Cell-to-cell interaction between N-13A ascitic hepatoma cells and normal cells maintained in short-term co-cultures: an optical, transmission and scanning electron microscopical study.

N-13A malignant ascitic hepatoma, induced by 4-dimethylaminoazobenzene in Wistar rats, does not produce distant mestastases when transplanted in vivo. The mixed co-cultures of N-13A tumor cells and several tissue explants of newborn Wistar rats show selective adhesivity between tumoral and hepatic epithelial cells, but not with fibroblast-like cells of nervous tissue, kidney or diaphragm. In short-term co-cultures, N-13A cells in contact with rat hepatocytes prepared by the collagenase perfusion technique, display a selective adherence capacity with the production of abundant microvilli and fingerlike protrusions (microspikes) which are elaborated by the neoplastic cells. Groups of tumoral cells tightly envelop the free surface of the cultured hepatocytes. Tight-junction formations are observed, and immature desmosomes and polydesmosomic systems are also seen between both tumoral and normal cells.