1128 RADIATION BIOLOGY 



sensitive to irradiation. Presumably this is in comparison with other 

 glands. Systematic studies in laboratory animals seem to be lacking. 



Liver. The liver is markedly radioresistant, although there are reports 

 of minor cytological changes. The most extensive and closely spaced 

 work as to time intervals and dosage is by Pohle and Bunting who 

 exposed the livers of adult rats to 600 to 2500 r at 100 and at 140 kv and 

 studied them at daily intervals for a month. Necrosis was not seen in 

 any liver. Minute cytoplasmic hydropic and fatty changes have been 

 reported, including temporary atrophy of liver cells, but such changes 

 may not have been due to irradiation. Hepatic cells may become 

 necrotic after a dose of 1880 to 5250 r of unfiltered X rays to the exposed 

 liver of dogs (Bollinger and Inglis, 1933) and after intravenous thorotrast, 

 which lodges in Kupffer cells. 



An unusual change results from the persistence of plutonium and 

 yttrium in liver (Rhoades, 1948a). Enormous liver cells with budding 

 nuclei are present after some months, and many of the dividing nuclei are 

 clearly polyploid. Irradiation of regenerating liver in rats likewise causes 

 marked chromosomal aberrations (Brues and Rietz, 1951). 



Gall Bladder and Biliary Passages. No changes were found in the 

 biliary epithelium after 2500 r of X rays (Pohle and Bunting, 1932). The 

 few who have examined the gall bladder believe it is definitely more 

 resistant than the intestine. 



Pancreas. Both exocrine and endocrine portions of the pancreas are 

 markedly radioresistant. The hypoglycemia reported after irradiation 

 of the pancreatic region is probably not due to effects on the pancreas. 

 The claim that irradiation of exteriorized portions of the pancreas in 

 rabbits causes degeneration of the organ with 750 r and scarring after 

 1000 r (Seino, 1937) is not consonant with the other reports in the litera- 

 ture. In our own experience with 800 r total-body irradiation (200 kv) in 

 rabbits and 1000 r in chickens there is no effect. 



URINARY SYSTEM 



Kidney. Total-body irradiation of rabbits and rats with 800 or 600 r 

 of 200-kv X rays does not produce visible renal changes (W. Bloom, 

 1948c), although there are contradictory reports in the literature. On 

 the whole, it seems that doses higher than 2000 r are necessary to produce 

 damage to the nephron. The proximal convolution is reported to be the 

 most sensitive portion, and with doses above 3000 r vascular damage 

 produces secondary renal effects (Stafford L. Warren and Whipple, 1922). 

 It is also claimed that the kidney is more sensitive than muscle (Des- 

 jardins, 1924). 



Radioactive isotopes lodging in the kidney, with the possible exception 

 of radium, have not been found to produce renal damage. 



