Which of the following cells are present in mammalian testes and help to nourish sperms?

When a male ejaculates sperms during coitus,for normal fertility,at least ....... percent of sperms must have normal shape and size,and at least ........... percent of them must show vigorous motility.

Define the following terms:
$(1)$ Spermiogenesis
$(2)$ Zona pellucida

If the number of chromosomes in a somatic cell is $42$,what will be the number of chromosomes in the cuboidal epithelial cells of the seminiferous tubules?

Explain the difference between the following terms:
$(1)$ Spermatid - Spermatozoa
$(2)$ First polar body - Second polar body

Given below are two statements :
Statement-$I$ : Each primary oocyte gets surrounded by a layer of granulosa cells and is called a primary follicle.
Statement-$II$ : At puberty,only $60,000-80,000$ primary follicles are left in each ovary.
In the light of the above statements,choose the most appropriate answer from the options given below :