Length of Gestation in Mice Under a 21-Hour Day
- 31 August 1977
- journal article
- research article
- Published by Oxford University Press (OUP) in Biology of Reproduction
- Vol. 17 (2) , 224-227
- https://doi.org/10.1095/biolreprod17.2.224
Abstract
Both premature and postmature births among mammals are hazardous to the offspring. Determinants of gestation length are therefore important. Circadian rhythms influence many biologic phenomena. We wondered whether gestation length was determined by the number of light-dark cycles or by an absolute length of time. C57BL mice were bred and raised under conditions of a 21-h light-dark cycle (10½L:10½D). Entrainment was demonstrated by measuring running activity. The animals were then used for these experiments. They were bred first (Period 1) under the 10½L:10½D cycle (21 pregnancies), then (Period 2) for a few weeks under a 12L:12D cycle (10 pregnancies), then again (Period 3) under a 10½L:10½D cycle (9 pregnancies). Gestation lengths (mode and range in 24-h days) were: Period 1: 20 (19-20), Period 2: 20 (20-21), Period 3: 21 (20-22). Our findings indicate that gestation length remained approximately constant in terms of absolute time when the mice were entrained to a shortened light-dark cycle.This publication has 1 reference indexed in Scilit:
- Modification of mammalian sexual cycles, VII—Fertile matings of raccoons in December instead of February induced by increasing daily periods of lightProceedings of the Royal Society of London. B. Biological Sciences, 1937