Extrusion of second polar body from egg occurs:

Options

A. Simultaneously with first cleavage
B. After entry of sperm but before fertilisation
C. After fertilisation
D. Before entry of sperm into ovum

Answer

B

Explanation

Extrusion of second polar body from egg nucleus occurs after entry of sperm but before fertilization.
The entry of sperm into the ovum induces completion of the meiotic division of the secondary oocyte.
Entry of sperm causes breakdown of metaphase promoting factor (MPF) and turns on anaphase promoting complex (APC).