Abnormality of Down Pigmentation Associated with Experimentally Produced Skeletal Defects of Chicks

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Abstract
When insulin, boric acid or pilocarpine hydrochloride were injd. into the yolk sacs of eggs of Black Minorca fowl at 96 hrs. of development, they produced skeletal malformations and also changes in down pigmentation which were similar for the 3 compounds. There seemed to be a correlation between extent of skeletal abnormality and degree of restriction in black pigmentation, with slight skeletal defects giving lack of black down only in the extremities, whereas with increased skeletal defects, lack of melanin formation often included the head and neck, all of the wings and large areas of the legs. Embryos and chicks which received protective supplements, remained free of skeletal defects after treatment with insulin, boric acid or pilocarpine and also developed normal pigmentation. Nicotinamide was the most effective protective supplement and confirmed the evidence that disturbances of pigmentation and skeletal defects traced back to common metabolic disturbances. It is suggested that damage to neural crest derivatives may be responsible for the syndrome of skeletal and pigmentary abnormalities.