bluuebunny/crossref_metadata_2025_split huggingface dataset:
Body structure of marine sponges. VI. Choanocyte chamber structure in the haplosclerida (porifera, demospongiae) and its relevance to the phylogenesis of the group
Authors: Langenbruch Paul‐Friedrich , Jones W. Clifford 
Published: February 2005

AbstractThe choanocyte chambers of eight different haplosclerid sponge species have been investigated with regard to their histological structure, their relation to the mesohyl, and their arrangement between the canal systems. Two fundamentally different organizational types occur in the investigated sponge species. In Haliclona rosea, H. oculata, H. elegans, H. simulans, H. rava, H. fistulosa, and Acervochalina limbata the choanocytes are separated from the mesohylar tissue, being more or less covered over the outer surface by pinacocytes belonging to the incurrent canal walls. In Haliclona indistincta, on the other hand, the choanocytes are, as in most other Demospongiae, in contact with the mesohyl at their outer surfaces. This indicates that the present order Haplosclerida is polyphyletic and contains sponges of a presumably poecilosclerid origin.
Morphology of the dorsal vessel in the abdomen of the blood‐feeding insect rhodnius prolixus
Authors: Chiang R. Gary , Chiang J. A. , Davey K. G. 
Published: February 2005

AbstractThe dorsal vessel (DV) in the abdomen of the blood‐feeding insect Rhodnius prolixus was divided functionally into two regions, the heart, into which haemolymph entered the DV through four pairs of ostia located in abdominal segment VII, and the aorta, along which the haemolymph was propelled from abdominal segment VI to the thorax. Osmium‐fixed whole mounts revealed the DV to consist of spirally arranged striated muscle fibers and to possess two rows of ventrally attached longitudinal fibers extending the length of the abdomen. Seven pairs of alary muscles were found attached to the DV in the posterior abdominal segments. Contractions of the alary muscles attached to the ventral surface of abdominal segments VII and VIII served to expand the heart. Electron microscopy revealed the DV to consist of a thin layer of contractile elements surrounded by an inner (intima) and outer (adventitia) connective tissue layer. Embedded in the intima along each lateral side of the DV were two large groups of endocardial cells extending the length of the DV. A small group of pericardial cells was embedded in the adventitia along the mid‐ventral side of the DV, and clusters of pericardial cells were found attached to the alary muscles. Nerve terminals were found only on the heart: they contained agranular synaptic vesicles approximately 30 nm in diameter and densely stained granules approximately 100–120 nm in diameter. These structural components are discussed in relation to the role of the DV in circulation.
Metamorphosis of cranial design in tiger salamanders (Ambystoma tigrinum): A morphometric analysis of ontogenetic change
Authors: Reilly Stephen M. , Lauder George V. 
Published: February 2005

AbstractWhile ontogenetic analyses of skull development have contributed to our understanding of phylogenetic patterns in vertebrates, there are few studies of taxa that undergo a relatively discrete and rapid change in morphology during development (metamorphosis). Morphological changes occurring in the head at metamorphosis in tiger salamanders (Ambystoma tigrinum) were quantified by a morphometric analysis of cranial osteology and myology to document patterns of change during metamorphosis. We employed a cross‐sectional analysis using a sample of larvae just prior to metamorphosis and a sample of transformed individuals just after metamorphosis, as well as larvae undergoing metamorphosis. There were no differences in external size of the head among the larval and transformed samples. The hyobranchial apparatus showed many dramatic changes at metamorphosis, including shortening of ceratobranchial 1 and the basibranchial. The subarcualis rectus muscle increased greatly in length at metamorphosis, as did hypobranchial length and internasal distance. A truss analysis of dorsal skull shape showed that at metamorphosis the snout becomes wider, the maxillary and squamosal triangles rotate posteromedially, and the neurocranium shortens (while maintaining its width), resulting in an overall decrease in skull length at metamorphosis.These morphometric differences are interpreted in light of recent data on the functional morphology of feeding in salamanders. Morphological reorganization of the hyobranchial apparatus and shape changes in the skull are related to the acquisition of a novel terrestrial feeding mode (tongue projection) at metamorphosis. Metamorphic changes (both internal and external) that can be used to judge metamorphic condition are discussed.
Ultrastructure of the mouth apparatus in Branchiobdella pentodonta (annelida, clitellata)
Authors: Farnesi R. M. , Tei S. , Vagnetti D. , Santarella B. 
Published: February 2005

AbstractThe mouth apparatus in Branchiobdella pentodonta was studied by electron microscopy. The opening is situated dorsal to the adhesive disk of the anterior sucker and is surrounded by a ring of 16 papillae. The papillae have mono‐layered epithelium, muscle fibers, glandular processes, and taste and olfactory organs like “sensitive buttons.” The oral cavity contains jaws with horny teeth and “sensitive buttons,” and is surrounded by a ring of circular muscle fibers that connect to the muscle fiber of the papillae. This apparatus shows some analogies to that of Hirudinea, such as the presence of sucker and jaws with horny teeth.
Ultrastructure of a possible new type of crustacean cuticular strain receptor in Carcinus maenas (crustacea, decapoda)
Authors: Schmidt Manfred 
Published: February 2005

AbstractA hitherto unknown sensillum type, the “intracuticular sensillum” was identified on the dactyls of the walking legs of the shore crab, Carcinus maenas. Each sensillum is innervated by two sensory cells with dendrites of “scolopidial” (type I) organization. The ciliary segment of the dendrite is 5–6 μm long and contains A‐tubules with an electron‐dense core and dynein arm‐like protuberances; the terminal segment is characterized by densely packed microtubules. The outer dendritic segments pass through the endo‐ and exocuticle enclosed in a dendritic sheath and a cuticulax tube (canal), which is suspended inside a slit‐shaped cavity by cuticular lamellae. The dendrites and the cavity terminate in a cupola‐shaped invagination of the epicuticle. External cuticular structures are lacking. Three inner and four to six outer enveloping cells are associated with each intracuticular sensillum. The innermost enveloping cell contains a large scolopale that is connected to the ciliary rootlets inside the inner dendritic segments by desmosomes. Scolopale rods are present in enveloping cell 2. Since type I dendrites and a scolopale are regarded as modality‐specific structures of mechanoreceptors, and since no supracuticular endorgan is present, the intracuticular sensilla likely are sensitive to cuticular strains. The intracuticular sensilla should be regarded as analogous to insect campaniform sensilla and arachnid slit sense organs.
Changes in lectin‐binding pattern in the digestive tract of Xenopus laevis during metamorphosis. II. Small intestine
Authors: Ishizuya‐Oka Atsuko , Shimozawa Atsumi 
Published: February 2005

AbstractThe binding of seven lectins (concanavalin A, Con A; Dolichos biflorus agglutinin, DBA; peanut agglutinin, PNA; Ricinus communis agglutinin I, RCA‐I; soybean agglutinin, SBA; Ulex europeus agglutinin, UEA‐I; and wheat germ agglutinin, WGA) to the small intestine in metamorphosing Xenopus laevis was studied by the avidin‐biotin‐peroxidase (ABC) method. The staining pattern of the epithelium with all lectins except for UEA‐I and Con A changed gradually during metamorphic climax; the main component of the epithelium, absorptive cells, gradually became positive for DBA, PNA, and SBA and the scattered goblet cells for RCA‐I and WGA. On the other hand, the change of the staining pattern in the connective tissue occurred only for Con A, RCA‐I, and WGA, and this change took place rapidly at the beginning of climax (stage 60). Increased staining for Con A and WGA at stage 60 was observed only in a group of connective tissue cells close to the epithelium and in the basement membrane. As metamorphosis progressed, this localization of the staining intensity became less clear. At the completion of metamorphosis (stage 66), the absorptive cells were stained with all lectins except for UEA‐I, whereas the goblet cells stained only with RCA‐I and WGA. These results indicate that lectin histochemistry can distinguish between larval and adult cells of both two epithelial types (absorptive and goblet cells). The technique may also identify a group of connective tissue cells, close to the epithelium, that possibly induce the metamorphic epithelial changes.
Ultrastructure of sperm development and mature sperm morphology in three species of commensal bivalves (Mollusca: Galeommatoidea)
Authors: Eckelbarger Kevin J. , Bieler Rüdiger , Mikkelsen Paula M. 
Published: February 2005

AbstractUltrastructural features of the ovotestes, spermatogenesis, and the mature sperm are described for three galeommatid bivalves,Divariscintilla yoyo, Divariscintilla troglodytes, andScintillasp., from stomatopod burrows in eastern Florida. All three species yielded similar results except with respect to mature sperm dimensions. The ovotestis contains three types of somatic cells within the testicular portion: flattened myoepithelial cells defining the outer acinal wall; underlying pleomorphic follicle cells containing abundant glycogen deposits; and scattered, amoeboid cells containing lysosomal‐like inclusions which are closely associated with developing sperm. Early spermatogenesis is typical of that reported from other bivalves. In contrast, the late stages of spermiogenesis involve the migration and gradual rotation of the acrosomal vesicle, resulting in a mature acrosome tilted about 70° from the long axis of the cell. The mature sperm possesses an elongated, slightly curved nucleus; a subterminal, concave acrosome with a nipple‐like central projection; five spherical mitochondria and two centnoles in the middlepiece; and a long flagellum. The rotational asymmetry and the presence of perimitochondrial glycogen deposits in these sperm are unusual in the Bivalvia and may be associated with fertilization specializations and larval brooding common among galeommatoideans.
Venom glands and some associated muscles in sea snakes
Authors: Gopalakrishnakone P. , Kochva E. 
Published: February 2005

AbstractThe venom glands and related muscles of sea snakes conform in their general structure to those of the terrestrial elapids. The venom gland, however, is smaller in size and the accessory gland is considerably reduced. A similar pattern is found in the Australian elapid Notechis.The musculus compressor glandulae is well developed in the sea snakes and in some species its posterior‐medial portion runs uninterruptedly from the origin to the insertion of the muscle. This might be considered as a primitive condition suggesting an early divergence of the sea snakes from an ancestral elapid stock.Three species of sea snakes, Aipysurus eydouxi, Emydocephalus annulatus, and E. ijimae, feed on fish eggs and have very small, but still functioning, venom glands.The reduced accessory gland of the sea snakes is apparently connected with their aquatic environment, as a similar condition is found also in the elapine Boulengerina annulata which lives in large lakes of Central Africa. The similarity in structure of the venom gland between sea snakes and Notechis scutatus may point to a possible phylogenetic relationship between this group of Australian elapids and hydrophiine snakes.
Histochemical and ultrastructural study of the alimentary tract of the freshwater snail Lymnaea stagnalis
Authors: Boer H. H. , Kits K. S. 
Published: February 2005

AbstractThe alimentary tract of the freshwater snail Lymnaea stagnalis, except the salivary glands and the digestive gland, was studied with histochemical and ultrastructural methods. The main focus was on the epithelia. Previous studies have indicated that the digestive gland, where intracellular digestion occurs, plays the major role in the digestion process. The main cell types of the tract are ciliated cells and cells with microvilli. The presence of ciliated cells reflects transport of food particles and faeces. In particular areas, viz. the prooesophagus and the pylorus, the epithelium is almost exclusively composed of ciliated cells. Both cell types show signs of endocytosis, lysosomal breakdown of substances, and storage of reserve materials (glycogen, lipid, protein). These features are very prominent in the crop and in the first part of the prointestine and they would indicate that absorption of energy‐rich substances can occur in the whole tract. Ten types of gland cells were distinguished. Their possible functions are discussed on the basis of their histochemical properties and ultrastructure of the secretion products. The observations suggest that some of the cell types produce two different substances, one of which may have enzymatic properties. The epithelium of the gizzard consists of cells possessing stout microvilli, which extend into a special coating produced by these cells. The morphology of the epithelium reflects the function of the gizzard, which is comminution of food particles. In the mid‐ and postintestine occur areas composed of villi cells that possess an extensive basal labyrinth. The morphology of the cells indicates that they may be involved in absorption of water and ions from the faecal pellets. The whole tract is richly innervated. Numerous neurons occur in the connective tissue and muscle layers. Furthermore, in several areas numerous intraepithelial neurons were observed.
Neuronal differentiation in the thalamic area triangularis of a lizard
Authors: Medina Loreta M. , Trujillo Carmen Maria , Diaz Carmen , Puelles Luis 
Published: February 2005

AbstractDevelopment of neurons in the area triangularis of Gallotia galloti was investigated in Golgi‐impregnated brain tissue. Four major neuronal types present in adults were found to originate from two migratory neuroblast types, which were followed from embryonic stage S.32. One type has a thick main medial process, whereas the second type has a long main lateral process. As they migrate toward the periphery of the nucleus, morphological characteristics of maturation appear, including growth cones, filopodia, and outgrowth of axons. Neuroblasts with a main lateral process differentiate into two immature neuronal types, bipolars and pyramidals, observed at S.33 and thereafter. The neuroblasts with a main medial process undergo some somatic translocation through a transitory tangential shaft. Then they develop into monopolar immature forms with a long varicose medial, process, appearing from S.36. onward. Immature bipolar neurons do not experience great changes in their dendritic arborization during development to the adult stage, but pyramidals and monopolars undergo a rapid development of the dendritic tree after S.36. By S.38 archetypes of adult neuronal forms are established. Hairlike appendages first appear on neurons at S.36 They decrease suddenly in S.38 and then proliferate in S.39 when spines first appear. Around the time of hatching, the hairlike appendages begin to disappear and spines become established. Reduction of spines occurs after hatching and continues to the adult stage. Possible influences of several external factors on neuronal maturation are discussed.
Morphogenesis of the pharyngeal teeth in the japanese dace, Tribolodon hakonensis(Pisces: Cyprinidae)
Authors: Nakajima Tsuneo 
Published: February 2005

AbstractThe appearance pattern of pharyngeal tooth germs was investigated in the larval Japanese dace, Tribolodon hakonensis, which has a bilaterally asymmetrical dentition. Teeth develop in a series of replacement waves beginning with the initial central tooth (Ce) and continuing with teeth of anterior (An) and posterior (Po) positions relative to the initial one. Identified by wave number (n) and tooth position (r), according to the formula n‐1[r], tooth germs appeared in the order of tooth 0[Ce0], 1[Po1], 1[Anl], 2[Ce0], 2[An2], 3[Po1], 3[An1], 4[Ce0], 4[An2], 5[Po1], 5[An1], 5[An3], 6[Ce0], 6[An2] during the larval period. Dentition on the right side, however, lacks the first tooth at position An2 (tooth 2[An2]) and teeth at position An3. Tooth germs on the first, second, and third replacement waves appeared simultaneously on the arches of both sides. During following waves, tooth germs on the left side appeared later than those on the right. Delay of tooth germ appearance On the left side is interpreted as an inhibitory influence of existing tooth germs in accordance with Osborn's (Proc. R. Soc. Lond. Ser. B 179:261‐‐289, '71) theory. The delay of tooth germ appearance on the left arch is most pronounced on the seventh replacement wave. Teeth of the right major row in adults of this species are replaced more frequently than those of the left major row, apparently in correlation with the absence of the first larval tooth at position An2 and teeth at position An3. It is hypothesized that cyprinids evolved the minor rows and specialized teeth of their adult dentition as apomorphic characteristics by the process of neoteny.
Morphology of the ovaries of Sphaerodema (Diplonychus) rusticum (Heteroptera, Belostomatidae)
Authors: Jawale S. M. , Ranade D. R. 
Published: February 2005

AbstractThe female reproductive system of Sphaerodema rusticum consists of a pair of ovaries, two lateral oviducts, a median common oviduct, and a median spermatheca. Accessory glands are absent. Each ovary has five free ovarioles branching from the oviduct. Each ovariole consists of a terminal filament, germarium, vitellarium, brown mass, and an exceptionally long pedicel. The terminal filament consists of a central core, interstitial cells, and an outer sheath. In the germarium, which consists of trophic and prefollicular regions, the trophic region or nurse cell chamber is divided into four histologically differentiated zones, distinguished as zones I–IV. Nutritive cords, originating from the posterior end of the trophic core in zone IV extend centrally and join the developing oocytes in the prefollicular chamber and the vitellarium. The compact prefollicular tissue at the base of the trophic core gives rise to prefollicular cells which, after encircling the young oocytes, become modified into follicular epithelial cells, the interfollicular plug, and epithelial plug. The young oocytes descend into the vitellarium and gradually develop into mature oocytes. A compound corpus luteum is observed simultaneously in all the ovarioles of both ovaries after ovulation. Below the epithelial plug there is an accumulation of material, the “brown mass,” which develops cyclically in correlation with the ovulation cycle. Each pedicel stores five mature chorionated eggs ready for oviposition. The epithelium of the anterior region of the pedicel secretes a PAS‐positive material. General morphology and histology of the subdivisions of the ovarioles are described.
Development and diversity of the suspensorium of trichomycterids and comparison with loricarioids (Teleostei: Siluriformes)
Authors: Arratia Gloria 
Published: February 2005

AbstractStudies of ontogenetic series of trichomycterids and other catfishes reveal that the suspensorium of siluroids is highly specialized; several synapomorphies separate siluroids from other teleosts. In siluroids, the palatoquadrate is divided into pars autopalatina and pars pterygoquadrata and both are usually connected by the autopaiatine‐metapterygoid ligament. The pterygoquadrate is broadly joined to the dorsal limb of the hyoid arch, forming a cartilaginous hyomandibular‐symplectic‐pterygoquadrate plate in early ontogeny. This produces a special alignment of the hyomandibula and quadrate which is characteristic of siluroids. A symplectic bone is absent. The interhyal is absent in trichomycterids and astroblepids. Dorsal and ventral limbs of the hyoid arch are connected by a ligament. A rudimentary interhyal and this ligament are present in primitive siluroids such as diplomystids and nematogenyids as well as loricariids. The metapterygoid arises as an anterior ossification of the pars pterygoquadrata in siluroids. The formation and position of the metapterygoid exhibit two patterns: (1) the metapterygoid develops as an ossification of a cartilaginous projection positioned between the future hyomandibula and quadrate in primitive catfishes (e.g., Diplomystes) as well as in Nematogenys, callichthyids, loricariids, and astroblepids; (2) the metapterygoid arises as an ossification of the cartilaginous projection (pterygoid process) positioned just above the articular facet of the quadrate for the lower jaw. An ossified anterior chondral pterygoid process of the complex quadrate is present in trichomycterids, whereas the process is absent (simple quadrate) in catfishes such as diplomystids, nematogenyids, callichthyids, and loricariids. The anterior membranous process of the quadrate of Astroblepus is non‐homologous with the chondral pterygoid process of trichomycterids; both structures arose independently within the loricarioids. Despite topological relationships, the origin and development of bones reveal the presence of a chondral hyomandibula which develops a large meinbranous outgrowth during ontogeny and a chondral metapterygoid in trichomycterids. The presence of a compound hyomandibula + metapterygoid or a compound metapterygoid + ectopterygoid + entopterygoid have no developmental support in trichomycterines or other siluroids. The “entopterygoid” of Nematogenys and Diplomystes arises as an ossification of a ligament. The dermal entopterygoid of other ostariophysans and the “entopterygoid” are homologous. An ectopterygoid or tendon bone “ectopterygoid” is absent in loricarioids. The suspensorium is an important structural system which has significant evolutionary transformations which characterize loricarioid subgroups; however, no character, of the suspensorium supports the monophyly of the loricarioids.
Feeding mechanics of teleost fishes (Labridae; Perciformes): A test of four‐bar linkage models
Authors: Westneat Mark W. 
Published: February 2005

AbstractThe feeding mechanisms of two labrid fishes (Cheilinus chlorurus and C. diagrammus: Labridae: Perciformes) are modeled using four‐bar linkage theory from mechanical engineering. The actions of the feeding mechanisms are simulated by a computer program that uses morphometric data to calculate the geometry of mechanism structure. The predictions of three different four‐bar linkages regarding the kinematics of feeding are compared to the movements observed through hign speed (200 fps) cinematography. A previously unidentified four‐bar chain was found to be an accurate model of the mechanism by which upper jaw protrusion, maxillary rotation, and gape increase occur in Cheilinus. This mechanism involves the anterior jaws including the mandible, maxilla, premaxilla, palatine, and suspensorium. The accuracy of two previously described four‐bar linkages was also tested by comparison of model predictions and film results. The opercular linkage proposed by Anker ('74) as a mechanism of jaw depression via opercular levation was found to be a poor predictor of feeding movements. This four‐bar chain involves the opercle, suspensorium, interopercle, and mandible. Muller ('87) proposed a mechanism of hyoid depression involving cranial elevation due to epaxial muscle contraction as input motion The links in this mechanism include the neurocranium and hyomandibula, hyoid, sternohyoideus muscle, and pectoral girdle. This model was an accurate predictor of hyoid depression in Cheilinus when simultaneous cranial elevation and sternohyoideus contraction were simulated. Quantitative kinematic models involve simplifying assumptions when applied to complex musculoskeletal systems, but such models have a wide range of applications to vertebrate functional morphology.