The Early Effects of X-Rays on the Ovaries of the Rat

Abstract

Irradiation of the ovaries with a sufficient dose of x-rays leads, after a certain time, to degenerative changes in these organs (1, 5, 6). Halberstaedter (2), in 1905, found in rabbit ovaries, ten to fifteen days after irradiation, disappearance of graafian follicles and degeneration of primary follicles, the numerous interstitial cells of the rabbit ovary being relatively resistant to x-ray irradiation. As regards alterations in the ovary in the first few hours following irradiation, a diversity of opinions exists. Reifferscheid (7) described alterations in the ovary of the mouse as early as three hours after irradiation. According to him, numerous pyknoses are visible at this time in the cells of the granular layer in the large follicles, which later degenerate and undergo lysis within the follicular cavity; at the same time, the nucleus of the ovule loses its normal configuration. Müller (4), however, has argued that the alterations observed by Reifferscheid cannot be ascribed to the action of x-rays, since similar observations have been made in ovaries of non-irradiated mice and guinea-pigs. On the other hand, certain authors have confirmed the findings of Reifferscheid twenty-four hours after irradiation (3). On the whole, the evidence concerning the early effects of irradiation on the ovary has been based on quantitative rather than qualitative changes. In fact, Reifferscheid (9) himself has recognized that the alterations described following irradiation may also be observed in normal ovaries, but in far less degree. In view of the existing diversity of opinion concerning early lesions of the irradiated ovary, we have carried out histologic examinations of ovaries of normal and irradiated rats with a view to ascertaining whether there is any difference in the distribution of the pyknoses in the follicles. Method and Technic The histologic studies were performed on ovaries of the following groups of highly inbred albino rats. Control group: 4 rats. Experimental groups: Rats irradiated with 50 to 2,000 r. (a) Seven rats, irradiated in the region of the abdomen, the ovaries being exposed directly to the action of the x-rays. (b) Two rats, irradiated in the region of the cephalothorax, the ovaries being protected from direct exposure by means of a lead plate. (c) Two young rats, irradiated totally. The radiation was delivered from a Machlett therapy x-ray tube, operated on a multivolt apparatus at 150 kv., 4 ma., A1 0.5 mm., distance 30 cm., 100 r/min. The animals were killed four hours after irradiation. Ovaries were fixed in Bouin's fluid and sectioned after embedding in paraffin. The sections were mounted on slides in complete series and stained with iron hematoxylin (according to the method of Masson) and eosin. Microscopic preparations were examined in series so as to obtain a complete picture of each follicle, including the ovule and its nucleus.