Morphogenesis of the thyroid gland of rats of the early period after the prenatal action of Dexamethasone

Abstract

Annotation. The aim of the study was to establish the features of the morphogenesis of the thyroid gland of rats at an early age of normal postnatal ontogenesis and after prenatal exposure to dexamethasone. The study material was the thyroid gland of rats (54 animals) of the Wistar line at the age of 1 to 14 days of postnatal development, which experimentally operatively, through the membrane, intrauterinely injected a solution of dexamethasone at a dose of 0.05 ml at a dilution of 1:40 on the 18th day of pregnancy; control group – 0.05 ml of 0.9% NaCl. Sections were stained with haematoxylin and eosin, azan, immunohistochemically (ki-67). Statistically used Student's parametric t-test, the normality of the distribution was checked using the Shapiro-Wilk test, the reliability is not less than 95%, the reliability at p<0.05. In animals experimentally prenatally exposed to dexamethasone for 1-3 days, the gland was more functionally excited: the number of resorption vacuoles in the colloid, which was dense, increased, but the height of thyrocytes was almost no different from the control. There were more colloid-type follicles with ki-67-positive cells. On the 7th day of postnatal life, the structure of the gland changed in the direction of increasing the manifestations of the process of blocking the excretion of thyroid hormones, but the synthesis and excretion of components into the follicle cavity was preserved. Follicles increased throughout the body. On the 11th day of postnatal life in the thyroid glands of animals prenatally exposed to dexamethasone, the number of microfollicles decreased, and the proportion of proliferating ki-67-positive cells in the follicle wall decreased insignificantly compared to the previous period, but compared to the control of proliferating cells was less than 1.8 times. On 14th day, the thyroid gland of experimental animals was characterized by a mosaic arrangement of large follicles with flattened thyrocytes. Thus, the morphogenesis of the thyroid gland by hypofunctional type after prenatal exposure to dexamethasone in young rats indicates an adaptogenic compensatory response and morpho-functional immaturity of the organ during this period, which may be the basis for provoking the preservation of such morphogenetic factors under the influence of stressors.