HISTOLOGICAL CHANGES AFTER IRRADIATION 1117 



the same in kind as of the externally applied radiations, the extremes of 

 damage are much greater at the LD 50 30-day level for the internally 

 administered substances; corresponding with their localized deposition, 

 the resulting damage tends to be localized. Radium, plutonium, and 

 Zr 93 -Cb 93 appear to be more destructive to the germinal epithelium than 

 Sr 89 , P 32 , Ba 140 -La 140 , and Y 91 . Following very low doses, injury and 

 repair may occur concomitantly, making it difficult or impossible to 

 evaluate the damage. 



After all types of irradiation, external and internal, the stem cells are 

 the most sensitive and the interstitial cells are extremely radioresistant. 

 Except in a few animals after neutron and radium treatment, the Sertoli 

 cells show no significant changes. 



There are but scanty reports on the male accessory organs and passages. 

 They all seem to be relatively radioresistant. 



FEMALE GENERATIVE SYSTEM 



Irradiation of the mammalian ovary causes marked atrophy of the 

 organ and may produce temporary or even permanent sterility if the 

 dosage is high enough (Halberstaedter, 1905; Lacassagne, 1913; Lacas- 

 sagne and Gricouroff, 1941 ; Shields Warren, 1942, 1943). If sterilization 

 is not permanent, there may be a reawakening of sexual activity after the 

 passage of months and even normal pregnancies may ensue. Dependent 

 on and following the changes in the ovary there is atrophy of tubes, 

 uterus, vagina, and mammary gland. 



The sensitivity of the ova and of the attached follicular cells varies 

 with their functional states at the time of irradiation (Lacassagne, 1913). 

 There are unusually marked species differences in sensitivity. The 

 corpora lutea and interstitial cells are relatively very radioresistant. 



Irradiation of the ovaries of a rabbit with 1200 r produces dramatic 

 effects (Lacassagne and Gricouroff, 1941). In primitive ova (surrounded 

 by a single layer of epithelium) the signs of degeneration are pyknosis or 

 chromatolysis and fragmentation of the cell. Debris of ovocytes is 

 phagocytosed by the follicular cells, but these also may degenerate and 

 the whole follicle disappear in 3 or 4 days. However, some primitive ova 

 escape destruction and after five months or more they may begin to 

 develop. When irradiated in the beginning growth phase, first the ovum 

 and then follicular epithelium degenerate within 2 weeks. In irradiated 

 large, growing follicles the first changes are seen in the follicular epi- 

 thelium, but the residue of large ova may persist for months. In mature 

 follicles the follicular epithelium disappears early after irradiation, while 

 the ovum, with more or less visible damage, may persist for some time. 

 There may be hemorrhages in the follicles. Apparently, definitive 

 destruction of all ova may take place with 2000 to 2500 r. 



