Observations on the Structure of Cysticerci of Taenia solium and Taenia saginata (Cestoda: Taeniidae)

The author reports a detailed histological study of the cysticerci of Taenia solium and T. saginata. In spite of minor apparent differences, the structure of the two species is very similar and their specific differentiation cannot be guaranteed when the scolex is not available. The cysticerci of Taenia solium and T. saginata have been described and illustrated by many different investigators. Early workers such as Moniez (1880) studied the gross morphology and some of the histology of both species. Numerous illustrations of sections of cysticerci are to be found in various medical or veterinary texts. In recent years human cysticercosis of the brain caused by T. solium has been studied extensively by Trelles (1952), who also described in considerable detail some of the tissues of the cysticercus. McIntosh and Miller (1960) recorded the gross morphological changes during early cysticercus development of Taenia saginata. Silverman and Hulland (1961) studied the histology of Cysticercus bovis with special reference to growth rates and host responses. In spite of these and many other careful investigations, the detailed histologic structure of cysticerci of T. solium or T. saginata has not been described, and studies comparable to those by Crusz (1948) on Taenia taeniaeformis have not been published. The purpose of the present investigation is to describe the morphology of fully developed cysticerci of T. solium and T. saginata and to determine whether specific identification of the two species can be made on the basis of tissues other than the scolex. Appreciation is expressed to Dr. J. O. Trelles, San Marcos University, Lima, Peru, and to Dr. K. Nasr-alla Soliman, Veterinary Research Institute, Cairo, Egypt, for supplying some of the materials used in this study; to Mr. Zane Price for preparing the photographs included here; and to Mrs. Nora Liu for technical assistance. MATERIALS AND METHODS Cysticerci of Taenia solium were obtained from human brains, Lima, Peru, and from the muscle of pigs, Los Angeles, California. Cysticerci of T. saginata were collected from cattle in Cairo, Egypt, in the Sudan, and in Los Angeles, California. The material was fixed in 10% formalin or in Zenker's fixative, embedded in paraffin, and sections cut at 7 p. Stains used were Haidenhain's iron hematoxylin, Mallory's aniline blue stain, Mayer's hemalum, Gomori's trichrome, and Davenport's protargol stain. All these were used as described by Voge (1960). Rinehart's modification of Hale's stain (Rinehart and Abul-Hay, 1951) was used for the demonstration of collagen, and Himes' triple stain (Himes and Moriber, 1956) for polysaccharide and protein. All observations were made on fully differentiated, undamaged specimens.