THE EFFECT OF MATERNAL DIETARY DEFICIENCY OF VITAMIN A ON DENTAL TISSUES IN RATS

¹ Department of Zoology, The University of Sheffield, England

1. Thirty female rats were fed from the age of 3 or 4 weeks on a diet deficient in vitamin A for several different periods up to 34 weeks before experimental breeding was begun. Many of these females produced young. Others (19 in all) taken from the same litters were reared on the same diet plus a daily dose of mammalian liver oil as a source of vitamin A. These were allowed to breed at the same time as their vitamin A deficient litter-mates.

2. Females on the vitamin A deficient diet for 12 to 13 weeks before casting their litters produced young with normal dental tissues, in spite of the fact that the mothers' store of vitamin A in the liver was on the point of exhaustion, and the young, with one exception, had no store of vitamin A.

3. Longer periods on diet such as 15 to 19 weeks before the litters were born, resulted in the dental tissues of the mothers (incisor roots and molar gingivae) showing slight changes due to the vitamin deficiency. In their young much more marked effects were noted from the age of one week onwards. The young remained alive for 16 to 18 weeks.

4. After the mothers had been 24 to 25 weeks on diet prior to the birth of their litters then their teeth became more affected by the vitamin A deficiency. Three weeks after the birth of their litters the molar gingival tissue particularly, showed pathological changes. The dental tissues of the babies of these mothers showed gross abnormalities from the age of a few days; their incisor teeth were very abnormal in shape, the teeth were retarded in development, and although the molars appeared to be less affected than the incisors, they too were misshapen particularly as regards their roots. No young lived longer than 10.5 weeks and most died much earlier.

5. After about 30 weeks on diet, practically all the young were stillborn, and dead fetuses were found unexpelled from the uteri. Some females 34 weeks on diet apparently never became pregnant in spite of receiving adequate supplies of vitamin E. Fairly severe signs of vitamin A deficiency were noted in the dental tissues of these animals.

6. 21 rats were given synthetic tocopherol acetate as a source of vitamin E instead of wheat germ oil. Those receiving vitamin A (10) developed and reproduced normally, but the others (11) were adversely affected by A deficiency in about half the time in which those receiving the wheat germ oil showed similar reactions. It is evident that a very small intake of vitamin A, as may be found as an impurity in the wheat germ oil, may greatly delay the onset of gross A deficiency in females.

7. In all experiments where abnormalities occurred, these were more pronounced in the young than in their mothers.