In human skin, melanosomes are released from melanocyte dendrites and taken directly up by keratinocytes through endocytosis or phagocytosis. Little was known concerning the relationships between the morphology and the melanin content or tyrosinase activities of the melanocytes. In previous keratinocyte and melanocyte co-culture studies, we found that as melanocytes lose their characteristic dendritic structures and adopt fibroblast-like bipolar forms, the cell–cell contact between melanocytes and keratinocytes is considerably reduced, resulting in a reduction in pigment transfer . Our previous two studies suggested that there might be some connections between the dendritic morphology changes and physiological properties of melanocytes . These potential relationships should be further investigated to understand their physiological significances.