[Study of Leydig cells and gonadotropin activity in 14-18 days old fetal mouse (author's transl)].

An organ culture system has been developed for mouse embryo testes and pituitaries at 14-18 days of gestation. The testosterone (T) production by fetal testes has been measured by RIA in the culture medium: it increases from day 14 to day 18 and may be specifically stimulated by ovine LH and hCG. Fetal pituitaries in culture release a gonadotropin activity at 16 and 18 days (not found at 14 days), which is detectable by an heterologous RIA of LH and by a significant increase in T production from age-matched testes in co-culture. The 18-days old pituitaries respond to synthetic LH-RH by an enhanced production of immunologically and biologically active LH.