Attachment and detachment of human epidermal melanocytes

Human epidermal melanocytes can leave their basal position following topical application of sodium lauryl sulphate. They thereby undergo changes which strongly indicate that the dense plates along their cytomembrane constitute a mechanism for attachment to the basal lamina. These detached melanocytes move rapidly to, or are transported to, more superficial levels of the living epidermis. They are probably not desquamated, but disintegrate within the stratum spinosum. It was remarkable that one melanocyte was found that broke the basal lamina, showing that melanocytes are capable of migrating, under certain conditions. A special fixation method which exposes the cytomembranes and allows the demarcation of cells and their finest cytomembrane protrusions was used to demonstrate that keratinocytes often bulge into the innermost spinous layer and become attached to the basal lamina only via more or less thin cytoplasmic protrusions. This is in contrast to the routine textbook description of a basal layer that consists of a strict single row of cuboid or columnar keratinocytes.