Male reproductive cells, also known as sperm, are produced in the testes.

Here's a breakdown:

* Testes: These are the male gonads, which are located in the scrotum.

* Seminiferous tubules: These are tiny, coiled tubes within the testes where sperm cells are produced through a process called spermatogenesis.

* Spermatogenesis: This is a complex process that involves several stages of cell division and differentiation, ultimately leading to the formation of mature sperm cells.

So, in summary, the testes are the primary site of sperm production.