Die eikapseln der proseriaten (turbellaria,neoophora)

The egg-capsules of the marine Turbellaria Proseriata are deposited in 4 different modes: No attachment to the substratum in calm biotops, sticking to solid objects by broad bases in muddy biotops, and attachment to grains by an elastic stalk in agitated beach sand. In the last case additional protective coats may surround the stalked egg-capsules.

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Mit Unterstützung der Deutschen Forschungsgemeinschaft.     

Monographie der Gattung Cyclamen auf morphologisch-cytologischer Grundlage

Ohne ZusammenfassungMit 21 Textabbildungen (82 Einzelbildern).D 8.     

Zusatz zur Monographie der Glanzstaare(Lamprotornithinae.)

Ohne Zusammenfassung     

R. B. Sharpe's Monographie der Alcedinidae

Ohne Zusammenfassung     

Expression of a neuropeptide similar to allatotropin in free living turbellaria (platyhelminthes)

Mechanisms coordinating cell–cell interaction have appeared early in evolution. Allatotropin (AT), a neuropeptide isolated based on its ability to stimulate the synthesis of juvenile hormones (JHs) in insects has also been found in other invertebrate phyla. Despite this function, AT has proved to be myotropic. In the present study we analyze its expression in two groups of Turbellaria (Catenulida, Macrostomida), and its probable relationship with muscle tissue. The results show the presence of an AT-like peptide in the free living turbellaria analyzed. The analysis of the expression of the peptide together with phalloidin, suggests a functional relationship between the peptide and muscle tissue, showing that it could be acting as a myoregulator. The finding of immunoreactive fibers associated with sensory organs like ciliated pits in Catenulida and eyes in Macrostomida makes probable that AT could play a role in the physiological mechanisms controlling circadian activities. Furthermore, the existence of AT in several phyla of Protostomata suggests that this peptide could be a synapomorphic feature of this group. Indeed, the presence in organisms that do not undergo metamorphosis, could be signaling that it was first involved in myotropic activities, being the stimulation of the synthesis of JHs a secondary function acquired by the phylum Arthropoda.     

Ultrastructure of spermiogenesis and spermatozoa in Prorhynchus sp. (Platyhelminthes,Lecithoepitheliata, Prorhynchidae)

Summary

Mature sperm of Prorhynchus sp. have an elongated nucleus, multiple mitochondria and dense bodies, and two free axonemes which are located in grooves of the main shaft for much of their length. The axonemes are subterminally inserted and have the typical 9+ ‘1’ arrangement unique to Platyhelminthes and synapomorphic for taxa of Trepaxonemata. The testis follicles examined had small numbers of developing spermatids and very few mature sperm were present. During spermiogenesis, spermatids remain joined in clusters by distinctive bridges. In each spermatid two centrioles (with an intercentriolar body between them) give rise to free axonemes which grow out in opposite directions from each other. Indistinct ciliary rootlets are present. The axonemes are carried distally from the main spermatid mass on an elongating process and turn back towards the main spermatid mass. Nucleus, mitochondria and dense bodies move into the shaft, and the spermatid elongates before detaching from others in the cluster. This is the first detailed study of sperm and spermiogenesis in Lecithoepitheliata. Mature sperm are distinctly different from those of prolecithophorans, to which they are reputedly related, the latter having aflagellate sperm without dense bodies.     

Structure of the epithelium of the parasitic turbellaria Notenera ivanovi (Turbellaria: Fecampiida)

The ultrastructure of the epithelium in Notentera ivanovi (Turbellaria, Fecampiida) has been studied. Notentera ivanovi lacks the digestive system but has a pad of the epidermal cells on the dorsal side of the body, which seems to be similar to the digestive epidermis on LM. Both the ventral and dorsal epithelium are cellular, ciliated and not insunk (fig. 1, a). The ultrastructure of the ventral and dorsal epithelium is similar in essential features. The cells bear abundant microvilli, cilia and are very rich in mitochondria, but the cytoplasm does not contain lysosomes and shows no other indications of phago- or pinocytosis. The basal membrane of epithelial cells forms deep invaginations (fig. 1, [symbol: see text]), partly with dilations (fig. 1, a; 2, a) containing the lamellated material (3, [symbol: see text]). In the basal part of the cells the numerous Golgi apparatus and rare cysternae of the smooth endoplasmic reticulum were observed (fig. 2, a, [symbol: see text]). The epithelium consists of several types of cells, which differ in the structure of secretory granules. The most abundant type of cells contains the granules with the rough-fibrillated content (fig. 1, a; 2, [symbol: see text]; 3, a). The cells of this type cover most part of the body. In some cells the content of such granules becomes condensed and electron-dense granules appear (fig. 3, a, [symbol: see text]). Another type of cells contains the giant granules with the rough-fibrillated content (fig. 3, [symbol: see text]). Third type of the secret is the granules with the finely fibrillated content which is ejected by exocytosis. The cells of the second and third types form a separate areas of the epithelium of the dorsal side of the body but occasionally were observed in the ventral epithelium too. The epithelium of N. ivanovi differs from that in Kronborgia by the abundance and diversity of secretory contents. The role of the epithelium in the digestion remains conjectural. It seems to be mainly the suckering tissue transporting the low molecular nutrients.     

Ultrastructure of the flame bulbs and protonephridial capillaries of Prorhynchus (Lecithoepitheliata, Prorhynchidae, Turbellaria)

The flame bulb of Prorhynchus is formed by a single cell. Its nucleus is not located in the cytoplasm at the base of the flame. Cilia of the flame have cross-striated hollow ciliary rootlets converging towards their tips. The maximum number of cilia counted was 13. The weir consists of a single row of longitudinal ribs that contain longitudinal filaments and possess regularly arranged protrusions along their surface appearing as transverse bands in horizontal section. A 'membrane' of extracellular material extends between the ribs. and loose material fills the places between the ribs, with a denser layer midway between adjacent ribs. Distally, the ribs fuse to form a continuous tube without a junction. Small protonephridial capillaries lack junctions, larger ducts have lateral flames and patches of long microvilli. Large excretory ducts open into a ciliated and lamellated cavity which is connected by a narrow canal to the excretory pore. The terminal part of the canal close to the pore possesses many cilia and microvilli. Phylogenetic implications of the findings are discussed.     

Ultrastructural features of the epidermis in turbellaria from the Lake Baikal Geocentrophora wagini (Lecithoepitheliata, Plathelminthes)

The epidermis of Geocentrophora wagini was studied using transmission electron microscopy. The turbellarian body was entirely covered by cilia, whose density was higher on the ventral surface compared with the dorsal one. In all regions examined, the epidermis was made up of a one-layered insunk epithelium. The basal matrix, underlying the epidermis, was a well developed basement membrane (BM) with bilayered structure, overlying the muscle network of circular and longitudinal fibers. The double plasma membranes, extending from the apical surface of epidermis to BM, were linked by specialized cell junctions. This suggested that epidermis had a cellular rather than a cyncytial arrangement. Each insunk epidermal cell was made of two unequal parts: a comparatively thin surface plate attached to BM by hemiadherens junctions, and a massive nucleated portion located below the body wall musculature in the parenchyma. A thin cytoplasmic bridge connected the epidermal plate with the nucleated cell body. The epidermal plates were joined by belt-like junctions along their adjacent surfaces. Inconspicuous zonula adherens (ZA) had a most apical position, and prominent septate junction was arrayed proximally to this zonula. Except ZA, cell boundaries in epidermis were frequently flanked by rows of light tubules and vesicles. In the basal half of the epithelial sheet, they were occassionally accompanied by single cisternae of rough endoplasmic reticulum (RER). The ultrastructure of the insunk cell body and that of the surface plate showed a considerable similarity. The common features were distinctive profiles of RER and GA, the presence of epitheliosomes, light tubules and vesicles, centrioles and fibrous granules. Thus, ultrastructural features allow a rather reliable identification of epidermal cells in the parenchyma, despite the absence of any visible morphological association between cell body and its epidermal plate.     

Comparative ultrastructure of adhesive systems in the turbellaria

Summary Glandular adhesive organs and other structures by which turbellarians attach themselves temporarily to surfaces have been studied by electron microscopy. Adhesive organs in representatives of the turbellarian orders Haplopharyngida, Macrostomida, Polycladida, Rhabdocoela, Proseriata, and Tricladida are composed of three cell types: two gland cell types and a modified epidermal cell type through which the necks of the glands project. One of the gland types is characterized by its dense membrane-bound, 0.2–0.7Μm diameter, secretion granules and is called here theviscid gland on the basis of evidence that it secretes the adhesive substance by which the organs attach to surfaces. The other gland type is characterized by smaller (0.1Μm), less-dense, membrane-bound secretion granules and is called thereleasing gland on the basis of evidence that it secretes a substance by which adhering organs are released from surfaces. The modified epidermal cell is called theanchor cell; it has a well-developed cell web and bears microvilli with fibrous cores surrounding the tips of the gland necks in a collar-like fashion. Adhesive organs that have the two gland types, viscid and releasing glands, are referred to here asduo-gland adhesive organs. Other turbellarians, including orders Nemertodermatida, Acoela, and Lecithoepitheliata, have adhesive glands or other adhesive structures with a morphology unlike that of duo-gland adhesive organs. Ultrastructural characters of the adhesive organs show that the Macrostomida and Haplopharyngida are related, and that the Polycladida, Rhabdocoela, Proseriata, and Tricladida are related, and that these two groups of orders share a common ancestor. The Nemertodermatida, Acoela, and Lecithoepitheliata, with morphologically different adhesive systems, are apparently derived separately from these orders.     

Comparative ultrastructure of the pharynx simplex in turbellaria

Summary The simple pharynges in thirteen species of Turbellaria in the orders Macrostomida, Haplopharyngida, Catenulida, and Acoela have been studied by electron microscopy. After consideration of the functional aspects of the pharynx simplex, the relationship of the pharynx simplex ultrastructure to the phylogeny of the above mentioned groups is analyzed.The Haplopharyngida and Macrostomida are united as a group by the following characters: a pharynx transition zone of 1–5 circles of insunk cells with modified ciliary rootlets or no cilia, pharynx sensory cells without stereocilia collars and with a variable number of cilia, a prominent nerve ring with more than 30 axons circling the pharynx at the level of the beginning of the pharynx proper distal to the gland ring, 2 or more gland cell types in the pharynx, with at least two layers of muscle present and the longitudinal muscles derived from regular and special body wall circular muscles and a prominent post-oral nerve commissure. This specific arrangement can be distinguished from the other pharynx simplex types and is called the pharynx simplex coronatus.The catenulid pharynx simplex is characterized by the lack of a prominent nerve ring, no prominent post-oral commissure, a transition zone with epidermal type ciliary rootlets, recessed monociliated sensory cells, and one or no type of pharynx gland cell. The Acoela are specialized because of the epidermal type rootlets in the pharynx proper. They also lack a transition zone and a prominent nerve ring and have monociliated sensory cells different from the catenulid type.Ultrastructural characters of the pharynx simplex support the view that the Haplopharyngida-Macrostomida are monophyletic. The more primitive catenulid pharynx probably arose from a common ancestral pool with the Haplopharyngida and Macrostomida, although it does not appear possible presently to establish a clear monophyletic line for these forms. The various pharynx types within the Acoela appear to indicate independent origins with no clear link to the basic pharynx simplex type in the three other orders.Abbreviations Used in Figures a nerve axon - ar accessory rootlet - bb basal body - bn brain-nerve ring commissure - c caudal rootlet - ce centriole - ci cilium - cm circular muscle - cp ciliary pit - cu cuticle - cw cell web - d dictyosome - dp proximal pharynx proper cell - e epidermis - er rough endoplasmic reticulum - f fibrous rod - g gastrodermis - gc gastrodermal gland cell - he heterochromatin - i intercellular matrix - lc lateral nerve cord - lm longitudinal muscle - m mitochondria - mo mouth - mt microtubules - mv microvilli - n nucleus - nr nerve ring - ns neurosecretory granules - p pharynx proper - ph pharynx - po post-oral commissure - r rostral rootlet - rm radial muscle - s sphincter - sc sensory cell - sj septate junction - sr sensory rootlet - t transition zone - u ultrarhabdite - v vertical rootlet - va food vacuole - za zonula adhaerens - 1 type I gland cell - 2 type II gland cell - 3 type III gland cell - 4 type IV gland cell - 5 type V gland cell - 6 type VI gland cell - 7 type VII gland cell     

Vorlufige Anzeige: Monographie derPipridae

Ohne Zusammenfassung     

Nachtrag zur Monographie des GenusCriniger

Ohne ZusammenfassungSiehe Januar-Heft, Seite 1–36.     

The turbellaria fauna of a small water reservoir in Central Russia

The Turbellaria fauna has been studied in the Uvod’ Reservoir. A total of 18 species have been found representing three orders: Catenulida, Macrostoimida, and Neorhabdocoela. The patterns of Turbellaria distribution in the reservoir have been analyzed. The most abundant species have been determined: Stenostomum leucops Duges, 1828, Microstomum lineare (O.F. Müller, 1774), Bothromesostoma essenii M. Braun, 1885, and Mesostoma lingua (Abildgaard, 1789).