Preferential retention of the human chromosome C-7 in human-(thymidine kinase deficient) mouse hybrid cells

On karyotyping human—mouse hybrid cells derived from various parental crosses, we found that if the mouse parental cells were thymidine-kinase deficient, the hybrid clones retained not only the human chromosome E-17 containing the thymidinekinase gene, but a high proportion (82%) also contained the human C-7 chromosome. Other human chromosomes were also found in these clones.