RESUMO
Forty female albino rats were divided into 4 groups, 10 rats each. The first group was used as control. The second group received whole body irradiation as a single dose of 9 Gy. The third group was given 9 Gy as a single dose of the liver [right hypochondrium]. The fourth group received a fractionated liver dose of 9 Gy divided into 3 equal fractions with an interfraction time interval of 2 weeks [right hypochondrium]. The animals of the second group were sacrificed 2 weeks after irradiation. One half of the rats in the third and fourth groups were sacrificed after 2 weeks and the other half 3 months after irradiation. Using light [LM] and electron microscopy [EM], various grades of degenerative changes could be seen. It was concluded that hepatocytes may express, under certain circumstances and using EM, signs of early damages. It is not clear, however, that the morphological changes observed by EM reflect a change in clonogenic activity