File:Schematic drawing of melanocyte development in the mouse..jpg

English: (A) During embryogenesis, melanoblasts emerge in the neural crest at embryonic day (E) 9.5–10.5. These earliest stages of melanoblasts are characterized by the expression of Dct, Kit, Mitf, Pax3, Sox10, and Si. Once arise from neural crest, melanoblasts migrate in the developing dermis toward the ventral midline. Subsequently, at E12.5–13.5, they enter the epidermis where they actively migrate and proliferate to distribute the entire body. In addition to the pre-migratory melanoblast markers, these migratory melanoblasts express several melanosomal proteins including Tyr and Tyrp1. Upon initiation of hair follicle morphogenesis, the melanoblasts enter the newly developing and are segregated into two populations: one locates in the hair matrix where melanoblasts are differentiated into mature melanocytes; and the other colonizes at the putative bulge region, where melanoblasts are restricted in a resting status to become melanocyte stem cells. Melanocytes in the hair matrix express Oa1 and Mcr1 in addition to the migratory melanoblast markers, whereas in the bulge melanoblasts, expression of several melanoblast markers including Kit, Mitf, Pax3, Sox10, Tyr, and Tyrp1 are gradually downregulated. (B) Melanoblast localization during hair follicle morphogenesis. Skin fragments from Dct-LacZ transgenic mice were whole-mount stained with LacZ to visualize melanoblasts in the developing hair follicle. Melanoblasts colonize at the putative bulge region at stage 5–6 of hair follicle morphogenesis, suggesting stem cell specification would take place from stage 5–6 of hair follicle morphogenesis onward.