Spermatogenesis and spermiogenesis of the monozoic caryophyllidean cestode Wenyonia virilis (Woodland, 1923), an intestinal parasite of Synodontis schall (Pisces: Siluridae), have been investigated by means of transmission electron microscopy for the first time in Egypt. Spermatogenesis is of a rosette type; each spermatogonium undergoes four mitotic and two meiotic divisions resulting in the formation of sixty four spermatids. These spermatids undergo spermiogenesis and transform into mature spermatozoa. The process of spermiogenesis begins by the formation of the zone of differentiation, at one end of the spermatid cell, with one pair of centriole but without an intercentriolar body. The left-handed centriole, firstly, forms a basal body but aborts forming a flagellar bud. The right-handed one develops externally into an axoneme growing parallel to a cytoplasmic extension protruding from the differentiating zone. The nucleus penetrates this extension followed by the proximodistal fusion of the axoneme in the sperm shaft. The spermatozoon of W. virilis lacks mitochondria and consists of five regions showing gradual increase in the nucleus width and the presence of glycogen granules. Some important differences between the present study and others done on monozoic and polyzoic worms are recorded and discussed.

The process of spermiogenesis in two paramphistomes, Sandonia sudanensis and Basidiodiscus ectorchis from the Nile fish Synodontis schall in Egypt was studied by transmission electron microscopy. Spermiogenesis is characterized by the outgrowth of the zone of differentiation, presenting two basal bodies separated by a microtubule organizing centre, each basal body developing into a flagellum. Proximodistal fusion of these flagella with a median cytoplasmic extension gives rise to the spermatozoon. The mature spermatozoon possesses two axonemes of the 9+'1' pattern typical of parasitic helminths. There are few ultrastructural studies on spermiogenesis in paramphistomes, which are considered the most primitive digenetic trematodes. The present study provides new and more detailed information on this process, including the presence of a lateral flange and external ornamentation of the cell membrane. The value of sperm ultrastructure as a taxonomic tool in phylogeny is also discussed.

is one of the most pathogenic and economically important parasites of sheep. Different antigens; crude somatic antigen (CSA), excretory/secretory antigen (ESA), crude larval antigen (CLA), glutathione-S-transferase antigen (GST) and recombinant protein (rhcp 26/23) were prepared and characterized using sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and western blot. The antigens were immunologically evaluated through indirect enzyme linked immunosorbent assay (ELISA) for diagnosis of haemonchosis in experimentally and naturally infected sheep. Analysis of the resultant bands of SDS-PAGE demonstrated that 13, 6, 11, 2 and 1 protein bands from CSA, ESA, CLA, GST and rhcp 26/23, respectively and analysis of the resultant bands of western blot showed that 13, 6, 4 and 1 reactive bands detected from CSA, ESA, CLA and GST, respectively. The results of ELISA of different antigens revealed that sero-prevelance of CSA, ESA, CLA, GST and rhcp 26/23 were 78.51, 82.34, 85.319, 45.319 and 90.8% respectively, sensitivity were 100, 90, 100, 96.66 and 90%, respectively and specificity were 0, 70, 10, 70 and 6.66%, respectively with diagnostic potency were 50, 80, 55, 83.33 and 48.33%, respectively. Statistical analysis using Chi square test found that GST is the best one that can be used. The cross reactivity of GST antigen, crude antigen and crude antigen tested versus their homologous hyper immune sera at different dilutions using ELISA. The current study reported that GST antigen could be considered as a promising antigen for diagnosis of haemonchosis.

Summary Paramphistomes are intestinal parasitic warms infecting a wide range of vertebrate animals and are considered, by various authors, as the most primitive digenetic trematodes. The karyotypes of Sandonia sudanensis McClelland, Basidiodiscus ectorchis Fischthal and Kuntz inhabiting a common fish host, and Synodontis schall Bloch-Scheinder were studied. We recorded that both Sandonia sudanensis and Basidiodiscus ectorchis have the same number of chromosomes with diploid number 2nϭ12 and nϭ6 at the end of meiotic divisions. As far as the authors know, the present work is the first chromosomal study of these 2 fish paramphistomes and the first karyological observation of fish-infecting paramphistomes. The results are discussed and compared with that of mammalian paramphistomes. Paramphistomes, Karyotype. Paramphistomes are intestinal parasitic warms infecting a wide range of vertebrate animals and are considered, by various authors, as the most primitive digenetic trematodes. Trematodes and cestodes, which are the major groups of phylum platyhelminthes, form a monophyletic taxon known as the Neodermata (Ehlers 1985) that is suggested by Rohde (1994) as a parasitic taxon either living in or on a host. Key wordsAlthough Barsiene (1993) and Barshene (1993) reviewed the chromosome numbers and the karyological data for 96 and 230 species of trematodes respectively, still and till recently, there have been relatively few studies on the chromosomes of digenetic trematodes. Concerning paramphistomes, several chromosome studies were carried out by Sey (1971), Grossman and Cain (1981), Mutafova (1983), Rhee et al. (1986Rhee et al. ( , 1987Rhee et al. ( , 1988, Li and He (1987), Barsiene (1991) and Ashour et al. (1995).The aim of the present work is to describe both the chromosome number and structure and to analyze the karyotypes of the 2 amphistomes Sandonia sudanensis and Basidiodiscus ectorchis collected from the fish Synodontis schall and comparing the result with that of other paramphistomes. Materials and methodsSynodontis schall fishes were collected from fishermen working in the area of El-Giza (ElBahr El-Aazam) and then dissected and the alimentary canal was opened. Living worms: Sandonia sudanensis McClelland and Basidiodiscus ectorchis Fischthal and Kuntz were put separately according to the species in 0.005% colchicine in saline (0.7% NaCl) for 2 h. The whole worms or sometimes isolated testes were minced using fine scissors and Pasteur pipettes, and then put in hypotonic solution of KCl (0.48%) for 30 min. The fixative 3 : 1 methanol : acetic acid was added and left for 2 h. Centrifugation was carried out at 2000 rpm for 10 min; the supernatant fluid was dis-

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