In vitro culture of cells isolate from dimethylnitrosamine-induced renal mesenchymal tumors of the rat. I. Qualitative morphology.

The in vitro morphology of cells isolated from renal mesenchymal tumors induced in rats by a single ip injection of dimethylnitrosamine was followed in short- and long-term culture. The morphology of cells isolated from normal rat-kidney cortex was studied for comparison. Primary tumor-cell isolates consisted of a range of mesenchymal cell forms interspersed between discrete, homogeneous islands of cohesive epithelium-like cells. The latter were presumably derived from renal parenchyma that had been engulfed within the in vivo neoplasm by proliferating tumor cells, since this epithelial component did not survive serial subculture. Established tumor cell lines consisted of a pleomorphic range of mesenchymal forms resembling the descriptions of various cell types in vitro, including fibroblasts, smooth muscle cells, and endothelial cells. A range of mesenchymal cell forms in culture therefore correlated with the heterogeneous histologic nature of the in vivo neoplasm in which fibroblasts, smooth muscle fibers, and endothelium-like cells were also represented. Multinucleate or polymorphonuclear giant cells were characteristic of tumor cell cultures, whereas large, expanded polygonal cells with longitudinal striations were characteristic of normal kidney cell cultures. Some tumor cell cultures were typified by cells with cytoplasmic vacuolation and some by the acquisition of an epithelioid form at high cell density, a change not preceded by islands of cohesive, epithelium-like cells at preconfluent stages.