A note on growth patterns of epithelial tumor cells in primary culture.

Mouse mammary tumors were dissociated to single cells. These were seeded in high-serum medium at three different densities. Three different culture morphologies and three different saturation densities of cells resulted. In contrast, embryo fibroblasts cultured under the same conditions grew to the same end point over a wide range of seeding densities. Growth of these neoplastic cells is density regu lated and is markedly different from growth of fibroblasts in culture.