Nursing HAP201 Chapter Notes - Chapter 29: Zona Pellucida, Gestational Sac, Fallopian Tube
19 Jan 2017
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Lo 29. 1: explain the major developmental events that occur during the embryonic and fetal periods. The embryonic period extends from fertilization through the eight week. The first week is characterized by several significant events including: fertilization, cleavage of the zygote, blastocyst formation. The genetic material from a haploid sperm cell (spermatozoon) and a haploid secondary oocyte merges into a single diploid nucleus. Occurs in the uterine (fallopian) tube within 12-24 hrs after ovulation. Sperm that reach the oocyte within mins after ejaculation cannot fertilize until seven hrs later. For fertilization to occur, a sperm cell must penetrate two layers: corona radiata: the granulosa cells that surround the secondary oocyte, zona pellucida: the clear glycoprotein layer between the corona radiata and the oocyte"s plasma membrane. Acrosome: helmet-like structure the covers the head of a sperm; contains several enzymes. These enzymes and strong sperm tail movements help penetrate the cells of the corona radiata and come in contact with zona pellucida.
