CELL-SUBSTRATE ADHESION DURING CELL CULTURE . AN ULTRASTRUCTURAL STUDY

Ultrastructural investigation of cell-substrate interactions has been undertaken by growing longterm mouse embryo cell strains on Nucleopore polycarbonate filters, a substrate which permits in situ processing for electron microscopy. Nucleopore filters have a smooth surface, a rough surface, and discontinuities in the form of pores. Close attachment of the cells to their substrate is limited to circumscribed areas of variable dimensions, and the basal surfaces of the lowermost cells have large areas lying a substantial distance from the substrate. In areas of closest apposition of cells to substrate, a minimal gap of approx. 100 Å occurs between the plasmalemma and the substrate surface. Cells grown on the rough surface have some zones of close apposition which exhibit marked conformity to the irregular form of the substrate. In other areas, segments of very close apposition occur without any substantial conformity. Most frequently, cells pass over pores without any alteration in their structure. Occasionally, bowing away from pores occurs. More frequently, cytoplasmic projections penetrate the filter pores. © 1969.