to keratinocytes of the skin and hair bulb.DermisMesenchyme from:Lateral plate mesoderm (supplying cells for dermis in limbs & body wall)Paraxial Mesoderm (Back)Neural Crest Cells (Face & Neck)

Corium : dermal PapillaeSubcorium: fatty tissue

Vernix caseosa: from sebaceous gland degenerated epidermal cells & hairsHAIR

begin development as solid epidermalproliferations from the germinative layer thatpenetrates the underlying dermis.

Hair buds1. Hair papillae- invagination, rapidlyfilled with mesoderm in which vessels and nerve endings develop 2. Hair shaft- cells in the center -spindle-shaped and keratinized3. Epithelial Hair Sheath- peripheral cells become cuboidal4. The dermal root sheath - formed by the surrounding mesenchyme. Sebaceous glands, sweat glands, and mammary glands -develop from epidermal proliferations

Supernumerary nipples (polythelia)and breasts (polymastia)Development of PlacentaDays after ovulationImportant Morphologic-Functional Correlations6-7Implantation of blastocyst7-8Trophoblast proliferate and invasionCytotrophoblast differentiate to syncitium9-11Lacunar period13-18Primary and secondary villi formed; body stalk and amnion form18-21Tertiary villi. Mesoblast invades villi. Fetal capillaries form in situ and tap umbilical vessels; fetoplacental circulation established21-40Chorion frondosum; multiple anchored villi; chorionic plate forms roof of intervenous spaceDevelopment of PlacentaDays after ovulationImportant Morphologic-Functional Correlations40-50Cotelydon formation:Trophoblast invasion opens 40-60 spiral arterioles with spurts of arterial blood forming localized hollows in chorion frondosum. Maternal Circulation estableshedConcentric orientation of anchoring villi around each arterial surt, separating chorionic plate and basal platMain supplying fetal vessels from first-order vessels of fetal cotyledonsAbout 150 rudimentary cotyledons with anchoring villi remain, but without cavitation and crowning . Sluggish pressure flow of maternal blood around them.Development of PlacentaDays after ovulationImportant Morphologic-Functional Correlations80-225Continued growth of definitive placenta. 10-12 large cotyledons form, with high maternal blood pressures (40-60mmHg) in the central intervillous spaces225-267Cellular proliferation ceases, but cellular hypertrophy continues.

HISTOLOGY

Hofbauer Cells

OVULATION

Placental HormonesHuman Chorionic Gonadotrophin-is secreted by the syncyitiotrophoblast cells -in the blood 8 to 9 days after ovulation-rate of secretion rises rapidly to reach a maximum at about 10 to 12 weeks of pregnancy -decreases back to a lower value by 16 to 20 weeksHUMAN CHORIONIC GONADOTRPOHINFUNCTIONS:1. Rescue and maintenance of corpus luteum in early pregnancy2. Down-regulation of hCG/LH receptors in corpus luteum with reduction in progesteronesecretion 3. LH-surrogate in fetal stimulating Leydig cells of the fetal testis to synthesize testosterone and promote male sexual differentiationESTROGENProduced almost exclusively by synthesis in syncitiotrophoblastSmall amount is produced by the maternal ovaries and limited to the first 2-4 postovulary weeks of prenancy

FUNCTIONS:1) enlargement of the mothers uterus2) enlargement of the mothers breasts and growth of thebreast ductal structure(3) enlargement of the mothers female external genitaliaProgesteroneCorpus luteum, placentaFunction:Causes decidual cells to develop in the uterine endometriumDecrease contractibility of uterusNutrition Human chorionic somatomammotropin5th week

Function:Development of breastFormation of protein tissueDecreased insulin sensitivity, and utilization of glucose in mother