GnRH from the hypothalamus
stimulates the secretion of LH
and FSH from the anterior
pituitary.
LH stimulates testosterone
secretion from the interstitial
cells.
FSH stimulates sustentacular
cells of the seminiferous
tubules to increase
spermatogenesis and to
secrete inhibin.
Testosterone has a
stimulatory effect on the
sustentacular cells of the
seminiferous tubules, as well as on
the development of sex organs and
secondary sexual characteristics.
Testosterone has a
negative-feedback effect on the
hypothalamus and pituitary to
reduce LH and FSH secretion.
Inhibin has a negative-feedback
effect on the anterior pituitary to
reduce FSH secretion.