bluuebunny/crossref_metadata_2025_split huggingface dataset:
An ultrastructural study of larval settlement in the sea anemone Urticina crassicornis (Cnidaria, Actiniaria)
Authors: Stricker Stephen A. 
Published: February 2005

AbstractLaboratory‐reared larvae of the sea anemone Urticina (= Tealia) crassicornis have been examined by electron microscopy prior to and following settlement on algal substrata. At 18 days postfertilization, the free‐swimming planula larva measures about 600 μm long. A stomodaeal invagination occurs at the narrow end of the larva and connects with a solid mass of endoderm in the core region. The endoderm possesses septa with well‐developed myonemes and is situated subjacent to a thin sheet of mesoglea. The uniformly ciliated ectoderm that constitutes the outer layer of the larva contains: (1) spirocysts, (2) nematocysts, (3) mucus, (4) three types of membrane‐bound granules, (5) a basiepithelial nerve plexus, and (6) a few nongranular cells that may represent sensory neurons. Within several minutes after the introduction of the algal substratum, the planula characteristically directs its broadened aboral end toward the alga and secretes a refractile sheet of material. As the aboral end attaches to the substratum, the larva becomes noticeably shorter along its oral‐aboral axis, presumably owing to the contractions of myonemes that are located within the endodermal septa. All three types of granules and the ectodermal mucoid substances are exocytosed during settlement, but spirocysts and nematocysts characteristically remain undischarged. Ovoid, PAS+ granules are believed to be at least partly responsible for adhesion, since these granules are concentrated at the aboral end prior to settlement and are somewhat similar in ultrastructure to putative viscid granules produced by other species. Contrary to a previous report based on light microscopy, no discrete sensory organ is evident in serial sections of the aboral ectoderm. The ability of planulae to detect suitable substrata appears to depend instead on sparsely distributed sensory cells that occur throughout the larval ectoderm.
The hemocytes of Heliothis armigera: Ultrastructure, functions, and evolution in the course of larval development
Authors: Essawy M. , Maleville A. , Brehélin M. 
Published: February 2005

AbstractFive types of hemocytes, prohemocytes, typical plasmatocytes, coagulocytes, spherule cells, and oenocytoides, have been defined in the last larval instar of Heliothis armigera on the basis of ultrastructural microscopy, smears, and optical phase‐contrast microscopy. Modifications in typical plasmatocytes and coagulocytes have been evidenced in the course of development in this instar, which suggests that these hemocytes are involved in physiological processes of development. Only coagulocytes exhibit endocytotic capacities. Phenoloxidase activity was observed in oenocytoides.
Fat distribution in the skin of bottlenose dolphins (Tursiops truncatus and Tursiops gilli)
Authors: Stromberg Melvin W. 
Published: February 2005

AbstractFrozen sections stained with Oil‐red‐O and semithin (0.5 μm) plastic sections stained with toluidine blue revealed an abundance of fat globules of various sizes in all strata of the epidermis of bottlenose dolphins (Tursiops truncatus and T. gilli). The fat was rather evenly distributed but sometimes appeared as circumscribed areas of heavier concentration involving hundreds of cells (as seen in a single plane). Occasionally, there were smaller groups of epidermal cells heavily loaded with lipid. The dermis presented a unique phenomenon in the presence of abundant extracellular fat distributed among the collagen bundles as droplets of various sizes or as larger, irregularly shaped lipid particles that seemed to conform to the spaces between collagen bundles. These lipid particles were sometimes seen to be closely applied to the dermal surface of the stratum basale. Equally unusual was the presence of lipid particles of various sizes and shapes in the lumen of some of the vessels of the dermal papillae. Granular cells resembling mast cells were commonly seen in the papillary dermis and some were closely associated with lipid particles. Blood vessels of the reticular dermis tended to have collections of lipid droplets in the loose connective tissue often found adjacent to the tunica adventitia. It is postulated that the extracellular dermal lipids (probably mainly triglycerides) are broken down to free fatty acids that diffuse into the basal layer of the epidermis and are there resynthesized into triglycerides. Possible uses for the epidermal lipids are discussed.
The unique fibrillar matrix of the marine sponge Stelletta grubii
Authors: Simpson Tracy L. , Langenbruch Paul‐Friedrich , Scalera‐Liaci Lidia 
Published: February 2005

AbstractIn this astrophorid sponge, both intercellular fibrils and spongin microfibrils are elaborated with the former forming exceptionally dense arrangements throughout much of the matrix. Fibrils are very dense below the surface where they surround the small silica asters and throughout the cortex in the form of bundles that can form pseudo‐plywood arangements. In the endosome, fibril bundles are isolated and fewer in number. The surfaces of the large silica spicules are uniquely encased by intercellular fibrils or compacted intercellular fibrils that form a type of “fibrillar spongin” or spongin microfibrils intermixed with fibrils. Well developed microfibrillar spongin, intermixed with some fibrils, encases larger spicules below the sponge surface within the tissue and extends above the tissue surrounding spicules that emerge from the sponge thus placing this fibrillar matrix in direct contact with the sea water. The results of other studies suggest that the fibrils and microfibrils of this species are collagenous. The elaboration of these special matrices indicates that the differentiation of spongocytes (which secrete microfibrils) is weak and that the activity of lophocytes (which secrete fibril bundles) is highly labile. The variability of the fibrillar arrangements in this species supports the view that astrophorid sponges are possibly important for understanding the phylogeny of the organic skeletal matrix of sponges.
The fine structure of the lateral‐line organs of larval Ichthyophis (Amphibia: Gymnophiona)
Authors: Wahnschaffe Ulrich , Fritzsch Bernd , Himstedt Werner 
Published: February 2005

AbstractLight and electron microscopic observations of the lateral‐line organs of larval Ichthyophis kohtaoensis confirmed earlier reports of the occurrence of two different types of lateral‐line organs. One type, the ampullary organ, possesses 15–26 egg‐shaped sensory cells. Each sensory cell extends a single kinocilium surrounded by a few microvilli into the ampullary lumen. This is in contrast to the ampullary organs of urodele amphibians that contain only microvilli. The second type of organ, the ordinary neuromast, has 15–24 pear‐shaped sensory cells arranged in two to three rows. Each sensory cell shows a kinocilium that is asymmetrically placed with respect to both a basal plate and approximately 60 stereovilli. The sensory cells of ampullary organs are always separated by supporting cells; those of neuromasts are occasionally in contact with one another. Numerous (neuromasts) or few (ampullary organs) mantle cells separate the organs from the epidermal cells. Only afferent synapses are found in the ampullary organs whereas vesicle‐filled fibers together with afferent nerve terminals are found in neuromasts. Both organs contain similarly sized presynaptic spheres adjacent to the afferent fibers. It is suggested that the neuromasts have a mechanoreceptive function, whereas the ampullary organs have an electroreceptive one.
Variations of the cephalic muscles in the colubrid snake genera Entechinus, Opheodrys, and Symphimus
Authors: Cundall David 
Published: February 2005

AbstractThe cephalic muscles in three species of Entechinus, two species of Opheodrys, and Symphimus mayae display patterns of interspecific variation that are largely congruent with patterns of variation previously described for the skulls of these species. This congruence does not stem from direct correlation between the shapes of associated bones and muscles. In these colubrid snakes, most interspecific variations in muscle form involve changes in the shape or relative position of attachment points that appear unrelated to changes in the gross form of the bony surfaces forming the attachment points and produce no major changes in the architectural array of fibers in the muscle. Data presented here, combined with information from previous comparative studies of colubroid cephalic muscles, support the hypothesis that these muscles are limited in their potential variability by factors favoring parallel arrangements of fibers.
Ultrastructural aspects of the surface coatings of eggs and larvae of the starfish, Pisaster ochraceus, revealed by alcian blue
Authors: Crawford B. , Abed M. 
Published: February 2005

AbstractEggs of the asteroid Pisaster ochraceus demonstrate cortical granules, a thick vitelline membrane, and a poorly stained jelly coat similar to that seen on the eggs of other echinoderms. When fixed in the presence of alcian blue the jelly coat is seen to be made up of three regions, an inner layer consisting of a meshwork of fibres, a middle layer of thicker fibres, and a dense outer layer. At fertilization the cortical granules release their contents into the potential space between the vitelline layers and a low fertilization membrane consisting of the vitelline layer and a dense component of the corticle granule is formed. Initially the remaining contents of the corticle granules form an amorphous hyaline layer that fills the space between the plasma membrane and the fertilization membrane. At hatching a distinct hyaline layer is present. It persists at least to the bipinnaria stage and consists of four distinct layers. A similar layer is also located over much of the early embryonic endoderm but is lost from the regions involved in the formation of the mesenchyme cells, coelom, and mouth just before these events take place. Numerous large clear vesicles are located in the apex of all cells associated with a hyaline layer. Where the hyaline layer is lacking, only scattered vesicles are present suggesting that the vesicles may be involved in maintenance of the layer. Attempts to identify elements of the hyaline layer by immunofluorescence demonstrated that it appears to bind both antisera and control sera in a nonspecific manner.
An ultrastructural analysis of coelomogenesis in the hoplonemertine Prosorhochmus americanus and the polychaete Magelona sp.
Authors: Turbeville J. McClintock 
Published: February 2005

AbstractFormation of lateral vessels in the esophageal region of Prosorhochmus americanus embryos and coelomogenesis in the pygidial region of larval Magelona sp. are examined and compared. Earliest vessel rudiments of P. americanus are composed of a compact band of mesodermal cells (mesodermal band), lying on a layer of extracellular matrix (ECM) and lacking intercellular junctions. Rudiments are surrounded by presumptive muscle cells. Rudiments at later stages of differentiation possess lumina of differing sizes formed by a separation of apposing cell apices (schizocoely). Aohagrens junctions are apparent between lining cels of vessels following cavitation, and overlying muscle cells exhibit many myofilaments. Mesodermal bands of the recognized coelomate, Magelona sp. consist of glycogen‐rich, mesodermal cells resting on ECM and joined by adhaerens junctions. Some of the cells possess a rudimentary cilium. Coelom formation occurs as a splitting of the cell band as is the case for P. americanus. Recognition of an accepted mode of coelomogenesis in P. americanus, correlated with morphological details of adult nemertine vessels, affirms the view that nemertine vessels are coelomic homologues.
Morphology and function of the feeding apparatus of the lungfish, Lepidosiren paradoxa (Dipnoi)
Authors: Bemis W. E. , Lauder George V. 
Published: February 2005

AbstractThe feeding mechanism of the South American lungfish, Lepidosiren paradoxa retains many primitive teleostome characteristics. In particular, the process of initial prey capture shares four salient functional features with other primitive vertebrates: (1) prey capture by suction feeding, (2) cranial elevation at the cranio‐vertebral joint during the mouth opening phase of the strike, (3) the hyoid apparatus plays a major role in mediating expansion of the oral cavity and is one biomechanical pathway involved in depressing the mandible, and (4) peak hyoid excursion occurs after maximum gape is achieved.Lepidosiren also possesses four key morphological and functional specializations of the feeding mechanism: (1) tooth plates, (2) an enlarged cranial rib serving as a site for the origin of muscles depressing the hyoid apparatus, (3) a depressor mandibulae muscle, apparently not homologous to that of amphibians, and (4) a complex sequence of manipulation and chewing of prey in the oral cavity prior to swallowing. The depressor madibulae is always active during mouth opening, in contrast to some previous suggestions.Chewing cycles include alternating adduction and transport phases. Between each adduction, food may be transported in or out of the buccal cavity to position it between the tooth plates. The depressor mandibulae muscle is active in a double‐burst pattern during chewing, with the larger second burst serving to open the mouth during prey transport. Swallowing is characterized by prolonged activity in the hyoid constrictor musculature and the geniothoracicus.Lepidosiren uses hydraulic transport achieved by movements of the hyoid apparatus to position prey within the oral cavity. This function is analagous to that of the tongue in many tetrapods.
The sphincter of the efferent filament artery in teleost gills: I. Structure and parasympathetic innervation
Authors: Bailly Yannick , Dunel‐Erb Suzanne 
Published: February 2005

AbstractPrevious studies have shown the existence of a sphincter in the efferent filament artery of the teleost gill and its constrictory response to acetylcholine (ACH) and vagal stimulation. This study deals with the muscular organization of this sphincter and the distribution of its innervation as elucidated by degeneration methods and cytochemistry. The sphincter innervation is supplied by the protrematic vagus nerves. Nerve endings filled with cholinergic‐type vesicles are located in close association with the adventitial smooth muscle cells and display a strong acetylcholinesterase (ACHE) activity. Section of the protrematic vagus nerve induces a nearly complete degeneration of the sphincter innervation. ACHE‐positive nerve cell bodies are present both in the sphincter area and in the protrematic vagus nerve. These results suggest that innervation of the sphincter in the efferent filament artery is cholinergic through the activity of postganglionic axons of the parasympathetic system.
The sphincter of the efferent filament artery in teleost gills: II. Sympathetic innervation
Authors: Dunel‐Erb Suzanne , Bailly Yannick 
Published: February 2005

AbstractIn addition to the cholinergic innervation described in the sphincter of the efferent filament arteries (Bailly and Dunel‐Erb, ′86), an aminergic component has been demonstrated by specific techniques. The Falck fluorescence technique reveals a network of nerve fibers displaying a green fluorescence characteristic of catecholamines. At the ultrastructural level two types of fibers are present, one with clear vesicles and another with densecored vesicles. Axo‐axonal synaptic relationships exist between the two types. Results of 5‐ and 6‐OHDA (hydroxydopamine) treatments confirm the presence of an aminergic component.These observations support the notion of a dual innervation: cholinergic and adrenergic of, respectively, parasympathetic and sympathetic origin. The presence of presynaptic modulation is suggested. The aminergic component could inhibit or reduce the release of acetylcholine from cholinergic nerve endings. These results suggest that the sympathetic innervation modulates the vasoconstriction effect of the parasympathetic component.
Morphology and function of the tongue and hyoid apparatus in Varanus (varanidae, lacertilia)
Authors: Smith Kathleen K. 
Published: February 2005

AbstractThe morphology and function of the tongue and hyoid apparatus in Varanus were examined by anatomical and experimental techniques. Morphological features unique to Varanus include a highly protrusible tongue that has lost a roughened dorsal surface, an exceptionally strong and mobile hyobranchial apparatus, a well‐defined joint between the ceratohyal and anterior process, and a series of distinct muscles inserting at the anterior hyobranchial region. Varanus is also unusual among lizards in a number of feeding behaviors; it ingests prey entirely by inertial feeding, as the tongue does not participate in food transport. Further specializations include an increased reliance on hyobranchial movements in drinking and pharyngeal packing and compression. The long, narrow tongue is most likely related to the mechanics of tongue protrusion; the increased amount, strength, and complexity of hyobranchial movement is related to the fact that the hyobranchium in Varanus replaces the tongue in many functions. Previous hypotheses for the origin of these adaptations are discussed, and the difficulties of attributing these specializations to any specific scenario of adaptation or constraint are emphasized.
An atlas of the brain of the horseshoe crab Limulus polyphemus
Authors: Chamberlain Steven C. , Wyse Gordon A. 
Published: February 2005

AbstractAn atlas of the brain of the horseshoe crab Limulus polyphemus is developed. All of the neuronal groups are identified and named, and regions of neuropil are segregated and named where possible. The nomenclature incorporates functionally neutral earlier names and assigns geographical names to newly distinguished structures. The atlas provides a basis for correlating the results of neuroanatomical, neurophysiological, and neurochemical studies, which yield information about individual neurons or groups of neurons in this species
The fate and role of openings formed in the mesentery of bullfrog tadpoles, with reference to the contour of mesothelial cells
Authors: Sugimoto Keiji , Fujii Sachiko , Ichikawa Yasuaki , Nakamura Itsuo 
Published: February 2005

AbstractUsing morphological techniques, histological changes of the mesentery were observed during the development of the bullfrog, Rana catesbeiana. The tadpoles of this species had many openings all over the mesentery from the duodenum through the large intestine. Most of the openings were elliptical and less than 3 × 2 mm in size. The openings became remarkably decreased in size and number with rapid narrowing of the mesentery occurring during the period of metamorphic climax, and had almost completely disappeared by the end of metamorphosis. Appearance and disappearance of the openings were closely correlated with the changes in the dimensions of the mesentery. Furthermore, in parallel with these changes in the openings, a noticeable alteration occurred in the shape of the mesothelial cells of the mesentery. In tadpoles having no mesenteric openings, the mesothelial cells had a polygonal contour, which became transformed once the openings were formed in the mesentery. The shapes of the transformed cells were classified into two types, one having many radiating cell processes and the other a very slender and spindle‐shaped contour. Both types of cells eventually became transformed into a definitive type of cell exhibiting a roundish polygonal contour by the end of metamorphosis. From these findings it was concluded that the growing mesentery might, of necessity, give rise to the openings and transformation of the mesothelial cells to enable rapid lengthening and shortining of the intestinal tract to occur during the postembryonic development of anuran amphibians.
Morphology of the tongue in the tuatara, Sphenodon punctatus (Reptilia: Lepidosauria), with comments on function and phylogeny
Authors: Schwenk Kurt 
Published: February 2005

AbstractThe morphology and histology of the tongue in Sphenodon punctatus are described and used to infer function and to determine character state polarities in lepidosaurs. The tongue lacks an anterior notch and is covered with filamentous papillae, including specialized gustatory papillae containing taste buds. Lingual glands are restricted to mucocytes covering the papillae. Three intrinsic tongue muscles are identified and shown to be discrete fiber systems and not merely elaborations of the M. hyoglossus. These muscles interact with a connective tissue skeleton, particularly three septal planes, to cause changes in tongue shape. Tongue protrusion is probably caused by hyoid protraction and contraction of posterior genioglossus fibers; retraction by hyoid retraction, hyoglossus contraction, and contraction of anterior genioglossus fibers.It is argued that taste is important in prey discrimination and possibly in courtship. Vomeronasal function is probably mediated by inhalation and not tongue movement.Insertion of genioglossus fibers into the buccal floor is a derived feature of lepidosaur tongues. Derived features of squamate tongues include an anterior bifurcation, a divided genioglossus comprising medial and lateral portions, ventral transverse and circular muscle fiber systems around the hyoglossus, and the presence of a median septum. The tongue of the squamate family Iguanidae shares many plesiomorphic features with Sphenodon.
Ultrastructure of the ileum of Locusta migratoria
Authors: Peacock A. J. 
Published: February 2005

AbstractThe epithelium of the ileum of Locusta migratoria is composed of a single layer of columnar cells surrounded on the luminal side by cuticle and on the haemocoel side by a circular muscle layer. Where the circular muscles contact the epithelium, longitudinal muscles are present and the epithelium is slightly reduced. Elsewhere, a subepithelial sinus separates the epithelium from the circular muscle layer. The epithelial cells are characterised by extensive infoldings of the apical and basal cell membranes, which in the latter case, produce a maze of interconnecting channels and spaces. Mitochondria are closely associated with both apical and basal infoldings, although the bulk of these organelles is located in the cytoplasm underlying the infoldings of the apical plasma membrane. Vesicles of assorted sizes occur throughout the cytoplasm. They are particularly abundant in the apical region, where they appear to be produced by pinocytosis. Larger vesicles, containing either material of varying electron density or smaller vesicles, occur in the medial and basal regions of the cells. The contents of some of these vesicles have, in section, a lamellar appearance, composed of concentric layers of material. Similar vesicles are present in the basement membrane as well as the cells and connective tissue of the subepithelial sinus. Microtubules and groups of ribosomes commonly occur throughout the cytoplasm, and lipid‐like droplets are also present in some of the cells. Ultrastructural features of the epithelial cells are discussed in relation to current knowledge of the function of the ileum.