bluuebunny/crossref_metadata_2025_split huggingface dataset:
Localisation of Vanadium, Sulphur and Bromine Within the Vanadocytes of Ascidia mentula Müller: A Quantitative Electron Probe X‐Ray Microanalytical Study
Authors: Lane D. J. W. , Wilkes S. L. 
Published: April 2010

AbstractLevels of vanadium, sulphur and bromine within the vanadopohores of Ascidia mentula vanadocytes have been determined by quantitative X‐ray microanalytical techniques. Values obtained for vanadophore vanadium in thin sections correspond to 2.5‐3.25% or 0.5‐0.65 molal aqueous solutions in vivo. Quantitation of sulphur in thin sections gives levels an order of magnitude lower than for vanadium, but it is likely that major losses of sulphur have occurred, since analysis of unfixed, air dried vanadocytes gives V/S atomic ratios close to unity. This 1: 1 ratio may have implications for the structure of the vanadium complex. Quantitation of bromine is less reliable, but levels of this halogen in vanadocytes are significant. The possibility that bromine, in the form of brominated metabolites, together with vanadium and acid, contribute to a multicomponent chemical defense role in ascidians is discussed.
Ultrastructural Study of Spermatogenesis and Mature Spermatozoa of Paravortex cardii (Platyhelminthes, Dalyellioida)
Authors: Cifrian Blanca , Garcia‐Corrales Pedro , Alós Susana Martinez 
Published: April 2010

AbstractThe spermatogenesis and mature spermatozoon of Paravortex cardii were studied by transmission electron microscopy. Meiotic divisions occur without cytokinesis and the spermatid nuclei appear embedded in a common cytoplasmic mass. The mature spermatozoon is filiform, very regular in contour and circular in cross‐section. A tubular lining of microtubules lying close to the plasma membrane is found along the spermatozoon. Rows of spherical glycogen particles with helical arrangement lay internal to the cortical microtubules. The spermatozoon of P. cardii may be divided into two regions, nuclear and cytoplasmic regions. The nuclear region contains an elongated nucleus with a densely packed nuclear material. The mitochondria are distributed throughout the cytoplasmic region; they pack tightly together and often fuse to form one large one. This spermatozoon lacks both acrosome and the so‐called dense bodies. A ciliary or centriolar apparatus was not observed. Accordingly, the spermatozoon of P. cardii is considered to be aflagellate in type. Spermatozoa are compared among flatworms, and some considerations on the significance of their ultrastructure for phylogeny in the Platyhelminthes are tentatively given.
A Scanning Electron Microscopic Study on the Thyroid Follicle of the Hagfish Eptatretus burgeri
Authors: Suzuki Shintaro , Kawabata Isuzu 
Published: April 2010

AbstractThe external form of the follicles was mostly spherical or oval and the large oval follicles reached more than 300 times 180 μm in size. Cytoplasmic inclusions of various sizes were observed in the follicular epithelium. Follicles were composed of hexagonal epithelial cells, and on the apical surface of the cells many microvilli were found (380–500 microvilli per cell) with globular or amorphic cytoplasmic protrusions. In a few cells a central cilium was also observed. From these results a relationship between thyroid structure and function in the hagfish is discussed.
The Fine Structure of the Testis of a Lancelet (=Amphioxus), Branchiostoma floridae (Phylum Chordata: Subphylum Cephalochordata= Acrania)
Authors: Holland Nicholas D. , Holland Linda Z. 
Published: April 2010

AbstractThe germinal and non‐germinal cells of the ripe lancelet testis are described by transmission electron microscopy. The visceral peritoneum of the testis is composed of myoepithelial cells, and the haemal layer consists of regions of narrow sinuses and conspicuously thicker blood vessels filled with blood plasma and bounded by basal laminae. Within the germinal epithelium and the testicular lumen, the non‐germinal cells, which are not abundant, contain conspicuous lysosomes and mitochondria with tubular cristae, indicating that they may be involved in steroid synthesis. In the ripe testis, the non‐germinal cells do not appear to be organized into a blood‐testis barrier. Ail types of spermatogenic cells may be flagellated and are joined in small groups by intercellular bridges. During differentiation of the spermatids, the Golgi complex is associated with formation of the acrosomal vesicle near the posterior pole of the cell. A remarkable feature is the dual origin of the subacrosomal material: one component originates at the posterior end of the spermatid, and the other at the anterior end. Subsequently, the two components merge into one after the acrosomal vesicle has migrated to its definitive anterior position in the mature spermatozoon.
Macrophages and Reticulum Cells in the Spleen of the Dogfish, Scyliorhinus canicula
Authors: Pulsford A. , Zapata A. 
Published: April 2010

AbstractThe presence and ultrastructural features of reticulum cells and macrophages were studied in the spleen of the dogfish Scyliorhinus canicula. Three morphologically distinguishable regions of the spleen were identified: the white pulp, the red pulp and the ellipsoids. In all three, the splenic parenchyma was a meshwork supported by reticulum cells and fibres. Reticulum cells in both the white and the red pulp are irregular elements, the processes of which are joined by cell junctions and embrace developing reticular fibres. The ellipsoids of the dogfish spleen are terminal branches of the splenic arteries of the white pulp, with a sheath consisting of reticulum cells, reticular fibres, ground substance, macrophages and occasional lymphocytes. Isolated melanomacrophages also occur in the ellipsoid walls as well as in the red pulp. In both the white and the red pulp phagocytic reticulum cells, and macrophages appear frequently forming cell associations with surrounding blood cells, mainly lymphocytes. The functional significance of the ellipsoids and the cell‐cell clusters of the white and the red pulp is discussed in relation to the immune capacities demonstrated in elasmobranchs.
Morphological Studies on the Testis of Adults of Moniliformis (Acanthocephala)
Authors: Asaolu S. O. 
Published: April 2010

AbstractThe morphology of the testis in young adult males of Moniliformis dubius developing in the rat has been studied with the aid of light and electron microscopes. In one‐day‐old male worms, the testis is organised as two zones. One zone consists of individual germ‐line cells, while the other consists of a supporting syncytium which embeds the cells and forms the boundary of the testis. The surface of the testis is covered by a fibrous non‐cytoplasmic coat. In seven‐day‐old male worms, the syncytium has lost its compact form, breaking down into multinucleate units connected by cytoplasmic processes and apparently forming a loose syncytial network throughout the testis. The germ cells are now randomly distributed and are surrounded by wide spaces among the segments of the supporting syncytium. The fibrous coat, lined internally by an irregular layer of the syncytium, forms the testis envelope. This basic structure is maintained in the testis of 14‐day‐old and sexually mature male worms.
Fine Structure of the Cellular Parenchyma and Extracellular Matrix of Ophiotaenia loennbergii (Cestoda: Proteocephalidea)
Authors: Conn David Bruce , Rocco Laura J. 
Published: April 2010

AbstractThe cellular parenchyma and extracellular matrix (ECM) of Ophiotaenia loennbergii were studied by light and transmission electron microscopy. The parenchyma consists primarily of muscle cells divided into three compartments that maintain some cytoplasmic continuity: (1) myofibrils; (2) broadly lobate nucleated myocytons (muscle cell perikarya) with the perinuclear cytoplasm dominated by greatly dilated cisternae of granular endoplasmic reticulum: (3) thin anucleated sarcoplasmic extensions formed in sheets with abundant glycogen and extremely large lipid droplets, which cause the cytoplasmic sheets to bulge. These cellular compartments are separated from each other by abundant ECM, which consists primarily of an electron‐lucent amorphous ground substance. Filaments are scarce in all ECM except the tegumental basement lamella. This is the first report of parenchyma and ECM fine structure in the Proteocephalidea. The results provide additional evidence that cestode parenchyma is formed from similar cells, but is subject to substantial variability between different species.
The Ultrastructure of the Proboscis in Psammorhynchus tubulipenis Karling, 1964 and Cytocystis clitellatus Karling, 1953 (Platyhelminthes, Rhabdocoela)
Authors: De Vocht Alain 
Published: April 2010

AbstractThe ultrastructural organization of the proboscis in two species of free‐living Platyhelminthes, Psammorhynchus tubulipenis and Cytocystis clitellatus is very alike but differs from previously described species. Both sheath and cone epithelium are composed of two circumferential belts. Only the basal cone epithelium is syncytial, while no nuclei were found in the distal belt of the sheath epithelium. The sheath epithelium is characterized by numerous infoldings of the basal plasma membrane. The nuclei present in the bulb belong to the proximal belt of the sheath epithelium and the apical cone epithelium. Nuclei of the basal cone epithelium are located insunk behind the proboscis bulb. The insunk cell parts pierce the septum of the bulb laterally near the proximal end. Different types of gland necks and sensory cells pierce the epithelia. Associated with the distal belt of the sheath epithelium, two sensory organs are found, containing multiciliary receptors with modified axonemata. Differences in organization of the proboscis musculature are described and compared with the organization in other species. The systematic position of both species is discussed in the light of the new findings.
Fine Structure of the Midgut and Hindgut in Lepidocampa weberi (Insecta, Diplura)
Authors: Xue L. , Dallai R. , Yin W.‐Y. 
Published: April 2010

AbstractThe fine structure of the alimentary canal, especially the midgut and hindgut of Lepidocampa weberi (Diplura: Campodeidae) is described. The general organization of the canal is similar to that of Campodea. The midgut epithelium is composed of columnar apical microvillated cells. Each nucleus contains a single intranuclear crystal. Close to the pyloric region, the posterior midgut cells are devoid of microvilli and intranuclear crystals. There is no special pyloric chamber as in Protura or pyloric cuticular ring as in Collembola but a morphological transformation from midgut to hindgut cells. Eight globular Malpighian papillae, consisting of distal microvillated cells and flat proximal cells, open into the gut lumen via ducts formed by hindgut cells. The structure of the hindgut is complicated and can be divided into three segments. The anterior hindgut cells have an irregular shape and compact cytoplasm. A striking interdigitation between the large bottle‐shaped epithelial cells and longitudinal muscle cells occurs in the middle segment of the hindgut. The thick cuticle gives rise to long spikes projecting into the gut lumen. The posterior hindgut cells possess the morphological features for water reabsorption. Some hypotheses are advanced about the function of the different regions of the gut.
Lectin Histochemistry on Glycoconjugates of the Epidermis and Dermal Glands of Xenopus laevis (Daudin, 1802)
Authors: Danguy André , Genten Franck 
Published: April 2010

AbstractWe performed an investigation at the light microscopical level of the differential distribution of lectin‐binding sites among cells of the epidermis and glandular domains of the African clawed frog Xenopus laevis. Using a panel of biotinylated lectins (Con‐A. PSA, LCA, UEA‐I, DBA, SBA, SJA, RCA‐I, BSL‐I, WGA, s‐WGA, PHA‐E and PHA‐L) and an avidin–biotin–peroxidase complex (ABC), we have identified specific binding patterns.The results show that expression of saccharide moieties in Xenopus epidermal keratinocytes is related to the stage of cellular differentiation, different cell layers expressing different sugar residues. Moreover, oliogosaccharides with “identical” biochemically defined sugar compositions can be distinguished. The method allowed further characterization of complex glycoconjugates of dermal glands. In view of these results, the ABC technique and the biotinylated lectins employed in the present study are believed to be a reliable method for the precise localization of saccharide residues of glycoconjugates present in ectothermic vertebrates.
Internal Organization of Limbate Polychaete Setae (Sabella penicillus), with Notes on Bending Stiffness
Authors: Kryvi Harald , Sørvig Tryggve 
Published: April 2010

AbstractThe internal architecture of the limbate setae of Sabella penicillus (Sabellidae) is described, based on transmission and scanning electron microscopy. The setae are composed of a number of cylindrical channels (mean= 877). The number of channels is less than one third of the number of spines on the distal swollen part of the setae. In the proximal shaft, channels are hollow and cylindrical. Towards the expanded distal part of the setae, the lumen gradually disappears, and the shape of the wall of the channels changes from circular to hexagonal. With no lumen, the term microrod is suggested as more descriptive than ‘channel’ for the units in this part of the seta. The solid microrods change from a strictly hexagonal shape to a more irregular indented shape, and gradually taper off towards the tip region. The cortical layer of the expanded part contains numerous irregular cavities. Morphometric data on the organization of the internal components are presented. When tested for flexibility, the setae broke when bent to a mean of 93.6° (±9°). Calculations based on morphometry show that the bending stiffness is up to 19 times greater in the swollen part than in the shaft, and it is reduced to about 1/50 in the distal whip.
Ultrastructure of the Geogarypus nigrimanus Spermatozoon (Arachnida, Pseudoscorpionida)
Authors: Dallai Romano , Callaini Giuliano 
Published: April 2010

AbstractThe ultrastructure of the spermatozoon of Geogarypus nigrimanus (Arachnida, Pseudoscorpionida) is described. The spermatozoon is composed of a small elliptic nucleus, a short flagellum and a very long and complex acrosome. In the male genital ducts, as in other studied species of pseudoscorpions, the sperm components are rolled up to form a globular structure enclosed in a cyst wall. The Geogarypus spermatozoon with a reduced flagellum and a giant acrosome seems to be evolutionary more advanced than spermatozoa from other pseudoscorpions.
FMRFamide‐like Peptides in the Nervous and Endocrine Systems of the Digenean Helminth Echinostoma liei
Authors: Riddell Jennifer H. , Whitfield Philip J. , Balogun M. A. , Thorndyke Michael C. 
Published: April 2010

AbstractFMRFamide‐like immunoreactivity has been demonstrated in the digenean trematode Echinostoma liei. The functions of FMRFamide‐like substances appear to be many and varied within the invertebrates, where they are involved in neurotransmission, cardiovascular regulation, muscular contraction and/or relaxation, and in co‐ordination of growth and maturation. It is clearly indicated that FMRFamide‐like substances function as neurotransmitter/neuromodulator in E. liei by the abundance of positively stained nerve fibres and perikarya seen throughout the CNS and PNS. A single endocrine‐like cell also showing FMRFamide‐like immunoreactivity is situated within the muscular cirrus pouch.
Trans‐epidermal Transport and Storage of Calcium in Holthuisana transversa (Brachyura; Sundathelphusidae) During Premoult
Authors: Greenaway Peter , Farrelly Caroline 
Published: April 2010

AbstractHolthuisana transversa reabsorbs much of its exoskeletal calcium in the last 3 days before ecdysis and stores it in circulating granules in the haemocoel and in non‐circulating granules in the subepidermal connective tissue. Calcium enters the epidermal cells from the moulting fluid, probably through their apical microvilli and is either incorporated into intracellular calcium granules or exits the cell via the basolateral membranes to be used in formation of two other granule types. Intracellular granules (0.4–2 μm long) form in large masses in the apical cytoplasm of the epidermal cells. They are formed as membrane‐bound vesicles by the Golgi, and calcium and organic matrix material are added from the surrounding cytoplasm. As development proceeds, lamellae appear and calcium carbonate is deposited in the matrix. Granule masses move basally and are stored in the connective tissue. Calcium is also incorporated into extracellular large granules (0.8–3.8 μm long) which are formed in narrow intercellular channels between epidermal cells. A third granule type (small granules, 0.26 μm diameter) is formed in subepidermal connective tissue cells and released into the haemolymph in very large numbers. Calcium was identified in the two larger granule types using X‐ray microanalysis and significant amounts of phosphorus and potassium were also present in the large granules. A model for ion cycling between the exoskeleton and granules is presented.
Egg Turning During Incubation has no Effect Upon the Growth of Embryos of Alligator mississippiensis
Authors: Deeming D. C. , Ferguson M. W. J. 
Published: April 2010

AbstractAlligator eggs are not turned during incubation, instead the embryo adheres to the top inside of the shell. Turning is alleged to shear off the embryo and kill it. Avian egg turning allegedly facilitates embryonic development by stimulating growth of the area vasculosa and minimizing the effects of unstirred yolk and albumen layers.From day 10 to day 45 of incubation, alligator eggs were experimentally turned, gently, through ± 60° in an hourly cycle. This turning regime killed only 6 out of 25 embryos. Compared with unturned controls, no significant effects were observed on the growth, production of extraembryonic fluids or utilization of albumen and yolk for those embryos that survived turning. The protein concentration of amniotic fluid at various stages of alligator development was examined in eggs incubated at 30 and 33°C. The fluid contained very little protein (max <8 mg) at any time: the protein concentration did not change consistently as development progressed. Differences in response to egg turning in birds and reptiles may be associated with the length of the incubation period, the protein content of the albumen and the mechanism of albumen utilization.
Comparison of Alimentary Systems in Shelled and Non‐shelled Sacoglossa (Mollusca, Opisthobranchia)
Authors: Jensen Kathe R. 
Published: April 2010

AbstractThe Sacoglossa (= Ascoglossa) comprise a ‘complete’ evolutionary series from species with a large shell into which the animal can withdraw completely, through species with a reduced shell covering only the visceral mass, to shell‐less (‘nudibranchiate’) forms some of which have lateral wing‐like extensions, parapodia, others bearing leaf‐like or cylindrical dorsal appendages, cerata. The Sacoglossa are all specialized suctorial feeders, and almost all are stenophagous herbivores. Hence many anatomical adaptations to a particular food occur in the alimentary system. However, a number of characters seem to reflect phylogenetic relationships as well. Among these are presence/absence, shape, and position of pharyngeal pouches, basic shape of radular teeth, branching pattern of digestive gland, and position of anus. The classificatory significance of these characters is discussed.
A Study of the Morphology and Biology of Thompsonia littoralis (Crustacea: Cirripedia: Rhizocephala)
Authors: Lützen Jørgen , Jespersen Åse 
Published: April 2010

AbstractInterna development within the intertidal tropical crab, Leptodius exaratus, requires up to 4.5 months; the roots become distributed from the CNS along the major nerves and, when the crab moults, results in emergence of numerous externae located symmetrically on the abdomen and bases of the thoracic appendages. As many externae drop off, their number is continuously reduced; the survivors reach sexual maturity and ovulate after 2.5 months and complete embryonic development after 2 more months. At the next moult a new and more numerous generation of externae appears, and this is repeated until the crab dies. Presence of externae significantly prolongs the host's normal intermoult period and minimizes its growth. The parasite has little effect on the host's sexual characters although females are normally sterilized. The cuticle of the externa is moulted once, leaving a distinct annulus around the stalk. Spermatogonia are presumably injected by male cyprids into the female externa and develop into sperm within one or more vesicular spermatogenic bodies in its mantle. The eggs are laid through a single oviduct into the mantle cavity where they become fertilized and develop into cyprids that are liberated at the disintegration of the externa.
A Study of the Alimentary Canal of the Brachyopterygian Fish Polypterus senegalus with Electron Microscopy and Immunohistochemistry
Authors: Burkhardt‐Holm Patricia , Holmgren Susanne 
Published: April 2010

AbstractThe gastro‐intestinal tract of Polypterus senegalus was investigated by means of electron microscopy and immunohistochemistry. Cilia‐bearing cells can be observed over the whole length of the intestine. All enterocytes along the intestinal tract are characterized by apical pinocytotic vesicles. However, a typical intestinal region, which in other fish is characterized by large supranuclear vacuoles, is lacking. By means of electron microscopy, four types of endocrine cells and three types of nerve cell processes can be identified. By means of immunohistochemistry, endocrine cells with immunoreactivity for bombesin‐, enkephalin‐, G/CCK‐, 5‐HT‐, somatostatin‐ and substance P‐antisera can be found. Nerve cell processes show immunoreactivity for bombesin‐, enkephalin‐, 5‐HT‐, substance P‐ and VIP‐antisera. The number of immunoreactive endocrine cells, nerve cells and nerve cell processes is different for each part of the gut.
Scanning Electron Microscopy and X‐ray Diffraction Studies of the Macular Crystals in the Chondrostean Fish Erpetoichthys calabaricus (Smith)
Authors: Marmo Francesco , Ariani Antonio P. , Balsamo Giuseppe , Avallone Bice 
Published: April 2010

AbstractMorphologic and crystallographic studies of the otoliths of the reed‐fish Erpetoichthys calabaricus showed (1) aragonite statoliths with a serrated surface, and (2) two populations of statoconia: one of numerous discoid biconvex crystals of vaterite, the other of pseudohexagonal crystals of aragonite. We suggest that the presence of two calcium carbonate polymorphs in the statoacoustic organs of this archaic fish may have an evolutionary, as well as a systematic and functional significance.