Question

During fertilization, zona pellucida is dissolved by
A. Hyaluronidase
B. Hyaluronic acid
C. Renin
D. Acrosin

Answer 1

During the fertilization, gametes and egg are fused to form a diploid zygote occurring in the ampulla of the fallopian tube. When an oocyte is formed a layer is formed to protect the oocyte called zona pellucida which is made by corona radiata. After a few weeks, zona hatching occurs to degenerate the oocyte to zygote.

Complete Answer:
- Fertilization is the process of fusion of gametes, egg and sperms in organisms to form a diploid zygote which is a union of the sperm cell and the egg cell, it is also known as fertilized ovum. Zygote begins as a single cell but divides rapidly during fertilization.
- The zona pellucida or egg coat is a glycoprotein layer around plasma membrane, it is produced in a unilaminar primary oocyte at first. Zona pellucida is covered by Corona radiata which has cells that care for the egg when the egg is emitted from the ovary.
- The Zona pellucida is hatched during zona hatching where zona pellucida degenerates and decomposes, where it is dissolved by Acrosin, which is a digestive enzyme that acts as protease and is converted by ACR gene. The Acrosin is released as a part of acrosome reaction.

From the above discussion, we can conclude that option D. Acrosin dissolves the zona pellucida during fertilization.

Note: The layer around the oocyte formed is zona pellucida which is covered by corona radiata. Once the zygote is formed as a single cell it divides fast in days during fertilization. After two weeks from zygote formation, zygote eventually becomes embryo by cell division. Embryo becomes a fetus after a certain period.