Factors regulating the multiplication of animal cells in culture

The multiplication of Vero cells in vitro as measured by population doubling time and final saturation density is regulated by the serum concentration in the medium and not by the substratum area available for cell growth. Vero cells at high density deplete the medium of a serum component(s) essential for continued growth. They also display a density dependent response to the removal of serum from the growth medium. At high densities, they continue multiplying longer than at low densities. No difference is noted in these properties among the epithelial cell types: CV-1, BSC-1 and 2 ° African green monkey kidney (AGMK) cells, nor among the fibroblast cell types: 3T3 and SV101. These data are consistent with the model that the growth of most cultured cells is controlled by medium components especially serum growth factors and that no difference exists in this respect between epithelial cells and fibroblasts.