Wool follicle arrangement and vascular pattern in the Australian Merino

Abstract

The relationships between blood supply and follicle arrangement patterns were studied in the Australian Merino with the intention of finding means of identifying individual primary follicle groups in new-born lambs and adult animals. It was found that individual primary follicle groups could be identified by using as a guide the blood supply pattern at sebaceous gland level, and that the individual groups were members of a higher unit composed of several groups called "fields". The observed differences in the "field" configuration in individual animals led to the identification of two extreme types of follicle arrangement in the vertical plane, called 'straight' and "tangled". It was also observed that the blood supply pattern in the straight type showed three distinctly recognizable vascular levels: the subepidermal, the mid-dermal net, and the dermal net. The connecting vessels between these three levels and the drainage and supply vessels between the dermal and mid-dermal net had a generally straight course. In the tangled type the pattern was distorted and the mid-dermal level indistinct. The supply and drainage vessels had an oblique and often tortuous course.