A quantitative cytochemical study of isolated epithelial cells of the hamster cheek pouch

1. Dissociation of the hamster cheek pouch epithelium by a method combining trypsin attack and EDTA exposure, yielded a mixture f highly viable isolated cells (basal, spinous, and granular cells). 2. Such heterogeneous cell population was reproducibly separated into 4 fractions by pycnic sedimentation: in order of increasing density, Fraction I and Fraction II predominantly contained cells of the basal layer (93% and 76%, respectively), Fraction III basal, spinous and granular cells in equivalent concentration, Fraction IV mainly granular cells (69%). Horny squamae sedimented at the bottom of the tube. 3. Individual cells of the whole population and those of the population fractions separated by density gradient, were analyzed and charcterized as regards morphology, viability, volume, dry mass, density and DNA synthesizing ability. 4. A positive correlation was found between morphology, dry mass and density of the cells, showing that differentiation occurs by increments in mass and density. The weights of the basal, spinous and granular cells were distributed within ranges well defined and scantily overlapping, and were positively correlated with cell differentiation. Also cell density increased with differentiation degree. On the contrary, volume distribution of the various types of cells showed differences of minor importance, indicating for an increase of solids concentration in the more differentiated cells. 5. DNA synthesis took place only in basal cells, the density of which was generally very low.