During the process of spermiogenesis,the heads of the sperm become embedded in which of the following cells?

The mother germ cells are transformed into a mature follicle through a series of steps. Provide the missing steps in the blank boxes.
$\boxed{\text{Oogonia}} \to \boxed{A} \to \boxed{\text{Primary follicle}} \to \boxed{B} \to \boxed{C} \to \boxed{\text{Mature or Graafian follicle}}$

$A$ sudden rise in the level of $LH$ stimulates . . . . . . .

What is the nature of the human egg?

In the head of a mature sperm,the cytoplasm is:

At the time of birth,in which form are the oocytes present?