MERKEL CELL AND NEUROCUTANEOUS SYSTEM

The Merkel cell is an epidermal neuroendocrine cell that can be identi fied by electron microscopy based on its neurosecretory granules or by immunolabeling based on its pattern of cytokeratin expression. Its or igin is controversial but may be epidermal rather than neural. Althoug h its functions have not been completely elucidated, there is strong e vidence that it produces neuromediators, is involved in the perception of mechanical stimuli, exerts trophic and attractant effects on nerve s, stimulates keratinocyte proliferation and differentiation, and play s a role in the spatial organization of the epidermis and epidermal ap pendages.