934 
GENETIC AND BIOLOGICAL EFFECTS OF RADIATION 
Figure 2. — Anatomic relations of Radiation Equivalent Source capsule implanted in the left costo- 
phrenic sulcus of a dog. 
long-term survivors have been studied with 
serial blood studies including chromosome anal- 
ysis; unequivocal changes reflecting radiation 
effects have not been observed. Studies of off- 
spring of RES-bearing parents have not re- 
vealed evidence of radiation damage although 
post natal survival rates for the first 2 litters 
were low, probably due largely to environ- 
mental factors. These offsprings resulted from 
gametes produced by radiated parents, and the 
pups developed in utero exposed to 5-170 
mrem/hr total radiation. 
The three animals which died were studied 
pathologically. One died at three months of 
pneumonia and had no evidence of radiation 
exposure. A second recipient had been exposed 
to 5 months of RES radiation before dying of 
wound infection. Although infection and foreign 
body reaction complicated the histopathological 
picture, some evidence of radiation-induced 
bone marrow suppression in a rib just adjacent 
to the capsule site was found. The most valuable 
pathological study was that of an animal sac- 
rificed 14 months post RES implantation.i*'^^ 
Detailed histopathology revealed no abnormal- 
ities attributable to intracorporeal radiation 
except within 6 mm of the RES capsule. In this 
area, which had been exposed to approximately 
2000 mrem/hr total radiation for 14 months, 
the following changes were seen : Necrosis with 
a halo of leucocytic infiltration, abnormal radia- 
tion fibrocytes, excess fibrosis and hyalinization, 
microvascular abnormalities including abnor- 
mal endothelial cells, endothelial proliferation 
and telangiectasis, and abnormal pulmonary 
alveolar cells and alveolar linings. (Figure 3) 
These changes represented more severe evi- 
dence of radiation effect than seen in the areas 
adjacent to the 24 watt ^sspu source. The latter 
tissue has been exposed to a somewhat lower 
radiation dose rate than the former, but for 26 
instead of 14 months. 
PRIMATE RES-50 MODEL 
The RES-50 radioisotope capsule was de- 
signed to produce neutron and photon dose 
rates roughly equivalent to a 50 watt ^^^Pu 
