Effects of short changes of environmental temperature and low atmospheric pressure on the ovulation of rats

¹ Worcester Foundation for Experimental Biology, Shrewsbury, Massachusetts

In order to elucidate the external and internal factors that may effect the occurrence of ovulation, white rats were exposed to a higher (103 ± 1°F) or to a lower (26 ± 1°F) environmental temperature, or to a low atmospheric pressure (410 cm Hg) for 5 hours a day on 2 consecutive days. When the animals were caged with fertile males soon after such exposures it was found that estrus and ovulation was inhibited significantly for a period of two normal estrous cycles. The number of subsequent ovulations, the maintenance of pregnancy and the development of embryos, however were not affected. This inhibition is discussed in the light of a shift from gonadotropic hormone secretion to ACTH secretion in the anterior pituitary gland following a stressful condition.