Qualitative and quantitative effects on the morphology of the small intestine after multiple daily fractionation

The behaviour of qualitative and quantitative morphologic parameters in rats exposed on the abdomen only to multiple daily fractionation (MDF) of 3 Gy X 2 and 3 Gy X 2 X 2 with 12 h splits was analyzed. Both doses were sublethal. The number of epithelial cells in the crypts and in the whole formation, the mitotic index, and the labelling index appeared to be markedly reduced at early intervals after irradiation. Repair and recovery quickly led to normal morphology. The effects of an 8 Gy single dose were compared with those from multiple fractionations.