Question

Which of the following is the correct sequence of layers of an ovum from outside to inside?

• A. Corona radiata, zona pellucida and vitelline
• B. Zona pellucida, corona radiata and vitelline membrane
• C. Vitelline membrane, zona pellucida and corona radiata
• D. Zona pellucida, vitelline membrane and corona radiata

Answer 1

The correct option is A Corona radiata, zona pellucida and vitelline

Corona radiata is the layer placed adjacent to the zona pellucida. It provides proteins to the developing ovum. It is made up of tall pillar-like cells.

Zona pellucida is a glycoprotein layer. It is paced outer to the plasma membrane of the oocytes. It binds to spermatozoa, and initiate the acrosome reaction.

The vitelline membrane surrounds the outer surface of the plasma membrane and it helps in the binding of spermatozoa.

So, the correct answer is option A.