Molecular characteristics and site specific distribution of the pigment of the silky fowl

Abstract

Silky fowl, a breed of chicken, is hyperpigmented in its various internal tissues. The pigment was extracted from various tissues of two strains of Silky fowl to determine its molecular structure and internal distribution. Analysis by infrared spectroscopy showed two spectrum patterns of the pigment in Silky fowl; one is from ovary and testis, the other is from periosteum and feather. The difference between the two spectra is possibly due to the sulfur contents of melanin. Especially, the spectra of the pigments from feather and periosteum shared the characteristics of synthesized melanin spectrum in common, which indicates that the melanocytes dispersed in these tissues were functionally the same. According to our quantitative analysis, the tissues examined were classified significantly in the order of the pigment content (p<0.05): periosteum > gonads (ovary or testis) = trachea > or = heart, liver, gizzard, cecum, muscles (Pectoralis and Supracoracoideus) and skin. In addition, the specific regions of embryonic neural crest derived cells, such as cardiac artery and various parts of cephalic tissues, were found to be locally hyperpigmented. These data suggest that hyperpigmentation (fibromelanosis) in Silky fowl chicken occurs in a tissue- and organ-specific manner, which is strongly related to neural crest cell development. It is hypothesized that neural crest cells of the bird, containing melanocyte progenitors, acquire unusual ability to differentiate into melanocytes excessively, and to extend the distribution of their descendant along the destinations of neural crest derivatives.