The Effects of a Deficiency of Iodine and Vitamin A on the Thyroid Gland of the Albino Rat

Abstract

Iodine deficiency in the diet produces an initial hypertrophy of the thyroid gland in both males and females. This persists for a longer time in females. It is followed in both sexes by atrophy. Vitamin A deficiency produces definite hypertrophy in the female, during the limited period of experimentation, but consistent atrophy in the male. A deficiency of iodine and vitamin A in the diet produces an initial hypertrophy in males and females. In males atrophy follows with continued deficiency. Enlargement of the thyroid gland, induced experimentally, is more pronounced and persists longer in females than in males. A study of the normal rat thyroid indicates that: a) Great variability exists in the histological structure of the normal gland, which may be regarded as evidence of a cyclic secretion of the glandular epithelium; b) colloid release in the normal rat thyroid is evidently a transcellular process.