Onset of menstruation is due to
Fall in level of progesterone
Increase in level of progesterone
Increase in level of $FSH$
None of these
How many chromosome numbers are present in primary spermatocytes of human ?
Trophoblast, is not involved in the formation of
Identify $A$ to $F$ in the diagram given below
An avian blastula is called
Sometimes the labor pains are less and uterine contractions have to be induced. What do you think the doctors inject to facilitate delivery?