In humans, at the end of the first meiotic division, the male germ cells form

The reproductive cycle in the female primate monkeys, apes and human beings is called

$A$ : In frog gray cresent is formed during fertilization.
$R$ : It is because the black granules move towards the point of entry of the sperm in animal half

$A$ : Failure of testes to descend into the scrotum causes sterility in man.
$R$ : Higher internal body temperature is not suitable for sperm development.

Test tube baby means a baby born when

In mammalian sperm, spirally arranged mitochondria are present in