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What is Zona Pellucida disappears by:- and explain in detail?
Zona pellucida is thick membranous covering made up of glycoprotein, the microvilli of oocyte and follicular cells project into zona pellucida for nutrition. it prevent polyspermy and implantation. Blastocyst forms at 4th day and by the end of 5th day, zona pellucida disappears and implantation takes place at 6th -7th day after feilization.