[Pathomorphological and histochemical changes in the liver of rabbits following fractional irradiation with Co-60].

Two groups of experimental animals, each consisting of 12 rabbits, were subjected to local fractional irradiation with cobalt 60. Group I received the total dose of 2580 R during 13 days, group II - 5100 R during 24 days. The effects of irradiation were estimated on the strength of histological examination of the liver immediately and after 7, 15, 30, 60 and 90 days after the last exposition. The histological sections were stained with haematoxylin and eosin, and colour reactions were performed for argentaffine and collagen fibres and for glycogen, neutral fats, alkaline and acid phosphatase, ATP-ase, glycose-6-phosphatase, non-specific esterase and succinic acid dehydrogenase. It was found that the dose of 2580 R is safe for the liver. The effects of irradiation were slight and limited to weak catabolic disturbances in the form of mild steatosis of the liver and of a transient and short-lived fall of glycogen and rise of hydrolytic enzymes. More pronounced and intense changes were observed in the other group of animals. During the early period, the changes were of a retrograde character and were typical of the acute post-irradiation effect. There was necrosis of the walls of the blood vessels, of the epithelium of the bile ducts and of the liver cells, accompanied by a rise in the hydrolytic enzymes and by a considerable fall of the level of glycogen and succinic acid dehydrogenase. During the late period (30-90 days), changes typical of the so-called post-irradiation hepatitis were found histologically.