Abstract:
:In seasonally breeding species, an animal's photoperiodic history (the daylength or photoperiod previously experienced) influences the reproductive response to new photoperiods. However, this has only been examined over a relatively narrow range of photoperiods. We assessed whether Djungarian hamsters (Phodopus sungorus) respond to daylength changes at extremely long and extremely short photoperiods. To determine the extent and temporal sequence of reproductive responses to photoperiod changes, ultrasonography was employed to determine serial changes in testis weight in individual animals; serial changes in body weight and pelage color were also assessed. Male animals (60-day-old) shifted from 6 h of light/day (6L) to 10L showed partial testicular recrudescence and darkening of the coat. In control animals remaining in 6L, testes remained small, and coat color continued to lighten. Animals shifted from 20L to 16L showed partial and transient testicular regression, whereas testes remained large in control animals remaining in 20L. There were no significant differences in body weight between control and experimental animals in either study. These findings indicate that Djungarian hamsters respond reproductively to changes in photoperiod at extreme daylengths, but the magnitude of the response appears to be dependent on the absolute daylength.
journal_name
Endocrinologyjournal_title
Endocrinologyauthors
Rivkees SA,Hall DA,Weaver DR,Reppert SMdoi
10.1210/endo-122-6-2634subject
Has Abstractpub_date
1988-06-01 00:00:00pages
2634-8issue
6eissn
0013-7227issn
1945-7170journal_volume
122pub_type
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