Circadian photosensitive phase and photoperiodic control of testis activity in the mink, a short-day mammal
Evidence of a circadian photosensitive phase in male mink, whose annual reproductive cycle is characterized by the recrudescence of testicular development in autumn, was based on the study of testicular response after interrupting the dark period by light breaks offered at various times. In this mammal, the experimental short days 4L:20D and 8L:16D stimulated testicular growth. Short photoperiods, including a main light period of 3.5 h and an additional 0.5 h light break 7.5 h after the beginning of the main photoperiod, were as effective as 8L:16D in stimulating testicular development. On the other hand, when a 0.5 h light break occurred 11.5 or 15.5 h after the beginning of the main photoperiod, the same inhibiting effect on testicular activity was obtained as for long photoperiods. However, when 0.5 h light breaks were given 19.5 after the beginning of the main light period, some minks recognized, as, the onset of the shorter of the two light periods offered. Thus our results proved the existence of a special phase in the day cycle in which light inhibited testicular development in the mink which appears to be a short-day animal. One explanation of the difference between long-day and short-day animals would be the following: if for long-day animals exposure to light during the photosensitive phase led to gonadostimulation, in short-day mammals, like mink, it exerted an inhibiting influence on testicular growth.
- Research Organization:
- Centre d'Etudes Biologiques des Animaux Sauvages, C.N.R.S., Beauvoir-sur-Niort, France
- OSTI ID:
- 6844881
- Journal Information:
- Biol. Reprod.; (United States), Vol. 26:1
- Country of Publication:
- United States
- Language:
- English
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MAMMALS
BEHAVIOR
PHOTOPERIOD
BIOLOGICAL EFFECTS
ANIMAL GROWTH
COMPARATIVE EVALUATIONS
DAILY VARIATIONS
INHIBITION
MALES
PHYSIOLOGY
REPRODUCTION
SEASONAL VARIATIONS
TESTES
VISIBLE RADIATION
ANIMALS
BODY
ELECTROMAGNETIC RADIATION
GONADS
GROWTH
MALE GENITALS
ORGANS
RADIATIONS
VARIATIONS
VERTEBRATES
550100* - Behavioral Biology
551000 - Physiological Systems