Expansion
LH acts on Leydig cells for testosterone; FSH acts on Sertoli cells for spermatogenesis
Expansion
- LH acts on Leydig cells (interstitial) to produce testosterone
- FSH acts on Sertoli cells to support spermatogenesis and produce androgen-binding protein and inhibin
Feedback
- Testosterone inhibits both LH and GnRH
- Inhibin B selectively inhibits FSH, giving independent control of the two gonadotrophins
Sertoli cells also form the blood-testis barrier, isolating developing germ cells from the immune system, which matters because they express antigens not present at the time of immune tolerance.
Spermatogenesis takes about 70 days plus a further 12 to 21 days of epididymal transit, which is why treatments affecting fertility take about three months to show an effect, and why a post-vasectomy semen analysis is deferred.
The testis requires a temperature about 2 degrees below core, maintained by the scrotum, the pampiniform plexus countercurrent exchanger and the cremaster muscle. This is why cryptorchidism and varicocele impair fertility.