Ageing of chick embryo fibroblasts in vitro. II. Relationship between cell proliferation and increased multinuclear cells.

The cell lines of chick embryo fibroblasts obtained from different embryos were sequentially cultivated and relationship between growth potential and increased multinuclear cells was examined. During ageing in vitro multinuclear cells increased with decreasing growth rate. Their percentage in the senescent cell populations reached 11--15% when the cells stopped growing, and 20--25% just before the cultures died out. This phenomenon may be useful as a parameter for cellular ageing. Most of the multinuclear cells were binucleates. The mean cell volume of the cells also increased through their lifespan with a sharp rise at the latest passages.