328 D. SLADIC-SIMIC, N. ZIVKOV16, D. PAV1(5, AND P. N. MARTINOVITCH 



expression in the F^ and F2 generations. Having this in mind we decided 

 to inckide in our studies on the ovaries the effects of sub-sterilizing doses 

 as well. 



In order to determine the effects of X-rays on the fertility of female rats 

 irradiated on 8th, 17th, and 90th day post-partum, the animals were exposed 

 to total-body irradiation of 400, 200 and 100 r imder the following conditions: 

 200 kV, 14 mA, 0-5 Cu, with a dose-rate of 42 r/min. Three months after the 

 exposm'e they were caged with male rats and their fertility was observed. 

 The results are shown in Table I. 



Table I 



Eight-day-old rats exposed to a dose of 100 r became sterile 3 months after 

 the exposure. Doses of 200 r and 400 r respectively are necessary to produce 

 steriHty in female rats 17 days and 3 months old. 



Changes in the ovaries of rats irradiated with a smaller dose of X-rays 

 were the subject of a special study. 



Eight-day-old female rats were exposed to doses of 50 r and 100 r whole- 

 body irradiation. These rats were sacrificed when 17, 24, 42, 46, 48 and 50 

 days old. The ovaries were fixed in Bouin's fluid, cut into sections 6 microns 

 thick and stained with haematoxylineosine. In the serial sections of both 

 ovaries the primary oocytes and the growing follicles (including the oocytes 

 with a layer of cuboidal granulosa cells and all larger foUicles) were counted, 

 by the method of Mandl and Zuckerman (1951). A separate count of follicles 

 exceeding 180 A in diameter was made in every fifth section and on this basis 

 the total number was calculated. The number of mitotic divisions in granulosa 

 cells was estimated by counting their number in every fiftieth section. The 

 volimies of the ovaries were also computed. The mean values were obtained 

 from 5 rats for each estimation. The results for 17- and 24-day-old animals 

 are given in Table II. The late histological changes were followed in rats 

 of the age of 42, 46, 48 and 50 days. For each age mentioned we sacrificed 

 one rat irradiated with 50 r, one irradiated with 100 r and one control 

 (Table III) 



