Cytochemical and Electron Microscope Studies on the Pharynx and Intestinal Epithelium of Nippostrongylus brasiliensis

Abstract

Pharynx and intestinal epithelium were studied with various cytochemical methods and the electron microsope. The pharynx possesses the characteristic triradiate lumen and is lined internally with cuticle. Its wall is muscular and myofilaments of two types, about 7 m[mu] and 15 m[mu] in diameter, can be seen in cross section. Besides the myofilaments, large branching mitochondria are present with many cristae. A pharyngeal gland is also present appearing in cross section as a single dense triangular cell, along the ventral margin. Cells of the intestinal epithelium are so large that a typical cross section of the intestine passes through only two or three cells. These show some of the properties of intestinal mucosa, such as a microvillar border, terminal web, and terminal bars at the cell margin. The nucleus is usually situated toward the base of the cell where most of the mitochondria also occur. The mitochondria contain cristae with characteristic triangular or forked apices. The cell also contains endoplasmic reticulum, Golgi apparatus, secretory granules, free ribosomal particles, and glycogen. The presence of a large quantity of ribosomes and also secretory granules in the cytoplasm suggests that the cell is involved in the synthesis and secretion of digestive enzymes. Several additional kinds of inclusion bodies are also present, suggestive of intracellular bacteria and lysosome-like bodies.