Separation of newborn rat epidermal cells on discontinuous isokinetic gradients of PERCOLL.

A one-step procedure has been developed for the separation of epidermal cells using PERCOLL (a new colloidal silica medium of low viscosity, osmolarity, and toxicity) for density gradient centrifugation. Newborn rat epidermal cells were dispersed with trypsin-EDTA and separated into 4 fractions in discontinuous isokinetic gradients. The cell fractions were characterized by their appearance in photomicrographs and their distribution by number and size. Preferential incorporation of 3H-thymidine and 14C-glycine, by basal and granular cells respectively, confirmed the identification of cell types. The basal cells, which were collected in the densest fraction (1.090), were the most homogeneous population with a mean diameter between 7-8 mum and showed 98% viability. The granular cells predominated in the least dense fraction (1.023). The intermediate fractions contained spinous cells admixed with the other cell types.