MEASUREMENT OF FIBER DENSITY AND FIBER-BUNDLES IN THE SKIN OF SHEEP FROM DIFFERENT BREEDS

A procedure for analysing digitised scanning electron microscope (SEM) images of impressions of sheep skin has been developed and tested. Th e new technique for measuring fibre densities and fibre bundles was ap plied to a small number of sheep from the Romney, Border Leicester, an d Suffolk breeds, and in fine-and strong-woolled Merinos. Skin impress ions were taken from small shaved areas of the skin, and fibres in dig itised SEM images of the skin impressions were counted and assigned to bundles. Estimates were made of the density of epidermal follicles, t he proportion of these which branch: the number of fibres (follicles) per bundle, and the proportion of skin left bare of follicles. An aver age distance between neighbouring epidermal follicles, lambda(E), was also measured. lambda(E) was found to be correlated with fibre diamete r. The total density of fibres (follicles) in the animals sampled rang ed from 10 to 100 follicles/mm(2), and fibre diameter ranged from simi lar to 35 to similar to 15 mu m. Despite this wide range. all animals examined were observed to have derived (branched) follicles. The fract ion of epidermal follicles which branched varied from similar to 0.15 to similar to 0.45, and the average number of fibres (follicles) per b undle ranged from 2.2 to 3.8. lambda(E) was used to calculate an indic ator of the fraction of skin which is bare of follicles. This was foun d to be substantial, varying between 0.4 and 0.7. Measurements were al so made using both serial transverse and serial longitudinal skin sect ions. The results obtained with the different techniques were compared .