Effects of prenatal and postnatal photoperiods and of the pineal gland on early testicular development in the marsh rice rat (Oryzomys palustris).
Prepubertal male rice rats are responsive reproductively to photoperiod early in postnatal development. Testicular growth was inhibited in animals gestated and reared to 28 days of age on photoperiods ranging from 8 to 13 h of light per day, and stimulated in animals reared on 14 h or more of light per day, suggesting a critical photoperiod between 13 and 14 h for testicular growth. In addition, postnatal photoperiod markedly affected testicular development in animals exposed to various prenatal and postnatal photoperiods. Postnatal exposure to constant light unmasked effects of the prenatal photoperiod on testicular development. Exposure of rice rats to short or long photoperiods during the period of lactation (Days 1-14 of life) affected testicular maturation. In addition, alteration of the photoperiod experienced after Day 14 of life (post-lactational) markedly affected testicular development and was the primary factor determining whether maturation would occur. Finally, pinealectomy had little to no effect on the magnitude of testicular development in animals maintained on the presurgical photoperiod, but did prevent animals from demonstrating the appropriate testicular response to a new photoperiod after surgery. These data suggest that early testicular development in rice rats is affected by the prenatal and postnatal photoperiod and that the pineal gland is involved in the transduction of this environmental information.
Edmonds
K E
KE
Physiology and Anatomy Section, School of Life and Health Sciences, University of Delaware, Newark 19716, USA.
Stetson
M H
MH
D000818:Animals; D008297:Male; D017440:Photoperiod; D010870:Pineal Gland / Q000502:physiology*; D016205:Sigmodontinae / Q000254:growth & development*; D013737:Testis / Q000196:embryology / Q000254:growth & development* / Q000528:radiation effects