What are the cells of the germinal epithelium that differentiate into spermatozoa called?

For normal fertility,what percentage of sperm in a human male ejaculate must have vigorous motility (in $\%$)?

If two primary spermatocytes and two primary oocytes undergo meiosis simultaneously,what will be the ratio of spermatozoa and ova produced at the end of the gametogenesis?

The unfertilized egg of a human contains,or when released from the ovary,the human egg contains:

In spermatogenesis,the growth phase results in the formation of:

The primordial germ cells make their appearance from the wall of