Electron-microscope studies of Fasciola hepatica II. The interrelationship of the parenchyma with other organ systems

Abstract

The structural relationship between cells of the parenchyma and those of the alimentary and excretory systems, and tegument are described.Junctional complexes are formed in areas of close cell apposition. They occur laterally on invaginations of parenchymal processes which are embedded in the epithelial cells of the alimentary and excretory systems, and on flat plaques between parenchymal cells and the tegument.The ultrastructure of the complexes has been resolved and a three-dimensional interpretation is put forward. It is suggested that the complex is a type of desmosome.The findings reported here add support to the suggestion made in a previous paper that the parenchyma may function as a transport system in this fluke.We wish to acknowledge grants from the Wellcome Trust and the S.R.C. for the purchase of an Akashi TRS 50 and an A.E.I. EM 6B electron-microscope respectively. This research and that reported in a previous paper were carried out while one of us (S.S.E.G.) was in receipt of a Training Studentship Grant from the Wellcome Trust.We also wish to thank Mr W. Ferguson and Mr A. Lyness for photographic and technical assistance.