1118 RADIATION BIOLOGY 



On the other hand, interstitial gland cells show little if any effects of 

 such an exposure, although these glands gradually decrease over some 

 months and imperceptibly disappear, owing to failure of new cells to 

 develop from corpora lutea. Interstitial cells give rise to cords and 

 "glands." Some also may develop as ingrowths from surface epi- 

 thelium. It should be noted that the interstitial glands, although 

 prominent in the ovaries of rodents, are inconspicuous and may even be 

 absent in the human ovary. 



The corpora lutea are not affected by doses which destroy ova and 

 growing follicles. Indeed, irradiation a few hours after copulation does 

 not hinder development of corpora lutea, although such corpora lutea 

 degenerate early. It has been reported that 500 to 1300 r administered 

 before ovulation has no effect on development of corpora lutea, while 

 after larger doses (1300 to 1800 r) small corpora lutea develop but their 

 secretion does not maintain an endometrial reaction for more than 6 days 

 (Lacassagne and Gricouroff, 1941). In any event, an amount of irradia- 

 tion which destroys all developing follicles will cause failure of corpora 

 lutea to develop. 



Although 600 r produces only minimal changes in the rat, most ova are 

 destroyed at 1600 to 1800 r, while sterilization requires 3000 r (Lacassagne 

 and Gricouroff, 1941). However, total-body irradiation of rats with 

 600 r produces great degenerative changes in the ovary, there being 

 practically no intact ova at any stage later than 2 days, although a rare 

 corpus luteum but no ova may be found after four months (W. Bloom, 

 1948d). The primitive ova of the mouse are exceptionally sensitive to 

 irradiation (Murray, 1931 ; Schugt, 1928). A dose of 54 r destroys many 

 follicles, and doses of 140-150 r produce histological sterilization. 



Daily irradiation with 8.8 r of y rays per 8-hour day produces apparent 

 sterilization of the mouse ovary at four months, with 4.4 r per day at 

 eight months, while with 1 . 1 r per day there are still some growing follicles 

 at sixteen months (Eschenbrenner, 1946; Spargo et al., 1951). 



The ovary is sensitive to only some of the radioactive isotopes, pre- 

 sumably because of the failure of many others to localize in the organ. 

 Radium and plutonium in small doses produce marked degeneration in 

 the ovaries of both mice and rats (W. Bloom, 1948d). 



The columnar epithelium of the oviduct and uterus is much less sensi- 

 tive than the stratified squamous epithelium of the vagina. In uteri of 

 rabbits exposed to 2000 r shortly after birth, all coats of the uterus show 

 some degeneration in a few hours and the organ atrophies (Gricouroff, 

 1930). But starting with the fifth day, mitoses reappear and the organ 

 continues to grow like that of controls, although regression of the ovaries 

 persists. 



It is noteworthy that the male keeps its secondary sex characters after 

 irradiation (Ancel and Bouin, 1907) whereas the whole female sex appa- 



