Select the correct option for Leydig cells.

Which of the following is a derivative of the $Mullerian$ duct in male rabbits?

Leydig cells secrete:

The organs which produce gametes are called $...A...$ and those which neither produce gametes nor hormones are called $...B...$. Here $A$ and $B$ represent:

Seminal plasma in humans is rich in which of the following?

How much lower temperature does the scrotum provide for spermatogenesis compared to the normal body temperature?