Morphological assessment of the ovarians after single and fractional local electron iradiation

BACKGROUND: When malignant neoplasms of the pelvic organs are irradiated, healthy ovarian tissues can get into the irradiation area. So, among all physico-chemical factors, ionizing radiation is the most common cause of ovarian failure, which has a negative impact on fertility. Conducting research in this area is especially important in connection with the active introduction of electron therapy in the protocols for the treatment of malignant neoplasms of the small pelvis with the need to find ways to prevent and treat post-radiation ovarian lesions. In addition, one of the main tasks of modern radiobiology is the creation of experimental animal models in order to reveal the mechanisms of radiation exposure with subsequent extrapolation of the results obtained to humans in order to level the side effects of radiation therapy and select optimal doses. AIM: The aim of the study was a morphofunctional assessment of the ovaries after local electron irradiation in single and fractional modes. MATERIALS AND METHODS: Wistar rats (n = 30) were divided into three groups: I — control (n = 10); II (n = 10) — subjected to a single local irradiation with electrons at a dose of 2 Gy; III (n = 10) — subjected to fractional local irradiation with electrons in a total dose of 20 Gy. RESULTS: After a single local irradiation with electrons at a dose of 2 Gy, multiple hemorrhages and a decrease in the number of growing follicles with a discontinuous theca layer, which were unevenly distributed over its volume, were noted in the ovary. A statistically significant difference in the number of follicles was revealed: a decrease in the number of primordial, primary, secondary and tertiary follicles and an increase in atretic follicles. The most pronounced difference in the number of follicles between the studied groups was found in the group of fractional electron irradiation at a dose of 20 Gy: the smallest number of primordial and the largest number of atretic follicles with signs of post-radiation fibrosis. CONCLUSIONS: The most profound damage to the ovary develops after exposure to fractional electron irradiation at a total dose of 20 Gy compared with a single exposure to ionizing radiation at a dose of 2 Gy: a reduced number of follicles, a decrease in the area and thickness of the cortical substance, as well as the thickness of the ovarian tunica, in combination with the growth of the connective tissue.