Different developmental trajectories of ovaries in Siberian hamsters raised in long and short day lengths

A genome-wide association study was performed on ovaries from Siberian hamsters raised in either long or short photoperiod. Few differences between long and short photoperiod were noted at 3 wk of age, when ovarian histology was identical, whereas many differences in gene expression were noted at 8 wk of age, when ovarian histologies were markedly different. Hamsters were gestated and maintained in 16 or 10 hours of light per day, the latter short photoperiod delays sexual maturity and alters ovarian histology. Differences in gene expression were evaluated by microarray at 3 and 8 wk of age, as were changes between 3 and 8 wk of age in each photoperiod.