title: Daylength influences pelage and plasma prolactin concentrations but not reproduction in the prairie vole, Microtus ochrogaster.
abstract: Short daylengths did not affect testes weight or spermatogenic index in male voles or uterine weight in female voles. Short daylengths did stimulate the growth of a winter pelage in both sexes; short-day voles had longer underhairs and guard hairs and a thicker, more dense pelage than did long-day voles. Plasma prolactin concentrations were five times higher in long-day than in short-day females and 25% higher in long-day males than in short-day males. The effect of short daylength on pelage was prevented by pinealectomy. We suggest that the growth of a winter coat is an obligate adaptation for winter survival, stimulated by exposure to short daylengths, but that changes in breeding activity are facultative and dependent to a greater extent on other cues for seasonal synchronization.
authors.affiliation: Department of Psychology, University of California, Berkeley 94720.
authors.forename: L
authors.initials: L
authors.lastname: Smale
authors.forename: R J
authors.initials: RJ
authors.lastname: Nelson
authors.forename: I
authors.initials: I
authors.lastname: Zucker
mesh_terms: D000818:Animals; D003411:Arvicolinae / Q000502:physiology*; D005260:Female; D006197:Hair / Q000254:growth & development*; D008297:Male; D010870:Pineal Gland / Q000502:physiology; D011388:Prolactin / Q000097:blood*; D012098:Reproduction; D012621:Seasons
chemical_list: D011388:Prolactin