Effect of Human Chorionic Gonadotrophin on Testosterone Secretion by the Foetal Human Testis in Organ Culture

Abstract

Foetal human testes (12-22 weeks gestation), maintained in organ culture, were treated with human chorionic gonadotrophin (HCG) and the amount of testosterone produced compared with control cultures. In all cases the testes produced testosterone, but from the 13th to 18th week of gestation significantly more testosterone was produced by, and the Leydig cell hyperplasia was maintained in, the HCG stimulated organ cultures. It is suggested that HCG is ultimately responsible for differentiation of the human male external genitalia.

Cellular Localization of Chorionic Gonadotropin in Human Fetal Kidney and Liver*

“…Second, hCG binds to the human fetal testis and stimulates testosterone secretion (15). Maximal testosterone levels in fetal serum are observed near the time of peak hCG secretion (16,17). Third, hCG stimulates fetal adrenal synthesis of dehydroepiandrosterone sulfate (18,19).…”

Development of the gonad in normal and anencephalic human fetuses

“…An early lesion might prevent the formation of interstitial tissue and so leave the seminiferous tubules closely apposed, while a later lesion (occurring after extensive Leydig tissue had formed) might result in the destruction or de-differentiation of the interstitial cells with consequent fibroblastic infiltration of the spaces. This hypothesis could be tested by studying human fetal testes grown in organ culture (see Abramovich et al, 1974).…”

“…The fact that the population of Leydig cells was considerably reduced in the testes of anencephalic fetuses was surprising since earlier studies indicated that Leydig cell number and androgen production were closely correlated with the levels of hCG (Abramovich et al, 1974) (Courot, 1970).…”

Differentiation of the Fetal Gonad

“…The h C G binding capacity of fetal testes is highest between 15 and 20 weeks [10|. Although certain studies have revealed that h C G can induce testosterone synthesis either in organ cultures [18] or fetal testicular homogenates [19,20], several groups have been unable to demonstrate induction o f testosterone secretion or steroidogenic gene expression by h C G in sec ond trimester human fetal testicular homogenates or in cul tured testicular cells [7. 211. It is not yet known at what ges tational age fully functional h C G receptors appear in fetal Leydig cells; the presence of specific h C G binding sites does not necessarily mean that h C G binding leads to the intracellular cyclic AMP-mediated signalling needed for induction of testosterone secretion.…”