A freeze-fracture study of the digestive tract of the parasitic nematode Trichinella

Freeze-fracture preparations of the esophagus and intestine of larvae and adults of the nematode Trichinella spiralis illustrate the distribution of intramembranous particles in membranes of a number of cell types, and several specializations were found. Esophageal glands are prominently linked by gap junctions, but gap junctions were not found between intestinal cells. Muscle cells of the esophagus have rectilinear arrays of particles, thought to be points of adherence of the muscles to the esophageal epithelium. Clusters of particles are associated with these arrays and particle-free areas (probably Z bodies) also occur. Intestinal cells have small particles in their microvilli, large particles in the cells' apical membranes, and intermediate size particles, similar to membranes of other cells, in the lateral and basal membranes. Apical smooth septate junctions and tricellular junctions occur between intestinal cells.