Langerhans' cell-free regions in orthokeratinizing sole-of-foot epidermis of the adult mouse.

The distribution of ATPase-positive Langerhans' cells was investigated in whole sheets of the glabrous sole-of-foot epidermis of the mouse. This completely orthokeratinizing tissue shows distinct morphological differences mainly with regard to the dermo-epidermal junction. Whereas the sharply outlined nodular prominences in the center of each footpad have a heavily undulated dermo-epidermal junction, the epidermal baseline in the surrounding tissue and the region just proximal to the footpad is flat. A dense population of evenly distributed ATPase-positive Langerhans' cells is found in the epidermis which surrounds the nodular structures. A slightly reduced population of Langerhans' cells is located in the epidermis of 80% of the nodules, occasionally showing a concentration in the pronounced epidermal ridges. Twenty percent of the nodules possess an epidermis which is completely free of Langerhans' cells. The results are discussed in view of the current hypothesis on the biological function of Langerhans' cells.