Abstract
Cell cultures of adult rat liver produced two distinct morphologic cell types: epithelial cells polygonal in shape and growing in nests of closely apposed cells, and fibroblast cells stellate in shape with little cell-cell contact at low density growth, but aligning in parallel arrays at high density. These two morphologic variants displayed dramatic differences in histochemically demonstrable 5'-nucleotidase activities. Fibroblast cells exhibited great activity throughout the cytoplasm with no concentration of activity in the cell membrane. The lesser activity in epithelial cells was concentrated on the cell membrane. The importance of this finding to the interpretation of data derived from experiments with whole liver homogenates is discussed.