Abstract
Surface ultrastructure of the bovine rumen mucosa was observed by the scanning electron microscope. The luminal surface was divided by the primary and secondary grooves, which run more regularly in the anterior pillar than in the rumen papillae. The boundaries of the horny cells in the stratum corneum were indicated by narrow lines of cell membrane devoid of any projections. Numerous granular or fold-like projections were noted on the cell surface which apparently originated from the thickened cell membrane of keratinizing horny cells. The type and density of these projections varied from cell to cell. As for the surface ultrastructure, no prominent difference was found after four different fixations. Colonies of a ruminal bacteria, probably of diplococcus type, were noted on the horny cell surface. The presence of the numerous projections provided extensive surface area to the rumen mucosa. This suggested that they are an important part of the absorptive apparatus in the rumen mucosa.
