Growth and Reproductive Development of Male Microtus montanus is Affected by the Prenatal Photoperiod

Abstract

Rates of growth and sexual maturation of microtine rodents vary in response to photoperiod. Previous work with M. montanus showed that the photoperiod present prior to weaning influences how voles will respond to photoperiods seen following weaning. Information about the photoperiod seen by the mother during pregnancy influences the postweaning development of male M. montanus. Adult M. montanus were paired in photoperiods consisting of 8, 14 or 16 h light/day. Their litters were conceived and born in these photoperiods. On the day of birth the litters were recorded and retained in the gestation photoperiod (Groups C8, C14 and C16) or transferred to the 14-h photoperiod (Groups E8 and E16). The growth of males was followed from weaning until 74 days of age, at which time the voles were sacrificed and their reproductive organs weighed. There were no differences in body weight or length between groups at 18 days of age. At 74 days of age the development of the voles could be ranked in the following sequence: C8 < E16 < C14 < E8 < C16.