EFFECTS OF THE CHANGE IN THE ENVIRONMENTAL TEMPERATURE ON THE INCIDENCE OF CLEFT PALATE IN THE MOUSE FETUSES INDUCED BY HYPERVITAMINOSIS-A

Abstract

In order to examine the effect of the change in the environmental temperature on the incidence of malformations induced by hypervitaminosis-A, four groups of pregnant ICR-JCL mice were prepared; the VA + HT group of mice was exposed to a temperature of 34 ± 1℃ for 16 hours after administration of 5,000 I. U. of vitamin A on day 10; the HT group of mice was exposed to a temperature of 34 ± 1℃ for 16 hours at the same time as the above; the VA group of mice was administered with 5,000 I. U. of vitamin A, but kept at normal temperature ; the control group of mice was kept at normal temperature without administration of vitamin A. A11 mice were sacrificed on day 18, and the mortality of embryos and fetuses, and gross malformations in the living fetuses were observed thereafter. The mortality of embryos and fetuses in the VA + HT group (22.4%) was higher than that of the other groups (10-11%) .The occurence of malformations of the living fetuses in the VA + HT, the VA, the HT and control groups were 66.2%, 48.1%, 2.4% and 0.9%, respectively. Cleft palate was observed in 40.3% and 27.2% of the living fetuses in the VA + HT and the VA groups, respectively. The above results indicate that the change in the environmental temperature affects the teratogenicity of an overdose of vitamin A. Other workers also reported that teratogenicity is influenced by various environmental factors such as the season, food, noise, etc. Therefore, environmental controls are very important in animal experiments in teratology .