Relationship of Epidermal Melanocytes and Langerhans Cells with Epidermal Cambial Cells

Studies of mouse ear epidermis showed that proliferative activity of basal epidermal cells has two active and two passive phases throughout 24 h. Active phases consist of two subphases: long (proliferation of cambial cell descendants) and very short (cambial cell proliferation). Cambial cells proliferate at the boundary between active and passive phases; this results in an increase in the counts of epidermal melanocytes and Langerhans cells resultant from division of epidermal cambial cells. The count of Langerhans cells almost 2-fold surpasses melanocyte count, because melanocytes gradually transform into epidermal basal cells.