After gastrulation the roof of archenteron is formed by

Sperms are released from the seminiferous tubules by the process called …..

Vitellogenesis occurs during the formation of

The mother germ cells are transformed into a mature follicle through series of steps. Provide the missing steps in the blank boxes.

$\boxed{{\text{Oogonia}}}$ $\to $ $\boxed{\text{A}}$ $\to $ $\boxed{{\text{Primary follicle}}}$ $\to $ $\boxed{\text{B}}$ $\to $$\boxed{\text{C}}$ $\to $ $\boxed{{\text{Mature or Graafian follicle}}}$

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