KINESIOL 1Y03 Lecture Notes - Lecture 2: Zona Pellucida, Zp3, Polyspermy
28 Oct 2018
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Document Summary
Sperm can live 48 hours to 6 days. When oocyte leaves the ovary it is known as a secondary oocyte because it hasn"t fully completed meiosis it has only finished one of the divisions. Corona radiata: loose cells that surround secondary oocyte. The zona pellucida is a clear glycoprotein membrane that surrounds cell membrane of secondary oocyte. Need multiple sperm cells to reach zona pellucida. Normally cells divide equally with cytoplasm, but instead there is unequal distribution. Many sperm cells penetrate the corona radiata of secondary oocyte. Zona pellucida has zp3 glycoprotein "sperm receptor" species specific. Acrosomal reaction causes digestion of zona pellucida (tip of sperm head called acrosome) the head has digestive enzymes which breaks down zona pellucida layer. One sperm binds to integrin a6b1 (alpha 6 beta 1) and causes depolarization which is a fast block to polyspermy a. b. What stops multiple sperm from fertilizing the oocyte. Intracellular release of ca 2+ exocytosis of h20.
