Studies of chromosome transfer in human hybridization systems have been hampered by the apparent inability of colchicine to induce micronucleation in human cells as it does in rodent cells. Cultured human cells (D98/AH2) were treated for 20-48 hr with 0.1 μg/ml Colcemid before detached blocked mitotic cells were harvested and thin-sectioned for EM. Approximately 20% of the cells formed clusters of membrane-bound cytoplasmic packets containing condensed chromatin. The remaining 80% whole cells contained closely associated condensed chromosomes surrounded by rows of mitochondria, aggregates of 10-nm filaments, and Colcemid-resistant microtubules. When floating D98/AH2 cells and normal human fibroblasts (Detroit 550) harvested after 20 hr Colcemid treatment were incubated in Colcemid-free medium, a majority attached to and spread on the substrate, and approximately 50-70% were micronucleate. The failure of some human cells to micronucleate under conditions suitable for micronucleation of rodent cells appears related to the inability of these human cells to attach and spread in the presence of Colcemid.
ASJC Scopus subject areas
- Molecular Biology