Histochemical and ultrastructural changes in locally gamma-irradiated rabbit intestine.

The effect of local irradiation of a 50-cm long intestinal segment outside the abdominal cavity in rabbits has been studied. The rabbits were killed at 12, 24, 48 and 72 hours after irradiation. Activities of succinate and lactate dehydrogenase, acid and alkaline phosphatase and thiamine pyrophosphatase were studied histochemically in the irradiated intestinal segment and in the part of the intestine remaining in the abdominal cavity. The same material was studied electron-microscopically. Changes in enterocytes of the intestinal crypts were observed mainly in the mitochondria and in the form of a chaotic distribution of endoplasmic membranes and densely scattered ribosomes. In intestinal crypt cells, irradiation was followed by a depression in the activities of succinate and lactate dehydrogenases and alkaline phosphatase. These changes were related to postradiation damage, not to recovery.