Cytogenetic analysis and morphology of malignant nuclear vlimata. The life cycle of malignant cells.

The karyotype of malignant nuclear vlimata (NVs) was investigated with the in situ and chromosomal spreading techniques. NV metaphases were recognised by the head with tail morphology, kept in situ and evaluated by the chromosomal spreading technique. It was shown that malignant NVs were produced by random, uncontrolled meiosis. NVs contain and carry single, hypodiploid, haploid, hypohaploid, hyperdiploid and atypical sets of chromosomes. NVs are unstable parasitic cellular elements, invading the cytoplasm or the nucleus of host cells, extruding and implanting their chromosomes in the host cell upon contact. Within a malignant cell culture, NVs play the role of chromosomal donors and host cells of chromosomal recipients. NVs were identified as episomatic on host cell nuclei or incorporated into host cell metaphases. The observations are discussed in terms of fertilization, viral infection and apoptosis. Comparison of malignant NVs with phytohaemagglutinin (PHA)-activated lymphocytic NVs is provided, as well as the life cycle of the malignant cells as follows: [Formula see text] cells (Logothetou-Rella, 1993). Phytohaemagglutinin (PHA)-activated lymphocytes also produced NVs by meiosis, carrying hypodiploid, haploid and hypohaploid sets of chromosomes (Logothetou-Rella, 1994a). In this study the cytogenetic analysis and morphology of malignant NVs are investigated, using a) the in situ cytogenetic technique, and b) the chromosomal spreading technique.