Morphological features of the rat’s thyroid gland after application of defect in the tibiae

Abstract

Aim to study the morphological features of the rats thyroid gland after application of a defect in their tibiae. Material and methods. Sixty white mature male rats were divided into two groups. Group I intact animals, Group II rats subjected to a through defect in the proximal metaphysis of the tibiae. The experiment time-line was: 3, 10, 15, 24, and 45 days. The qualitative features of the thyroid gland structure were studied using light and electron microscopy; the quantitative features with histomorphometry. Results. The large follicles lined with simple squamous epithelium on the periphery of the gland as well as large and medium-sized follicles lined with low simple cuboidal, less often squamous epithelium in the center were observed in rats of Group II on days 3, 10, 15 of the experiment. The colloid filled completely or most of the follicle; there were desquamated epitheliocytes and cells with signs of apoptosis. The height of the follicular epithelium of the thyroid gland was smaller than the values of the Group I by 8.44%, 5.52%, 3.86% and 5.53%, 3.70%, 3.25% from 3rd to 15th days; the area of nuclei of follicular cells by 5.22%, 4.93% from 3rd to 10th days and by 5.31% on 3rd day; nucleo-cytoplasmic ratio by 3.11%, 2.29%, 2.28% from 3rd to 15th days and by 4.63%, 3.01% from 3rd to 10th days in the central and peripheral parts of the gland respectively. On the 3rd day, electron-microscopically, thyrocytes were low cuboidal or flat shape, the nucleus had tortuous contours and accumulations of heterochromatin under the karyolemma and in the karyoplasm. The cisternae of the rough endoplasmic reticulum were collapsed or had small slit-like spaces. Single lysosomes and secretory granules in the apical part of the cells and short microvilli were visualized. Conclusion. The application of a defect in the tibiae of rats is accompanied by morphological changes in the thyroid gland from the 3rd to 15th days and then organ adapts to the trauma by the 24th and 45th days.