Photoperiod and the termination of embryonic diapause in the marsupial macropus eugenii.

Abstract

The effects of the photoperiod on embryonic diapause in tammar wallabies (Macropus eugenii) were investigated. The animals were subjected to the following photoperiods: A) normal daylight photoperiod B) 15 hours light:9 hours dark and C) 12 hours light:12 hours dark at the vernal equinox. On January 19th the photoperiods for Groups B and C were reversed. Reducing the photoperiod by 3 hours caused a termination of embryonic diapause though this was independent of the previous light regimen. The results suggest that the reactivation of embryonic development may be related to the time of the full moon in December relative to the summer solstice.