A multiple technical approach to the study of apoptotic cell micronuclei

Apoptotic micronuclei have been studied, in different cell types, from a mo rphologic and functional point of view. Conventional electron microscopy, i n various staining conditions, selective cytochemistry for DNA, and freeze fracture for the analysis of chromatin fiber organization and size were per formed. In situ TdT and Pol I immunofluorescent techniques were carried out to detect double- and single-strand DNA breaking points by confocal laser scanning microscopy. Apoptotic cell ultrathin cryosections were also perfor med and were analysed by field emission in lens scanning electron microscop y. Double/single strand massively cleaved DNA was detected in micronuclei, with a highly supercoiled, uniformly packed, very dense arrangement.