Current Challenges in Understanding the Story of Skin Pigmentation — Bridging the Morpho-Anatomical and Functional Aspects of Mammalian Melanocytes

Melanocytes are specialized dendritic melanin producing pigment cells, which have originated from the pluripotent embryonic cells and are termed as neural crest cells (NCC). The primary locations of these cells are basal layer of epidermis and hair follicles. Besides this, they are also found in the inner ear, nervous system, and heart with spatial specific functions. There are other cells able to produce melanin but of different embryonic origin (pigmented epithelium of retina, some neurons, and adipocytes). Melanocytes of the epidermis and hair are cells which share some common structural features but in general they form biologically different populations living in unique niches of the skin. Ultra structurally, melanocytes differ from each other on the basis of their locations and function. Principal function of epidermal melanocytes is photoprotection and thermoregulation by packaging melanin pigment into melanosomes and delivering them to neighboring keratinocytes. It is unfair to think that melanocytes reap all the glory for their role in pigmenting the skin and providing it critical protection against UV damage. They probably play a significant role in diverse physiological functions and their particular functions in all target places are much wider than the melanin synthesis only. Alternation in any structure and function of these pigmentary cells affects the process of pigmentation/melanogenesis which leads to pigmentary disorders like hyperpigmentation or hypopigmentation.