Changes in Wool Follicles of Sheep following Administration of Dexamethasone Trimethylacetate

Abstract

Intramuscular injection of 50 mg dexamethasone trimethylacetate produced variable effects on the fleeces of Merino sheep, ranging from an obvious discontinuity in the fleece, due to inhibition of growth of the majority of fibres, to no macros copically observable effect. In the most affected animals, the mitotic activity and size of the follicle bulbs decreased during thefirst five days. Subsequently, fibre and inner roots heath cells with drew from around the dermal papillae and were replaced by cells from the outer roots heaths. Autophagic vacuoles developed in these replacement cells. Regression of follicles proceeded until brush-ends formed on the fibres after 9–15 days. The amount of glycogen decreased in the outer roots heath cells, which exhibited various responses at different levels in the follicles. The proportion of regressed follicles and to some extent the rate of regression were highest in the sheep with the most obvious discontinuity in the fleece. Regeneration of follicles was well advancedin all sheep 29 days after the injection.