On the histology and ultrastructure ofCysticercus longicollis, the cysticercus ofTaenia crassicepsZeder, 1800, (Cestoda, Cyclophyllidea)

Studies with both the light and electron microscope on the bladder wall ofCysticercus longicollishave revealed details of its structure and shown that it contains structures comparable with those of adult cestodes. The structure of the everted scolex of the fully developed cysticercus has also been studied. Development of the scolex and rostellum has been briefly considered and is similar to that ofC. fasciolarisandC. pisiformis. The importance of the tegument in both bladder wall and scolex is emphasised. The rostellar hooks appear first as small cones to which a base is added after some growth has occurred. Mature and immature hooks probably contain keratin. Results of histochemical tests on this and other parts of the cysticercus have been given. Thanks are due to Dr L. G. Goodwin, Director of the Nuffield Institute of Comparative Medicine, London Zoo, for allowing the author to use the EM 6 B and photographic facilities. Dr J. Mahon of Imperial College, London, kindly read the script, gave advice on it and provided photomicrographic facilities. The author is grateful to the Principal and Governors of West Ham College of Technology for general and financial support of the project.