A histoquantitative study of the effect of maternal hypervitaminosis A on the differentiation of the foetal mouse skin.

The skin of albino mouse foetuses aged 13, 15, 17, 19 and 21 days was studied histologically and quantitatively. The skin of foetuses aged 21 days after maternal hypervitaminosis A, was compared with that of 21 days controls. On the 13th day, the epidermis consisted of one layer of cuboidal cells. The stratum intermedium appeared on the 15th day, the stratum granulosum on the 19th day and the stratum corneum on the 21st day of intrauterine life. The quantitative study showed that although the epidermis increased more rapidly in thickness in the interval between the 13th and 17th day than in the subsequent 4 days, yet in the latter period differentiation of the stratum granulosum and corneum took place. On the other hand, the rate of proliferation of the epithelial cells concerned in the follicle formation was more rapid in the last two days of intrauterine life than in any previous prenatal stage. After maternal hypervitaminosis A, the whole thickness of the epidermis was reduced by 50% and the dermis showed an oedematous appearance. The hair follicle primordia showed a decreased volume.