Influence of a skeleton photoperiod on reproductive organ atrophy in the male golden hamster.
The timing of reproductive events is critically related to the exposure of a photosensitive animal to environmental light. Male hamsters were maintained in long photoperiods, short photoperiods or in darkness interrupted by brief periods (15 min) of light at 6 h intervals for 11 weeks. Gonadal atrophy did not occur in hamsters maintained in long photoperiods or in those maintained in the interrupted photoperiodic cycle, although hamsters maintained in a photoperiod of 2L:22D showed severe involution of the gonads and accessary sex glands (seminal vesicles and coagulating glands). The results indicate that the time of occurrence of environmental light during the photoperiodic cycle in which an animal is maintained is more important in determining the reproductive status of an animal than is the total amount of darkness or the dark to light ratio.