bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cellular Events of Wrinkled Blastula Formation and the Influence of the Fertilization Envelope on Wrinkling in the Seastar Patiriella exigua
Authors: Cerra Anna , Byrne Maria 
Published: April 2010

AbstractLike many echinoderms, the seastar, Patiriella exigua has a wrinkled blastula rather than the smooth‐walled blastula typical of most phyla. The cellular events of wrinkled blastula formation in P. exigua were documented using light, confocal and electron microscopy. Wrinkled blastulae have a highly infolded epithelium. Prior to wrinkling, the blastomeres are cuboidal with lipid droplets and yolk granules distributed throughout their cytoplasm. During wrinkling, the cells become columnar and the lipid and yolk reserves become redistributed to the basal and apical ends of the cells, respectively. Gastrulae have a tall columnar epithelium, with a basal accumulation of lipid. Interdigitation of numerous cell projections, including short lateral processes, basal lamellipodia and apical filopodia, assists in maintaining epithelial integrity during wrinkling. Apical filopodia have not been observed in other echinoderm embryos. Although 1 M urea caused elevation of the fertilization envelope, the embryos did not expand into the newly‐created space. This is suggested to be due to the adhesive properties of the hyaline layer. Embryos removed from their envelope were enlarged with shallower and fewer wrinkles compared with controls. It appears that the integrity of the hyaline layer and fertilization envelope both influence the compact wrinkled profile of P. exigua blastulae.
Gill Respiratory Area in the Pelagic Sculpins of Lake Baikal, Cottocomephorus inermis and C. grewingki (Cottidae)
Authors: Jakubowski Michał , Halama L. , Zuwała K. 
Published: April 2010

AbstractMorphometric investigations of the gill apparatus in the pelagic Baikal sculpins (Cottocomephorinae) reveal a relatively large gill respiratory area (GRSA). Allometric relationship between GRSA and body weight is expressed by the equation: Y = 746.61W0.918 for C. inermis and that Y = 655.68W0.913 for C. grewingki. In calculations per body weight unit the GRSA values C. inermis are a little higher than those in C. grewingki. Obtained numerical data seem to be in accordance with difference in biological activity of species examined. Their GRSA is several times larger than that in previously examined the bathypelagic Comephorus dybowskii and deep bottom dweller Cottinella boulengeri.
Changes in Structure and Function of Ventral Epidermis in Hyla arborea savignyi Aud. (Anura; Hylidae) Throughout Metamorphosis
Authors: Rosenberg Mira , Warburg M. R. 
Published: April 2010

AbstractThe changes in epidermal ultrastructure during the metamorphic cycle of Hyla arborea are described. The number of cell layers increased from two to four in the late tadpole stages. The cell layers flatten and the process of stratification reaches its peak after the completion of metamorphosis. The mitochondria‐rich cell appears early in the tadpole stages. Numerous flask cells are noticeable in the post‐metamorphic stages.K+–p‐NPPase activity was localized cytochemically in the epidermis of H. arborea during its metamorphic cycle. In the epidermis of the legless tadpole, evidence for K+–p‐NPPase activity was confined intracellularly. During the later tadpole stages, preceding metamorphic climax, the main ATPase activity shifted to the baso‐lateral cell membranes bordering with the intercellular spaces under the surface and later the stratum corneum. This continued after metamorphic climax in the juvenile toadlets, diminishing later in the adult stage.
Spermatogenesis in Tenebrio molitor (Tenebrionidae, Coleoptera): A Fine Structure and Anti‐tubulin Immunofluorescence Study
Authors: Wolf Klaus Werner , Hellwage Jens 
Published: April 2010

AbstractSpermatogonia and both generations of spermatocytes of Tenebrio molitor possess conventional bipolar spindles with only few aster MTs. Spindles in metaphase spermatogonia are surrounded by fenestrated two‐layered cisternae and do not contain intraspindle membranes. In metaphase spermatocytes, a spindle envelope is missing, but intraspindle membranes are abundant. Mitochondria form long threads lateral to the nucleus in prophase I of meiosis. The elongated mitochondria also align parallel to the spindle apparatus in prometaphase I. As a consequence, the spindles reside in a cage formed of mitochondria. This arrangement may guarantee proper bisection of the chondriome during division. Cells are tightly packed during spermatogonial divisions and in prophase I, but large intercellular spaces develop when the first meiotic spindle assembles. Then, cytoplasmic bridges which persist between the cells as a result of incomplete cytokinesis appear as slender tubes. Anti‐tubulin immunofluorescence using an antibody against acetylated α‐tubulin revealed intense acetylation throughout spermatogonial mitosis but a low degree of α‐tubulin acetylation in meiotic spindles prior to telophase. This may indicate a high microtubule turnover in meiosis.
Anatomy and Histology of the Cephalic Arterial Coilings in Hammerhead Sharks (Genus Sphyrna)
Authors: Muñoz‐Chápuli R. , De Andrés A. V. 
Published: April 2010

AbstractHammerhead sharks (genus Sphyrna) show two large arterial coilings in a posteroventral hollow of the orbitary cavity. The posterior is made up of the hyoid artery which, after giving rise to the stapedial artery, enters the chondrocranium to originate the internal carotid and the cerebral arteries. The efferent pseudobranchial artery forms the anterior coiling, gives rise to the ophthalmic artery, enters the orbitary wall and joins the internal carotid artery. The histological sections of the arterial coilings showed the scarcity of smooth muscle cells in the tunica media as well as an important collagenic and elastic component in the arterial wall. Several venous vessels percolate through the coilings. A large amount of small (mean diameter = 73 μm), spheric corpuscles were observed in the connective tissue around the coilings. These corpuscles were also present in the palate and under the skin of the head of these sharks. They are comprised of spirally‐arranged cells around a bundle of collagen fibres. We hypothesize that their association with the coilings could suggest some kind of involvement in detecting pressure changes in the blood supply to the head.
Functional Morphology of the Introvert and Digestive System of Myzostoma cirriferum (Myzostomida)
Authors: Eeckhaut Igor , Dochy Bruno , Jangoux Michel 
Published: April 2010

AbstractMyzostoma cirriferum feeds by diverting food particles carried by the ambulacral grooves of its comatulid host Antedon bifida. When searching for food, the myzostome uses its protrusible introvert to fulfil two major functions: sensory perception and the capture of food particles. The digestive system is composed of four parts, viz. a pharynx, that is contained within the introvert, a stomach, a series of paired caeca and an intestine that lie in the myzostome's trunk. The pharynx is supplied with a thick muscle which, thanks to peristaltic movements, carries food particles from the mouth to the stomach. Both stomach and caecal cells are able to absorb dissolved nutriments and to store lipids, whereas intestinal cells are only capable of absorption. Due to the beating of their cilia, stomach cells also carry food particles into the caecal lumen, where they are subjected to endocytosis and intracellular digestion by caecal cells. Undigested food fragments eventually gather in a very large, apical vacuole, and the cell apices containing vacuoles are eliminated into the caecal lumen by an apocrinal process. Detached cell apices reach the stomach, where they are embedded in a matrix, together forming a spindle‐shaped faecal mass that is expelled through the postero‐ventral anus. The observed digestive process—entailing the regular elimination of the apical part of the caecal digestive cells—appears to be unique among the Spiralia.
Wettability and Contaminability of Insect Wings as a Function of Their Surface Sculptures
Authors: Wagner Thomas , Neinhuis Christoph , Barthlott Wilhelm 
Published: April 2010

Abstract The wing surfaces of 97 insect species from virtually all relevant major groups were examined by high resolution scanning‐electron‐microscopy, in order to identify the relationships between the wing microstructures, their wettability with water and their behaviour under the influence of contamination.Isolated wings with contact angles between 31.6° and 155.5° were artificially contaminated with silicate dusts and subsequently fogged until drops of water (“dew”) formed and rolled off. The remaining particles were counted via a digital image analysis system. Remaining particle values between 0.41% and 103% were determined in comparison with unfogged controls. Some insects with very unwettable wings show a highly significant “self‐cleaning” effect under the influence of rain or dew.Detailed analysis revealed that there is a correlation between the wettability and the “SM Index” (quotient of wing surface/(body mass)0.67) with values ranging from 2.42 to 57.0. Furthermore, there is a correlation between the “self‐cleaning” effect and the SM Index, meaning that taxa with a high SM Index, e.g. “large‐winged” Ephemeroptera, Odonata, Planipennia, and many Lepidoptera, have very unwettable wings and show high particle removal due to dripping water drops. The “small‐winged” insects, such as Diptera and Hymenoptera, and insects with elytra, such as Blattariae, Saltatoria, Heteroptera and Coleoptera, show completely opposite effects. This is clearly a result of the fact that species with a high SM Index are, in principle, more restricted in flight by contamination than species with a low SM Index which can also actively clean their own wings. The wings primarily serve a protection function in insects with elytra, so that the effects of contamination are probably of minor importance in these insects. Copyright © 1996 The Royal Swedish Academy of Sciences. Published by Elsevier Science Ltd.
Morphological Evidence for the Existence of Two Distinct Types of Mitochondria Rich Cells in the Gill of the Crayfish Astacus leptodactylusEschscholtz
Authors: Dunel‐Erb Suzanne , Barradas Cristina , Lignon Jacques 
Published: April 2010

AbstractAn ultrastructural study was performed on gill epithelia of the crayfish Astacus leptodactylus. The filament and the lamina of the podobranch were examined. In both structures a vascular system is lined by a specialized epithelium covered by a cuticle. Different types of epithelium were described in the gill filaments: either a thin epithelium with few organelles and probably involved in gas exchange or, in other filaments, a thick epithelium with characteristics of a transporting epithelium (abundant mitochondria in close association with plasma membrane infoldings). The epithelium of the lamina is also of a transporting type but in this case the complex of membrane infoldings and mitochondria is in an opposite orientation to that of the filament epithelium suggesting a different role in osmoregulation. © 1997 Published by Elsevier Science Ltd on behalf of The Royal Swedish Academy of Sciences.
Ultrastructure of the Pharyngeal Cuticle and Lectin Labelling with Wheat Germ Agglutinin‐gold Conjugate Indicating Chitin in the Pharyngeal Cuticle ofOesophagostomum dentatum(Strongylida, Nematoda)
Authors: Neuhaus Birger , Bresciani José , Peters Werner 
Published: April 2010

AbstractThe ultrastructure of the pharynx of the first juvenile stage and of adultOesophagostomum dentatum(Nematoda, Strongylida) is investigated by TEM. Additional light microscopical and SEM data are presented for the anterior alimentary canal of all life‐history stages and for adultO. quadrispinulatum. Ultrathin sections of adult and the first juvenile stageO. dentatumare labelled with the lectin wheat germ agglutinin coupled to colloidal gold. The pharyngeal cuticle consists of a trilaminate epicuticle and an amorphous basal layer, which also exhibits individual fibres in adult worms. The pharyngeal cells of the first juvenile stage are already arranged as in the adult worm. In comparison with data for additional nematodes taken from the literature, a trilaminate epicuticle and an amorphous basal layer are postulated for the pharynx in the ground pattern of the Nematoda. Lectin‐gold labelling reveals a strong binding to the pharyngeal cuticle ofO. dentatum. Competitive inhibition experiments withN‐acetyl‐D‐glucosamine and triacetylchitotriose, as well as treatment with chitinase, neuraminidase and sulphuric acid, indicate that the pharyngeal cuticle contains chitin. This finding is supported by staining of the pharyngeal cuticle by the fluorescent brightener calcofluor white in cryosections ofO. dentatum. The occurrence of chitin is interpreted as an original character of the Nematoda. © 1997 The Royal Swedish Academy of Sciences. Published by Elsevier Science Ltd.
Shark Pharyngeal Muscles and Early Vertebrate Evolution
Authors: Mallatt Jon 
Published: April 2010

AbstractThis study provides a new classification of shark pharyngeal muscles, leading to a re‐interpretation of the evolutionary history of these muscles. It begins with Edgeworth's developmental classification but also incorporates phylogenetic and functional information. The two basic groups of pharyngeal muscles are (1) branchial(including deep interbranchials and superficial constrictors) and (2) spinal(including epaxial and hypobranchial muscles). Most of the branchial muscles are also present anteriorly in the mandibular and hyoid segments, indicating that these were once typical branchial segments. The extrabranchial cartilages and gill septa are used as landmarks for dividing the interbranchials from the superficial constrictors. These landmarks reveal that the most important expiratory muscles in the anterior pharynx (most parts of “constrictor hyoideus”, interhyoideus, levator palatoquadrati, spiracularis, and intermandibularis) are actually enlarged interbranchial muscles that have taken on a surface location. “Shrinking” these enlarged interbranchials and returning them to a deep location produces a simple, metameric reconstruction of the pre‐gnathostome pharynx that fits what is known about thelodonts and other fossil agnatha related to gnathostomes. Finally, the pharyngeal muscles of bony fishes are considered, and concluded to have evolved from a sharklike condition through an acanthodian‐like intermediate. © 1997 The Royal Swedish Academy of Sciences. Published by Elsevier Science Ltd.
Development, Ultrastructure and Function of the Pharynx of Halobiotus crispaeKristensen, 1982 (Eutardigrada)
Authors: Eibye‐Jacobsen Jette 
Published: April 2010

AbstractThe ultrastructure of the adult pharynx of the eutardigrade Halobiotus crispaeis described for the active, sexually mature summer form as well as for the winter form known as pseudosimplex 1. The total number of cells is 54: 27 muscle cells, 12 apical cells, nine nerve cells and six buccal tube cells. The development of the pharynx is described on the basis of five ontogenetic stages. Three of them are reconstructed three‐dimensionally with the help of computer techniques. The number of cells composing the pharynx remains constant from an early embryological stage and each cell can be traced and recognized in the adult pharynx. The findings regarding the ultrastructure of the pharynx are compared to previous descriptions. A hypothesis regarding the coordinated function of the organ and a preliminary attempt to define the plesiomorphic condition of the tardigrade pharynx are presented. © 1997 The Royal Swedish Academy of Sciences. Published by Elsevier Science Ltd.
Ultrastructural Diversity of the Manchette in Spermatids of Mosquitoes (Diptera: Culicidae)
Authors: Ndiaye Mady , Mattei Xavier , Thiaw Omar T. 
Published: April 2010

AbstractAn ultrastructural study of the manchette was carried out on 21 species belonging to the culicid genera Aedes, Anopheles, Culex and Toxorhynchites. Each genus has a characteristic morphological type of manchette. Toxorhynchites seems to have the type found in many other Diptera, while the other genera have unusual types.
Structure and Development of Teeth in Three Armoured Catfish, Corydoras aeneus, C. arcuatus and Hoplosternum littorale (Siluriformes, Callichthyidae)
Authors: Huysseune A. , Sire J.‐Y. 
Published: April 2010

AbstractWe have studied the premaxillary teeth in three armoured catfish, Corydoras aeneus, C. arcuatus and Hoplosternum littorale, by means of light and electron microscopy, in order to compare their development, fine structure and mode of attachment with that of odontodes and other teleost teeth. A premaxillary dentition consisting of small (50–100 μm long) slender pointed teeth showing no true replacement is only present in larval and juvenile stages and is subsequently lost, possibly in relation to a change in feeding mode from predatory to bottom feeder. Like odontodes, teeth are composed of dentine surrounding a pulp cavity and are covered by a hypermineralized cap. Particular features, also found in odontodes, are the absence of dentinal tubules and of nerves and capillaries in the pulp cavity, both possibly related to the small size of the teeth. The irregular pattern of implantation and the variability in attachment mode (primary and/or secondary attachment bone, fusion, mere apposition or ligamentous connection) distinguish the teeth from most other teleost teeth and from odontodes and are interpreted as reflecting considerable differences in dynamics of remodeling of the supporting element (premaxillary bone vs scute). This comparison of teeth and odontodes strongly supports current views according to which teeth and odontodes are two very closely related phenotypic expressions of a single, modifiable, morphogenetic system probably rooted in the earliest stages of vertebrate evolution.
External Anatomy of the Female Genital (Eighth) Limbs and the Setose Openings in Myodocopid Ostracodes (Cypridinidae)
Authors: Cohen Anne C. , Morin James G. 
Published: April 2010

AbstractThe external anatomy of various cypridinid female genital (8th) limbs is described. Scanning electron microscopy shows that each female cypridinid genital limb has a medial depression and associated pore (= spermatophore pore); over all of which a male cements a spermatophore. The limb terminates laterally in a superficially smooth rounded knob bearing an additional small opening (= lateral pore). Dorsolateral to this genital limb there are grouped setae, previously called “brush organs”, that are really paired, slit–like posterolateral openings, which are probably subdermally united to the female genital limbs. The “brush organs” of all myodocopid females also are likely to be the setose openings. The setose openings are probably homologous to the setose central lobe of male cypridinid copulatory limbs, but nothomologous to the limb–like “brush organ” described for some podocopid males. We speculate that the eggs are fertilized via the spermatophore pore associated with the attached spermatophore, and that they are released from the slightly larger and more lateral setose openings into the brood chamber of the posterodorsal area of the bivalved carapace.
The Structure of the Gular Pouch of Mature Males of the Lamprey Geotria australis
Authors: Potter I. C. , Welsch U. 
Published: April 2010

AbstractMales of the southern hemisphere lamprey Geotria australisdevelop a large gular pouch during sexual maturation. The wall of this pouch contains (I) an epidermis comprising typical lamprey epidermal cells, (II) a thick dermis consisting of layers of collagen fibres, with intervening oxytalan fibres, and a vascular network, and (III) a hypodermis. The hypodermis contains active fibroblasts embedded in an extracellular matrix, comprising collagen fibrils, some of which form dense bundles, together with oxytalan fibres and an amorphous material that contains glycosaminoglycans. The hypodermis also contains arteries, which are innervated and confluent with a large anastomosing system of sinuses. Since these sinuses open at intervals into the large central cavity of the pouch, it is proposed that, at maturity, they discharge blood into the central lumen of the pouch, thereby causing the pouch to become distended. The degree of such distension would be regulated by the limited elasticity of the dermal collagen fibres. The dermis is thickest in those regions where the pouch is most susceptible to abrasion. The Weibel–Palade bodies, which are abundant in the sinus endothelia, may facilitate tissue repair where neccessary. The gular pouch is thus a specialised structure, which may play a role in courtship or the spawning act.
Skeletal Ultrastructure in some Tubuliporine Cyclostome Bryozoans
Authors: Weedon Michael J. , Taylor Paul D. 
Published: April 2010

AbstractThe ultrastructure of the calcareous skeleton is described in twenty–one species of recent tubuliporine cyclostome bryozoans, using field emission SEM. The succession of skeletal fabrics in interior walls may be classified into four different fabric suites. The first–formed part of the calcitic skeleton in all species for which it has been observed is a precursory fabric of tiny, wedge–shaped crystallites. This is succeeded in about half of the species studied by a fabric of transverse fibres, followed by foliated fabric and often semi–nacre (fabric suite 1). Most of the remaining species lack transverse fibres and have interior walls largely comprising semi–nacre (fabric suite 2). A few species have skeletons consisting of predominantly distally–oriented, irregularly or regularly foliated fabric (fabric suite 3). A single species has a skeleton of proximally–oriented foliated fabric (fabric suite 4). Basal exterior walls in all species have a precursory fabric of tiny wedge–shaped crystallites without a strong preferred orientation, deposited directly upon the organic cuticle, followed by a layer of planar spherulitic structure, which in turn is succeeded by a similar fabric to that developed in the interior wall of the species concerned. Outermost layers of frontal exterior walls exhibit one of the following combinations of three fabrics: an outer layer of (1) finely granular or wedge–shaped crystallites; a thin dense granular layer followed by (2) distally accreting planar spherulitic fabric., or (3) obliquely accreting planar spherulitic fabric growing partly towards the midline of the frontal wall. Terminal diaphragms usually have outer layers dominated by planar spherulitic ultrastructure with centripetal growth directions. The fabric suites present in tubuliporines encompass most known fabrics found in the other cyclostome suborders and support the notion that this species–rich suborder occupies a central position in cyclostome evolution.
Morphological Development of the Opercular Apparatus in Kneria wittei(Ostariophysi: Gonorynchiformes) with Comments on its Possible Function
Authors: Grande Terry , Young Bruce 
Published: April 2010

AbstractThe structure, development and function of the male opercular apparatus were examined in the freshwater ostariophysan Kneria witteiusing a combination of techniques (i.e. histology, SEM, skeletal clearing and staining). Specimens ranged in standard length from 10 to 65 mm. Morphological comparisons were also made between males and females, as well as comparisons with closely related taxa. Our study shows that the Kneriaopercular apparatus consists of two structures: an opercular cup and a posteriorly positioned opercular flange, each of which is composed largely of connective tissue with keratinized papillae and ridges positioned on the surface. Our results further show that the development of the opercular apparatus is linked directly to the development of the anterior vertebral elements (i.e. epicentral intermuscular bones and neural arches). Understanding the function of the opercular apparatus must therefore include an understanding of its associated skeletal elements. As a result of our morphological observations two hypotheses for the function of the opercular unit are addressed; as an auditory specialization, and as an adhesive device. Copyright