An extended protein coat of some cells in tissue cultures.

A proteinlike substance attached to the surface of separate or marginal cells in coverslip cultures (HeLa, HEp2, RK, M7) has been found by interference and also light microscopy after Fast-green staining. The size, concentration and refractive index of this cell coating, for which the authors have suggested the term "extended cell coat", were measured. Its possible role in the regulation of cell growth and a broader interpretation of the cell border are also discussed.