Origin, Proliferation and Development of Vertebrate Pigment Cells-Melanophores and Melanocytes

Skin color in vertebrates predominantly depends on the presence of specialized cells that produce pigment. These special cells absorb or reflect light in a specific way to impart color to the skin and are called as chromatophores. Chromatophores are grouped into melanophores, erythrophores, xanthophores, leucophores and iridophores which largely depend on the pigment they produce. Melanophores are the most important type of chromatophores responsible for dorsal pigmentation in many vertebrates including fishes, amphibians and reptiles. In birds and mammals, melanophores are called melanocytes. All melanophores or melanocytes store thousands of dark brown/black biopolymer pigment melanins, packaged into membrane bound intra-cytoplasmic vesicles called as melanosomes. Melanophores or melanocytes originated from the neural crest cells, induced by several extracellular signals. Melanoblasts, precursor of melanocytes migrate, proliferate, differentiate and spread to their final destination in the basal layer of epidermis and hair follicles, however, distribution of melanocytes varies among different species. The embryonic development of melanocytes offers an opportunity to better understand the concept of vertebrate pigmentation. Thus the present chapter provides siginificant knowledge on the vertebrate pigment cells from origin to different stages of their development.

Keywords: Chromatophores, Epidermis, Melanoblast, Melanocytes, Melanophores, Neural crest cells.