The migration of sebum and suint components along wool fibres of Merino sheep

It has been shown that isotopically labelled sheep wool wax is carried passively along the wool fibre as a band by growth of the wool, and that it does not flow along the fibre to any large extent during experiments of several months. This supports the view that the function of sebum, in mammals in general, is to protect the hair (wool) fibre and the condition of the coat, and contrasts with the reported rapid spread of sebum over the human skin surface. It also seems unlikely that wax lost from the fleece during exposure to rainfall is replenished with sebum freshly secreted onto the surface, since sebum does not migrate. Two methods were used to obtain labelled wax, direct application of labelled cholesterol to the skin surface and intradermal injection of labelled sebum substrate. Prior washing of the wool with detergent showed that wax already on the fibre was not the cause of the observed lack of flow of newly formed wax. Isotopically labelled suint components were also carried passively by wool growth. It is unlikely that wax is transported to any extent by suint in the wool; this is in contrast to the suggested role of sweat in facilitating the spread of sebum over the human skin surface. Some spreading of radioactive wax and suint bands was noted however, possibly because of diffusion and mechanical disturbance of the wool.