Relationship Between Cyclic Changes in the Hair Follicle and Sweat Gland Size in Cattle

Abstract

The morphology of hair follicles was studied in 23 Africander -Hereford crossbred yearlings. Eleven hair growth phases were recognized as a result of work on 2 animals. The piloapocrine units representing each phase were illustrated by tracings. The mean length, diameter, length diameter ratio, and area of sweat glands corresponding to each phase were tabulated and illustrated. Gland size was very significantly influenced by follicle phase. Glands were largest in anagen VI and catagen c and were completely regressed in telogen. The effect of differences in follicle phases on sweat gland size was studied in all 23 animals. The inherent difference between animals in gland size was determined by a comparison of mean gland size for common phases. Actual mean gland size is also influenced by frequency of the various follicle phases. In the present study the contributions of inherent differences and differences due to phase distribution were in the ratio of 3.2:1. Although doubt is cast on sweat gland morphology as the sole criterion of sweat gland activity, the association between hair growth phase and sweat gland size offers a partial explanation of the association between coat character, sweat gland size, and sweat gland activity. These 3 vary together when comparisons are made between breeds or strains, between animals within breeds, between different body regions, and between seasons.