Ultrastructure and Cytochemistry of the Mature Spermatozoon of Khawia Armeniaca (Cholodkovsky, 1915) (Caryophyllidea: Lytocestidae), a Parasite of Capoeta Capoeta Sevangi (De Filippi, 1865) (Teleostei, Cyprinidae).

The mature spermatozoon of Khawia armeniaca, a monozoic caryophyllidean parasite of templar fish Capoeta capoeta sevangi (De Filippi, 1865) from the Lake Sevan, Armenia, has been studied using transmission electron microscopy and cytochemical technique of Thiéry (1967) for the first time. The mature spermatozoon of K. armeniaca consists of a single axoneme with the 9+'1' trepaxonematan structure, cortical microtubules and nucleus which are situated parallel to the longitudinal axis of the spermatozoon, and a moderately electrondense cytoplasm with glycogen particles. The cortical microtubules are arranged in one continuous semicircle beneath the plasma membrane in Region II and anterior part of Region III of the mature spermatozoon. The two opposite rows of cortical microtubules are observed in the remaining nuclear and at the beginning of the postnuclear part (Regions III, IV) of the male gamete The number of cortical microtubules is remarkably variable in the spermatozoa of various Khawia species. K. armeniaca exhibits the highest number of cortical microtubules in comparison with K. sinensis and K. rossittensis. Glycogen was detected in the cytoplasm of prenuclear (II), nuclear (III) and postnuclear (IV) regions with different ultrastructural organization of the mature spermatozoon of K. armeniaca. Variations of sperm ultrastructural characters within caryophyllideans and other cestodes are discussed.

Ultrastructure of presumed sensory receptors in the scolex of adult Proteocephalus exiguus (Cestoda, Proteocephalidea).

The ultrastructure of six type of putative sense receptors including three nonciliate (Types I-III) and three ciliate (Types IV-VI) types found in the tegument of the scolex of adult Proteocephalus exiguus has been described for the first time. Type I has a simple tegumental sensory ending, containing one electron-dense collar, circular septate desmosome, electron-lucent vesicles and microtubules. Type II is represented by a receptor with a large rootlet. Type III is a receptor with a very long cross-striated rootlet, with two electron-dense collars and septate junction. The ciliated receptors differ in the length of the cilium, in the number of electron-dense collars and in the shape of sensory bulb. A comparison of structural features of receptors in different systematic group within Platyhelminthes is made.

Toxocara canis (Nematoda:Ascaridae): the fine structure of the oviduct, oviduct-uterine junction and uterus.

The fine structure of the oviduct, oviduct-uterine junction and uterus of the nematode Toxocara canis (Werner, 1782) is described. Columnar-type epithelioid cells with numerous microvilli at the apical membrane border the oviduct lumen. Many electron dense secretory products are present in these cells. The cells lining the oviduct-uterine junction have no microvilli. They are coated with an electron-dense layer and contain numerous membrane-bound dense material containing bodies. Externally, the cells are surrounded by a basal lamina and muscle cells. The epithelial cells lining the greater part of the paired uteri appear to be rather flat. The oocytes inside the oviduct are covered with a dense thick plasma membrane and contain lipid droplets, dense granules and glycogen. The morphology of the oocytes before the fertilization inside the oviduct-uterine junction resembles that of the oocyte in the oviduct. After the fertilization the egg shell formation takes place. The egg shell of T.canis is composed of four layers: uterine, vitelline, middle chitinous and inner layer. The differences between the fine structure of the egg shell of T. canis and other related nematodes are discussed.

Toxocara canis (Nematoda, Ascarididae): ultrastructure of the rachis and the ovarian wall.

The oogonia and oocytes in the ovaries of Toxocara canis are joined to a cytoplasmic process called the rachis. The rachis is a much branched cytoplasmic mass without cell components in the germinal zone. At the end of the germinal zone and in the growth zone the cytoplasmic mass is formed into a central axial cylinder, containing small dense granules, lipid drops and glycogen. Throughout the growth zone shell granules similar to those present in the oocytes are also present in the rachis. Anterior to the opening of the ovaries into the oviduct the rachis disappears. The ovarian wall is composed of epithelial cells, adjoining the basal lamina. They are characterized by the presence of large numbers of mitochondria, especially in the germinal zone. The epithelial cells in the growth zone also contain rough endoplasmic reticulum, ribosomes and bundles of microfibrils. A dense tubular material occurs between the basal membrane of the epithelial cells and the basal lamina as well as in the wall intercellular spaces in the ovarian growth zone. Multivesicular labyrinth-like formations can also be observed in the epithelial intercellular spaces in the central portion of the T. canis ovary.

Vitellogenesis in Archigetes sieboldi Leuckart, 1878 (Cestoda, Caryophyllidea, Caryophyllaeidae), an intestinal parasite of carp (Cyprinus carpio L.).

Vitellogenesis in the caryophyllidean tapeworm Archigetes sieboldi Leuckart, 1878, from carp Cyprinus carpio L. in Slovakia, has been examined using transmission electron microscopy and cytochemical staining with periodic acid-thiosemicarbazide-silver proteinate (PA-TSC-SP) for glycogen. Vitelline follicles extend in two lateral bands in the medullary parenchyma along both sides of the monozoic body. They are surrounded by an external basal lamina and contain vitellocytes and an interstitial tissue. The general pattern of vitellogenesis is essentially like that of other caryophyllideans. It involves four stages: immature, early maturing, advanced maturing cells and mature vitellocytes. During vitellogenesis, a continuous increase in cell volume is accompanied by an extensive development of cell components engaged in shell globule formation, e.g. granular endoplasmic reticulum and Golgi. Shell globule clusters are membrane-bound. Nuclear and nucleolar transformation are associated with formation and storage of large amounts of intranuclear glycogen, a very specific feature of the Caryophyllidea. For the first time, (a) additional vitelline material in Archigetes is represented by lamellar bodies and (b) lipid droplets are described in the mature vitellocytes from vitelline follicles and vitelloduct of the Caryophyllidea. Our results indicate that there may be a double origin of lamellar bodies: either from the endoplasmic reticulum or through transformation of shell globule/shell globule clusters. Lamellar body clusters and some single lamellar bodies appear to have a membrane. Other ultrastructural features of vitellogenesis and/or vitellocyte in A. sieboldi from its vertebrate (fish) and invertebrate (oligochaete) hosts are briefly compared and contrasted with those in other caryophyllideans and/or Neodermata.

Ultrastructure of the spermatozoon of the proteocephalidean cestode Proteocephalus torulosus (Batsch, 1786).

The fine structure of the mature spermatozoon of the proteocephalidean tapeworm Proteocephalus torulosus, a parasite of cyprinid fishes, was studied by transmission electron microscopy for the first time. The mature spermatozoon of P. torulosus is filiform and tapered at both extremities. It contains two axonemes of the 9+"1" type and of unequal length. The anterior extremity of the spermatozoon bears a helicoidal crested body approximately 100 nm thick. Cortical microtubules of two types lie parallel to the spermatozoon axis. The nucleus is a fine cord of condensed chromatin. The slightly electron-dense cytoplasm contains electron-dense granules in regions II and III of the spermatozoon. The anterior and posterior extremities of the spermatozoon contain a single axoneme. The mature spermatozoon of P. torulosus differs from that of other Proteocephalusspecies in the presence of a single crested body and in the morphology of its posterior end.

Spermiogenesis in the proteocephalidean cestode Proteocephalus torulosus (Batsch, 1786).

Spermiogenesis of the proteocephalidean cestode Proteocephalus torulosus (Batsch, 1786) was examined for the first time using transmission electron microscopy. Spermiogenesis begins with the formation of a distal cytoplasmic protrusion, a differentiation zone, at the periphery of the early spermatid. This differentiation zone is lined with cortical microtubules and contains two centrioles aligned along the same axis. Subsequently, each centriole is associated with the striated root and the intercentriolar body appears between them. A flagellar bud arises from each centriole, growing later as a free flagellum. Simultaneously, a median cytoplasmic process (MCP) develops distally to the flagella. The two flagella, which are of unequal length, become longer and rotate towards the MCP. At this stage, two arching membranes appear at the base of the differentiation zone. The nucleus elongates and when both flagella are fused with the MCP, the nucleus subsequently migrates into the MCP. Finally, the advanced spermatids detach from a condensing residual cytoplasm at the level of the arching membranes.

Ultrastructure of the spermatozoon of the pseudophyllidean cestode Eubothrium crassum (Bloch, 1779).

The fine structure of the mature spermatozoon of the pseudophyllidean tapeworm Eubothrium crassum, a parasite of salmonid fishes, has been studied by transmission electron microscopy for the first time. The mature spermatozoon of E. crassum is filiform and tapered at both extremities. It contains two axonemes of unequal length showing the 9 + "1" pattern of Trepaxonemata. The anterior extremity exhibits a crested body 50-100 nm thick. It spirals around the outside of the anterior region of the spermatozoon. The nucleus is electron-dense, exhibiting a fibrous appearance in its middle (the broadest) region. The cortical microtubules are of two types and are situated parallel to the spermatozoon axis. The cytoplasm is slightly electron-dense and contains numerous electron-dense granules in region II of the spermatozoon. A ring of electron-dense, centred microtubules surrounds the axoneme, together with the underlying ring of moderately electron-dense, subjacent submicrotubular material in region V. The anterior and posterior extremities of the spermatozoon lack cortical microtubules and contain a single axoneme. Our results reveal several peculiarities, in which the spermatozoon of E. crassum differs from those of other pseudophyllidean cestodes.

Spermiogenesis in the pseudophyllid cestode Eubothrium crassum (Bloch, 1779).

Spermiogenesis of the pseudophyllidean tapeworm Eubothrium crassum has been described by the aid of transmission electron microscopy for the first time. Initially, early spermatids form a distal cytoplasmic protrusion, a differentiation zone containing a small electron-dense, apically oriented region. Out of this region, two centrioles with rootlets develop. The centrioles become orientated in the same plane with the appearance of an intercentriolar body. Now, the long axes of the rootlets are parallel with each other and with the long axis of the nucleus. Two flagella of subsequently unequal length are formed very rapidly. Simultaneously, a median cytoplasmic process (MCP) develops distal to the flagella. Two arching membranes appear at the base of the differentiation zone. Each flagellum, still being in contact with an intercentriolar body, rotates to a position parallel with the MCP. The nucleus migrates very rapidly into the MCP at this stage. Subsequently, the two flagella fuse with the MCP. Finally, the basal bodies with the rootlets detach from the flagella, the intercentriolar body changes its structure and spermatids are pinched off from a condensing residual cytoplasm at the level of the arching membranes.

Ultrastructure studies of Proteocephalus longicollis (Cestoda, Proteocephalidea): transmission electron microscopy of scolex glands.

The ultrastructure of two types of secretory glands in the scolex of preadults of Proteocephalus longicollis is described for the first time in the present report. The gland cells contain extensive cisternae of granular endoplasmic reticulum and Golgi complexes, which participate in the production of secretory globules. Type I scolex glands produce electron-dense globules of various size. The secretory globules enter the secretory canal, openings of which were not observed in the preadults. The secretory product of type I was found at the inner sucker surface and in the tegument of the sucker edges. In addition, electron-dense globules in adult worms are secreted via an eccrine mechanism. Type II scolex glands are characterized by secretory globules of lower electron density and occur mainly in preadults. The electron-lucent, membrane-bound secretory globules are transported via microtubule-lined ducts opening to the exterior at the tegumental surface. Secretory globules of type II are released by an eccrine process.

Ultrastructure studies of preadult Proteocephalus longicollis (Cestoda, Proteocephalidea): transmission electron microscopy of scolex sensory receptors.

The ultrastructure of five types of presumed sensory receptors in the scolex of preadults of Proteocephalus longicollis is described. Two types of nonciliate sensory receptors are situated on the inner surface of the lateral sucker. They differ from each other in the shape, presence, or absence of a large rootlet, electron-dense collars, desmosomes, microtubules, and/or vesicles. In addition, three types of ciliate sensory receptors are found along the edges of the lateral suckers. They can be differentiated by the length of the cilium, by the number of electron-dense collars (one or two), and by types of vesicles. Four types of vesicles were found inside the ciliate sensory receptors. One type of ciliate sensory receptor occurring in preadults differs markedly from any of the sensory receptors previously described in adult P. longicollis.