Ultrastructural modifications of the cell surface and intercellular contacts of some transformed cell strains.

SUMMARY Normal contact-inhibited and transformed cell cultures have been fixed and embedded in situ for an electron microscopic study of the cell surface and intercellular connections. In a number of experiments, ruthenium red was added to the fixa tives following Luft's technic for visualizing the mucopoly saccharide layer on the cell surface. Cultures of normal rat, Chinese and Syrian hamster embryo cells were compared with 5 different strains of transformed cell lines: Chinese hamster cells transformed in vitro by adenovirus 12, Syrian hamster cells transformed in vivo by adenovirus 12, Syrian hamster cells transformed in vivo by SV4O virus, spontaneously trans formed BHK21 cell line, and finally a spontaneously trans formed rat fibroblast strain. Two main observations are re ported: (a) The character of intercellular contacts was changed in the transformed cells. Whereas close junctions and desmo some-like structures are as frequent as in controls, the so-called tight junctions practically disappeared in the transformed cul tures. (b) The ruthenium red layer was considerably increased in all the five transformed strains compared to the normal controls, suggesting an increase of the mucopolysaccharide de posit at the cell surface.