Where are the $Leydig$ cells found?

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

Identify $A$ to $F$ in the diagram given below.

The ...... helps in maintaining the low temperature of the testes.

When do the Leydig cells mature in males?

What are the seminiferous tubules in the human testis?