The morphological characteristics of mouse hair follicles during radiation damage

The epidermis and its derivatives, including hair follicles, as highly radiosensitive structures, serve as markers of the course of reparative histogenesis, which allows assessing the degree of tissue damage and their regenerative potential. The aim of the work was to conduct a comparative morphological analysis of reactive changes in the hair follicles of mouse skin in various experimental models. The object of the study was white outbred male mice aged 12 weeks and weighing 25-30 g. The animals were divided into two experimental groups corresponding to different irradiation models. Mice of the first group (n=20) were irradiated once with an absorbed dose of 14 Gray. Animals of the second group (n=20) were repeatedly exposed to X-ray irradiation of 1 Gray for 30 days, followed by a 20-day period without irradiation (18 Gray in total). Skin fragments taken on the 25th and 50th days were fixed in 10% buffered neutral formalin solution and processed according to the standard method for light microscopy. To count the number of hair follicles per unit area, the method for determining the degree of skin damage was adapted taking into account the phases of mouse hair growth. Visually, skin damage in all experimental animals is characterized by varying degrees of hyperemia and hair loss. In the animals of the first exper-imental model, significant disorganization of epidermal cells and hair follicles is detected. The number of hair follicles decreases by 33.1% compared to the initial value. Epithelial cells of the outer and inner root sheaths are deformed, the cells of the epithelial matrix of the hair are almost not visualized. The degree of damage to hair follicles is 100%. The morphological picture of the skin in mice of the second experimental group is characterized by less pronounced changes, the shape of the keratinocytes of the epidermis and hair follicles is preserved, the degree of one type histogenesis cells heteromorphy expression is reduced. The number of follicles decreases by 24.3% compared to the initial values, and the degree of their damage is 37.8%. The conducted study confirms the primary lesion of the most radiosensitive tissue elements of the skin with the further development of its complex damage. The study of changes in hair follicles showed the clarity and accessibility of assessing the degree of expression of reactive changes in the epithelial structures of the skin.