Initiation

The hypothalamus releases GnRH.

This stimulates the anterior pituitary gland to release FSH and LH, which act on the testes.

Production

FSH triggers spermatogenesis from Sertoli cells.

LH triggers testosterone production from Leydig cells.

Reduction

To control things for homeostasis, Sertoli cells release inhibin to dampen the release of FSH and LH from the anterior pituitary gland.

Testosterone gives negative feedback to the anterior pituitary gland and the hypothalamus.

References

1. Boundless Biology. (n.d.). Hormonal Control of Human Reproduction. [online] Available at: https://courses.lumenlearning.com/boundless-biology/chapter/hormonal-control-of-human-reproduction/ [Accessed 4 Mar. 2018].