Question
Biology Question on human reproduction
Extrusion of second polar body from egg nucleus occurs:
A
before entry of sperm into ovum
B
simultaneously with first cleavage
C
after entry of sperm but before fertilization
D
after fertilization
Answer
after entry of sperm but before fertilization
Explanation
Solution
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).