The effect of preweaning undernutrition upon the sexual development of male mice.

Sexual maturation was evaluated in male mice subjected to preweaning undernutrition by separating pups from their mothers. Underfed and normally fed males were sacrificed at 20, 30, 40, 50 and 60 days of age. From 20 to 60 days, body and organ weights (testes, seminal vesicle) were lower in underfed males. Plasma testosterone levels were lowered in undernourished males at 20 and 30 days of age, and thereafter they were not significantly different from controls. First fertile matings, which occurred between 36 and 46 days (mean age: 40.6 +/- 0.6) in controls, were delayed in underfed males and occurred between 42 and 58 days (mean age: 48 +/- 1.7). The mean body weight, at the time of first fertile matings, was significantly different in controls (29.5 +/- 0.5 g, range 25.9-32.4) and in undernourished males (24.3 +/- 0.3 g, range: 22.0-25.6). Testicular weight and plasma testosterone concentrations were also significantly lower in underfed males, at the time of first fertile matings. The data lead to the conclusion that puberty did not occur at the same body weight in normal and undernourished male mice.