Fig. 1.

Electron micrographs of artificial skin 10 days after treatment; At the artificial skin bottom layer, melanocytes extended multiple dendritic extensions (a: *) acting as a pipe for transport of mature melanosomes to neighboring keratinocytes, which bore cell-to-cell connections via desmosomes (b: arrow and inset picture and d: arrow). Immature melanin is transferred from the perinuclear region to dendritic tips, a maturation site, via the cytoskeletal system (c, e: thick arrow). Four mechanisms of melanin transport have been postulated: (i) direct fusion of melanocytes and keratinocytes and (ii–iv) keratinocyte phagocytosis (c: inset picture, e) of (ii) membrane-bound vesiculate melanosomes (a) (iii) exocytosis of melanin cores from dendritic tips (a, d), and (iv) dendritic tips