interstitial cells of the mammalian testis, involved in synthesis of testosterone.
Leydig cells, also known as interstitial cells of Leydig, are found adjacent to the seminiferous tubules in the testes. Leydig cells can synthesize testosterone and are often closely related to nerves. Leydig cells have round vesicular nuclei and a granular eosinophilic cytoplasm.
Leydig cells are named after Franz Leydig, who discovered them in 1850.
They release the class of hormones called androgens (C19 steroids). They secrete testosterone, androstenedione and dehydroepiandrosterone, when stimulated by Luteinizing hormone (lh). Lh increases cholesterol desmolase activivty, leading to testosterone secretion by Leydig cells.
fsh (follicle Stimulating hormone) increases the response of Leydig cells to lh (Luteinizing hormone) by up regulation. (fsh increases the number of receptors for lh)
Leydig cells form during the 16th and 20th week of gestation. They are quiescent until puberty.