In human females at the time of birth there are two million ova: how many of them normally reach maturity in the course of normal reproductive life

Releasing of sperms from seminiferous tubules is called

The embryo of man is protected by

During cleavage $DNA$ synthesis

After implantation, finger-like projections on the trophoblast are called $…A….$ which are surrounded by  $…B..$ and maternal blood. Here $A$ and $B$ refers to