Examination of a spontaneously transformed aortic smooth muscle cell line. I. Morphological examinations.

Spontaneous transformation was observed of a mini-pig aortic smooth muscle cell line in its 21st passage in vitro. The transformed cells exhibited changed phenotype, heteroploidy and excessive proliferative activity. The initially elongated cells developed a polymorphous essentially polygonal appearance. The longitudinal filaments characteristic of normal cells disappeared and only finely granular double refracting matter was detectable in polarized light. The transformed cells exhibited microvilli in both transmission electron microscopic and scanning electronmicroscopic preparations. The appearance of spontaneous lectin binding in the transformed cells is a sign of altered plasma membrane structure. The possible contaminational origin of the transformed cells was carefully excluded.