Changes in the ovary of the mouse following exposure to X-rays. Part II.—- Irradiation at or before birth

Abstract

The ovaries of 6 mice jx-rayed in utero and of 30 x-rayed at birth are described. The results confirm those obtained with mice x-rayed when 3 weeks old. Degeneration of oocytes and follicles is followed by 2 successive proliferations from the germinal epithelium in the form of cords. Some of the degenerating follicles produce cysts or corpora lutea atretica. The latter may persist indefinitely but have no effect on the estrous cycle. Of the animals irradiated at birth, 24 were allowed to become adult. Cords of the 1st proliferation constituted the bulk of the ovaries, and those of the 2nd were found in only 11 cases. Follicles were completely absent in all but 1 case. These 24 animals are divided into 3 groups: (1) the cells of the 1st proliferation are small, shrunken, and vacuolated. The estrous cycles are irregular and in some cases prolonged vaginal cornification occurred. (2) The cells of the 1st proliferation are large, healthy, and glandular in character, and somewhat resemble luteal tissue. The estrous cycles were normal and regular. (3) The cells of the 1st proliferation very closely resemble luteal tissue. The estrous cycle was absent or had ceased for at least 36 days previous to being killed. It is concluded that the cells of the 1st proliferation are mainly responsible for the production of estrin and the regulation of the estrous cycle. The production of estrin appears to stop when the differentiation into luteal-like cells attains a certain degree.