Unformatted text preview: the non‐neural ectoderm, and following the closure of the neural tube, they become located on the dorsal side of the neural tube. After delamination and migration from the neuroepithelium, these progenitor cells differentiate, committing to several 4 Chapter I – Thesis Overview lineages, including melanocytes, neurons, bone and endocrine cells, smooth muscles and craniofacial cartilage (Figure 1.1.1.B) [37,38]. Figure 1.1.1. Neural crest formation and diversification. A) Schematic representation of the emergence of neural crest progenitors at the boundary between the neural plate (np) and the non‐neural epidermis (epi). Following the closure of neural folds (nf), neural crest cells become located at the top of the closed neural tube (nt), from where migrating neural crest (nc) cells are observed. B) Diagram of various cell types arising from multipotent neural crest progenitors (adapted from ). A subset of neural crest cells (Pax3, Sox10 (SRY (sex determining region Y) box 10)‐
expressing cells) give rise to melanocyte precursors, termed melanoblasts, which are firstly observed in the cells overlaying and lateral to the neural tube. These cells are further characterised by expression of the melanoblast markers Kit (vkit HardyZuckerman 4 feline sarcoma viral oncogene), Mitf (microphthalmia
associated transcription factor) and Dct (dopachrome tautomerase) [12,39‐43]. Melanoblasts expand/proliferate in the migration staging area, before entering the dorsolateral pathway and start migrating towards the developing epidermis [12,44,45]. Upon reaching their final destination in the skin, melanoblasts differentiate into melanocytes, expressing Tyr (tyrosinase) and Tyrp1 (tyrosinase
related protein 1), marking the start of melanogenesis (melanin synthesis) . In prenatal skin, a proportion of melanoblasts become incorporated into developing hair follicles, while others remain located at the border between the epidermis and dermis; the latter are lost in murine post...
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