Polyploid cells in ageing hamster fibroblasts in vitro: possible implication of the centrosome

Fibroblasts from hamster embryos cultivated in vitro present the typical ageing process of other fibroblastic lines, but they also suddenly give rise to giant non dividing cells which could be considered to represent terminally differentiated cells [36]. We investigated the latter mechanism, first by showing that microtubules in these cells depolymerized from the centrosome and not from the cell periphery as in other cells; secondly we analysed the structure of the centrosome on serial sections and found a diminished pericentriolar material; finally time lapse sequence studies of cell division confirmed that this process sometimes aborts giving rise to these giant polyploid cells. As a consequence, what first appeared as a differentiation process is in fact the result of an environmental deterioration which probably reaches a critical level thus creating a catastrophic consequence for the cell.