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Lecture 3

Reproduction Lecture 3 - Pregnancy

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University of Toronto St. George
Michelle French

Reproduction L3 Dec 05 11 Pregnancy depolarization of oocyteCa2 gates openwave of intracellular Ca2Where does fertilization occur Fusion of cortical granules vesicles w Oocyte released form ovary into fallopian tuvemembraneOocyte viable for viable for 24h Contents coat oocyteprevent Spermatozoa viable 46 days inside female penetration of other sperm ie prevents reproductive tractpolyspermyIf fertilizedzygoteregular mitotic divisionsSperm nucleus goes in female chromatids blastocystafter wk implants in uterus wallseparatecomplete meiotic divisionover time formation of placentaembryofetusFor a time see two separate nucleifuse to form nucleus of zygotendSperm deposited in vagina must maturetravel b4 Note 2 polar body expelled from meiosis IIfertilizationSperm undergoes capacitation in What happens after fertilizationvaginahyperactiveAlbumin enzymes lipoproteins bind to spermglycoprotein coat removedintracellular changes to activate cytoskeleton flagellum develop strong whiplike motionSperm must pass thru 30 min cervical mucousOptimal conditions when cervical mucous Blastocyst already begun differentiation relatively thinstrandlikehigh estrogenhollow sphere of cells purpletrophoblastIn luteal phase 1wk after ovulation eventually placentaprogesterone present causes mucous to Inner cell massgives rise to embryoother thicken like plugharder to sperm to structuresget thruUterineoviduct contractions aid Implantationtransport estrogen from female protaglandins from semenFertilization100 sperm reach oocyteGuided by chemotaxis sperm attracted to progesterone from cumulus cellsSperm tunnel thru zona Implantation from day 59 wi uterus in decidua pellucida oocyte barriers wproduce hormonesgrowth factors that acrosomal enzymesndaid in development of early embryo2ary oocyte suspended in Decidua produced from endometrial cellsmeiosis IIst1 sperm fusing w egg winsWhat prevents mensesAcrosomal reactionCorpus luteum makes a lot of inhibin estrogen progesterone starts to degenerate after 14dys if no fertilizationPlasma membrane at head of sperm breaks Want it to keep fning to keep high estrogendownprogesterone levelsso dont start new cycleendometrium stays intactFertilization continuedHuman chorionic gonadotropin hCG secreted st from trophoblast later by placenta1 of 1elevated hormones in pregnancySimilar in structure to LHglycoprotSperm fuses w eggSperm docks w spermbinding prots on oocyte membrane
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