EFFECTS OF TEMPERATURE AND LIGHT ON THE CYCLICAL CHANGES IN THE SPERMATOGENETIC ACTIVITY OF THE LAKE CHUB, COUESIUS PLUMBEUS (AGASSIZ)'

摘要: Lake chub obtained from their natural habitat, at three different periods of annual reproductive cycle, were subjected to four combinations photoperiod and temperature. Temperature is the major environmental factor controlling spermatogenesis. Higher temperatures (16–21 °C) promote prespermatocytal changes (proliferation spermatogonia) hasten or terminate spermiation in prespawning fish; low (5–12 are essential for normal gonadal proliferation formation primary spermatocytes. effects not overridden by either two contrasting photoperiods, but lower a definite, although slight, photoperiodic effect evident terminal part all experiments, Photoperiod does appear dominate spermatogenetic processes any stage. Evidence presented that an endogenous rhythm activity also present may be partly responsible timing various testicular changes.