SEM of of free surfaces of cultured HeLa cells are seen to be covered by large numbers of long slender mircrovilli. Cultured cells are particlarly useful for scanning microscopy. Uncultured cells would escape detection by light microsopy, and appear to be short and relatively sparse in micrographs of thin sections. These are highly responsive to the nutritional state of the cells and vary in abundance in different phases of the cell cycle.
