bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Protonephridia of the Arctic Kinorhynch Echinoderes aquilonius (Cyclorhagida, Echinoderidae)
Authors: Kristensen Reinhardt Møbjerg , Hay‐Schmidt Anders 
Published: April 2010

AbstractThe cyclorhagid kinorhynch Echinoderes aquilonius Higgins & Kristensen, 1988 possesses a single pair of protonephridia located in segments 10 and 11. The protonephridia consist of: (1) three terminal cells T‐1, T‐2. T‐3, each with two cilia; (2) a single non‐ciliated canal cell; (3) a nephridiopore cell with many microvilli and a cuticular sieve plate.The protonephridia of Echinoderes are presumed to develop from the ectoderm near the area of the sieve plate on the eleventh segment, and are suspended in the dorso‐lateral pseudocoelomic cavity where they are surrounded by a basal lamina. One of the terminal cells (T‐1) secondarily penetrates the basal lamina of the tenth segment and a part of the cell attaches to the cuticle. The kinorhynch protonephridia are compared with the excretory organs of other Bilateria. expecially the ‘aschelminths’, and apomorphic characters of the kinorhynch protonephridia are defined.
Fine Structure of the Labial Gland in Macrotermes bellicosus (Isoptera, Termitidae)
Authors: Billen J. , Joye L. , Leuthold R. H. 
Published: April 2010

AbstractThe labial gland in M. bellicosus corresponds with the acinar type, and occupies the greater part of meso‐ and metathorax. The acini comprise three secretory cell types, in addition to the central ductule cells and the epithelial cells that make up the efferent ducts. Cell types are mainly distinguished by the size and appearance of their secretory vesicles and the extent of the microvillar contact area with the ductule cells. They probably produce a proteinaceous secretion that may contain digestive enzymes. The labial gland acini in soldiers, on the other hand, contain only one type of secretory cell, which is not comparable with any of the cell types in the worker caste. This difference is in agreement with the multifunctional role of the labial gland according to the termites' polyethism.
The Oral Papilla of the Lancelet Larva (Branchiostoma lanceolatum) (Cephalochordata)
Authors: Andersson Eva , Olsson Ragnar 
Published: April 2010

AbstractThe oral papilla is a prominent larval organ in the lancelet, which develops early during ontogenesis and disappears completely at metamorphosis. Electron microscopic studies indicated that the prevailing theories of its function are unlikely. Its cells lack the cytological characteristics of sensory or mucus producing cells, and the organ is not equipped with a tuft of flagella. It was not possible to reveal the function of the papilla, but its cells seem to be involved in a pronounced substance transport through the basal cell membrane as well as in the cytoplasm. Apical specializations indicate exo‐ or endocytotic activity and vesicles imply some exchange also between papilla cells and the sea water.
Sperm Structure in the Psocoptera
Authors: King P. E. , Ahmed K. S. 
Published: April 2010

AbstractAn account is given of the ultrastructure of the sperm in Psocoptera. Three main types of sperm occur. Type one, in Suborder Trogiomorpha, is an uncoiled long sperm with a filamentous head and a flagellum containing two or three lateral ridges and two central tubules. Twenty three per cent of this type has two axonemes and four mitochondrial derivatives. The second type, in the Suborder Psocomorpha, lacks both central tubules and lateral ridges. Four per cent of this type contain biaxonemes and four mitochondrial derivatives. In the third type, in the Suborder Troctomorpha. 100% of the sperm have two axonemes and two mitochondrial derivatives. The possible function and the method of locomotion of these types are described. The similarity between sperm structure in the Psocoptera and in Anoplura and Mallophaga suggests a close phylogenetic relationship between the three orders.
Apertures of Craniate offactory Organs
Authors: Bjerring Hans C. 
Published: April 2010

AbstractThe olfactory organs of craniates appear to derive from an anterior pair of erstwhile branchiothyria and their adjacent epidermal, neurogenic placodes. The organ is termed saccus nasalis if its source is the ectobranchial invagination of the branchiothyrium, and the saccus rhinalis if its source is the entobranchial evagination of the branchiothyrium. Nasal sacs occur in gnathostomes and lampreys, and rhinal sacs in hagfish. It is difficult, therefore, to avoid the conclusion that the olfactory organ has evolved more than once. The rhinal sac has only one aperture, the postica, which represents an internal branchiothyric orifice. Partial fusion of the right and the left rhinal sac led to the development of a postica communis. The nasal sac has either one, two or three apertures. Altogether there are nine different aperturae sacci nasalis, viz. the naris, the foris, the tremiscus, the two nariculae, the rimilla, the portula, the opiscus and the janua. The janua represents an external branchiothyric orifice and occurs in lampreys. The naris and the foris arose by subdivision of the orifice from which the janua emanated; they are found in osteolepipods. The naris is also found in urodeles, porolepiforms and some teleosts. The incurrent and excurrent naricules resulted from bipartition of a naris and are present in actinopterygians, coelacanthiforms, brachiopterygians, dipnoans and elasmobranchiomorphs. Of the four remaining openings of the nasal sacs the rimilla results from an inpushing of the epidermis, the portula from an outpocketing of the nasal sac, and the tremiscus from a combination of two such movements, the one inward and the other outward. Rimillae occur in cyprinodonts, anurans, urodeles, caecilians and porolepiforms, portulae in uranoscopids and bathydraconids, and tremisci in urodeles and porolepiforms. The opiscus, finally, is the opening through which the vomeronasal organ communicates with the oral cavity. It occurs in most lizards and snakes and probably also in some mammals.
Further Evidence that Synaptic and Synaptoid Vesicles Constitute a Single Category of Inclusions: Dense‐cored Synaptic and Synaptoid Vesicles in Helix Discharge their Contents by Exocytosis
Authors: Bayraktaroglu Emine , Golding D. W. , Whittle A. C. 
Published: April 2010

AbstractIn the pulmonate mollusc Helix, neurosecretory cells have perikarya that form neurohaemal complexes peripherally beneath the inner surface of the neural lamella and give rise to axons with varicosities in the neuropile. Two categories of secretory inclusions are present throughout the cytoplasm and these accumulate adjacent to sites of release. Secretory granules invariably have electron‐dense contents, whereas smaller vesicles have fairly lucent contents following fixation in OsO4, but are dense‐cored in material fixed initially with aldehyde. Vesicles (‘synaptic vesicles’) at central sites appear identical to those (‘synaptoid vesicles’) at peripheral, neurohaemal locations. At both neurohaemal and central sites, both granules and vesicles discharge their contents by exocytosis, this process being most clearly visualized in tissues treated with tannic acid.
On the Fine Structure of the Nervous System of Tubiluchus philippinensis (Tubiluchidae, Priapulida)
Authors: Rehkämper Gerd , Storch Volker , Alberti Gerd , Welsch Ulrich 
Published: April 2010

AbstractAt the mouth tube/introvert border a circumenteric intraepithelial nerve ring occupies a circular ridge protruding into the body cavity. The ring has a centrally located neuropile nearly free of perikarya and two zones of different perikarya above and below the neuropile.Presumably non‐neuronal perikarya have an oval nucleus, large heterochromatin clumps and marked filament bundles. Such elements resemble tanycytic glial cells.Two types of presumably neuronal perikarya contain small cytoplasmic granules, similar to those in nerve fibre profiles. One of these neurons has a pale nucleus with a prominent nucleolus, the other a rather inconspicuous nucleus similar to that of the tanycytic cells.The neuronal processes of the fibre ring differ in diameter and contain clear and dense core vesicles, small granules (high or medium electron density) or granules with a dense periphery and a light centre. Sometimes neighbouring processes seem interconnected by electrical synapses. Images suggesting chemical synapses are rare.A large intraepithelial nerve lies in the wall of the introvert and ventral body wall close to the musculature, possibly innervated by this nerve.Frontal of the anus lies an intraepithelial ganglion demonstrating again a central neuropile. two neuronal types and tanycytic elements with filament bundles.Comparative aspects of the characters of the Tubiluchus nervous system are also discussed.
The Tentacle Cilia of Aglantha digitale (Hydrozoa: Trachylina) and their Control
Authors: Mackie G. O. , Nielsen Claus , Singla C. L. 
Published: April 2010

AbstractThe tentacles of Aglantha have ciliary bands along the sides. Metachronal waves pass along these bands. The strong ciliary currents produced propel water past the tentacles, increasing the probability of prey capture. The ciliated cells are unusual in having many (up to about 500) cilia per cell, where most cnidarian ciliated cells have only one. The cells are also peculiar in containing numerous axonemes without membrane coverings, lying loose in the cytoplasm.Tentacles show independent, rhythmic, slow flexions in the oral direction and groups of tentacles show coordinated, slow flexions as part of a regularly repeated fishing cycle. In both cases, these slow, graded movements are mediated by a slowly conducting system, probably the network of small neurons present in the ectoderm, and are accompanied by ciliary arrests. Much faster, more powerful, coordinated contractions of the tentacles occur in the context of escape behaviour; these are mediated by giant axons which run down the tentacles and are also accompanied by ciliary arrest. Ciliary and muscle effectors evidently share a common motor innervation. Electron microscopy shows that the giant and non‐giant nerves both synapse with muscle cells. The latter are joined to the ciliated cells by gap junctions, and it is suggested that whenever the muscles are excited depolarizations spread to the ciliated cells through the gap junctions and cause ciliary arrests. Neuronal control of ciliary activity has not previously been reported in the Hydrozoa.
Ultrastructure of the Protonephridial Terminal Organ in the Terrestrial Nemertean Geonemertes pelaensis (Rhynchocoela, Enopla, Hoplonemertini)
Authors: Jespersen Å. , Lützen J. 
Published: April 2010

AbstractThe protonephridial terminal organ of Geonemertes pelaensis consists of two cells that are equal in both size and shape and form mirror images of each other. From the perinucleate lump‐shaped region basally in each cell arises a cytoplasmic column which branches at regular intervals to form 3–4 nearly circular bars. The opposed columns and alternating bars of the two cells are arranged in such a way that they form an obviously rigid, cylindrical structure which both supports and gives rise to the thin‐walled weir. The fenestration of the weir consists of a single, enormously extended and sinuous cleft which represents part of the boundary between the two terminal cells. The ciliary flame comprises 92–118 cilia that originate basally in the two cells and is surrounded by a palisade of long, straight microvilli, positioned immediately within the weir's wall. The structure is very similar to that of the terminal organ of the land nemertean Pantinonemertes, except that the cytoskeleton which supports columns and bars consists of a fibro‐granular substance, not, as in Pantinonemertes, of an abundance of oriented microtubules.
Sensilla and Cuticular Appendages on the Female Abdomen of Lasioptera rubi (Schrank) (Diptera, Cecidomyiidae)
Authors: Tastás‐Duque Ruben , Sylvén Edvard 
Published: April 2010

AbstractStudies by SEM and TEM revealed 6 types of integumental appendages on female uromeres VIII‐X in Lasioptera rubi: microtrichia, not innervated; spines, probably without sensory function; nonporous sensory hairs, each containing one dendrite ending with a tubular body indicating a tactile function; uniporous sensory hairs, each innervated partly by 3 dendrites indicating a chemosensory function, partly by an additional dendrite with a tubular body indicating a tactile function; scoop‐like sensilla, each containing partly a branched structure of dendrites in the distal half of the sensillum indicating an olfactory function, partly an unbranched dendrite ending at a pore near the base of the sensillum, most probably registrating chemical stimuli by contact or gustation; finally, nonporous bristles, all or some of them innervated, in a manner indicating a tactile function. In addition, two scolopophorous proprioceptors were found inside uromere X. The nonporous sensory hairs, the uniporous sensory hairs and the scolopophores may be used by the midge to determine the mechanical and chemical properties of potential oviposition sites. The spines and nonporous bristles may function as conidia carriers.
The Anatomy of Melanodrymia aurantiaca Hickman, a Coiled Archaeogastropod from the East Pacific Hydrothermal Vents (Mollusca, Gastropoda)
Authors: Haszprunar Gerhard 
Published: April 2010

AbstractThe anatomy of Melanodrymia aurantiaca Hickman, 1984, a coiled archaeogastropod from the East Pacific hydrothermal vents, is described based on reconstructions of paraffin and semi‐thin section series. Whereas the large protoconch with net‐like sculpture and the lack of a secondary larval shell, the bipectinate gill lacking skeletal rods, the rhipidoglossate rasdula and in particular the hypoathroid nervous system with pedal cords reflect an archaeogastropod level of organization, the single set of pallial organs, the monotocard heart, the single left kidney, the glandular gonoduct and internal fertilization indicated by penis (males) and receptaculum (females) resemble conditions of higher streptoneurans. The latter similarities are regarded as convergences, however.The unique combination of primitive and advanced features as well as specific peculiarities (e.g. neural sexual dimorphism) prevents an inclusion of Melanodrymia aurantiaca in any of the known archaeogastropod groups. Based on similarity of snout formation and similar radula type several other recently described archaeogastropods (Peltospiroidea) are possibly related to M. aurantiaca.
The Biology of Eurypharynx pelecanoides (Pisces, Eurypharyngidae)
Authors: Nielsen Jørgen G. , Bertelsen E. , Jespersen Åse 
Published: April 2010

AbstractThis paper is based on 760 Atlantic specimens of pelican eels caught from off Iceland to 48°S in depths between 2750 and c. 500 m. Stomach contents from 120 specimens show a varied diet dominated by crustaceans, fish and squid. The frequent occurrence of Sargasso weed consumed by Eurypharynx indicates a lack of prey‐item discrimination. The forward directed eyes appear to enable stereoscopic prey localization, possibly aided by the well developed lateral line. The huge gape is unsuitable for suction feeding. It is proposed that prey engulfing is accomplished by a forward thrust of the head by which the produced water pressure will expand the buccal cavity to a volume several times that of the fish itself. When ripening, males especially show morphological changes in some characters, indicating that the pelican eel breeds only once, a condition which seems to be the rule among eels.
Changes in the Visual Cell Layer of the Duplex Retina During Growth of the Eye of a Deep‐sea Teleost, Gempylus serpens Cuvier, 1829
Authors: Munk Ole 
Published: April 2010

AbstractOntogenetic changes in the visual cell layer of the duplex retina during growth of the eye of the deep‐sea teleost Gempylus serpens, the snake mackerel, are illustrated by comparing the retina of a small specimen with that of a previously studied adult fish.The small specimen has tightly packed cones spanning the whole width of the visual cell layer and small rods situated in its vitread part. Over most of the retina the cone population consists of single cones arranged in a very regular hexagonal mosaic. The temporalmost retina has a cone population consisting mainly of twin cones arranged in meridional rows.Growth of the eye is associated with an increase in the thickness of the visual cell layer and the density of rods and a total elimination of the densely packed single cones, the retina of the adult fish possessing only a temporally located population of double cones.The radical differences between the retina of the small and adult snake mackerel are probably associated with the different light regimes encountered by small and large specimens.
Vaterite Otoliths from the Opah, Lampris immaculatus, and Two Species of Sunfish, Mola mola and M. ramsayi
Authors: Gauldie R. W. 
Published: April 2010

AbstractThe cosmopolitan opah Lampris immaculatus (also known as the moonfish or mariposa) occurs commonly in New Zealand waters. The otoliths of 23 individuals were examined by light microscopy. All three of the otoliths of the endolymphatic sac of the opah have the characteristic appearance of the Stolkowski crystal form of the vaterite morph of calcium carbonate. Five randomly chosen pairs of asterici and sagittae and two lapilli otoliths were shown by X‐ray diffraction to be composed of vaterite. In addition to their mineral composition, the sagitta and astericus of the opah present an unusual combination of anatomical features found in both what are generally regarded as primitive and as advanced fish. Vaterite otoliths also occur in the sunfish Mola mola and M. ramsayi, but with a different crystalline habit to that found in the opah, and in a distinctively different anatomical arrangement of the endolymphatic sac. It is argued that, based on their otolith mineralogy and morphology, the opah and the sunfish are each side of one of the biochemical and anatomical boundaries involved in the separation of the teleosts from other actinopterygian fish (sturgeons, paddle fish, gars and bowfins).
Ultrastructure of the Flame Bulbs of Urastoma cyprinae (Platyhelminthes, ‘Prolecithophora’, Urastomidae)
Authors: Rohde K. , Noury‐Sraïri N. , Watson N. , Justine J.‐L. , Euzet L. 
Published: April 2010

AbstractThe ultrastructure of the flame bulbs of the turbellarian Urastoma cyprinae from Mytilus galloprovincialis in the Mediterranean is described. The nucleus of the terminal cell is located some distance basal to the rootlets of the cilia forming the flame; the cytoplasm contains numerous tubules approximately 54–66 nm in diameter, and vesicles. Thick walled, densely packed rod‐like structures coil around each other with a tendency towards longitudinal orientation close to the flame. The rod‐like structures tightly surround the basal part of the flame and the distal cytoplasmic tube in the apical part of the flame. Some of them, including the inner predominantly longitudinally directed ones, are continuous with the cytoplasm of the terminal cell, others are continuous with the cytoplasm of the distal cytoplasmic tube. Internal leptotriches arise from the cytoplasm of the terminal cell and intrude between the basal parts of the cilia of the flame. The distal cytoplasmic tube possesses a septate junction. The flame bulb of Urastoma differs distinctly from those known from other Platyhelminthes; implications for the phylogeny of Platyhelminthes are discussed.
The Ultrastructure of the Compound Eye of Two Species of Marine Ostracodes (Crustacea: Ostracoda: Cypridinidae)
Authors: Huvard Andrea L. 
Published: April 2010

AbstractUltrastructurally, the compound eyes of the luminescent marine ostracodes Vargula graminkola and V. tsujii are similar. These ostracodes have two lateral compound eyes, with relatively few ommatidia (13 and 20 respectively). They exhibit apposition type compound eyes as seen in many other arthropods. Each ommatidium includes: a flat, ectodermal cuticular covering, corneagen cells, two long cone cells that give rise to a large conspicuous crystalline cone, retinular cells, pigment cells, a microvillar rhabdom and proximal axonal neurons. The axons merge to form an optic nerve that extends into the brain through a short, muscular stalk that is surrounded externally by a cuticle. The number of retinular cells is typically six per ommatidium in V. graminicola and eight per ommatidium in V. tsujii. Screening pigment cells surround each ommatidium forming a layer that is about 5–15 pigment granules thick. In addition to pigment cells, the cytoplasm of the retinular cells includes numerous screening pigment granules. In light/dark adaptation, there are no obvious morphological differences in the orientation of the rhabdom or in the organization of the screening pigments. Both Vargula species studied are nocturnally active and bioluminescent suggesting that these eyes are capable receptors of the bright conspecific luminescence.
Structure, Ultrastructure, and Function of the Preoral Heart‐Kidney in Saccoglossus kowalevskii (Hemichordata, Enteropneusta) Including New Data on the Stomochord
Authors: Balser Elizabeth J. , Ruppert Edward E. 
Published: April 2010

AbstractThe heart‐kidney of Saccoglossus kowalevskii, which is situated within the anterior preoral proboscis coelom (protocoel), consists of the stomochord, pericardium, heart sinus, and glomerulus. The stomochord, a diverticulum of the gut, is characterized by vacuolated epithelial cells surrounded by basal lamina and connective tissue. The pericardium, a myoepithelium, lies dorsal to the central heart sinus. Opening into the protocoel and connecting with the outside via the proboscis pore is the protocoel duct, which is, in part, composed of multiciliated absorptive epithelial cells. Perfusion of the dorsal trunk vessel with vital dyes reveals a rapid flow of blood into the glomerular blood vessels. Examination of the permeability characteristics of the extracellular matrix underlying the glomerular podocytes reveals the movement of iron dextran (mol. wt 5000 daltons) from the central heart sinus into the protocoel. Iron dextran uptake by glomerular cells and protocoel lining cells is demonstrated. These results suggest that vascular fluid is filtered by the glomerulus, producing a primary urine in the protocoel which may be modified as it passes over the peritoneum, through the protocoel duct, and out of the proboscis pore. New data concerning the morphology of the stomochord are presented. The controversial homology between the hemichordate stomochord and the chordate notochord is addressed.
The Nephridium of the Bonellia viridis Male (Echiura)
Authors: Schuchert Peter 
Published: April 2010

AbstractThe nephridium of the dwarf male of Bonellia viridis was investigated by means of transmission electron microscopy. The nephridium proved to be of a distinct protonephridial type and not a metanephridium as maintained in the older literature. The nephridium is composed of a ciliated duct that projects into the coelom. Five crown cells at the end of the duct function as terminal filtration cells. Each crown cell has a bundle of about 20 cilia, surrounded by a labyrinthic weir of cell processes that are presumably involved in filtration. The ciliary bundles enter the nephridial duct through perforations of the adjacent tubule cells. This finding of a protonephridium in a minute, coelomate animal that lacks a circulatory system corroborates a recently formulated functional theory on the distribution of nephridial types.