The effects of the E alleles upon melanocyte differentiation in the fowl.

Abstract

The time of melanocyte differentiation in embryos and regenerating adult feathers was determined for three alleles at the E pigment locus in the fowl. Melanocytes were identified in dissociated embryonic skin tissue using the dopa reaction. In both embryos and female breast feathers, extended black (E) melanocytes differentiated early and produced eumelanin, while recessive wheaten (ey) melanocytes differentiated significantly later and synthesized pale phaeomelanin. Wild type (e+) melanocytes produced a more intense phaeomelanin and differentiated at an intermediate time. However, melanocytes in the male breast feathers of each genotype differentiated early and produced eumelanin. This suggests that the temporal variation in melanocyte differentiation is related directly to the type of melanin synthesized and only indirectly to genotype. It is suggested that the E allele present interacts with the morphogenetic factors of the growing feather to determine the type of melanin that will be synthesized. The time of observed melanin deposition then becomes a secondary effect of this 'decision', eumelanin being deposited early and phaeomelanins significantly later.