"Spontaneous" neoplastic transformation in vitro: the ultrastructure of the tissue culture cell

The ultrastructure of 11 tumour-producing and 13 non-tumour producing cell lines derived from different organs of young and old C57BL and C3H mice has been examined. In cultures from all organs examined (kidney, lung, bladder, tongue, heart, spleen, prostate, peritoneum and spinal cord) two predominant cell types were found. These cells had morphological characters suggesting that they may have been derived from endothelial cells and vascular pericytes. Cells in 7 11 tumour lines had cytoplasmic glycogen deposits but there were no other morphological differences between tumour and non-tumour lines from young and old mice, or between different transfer generations, or between lines derived from different mouse strains.