PHYSL 210 Lecture Notes - Lecture 23: Fallopian Tube, Capacitation, Oviduct
23 Dec 2019
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Fertilization: why is polyspermy not favoured and how is it prevented, we dont want extra chromosomes, need to keep it accurate. Events of fertilization: block to polyspermy, change in membrane potential, release of contents from cortical granules, enzymes enter and harden zona pellucida, enzymes inactivate sperm binding receptor. What happens to the oocyte during fertilization: fusion of sperm w/ oocyte stimulates 2nd meiotic division of oocyte, becomes ovum, sperm plasma membrane disintegrates, chromosomes from sperm and ovum migrate to center, dna replicated -> zygote. Early embryonic development and implantation: mitotic divisions -> morula, cell cleavage, doesnt increase overall size, totipotent up to 16-32 cell stage. Identical twins - division of totipotent morula cells: fraternal twins - fertilization of 2 oocytes. Blastocyst: lost zona pellucida, outer cell layer - trophoblast, fetal placenta. Inner cell mass: will become embryo, fluid-filled cavity = blastocoele.
