Question

Which event becomes possible due to formation of egg membrane?

• A. Sperm can enter into ovum
• B. Prevents entry of other sperms in to ovum
• C. Prevents the process of fertilization so pregnancy is prevented
• D. Makes fertilization process possible and causes pregnancy

Answer 1

The correct option is B Prevents entry of other sperms in to ovum

The sperm that successfully reaches the secondary oocyte is initially prevented entry by both corona radiata and the zona pellucida. When the sperm reaches the corona radiata, their motility allows the sperm to push through the cell layers. After the sperm has made a pathway through the corona radiata, they release digestive enzymes from their acrosomes to penetrate the zona pellucida. When one sperm successfully penetrates the zona pellucida and its nucleus enters the secondary oocyte, immediate changes occur in both the zona pellucida and the oocyte, so that no other sperm can enter. In essence, the zona pellucida hardens, preventing entry of other sperms into the ovum.

So, the correct answer is option B.