Which part of the sperm is formed from the centriole?

The layer of cells immediately surrounding the ovum but outside the zona pellucida is called:

Given below are two statements:
Statement $I$:
The release of sperms into the seminiferous tubules is called spermiation.
Statement $II$:
Spermiogenesis is the process of formation of sperms from spermatogonia.
In the light of the above statements,choose the most appropriate answer from the options given below:

Males in whom testes fail to descend into the scrotum are generally infertile. Why?

Which one of the following statements is false in respect of the viability of mammalian sperm?

The process of conversion of non-motile spermatids into motile spermatozoa is called: