Electron microscopic study on parakeratotic ruminal epithelium in beef cattle.

Abstract

The ultrastructure or the ruminal epithelium non the rumens or five rat-tened-beef cattle affected severely by gross parakeratosis was reported. In rumen para-keratosis the tonofibrillar bundles appeared in stratum basale, while rough-surfaced endo-plasmic reticulum and ribosome clusters disappeared. The appearance of the bundles instratum spinosum was more pronounced and it was suggested that the keratin synthesismight be complete in these strata and that the rate of post-mitotic aging was much fasterin parakeratotic ruminal epithelium. The retension of nuclei and fibrous network instratum corneum suggested that the disturbance of the activities of Iysosomal enzymes mighttake place in rumen parakeratosis. Lipid droplets were present throughout the epitheliumand they were large and abundant in stratum corneum. The development of extensiveproximal projections of the basal cells indicated that the high intake of concentratesstimulated the increase in cell metabolism in stratum basale.