Testicular response to HCG stimulation and sexual maturation in mice.

2 IU HCG/10 g body weight were administered intraperitoneally to male mice at 1, 20, 30, 40, 60 and 90 days of age. Testosterone was quantified by radioimmunoassay 1 h later in the plasma and the testes. At all stages studied HCG significantly increased testicular and circulating testosterone over the concentrations determined in saline-injected controls. The testicular response to HCG stimulation was age-dependent, it increased from birth to sexual maturity, particularly between 20 and 40 days. This study demonstrates that the testicular responsiveness is probably an important factor in the sexual maturation of mice, especially for the pubertal increase of androgens.