The excretory system ofDiphyllobothrium dendriticum (Nitzsch 1824) plerocercoids as revealed by an injection technique

Abstract

The excretory system ofDiphyllobothrium dendriticum was studied morphologically and functionally. In living plerocercoids, one of the large excretory ducts was injected with latex-based stain. The excretory system was found to consist of a peripheral network of ducts, a central system of two longitudinal ducts, communicating through transverse ducts, a capillary plexus in the scolex and the excretory bladder and pore in the tail. The central and peripheral duct systems were both found to communicate with the capillary plexus in the scolex. In the peripheral network the stain was mainly spread by those contractions of the plerocercoid, which start in the neck region and are propagated through the body. The flow in the central ducts was usually independent of the contractions. Occasional reverse contractions led to a rapid flush in the central ducts. From the peripheral and central ducts the stain was transported out through the excretory bladder and pore. The distributive role of the excretory system is discussed.