Ultrastructure of the scolex of Orygmatobothrium schmittii (Cestoda: Phyllobothriidea)

The ultrastructure of the scolex of Orygmatobothrium schmittii (Cestoda: Phyllobothriidae) was studied using histochemistry, scanning, and transmission electron microscopy. The central bothridial structure resulted in a glandulomuscular organ formed by a mass of syncytial glands and radial muscles, with glycoprotein secretions potentially adhesive. Among the sensory receptors found on the scolex, a particular type was found surrounding the glandulomuscular organ, which might be related in the regulation of the secretions. The internal structure of the microtriches revealed a diversity of configurations according to their morphotype and distribution on the scolex. Microtriches with larger caps are thought to be useful for attachment purposes. In addition, the thick bounding membranes of the attachment organs and the circular musculature in the bothridia, seem to aid to the attachment of the scolex to the mucosa of the host. The ultrastructure of the microtriches, glandulomuscular organ, sensory receptors, bothridial musculature, and bounding membranes reflect the adaptive specialization of the scolex for attachment to the host. Morphology of these structures is discussed in cestodes.