Proposed Terminology for Wool Follicles in Sheep

THE terminology proposed by Wildman and Carter 1 for hair follicle types in Mammalia has been widely used in studies on sheep, although it is in some respects unsuitable for certain other species 2,3 . However, recent workers 4–6 on the histology of sheep skin have independently extended this terminology, but not always consistently, so that confusion has arisen. To overcome this a unified system of terms and symbols for wool follicles in sheep is here proposed. Based on that of Wildman and Carter, with the major division into primary and secondary follicle types, it provides for a recent contribution to the study of the development of the wool follicle, namely, the distinction between original secondary follicles which arise directly from the epidermis, and derived secondary follicles which arise from them by branching 7,8 .