The viability and capacity for further division, following tripolar mitosis, of cells of a murine ascites carcinoma in vitro

This paper records the viability and capacity for further mitosis in vitro of cells of an ascites subline of a naturally‐occurring murine epithelioma following their rare tripolar mitosis. Under the conditions of these experiments it was found that the cells resulting from tripolar mitosis could be uninuclear cells only, one uninuclear and one binuclear cell, or a single trinuclear cell depending upon the degree of success of cytoplasmic cleavage. When uninuclear daughters only were formed, they were not seen to divide further. When one uninuclear and one binuclear cell were formed, the uninuclear daughter was seen to divide further, apparently normally, up to a maximum of six further cell generations, while the binuclear cell could form two uninuclear cells at its next mitosis which were themselves seen to divide, apparently normally, for up to two further cell generations. In addition, cells underwent complex sequences of variance involving bipolar and tripolar mitosis, the resulting cells of which were usually viable and might, in some cases, be seen to undergo further, apparently normal, mitosis. It is proposed that these mechanisms lead to viable heteroploid cells in a tumour‐cell population, and the relevance of these findings to the initiation of new stem cell lines is briefly discussed.