Short day length alone does not inhibit spermatogenesis in the seasonally breeding four-striped field mouse (Rhabdomys pumilio)

This study was an examination of the effect of photoperiod on spermatogenes is and the accessory glands of the four-striped field mouse (Rhabdomys pumi lio), a seasonally breeding rodent that occurs through Southern Africa. Adu lt scrotal males were exposed to either short day length (10L:14D), long da y length (14L:10D), or natural photoperiod in constant-environment rooms (2 5 degrees C, 41% humidity; food and water ad libitum) for 8 wk in late summ er, when males in the wild were spermatogenically active, and in mid-winter , when they were inactive. In neither experiment did prolonged exposure to short day length or naturally decreasing day length inhibit spermatogenic a ctivity and we conclude that the normal cessation of spermatogenesis that o ccurs in most male four-striped field mice in winter is not stimulated by d ay length alone.