An Analysis of Feather Color Pattern Produced by Grafting Melanophores during Embryonic Development

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Abstract
Grafting melanophores from one embryo to another of a genetically different breed of fowl or species of bird has furnished a means for getting at the role that the donor melanophore and host feather germ plays in the control of feather color pattern. The color pattern produced in the host feather is in accord with the genotypic composition of the donor melanophore. Thus, Barred Rock melanophores produce a barred pattern in non-barred host breeds (N. H. Red, White Leghorn and Black Minorca). Those from a [male] donor (1 gene for barring) produce a darker colored host feather than those from a [female] donor (2 genes for barring). Similarly, melanophores from [male] and [female] embryos (sex of donor ascertained after hatching) of the F1 hybrid (R. I. Red [male] X Barred Plymouth Rock [female]) produce respectively barred and non-barred contour feathers irrespective of the sex of the host. In the production of pigmentation pattern the melanophore is shown to have a specific innate reaction capacity responding to specific physiological conditions within the individual feather germ. The barred melanophore responds to an inherent rhythmic activity of the feather germ, the pattern actually formed being dependent upon the growth rate peculiar to the individual feather germ. In a rapidly growing host feather, i.e., some flight feathers, the feather is almost wholly black, only traces of alternating white bands showing in the shaft. In a slow growing breast feather the alternating bands of white and black are very distinct. Similarly, the pattern produced in White Leghorn host feathers by guinea melanophores varies greatly with the rate of growth and the position of the feather on the wing and breast, ranging from one which has no resemblance to a barred pattern to one which is typically barred. On the other hand, a Black Minorca melanophore is so constituted that it does not respond to the inherent rhythmicity and differences in growth rate of the feather germ.