In mammalian sperm,spirally arranged mitochondria are present in

During the differentiation of spermatids,they are associated with which of the following?

$A$: Middle piece of sperm is called the powerhouse.
$R$: It contains mitochondria.

Which of the following statements are true for spermatogenesis but do not hold true for Oogenesis?
$(a)$ It results in the formation of haploid gametes
$(b)$ Differentiation of gamete occurs after the completion of meiosis
$(c)$ Meiosis occurs continuously in a mitotically dividing stem cell population
$(d)$ It is controlled by the Luteinising hormone $(LH)$ and Follicle-Stimulating Hormone $(FSH)$ secreted by the anterior pituitary
$(e)$ It is initiated at puberty
Choose the most appropriate answer from the options given below:

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

Spermatogonia undergo ....... to produce spermatozoa.