The structure and function of the adhesive organ in strigeid trematodes

Abstract

A short account of the biology and life-cycle of Diplostomum spathaceum is given.The morphology of the forebody is described in some detail. The lappets are well developed and function as organs of attachment as well as being reservoirs for the secretion from the forebody gland cells. The adhesive organ is variable in form and the muscles facilitating the movements are described in detail. Pressure changes in the excretory system are thought to assist in evaginating the adhesive organ.The histochemical tests gave the following results. The phosphatases present in the adhesive organ and the forebody gland cells are of the acid variety, the alkaline phosphatase is only present in the cuticle, traces of it occur in the lappets and forebody gland cells. No leucine aminopeptidase activity was observed. The esterase present is either a pseudocholinesterase or a non-specific B-esterase. The presence of RNA is confined to areas of enzyme formation.The in vitro studies confirmed the absence of alkaline phosphatase and the presence of acid phosphatase and esterase in the forebody. They also showed a secretion of acid phosphatase and esterase to the exterior of the parasite.Diplostomum spathaceum has very little effect on the host mucosa, but some lysis of the host tissues in contact with the forebody and especially the lappets, is observed. The response of the host to the parasite is likewise very small.The source of nutrients for D. spathaceum is believed to be the contents of the host alimentary tract, host mucus secretions and to a small extent disintegrated host tissues.I am very grateful to Dr D. A. Erasmus for advice and encouragement during this study and to Professor J. Brough for his interest and for provision of excellent working facilities. The work was conducted during the tenure of a Rotary Foundation Scholarship for International Understanding and a grant from Nylands Nation (Helsingfors, Finland).