Arrange the following cell layers/structures around the female gamete from outer to inner side :

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

Choose the correct answer from the options given below :

To determine the correct sequence of structures surrounding the female gamete (the ovum), we examine each layer from the outermost to the innermost:

1. Corona radiata (C) – This is the outermost layer. It consists of follicular cells that remain attached to the ovum after ovulation, forming a cloud of cells around it.

2. Zona pellucida (A) – Directly beneath the corona radiata is the zona pellucida, a thick glycoprotein coat that protects the ovum and mediates sperm binding.

3. Perivitelline space (B) – This is the fluid‑filled cavity that lies between the zona pellucida and the plasma membrane of the ovum.

4. Plasma membrane of the ovum (D) – The innermost structure is the ovum’s own cell membrane, which encloses the cytoplasm and nucleus.

Putting these layers together from outer to inner yields the order: C, A, B, D.