Question

To which of the following layers of the oocyte does the spermatozoa bind to carry out acrosomal reactions?

• A. Corona radiata
• B. Zona pellucida
• C. Perivitelline space
• D. Plasma membrane

Answer 1

The correct option is B Zona pellucida

Once a sperm enters the female reproductive tract, it swims towards the ovum and reaches the zona pellucida layer. It binds to the receptors on the zona pellucida (ZP3 molecules) to bring about the acrosomal reactions.

The hydrolytic enzymes/ digestive enzymes present in the acrosome of the sperm help in the degradation of the zona pellucida layer. This enables the sperm to penetrate the zona pellucida layer, perivitelline space (the space between the zona pellucida layer and the plasma membrane) and plasma membrane of the oocyte.