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Coat colors are determined by melanin (eumelanin and pheomelanin). Melanin is synthesized in melanocytes and accumulates in special organelles, melanosomes, which upon maturation are transferred to keratinocytes. Melanocytes differentiate from undifferentiated precursors, called melanoblasts, which are derived from neural crest cells. Melanoblast/melanocyte(More)
Mammalian melanins exist in two chemically distinct forms: the brown to black eumelanins and the yellow to reddish pheomelanins. Melanogenesis is influenced by a number of genes, the levels of whose products determine the quantity and quality of the melanins produced. To examine the effects of various coat-color genes on the chemical properties of melanins(More)
In order to clarify the time of onset of the differentiation of epidermal melanoblasts and melanocytes in C57BL/ 10J mice, pieces of skin were excised on various days after gestation and subjected to the dopa reaction and to the combined dopa- premelanin reaction. Cells positive to the combined dopa- premelanin reaction ( melanoblast -melanocyte population)(More)
A high frequency of X-Y chromosome dissociation (95%) was found at first meiotic metaphase (MI) in spermatocytes of interspecific hybrids between laboratory mice, C57BL/6J (BL/6) and Mus spretus, compared with an X-Y dissociation frequency of only 3-4% in parental mice. The X-Y dissociation in F1 hybrids occurred before diakinesis rather than as a(More)
The number of melanocytes positive to the dopa reaction in the epidermis was shown to increase after newborn mice were injected with alpha-MSH or DBc-AMP. The agents seemed to induce the initiation of melanogenesis in the pre-existing melanoblasts. Electron-microscopic observation also demonstrated that alpha-MSH induced not only maturation of melanosomes(More)
Melanocytes characterized by the activities of tyrosinase, tyrosinase-related protein (TRP)-1 and TRP-2 as well as by melanosomes and dendrites are located mainly in the epidermis, dermis and hair bulb of the mammalian skin. Melanocytes differentiate from melanoblasts, undifferentiated precursors, derived from embryonic neural crest cells. Because hair bulb(More)
Using the epidermis-specific cytokeratin 14 promoter to deliver HGF exclusively from epidermal keratinocytes, we have examined the potential of hepatocyte growth factor (HGF) secreted from the normal environment to control morphogenesis. The transgenic mice displayed a significant increase of the number of melanocytes and their precursors in embryos(More)
The levels of tyrosinase activities, tyrosinase cross-reacting material (TY-CRM), and tyrosinase mRNA were determined for skins from five congenic strains of mice (Mus musculus) with different coat colors. The dopa oxidase activity and melanin formation activity were directly proportional to the abundance of TY-CRM in all of the mutants. The levels of the(More)
  • T Hirobe
  • 1995
Melanocytes characterized by their tyrosinase activity, melanosomes and dendrites locate in the basal layer of epidermis and hair bulb in the skin of mice. Melanocytes differentiate from undifferentiated melanoblasts derived from embryonic neural crest. Melanocyte-stimulating hormone plays an important role in the regulation of the differentiation of mouse(More)
  • T Hirobe
  • 1982
In the dorsal epidermis of both C57BL/10J and C3H/He mice, the number of melanocytes positive to the dopa reaction increased from birth to 3 or 4 days of age, and then gradually decreased and disappeared by 30 days of age. However, the number of melanoblasts plus melanocytes positive to the combined dopa-premelanin reaction remained constant until 3 or 4(More)