A COMPARISON OF MODE OF ATTACHMENT AND HISTOPATHOGENICITY OF 4 TAPEWORM SPECIES REPRESENTING 2 ORDERS INFECTING THE SPIRAL INTESTINE OF THE NURSE SHARK, GINGLYMOSTOMA-CIRRATUM

This study was undertaken to compare 2 species of Tetraphyllidea and 2 species of Trypanorhyncha with regard to the relationship between attachment structure morphology, mode of attachment, and tapeworm size, to damage al the sites of attachment in the Atlantic nurse shark, Ginglymostoma cirratum. Regions of the spiral intestine with worms attached were removed from 8 nurse sharks and sectioned according to conventional techniques. Sections of 5-50 specimens of each tapeworm species were examined. Regions of the spiral intestine devoid of worms were processed for characterization of the normal mucosa. The normal mucosa was found to consist of a folded surface covered with round-to-oval primary mucosal crypts. In the first 7 or 8 chambers of the spiral intestine the mucosal surface was thrown into secondary folds, forming ridges and secondary crypts. The primary mucosal crypts were lined with a single layer of columnar epithelium resting on a basement membrane. A highly cellular lamina propria and submucosa were found between the crypts and the muscularis mucosa. The small tetraphyllidean Pedibothrium brevispine was found with its scolex lying within the primary mucosal crypts with its hooks embedded in the basement membrane. Epithelial denudation was evident. The large tetraphyllidean Pedibothrium globicephalum was found with its bothridia engulfing large portions of the mucosa and its hooks embedded into the lamina propria. It was associated with moderate to severe mucosal necrosis. The small trypanorhynch Prochristianella tenuispine was found lying between the mucosal ridges in the secondary crypts with its tentacles either penetrating the epithelium, or occasionally, the lamina propria. The large, spiniform microtriches of the scolex often were found in contact with the mucosal epithelium. Little necrosis or inflammation was associated with this species. The large trypanorhynch Grillotia similis was found with its bothridia engulfing large portions of mucosal tissue. The tentacles of this species were embedded deep in the submucosa. The scolex was associated with moderate mucosal necrosis, but no inflammation was seen. No specimen of either trypanorhynch species was seen with its tentacles entirely everted. In general, large tapeworms, regardless of order and therefore scolex structure, were associated with greater mucosal damage.