The relationship between culture density and the number of microvilli on the cell surface has been studied using BHK21 cells in established monolayer culture. The number of microvilli can be estimated quantitatively by a scanning electron-microscope technique. It can be increased by applying specific antiserum, but whether antibody is applied or not a significant number of cells regularly bear microvilli. This number is characteristic of the culture density. In sparse cultures above a certain minimum density it is relatively high, and in confluent cultures it is much reduced. These results indicate that microvilli may be inhibited by cell contact.
A simple technique for the examination of cell surfaces by shadowing them with a heavy metal and examining by light microscopy has been described. Stained preparations can be examined and photographed initially prior to investigation by this technique. It is suggested that this technique could be used instead of the scanning electron microscope or replica techniques where the limited resolution of the light microscope is sufficient.
Scanning-electron-microscope technique for measuring electrical conductivity: Application to tetrathiafulvalene-tetracyanoquinodimethane
