Ultrastructural Studies of Surface Features of Human Normal and Tumor Cells in Tissue Culture by Scanning and Transmission Electron Microscopy

Human tumors of a variety of histopathologic types have been established in tissue culture. The surface features of these cell lines were investigated by scanning electron microscopy (SEM) with the use of new techniques for specimen preparation. Tumor cells demonstrated striking degrees of surface activity with numerous microvilli, filopodia, blebs, and ruffles. Intercellular contacts were also prominent in cultures of most solid tumors observed by SEM. At low cell density, normal human fibroblasts exhibited some surface features such as microvilli and blebs, but at higher cell density they lacked extensive surface modifications. By transmission electron microscopy (TEM), the cytoskeleton of normal fibroblasts was shown to be well organized, with parallel orientation of microfilaments, filaments, and microtubules. These structures were also in tumor cells, but they lacked the degree of organization of fibroblasts. Desmosomes were readily demonstrated in normal fibroblasts and carcinoma cells in culture but not in sarcomas, melanomas, or tumors of neural origin. These studies have provided the first correlative SEM and TEM analyses of solid human tumor cells of diverse pathologic types in vitro.