ADMINISTRATION OF CORTISONE TO THE PREGNANT RAT. EFFECTS ON THE LYMPHOID TISSUE OF THE OFFSPRING

Abstract

ABSTRACT The lymphoid tissue of newborn rats from mothers treated during pregnancy by adrenalectomy or various doses of cortisone was studied morphologically. The size of the adrenal glands of the newborn was used as a morphological indicator of the amount of cortisone circulating in the foetal blood. Only the highest dose used – 4.5 mg cortisone daily to the pregnant rat from the 13th day of pregnancy to parturition significantly reduced the size of the thymus in newborn animals. Adrenalectomy induced a slight but significant hyperplasia of the thymus of the newborn. Histologically the thymus cortex appeared to be thinner after the highest dose of cortisone and thicker after adrenalectomy. This high dose of cortisone increased the size of the spleen of the newborn but no definite histological changes were observed in any of the experimental groups as compared with the spleen of the controls. It is concluded that the rat foetal lymphoid tissue is less sensitive to cortisone than that of the adult rat.