Dr. Murai Éva szerk.: Parasitologia Hungarica 22. (Budapest, 1989)

The adult form (

T. hydatigena) was obtained from experimentally infected dogs by dehelmintization with 1% arecoline solution. With the aim of tracing possible changes of the surface structure in the course of proglottid development, samples from the neck region and from sexually mature proglottids were fixed and processed separately. For scanning electron microscopy (SEM) small tissue samples were fixed in 6 % glutaraldehyde and postfixed in 5% OsO^. The material was further processed by the method of acetone dehydration and air drying of BARBER and BOYDE (1968). For the transmission electron microscopic study the samples were fixed in 4% glutaraldehyde, then in 1 % OsO^, and embedded in Durcupan according to the standard method. The observations were carried out with a JEM 100 B scanning and transmission electron microscope. RESULTS Larval form (C tenuicollis) The bladder wall consists of two main layers. Scanning electron microscopy showed that the outer surface of the bladder is a rough surface consisting of numerous sparsely situated microthriches with no apparent pattern of distribution. They are long and fine as a result of which they are intertwined, forming something like a network among which closed areas, lagoons, are formed (Fig. 1). The thin elongated microthriches are in most cases connected with each other by transverse connections. The transmission electron microscopic study gives a more precise idea about the form and structure of the microthriches (Fig. 2). They are long, cylindrical structures situated at large distances from each other at their bases, and intertwined at their apical parts. The microthriches consist of two parts: a wide base and a long, fine apical part. The surface of the microthriches is covered with a plasma membrane (Figs 3a, 3b). The heart of the cylinLegend to the figures Fig. 1 Scanning electron microscopy of the bladder wall, x 30 000 Fig. 2 Microthriches from the wall of c. tenuicollis. x 23 000 Fig. 3 Longitudinal and transversal sections of microthriches from c. tenuicollis. x23 000 Fig. 3aDetail of Fig. 3 Fig. 3bDetail of Fig. 3 Fig. 4 Scanning electron microscopy of the tegument of the neck region of T. hydatigena. x 3 000 Fig. 5 Longitudinal and transversal sections of microthriches of the neck region, x 26 500 Fig. 5a Detail of Fig. 5 Fig. 6 Scanning electron microscopy of the tegument of a mature proglottid of T. hydatigena. x 20 000 Fig. 7 Microthriches of the tegument of a mature proglottid, x 26 500 Fig.7a Detail of Fig. 7 Fig. 8 Longitudinal and transversal section of microthriches of a mature proglottid of T. hydatigena. x 20 000 Fig.Ra Detail of Fig. 8