Electron Microscopic Study of Fused Cells, With Special Reference to Chromosome Pulverization<xref ref-type="fn" rid="FN2">2</xref>

Abstract

Fused cells, induced by Sendai virus in cultured cells of the Chinese hamster, were observed with the electron microscope to characterize their pulverized chromosomes. Consisting of interphasic and mitotic cells, these cells were examined without hypotonic treatment for chromosome analysis. Most of them had no morphological changes in the interphase nuclei, and in rare instances, fused cells contained metaphasic chromosomes and pulverization-like nuclei. These abnormal nuclei were dense masses, consisting of irregular chromatin clumps of various sizes often surrounded by a fragmented nuclear envelope. Occasionally, spindle tubules also were found in association with these abnormal nuclei. Most of these nuclei seemed to be in the prophase or early metaphase stage. Hypotonic treatment may bring out and/or induce chromosome pulverization in the fused cells containing mitotic nuclei and interphasic ones and, thus, may account for the higher incidence of chromosome pulverization observed following such treatment. In addition, the relation of mitosis to chromosome pulverization is briefly discussed.