Dependence of cellular surface area on growth density of 3T3 and SV40-3T3 cells.

The cell surface areas of 3T3 and SV40-3T3 cells both for suspended and for flat cells growing on the culture substrate have been determined in dependence on growth density. The surface areas of flat 3T3 and SV40-3T3 cells turn out to be independent of growth density over a wide range. For 3T3 cells the surface area of flat cells compares well with that determined by Collard and Temmink for suspended 3T3 cells taking the surface area of their coverlayer of microvilli into account. This indicates that upon suspension of flat 3T3 cells the surplus surface area is disposed of in the form of microvilli. For SV40-3T3 cells we obtained a surface area of flat cells which differs by a factor of about two from that of suspended cells as determined by Collard and Temmink including the surface area of microvilli. Microscopical diameters and electrical ("Coulter") volumina of suspended 3T3 and SV40-3T3 cells depend only little on cell density in the range investigated.