Proliferative Pattern of Seminal Vesicle Cells and the Production of Testosterone and 5α-Androgens from Birth to Adulthood in Mice*

Proliferation of seminal vesicle cells and the concentration of testicular and serum androgens (testosterone and 5 alpha-androgens) from birth to adulthood were investigated in mice. The weight of the seminal vesicles increased significantly from day 0 to day 10 after birth (approximately 0.1-1 mg), remained nearly constant in the next 10 days, and increased again (1-50 mg) thereafter. As an index of cell proliferation, two distinct peaks of 5-[125I]iodo-2'-deoxyuridine ([125I]IdUrd) uptake by the whole seminal vesicles were found at days 8 and 30. Types of proliferating cells examined by autoradiography after injection of [3H]thymidine were partially testis-dependent fibromuscular and epithelial cells in the first peak and largely testis-dependent epithelial cells in the second peak. The [125I]IdUrd uptake values found around day 20 and after day 40 were similar to those in neonatally castrated mice. Concentrations of testicular and serum androgens were relatively high on days 8, 30, 35, 40, and 60 (0.2-0.7 ng/mg tissue and 1.3-2.2 ng/ml, respectively) but were very low on day 18 (0.02 ng/mg tissue and 0.4 ng/ml). These findings lead to the hypothesis that androgens secreted from neonatal and prepubertal mouse testes play a major role in the proliferation of seminal vesicle cells and that the quiescent interval of androgen secretion and action occurs around the 20th day after birth in mice.