ABSTRACT
Anaerobic fungi indigenous to the rumen are a part of the fiber-degrading population in this ecosystem. In studies of the ultrastructure of plant cell-wall degration, several methods have been used to evaluate the activity of the anaerobic fungi. Microscopic studies using histochemical stains for lignin have provided information on the anatomy and structure of plants used as substrates for microorganisms. The mestome sheath and xylem of leaf blades are generally more resistant to biodegradation than the sclerenchyma. While often the sclerenchyma is eventually totally degraded, the mestome sheath and xylem are invaded by fungal filaments and degraded in few sites, resulting in an only partially degraded plant wall. Flow of feed particles from the reticulorumen has been reported to be the major process controlling both intake and nutritive value of forages. The colonization of exposed areas of plants by anaerobic fungi is accompanied by invasion of tissues by rhizoids or rhizomycelia, resulting in degradation of plant walls.
