Structural Reorganization of the Thyroid Gland in Males of the Republic of Sakha (Yakutia) Depending on Ethnicity and Climate

Histomorphometric and immunohistochemical analyses showed season-dependent changes in the morphofunctional parameters of the structural components of the thyroid gland in males of indigenous (Yakuts, Evens, and Evenkis) and non-indigenous (Russian and Ukrainians) populations of the Republic of Sakha (Yakutia) in different seasons. External and internal diameters of follicles and area of the colloid in the thyroid gland was higher in non-indigenous than in non-indigenous individuals both in summer and in winter. The height of thyroid epithelium, areas of thyrocytes and their nuclei, and nucleocytoplasmic index of the thyroid gland were lower in men from non-indigenous population in summer, and higher in winter than in non-indigenous inhabitants. Transition of a part of follicular apparatus of the thyroid gland to enhanced activity during winter was less pronounced in indigenous males in comparison with non-indigenous subjects.