In mammals,growing oocytes are surrounded by special nutritive cells called:

In which of the following are 'homolecithal' (isolecithal) eggs found?

Spermiogenesis or spermateliosis is:

Given below are four statements $(A - D)$ each with one or two blanks. Select the option which correctly fills up the blanks in two statements:
$A.$ The human male ejaculates about $(i)$ $200-300$ million sperms during a coitus. Out of which, for normal fertility at least $(ii)$ $60$ percent sperms must have normal shape and size.
$B.$ $A$ primary spermatocyte completes $(i)$ first meiotic division leading to the formation of two equal haploid cells called $(ii)$ secondary spermatocytes.
$C.$ Spermatogenesis starts at the age of $(i)$ puberty due to significant increase in the secretion of $(ii)$ $GnRH$, a hypothalamic hormone.
$D.$ Oogenesis is initiated during embryonic development and at puberty only $(i)$ $60,000-80,000$ primary follicles are left in each ovary.

Which of the following provides nutrition to sperm?

What is the acrosome and its membrane called?