Non‐keratins of Avian and Mammalian Skin Flakes

Abstract

The human scalp produces horny flakes or scales which, when occurring in readily visible quantity, are referred to as scurf or dandruff (Pityriasis capitis). These scales are cast off from the cranial skin, which, like skin in general, constantly renews its surface. Where there is a dense growth of hair, the skin flakes formed on the scalp are retained, but on the hairless skin they are usually detached and quickly disappear. Similar scales are produced and retained to a large extent by fur-covered mammalian skin in general, and by the feathercovered skin of birds. All skin scales are keratinous in nature and contain, in addition to the insoluble keratin, considerable amounts of water-soluble organic substances, the so-called non-keratins. These skin-flake non-keratins were studied on a number of birds and mammals, excluding man, and were compared with the respective non-keratins of furs and feathers. METHODS.The skin flakes were obtained by immersing and agitating clipped mammalian fur or plucked birds' feathers in ethyl or petroleum ether and filtering the resulting suspension. This washing process releases the fine flakes from the greasy fur or feathers to which they are attached. The skin flakes are collected on filter paper, washed with ether and dried. Frequently they are characterized by acgrey silvery sheen.Skin flakes were also obtained by immersing a sufficiently clean animal wholly or partly in ether. Prior to immersion, the surface of the animal may be cleaned by dry brushing and sponging with ether. Agitating the immersed animal, combing the fur and renewing the ether once or twice increased the yield. This method, which also removes the skin flakes still loosely attached to the akin, appears to be very satisfactory, particularly for small or short furred animals. By evaporating the ether in which the animal has been immersed, the dissolved sebum can be isolated.Ethyl ether is usually preferable to petrol ether inasmuch as it releases the skin flakes more readily and the ensuing suspension filters more rapidly. In the rabbit only ethyl ether is satisfactory, petrol ether releases no skin flakes whatsoever. On the other hand, ethyl ether carries the danger of anaesthetic death for the experimental animal. Skin flakes may be purified by resuspending in ether and filtering. Solid impurities are usually heavier than the flakes and sink to the bottom of the vessel. Hairs still present in the skin flakes may be removed by sieving.

A histochemical study of keratinization in the domestic fowl (Gallus gallus)

“…Soluble amino acids, polypeptides and other substances in feathers have been shown by Bolliger & Gross (1954), Gross (1956) and Bolliger & Varga (1960). It is also known that the amino acid composition of the keratin protein in washed feathers is slightly different to that of hair (Ward & Lundgren, 1954;Blackburn, 1961).…”