The eggs in which fate of every part of the egg becomes fixed are called

$A$ : In frog gray cresent is formed during fertilization.
$R$ : It is because the black granules move towards the point of entry of the sperm in animal half

In human, beings, after .............. month of pregnancy, the embryo's heart is formed.

The extra embryonic membranes of the mammalian embryo are derived from

A change in the amount of yolk and its distribution in the egg will affect

The fold of skin covering the penis is called