Contractility of isolated stratum granulosum cells.

Single cells isolated from the stratum granulosum and observed by phase microcopy were seen to contract upon exposure to asdenosine triphosphate (ATP) in the presence of calcium and magnesium. These cells, mechanically isolated from trypsin-treated epidermis of guinea-pig, man and cattle, had been briefly exposed to glycerol or triton X-100. The treatment with glycerol itself, but not Triton X-100 also induced a reversible contraction of the granular cell. Other keratinocytes showed no changes, nor was contraction observed in granulosum cells pretreated with cytochalasin or colchicine. These single celll experiments support the view that the stratum granulosum contains cells which are myoepithelial in nature.