bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of the muscle mechanics of the forelimb of three climbers
Authors: Stalheim‐Smith Ann
Published: February 2005

The climbing behavior, muscle mechanics, and functional properties of selected forelimb muscles were examined to ascertain how three distantly related mammals may be adapted for climbing. To determine if features of the fox squirrel (Stalheim‐Smith: J. Morphol.180:55–68, apos;84) are general or unique features for a climber, two distantly related climbers, the raccoon (Procyon lotor) and the opossum (Didelphis virginiana), were studied. Muscle mechanics varied: the elbow flexors of the fox squirrel produced significantly more torque per unit mass than did the corresponding muscles of the opossum except at 80°, but not more than the corresponding muscles of the raccoon. On the other hand, there were no statistically significant differences in torque per unit mass among the elbow extensors of the three climbers. Both elbow flexors and elbow extensor had faster contraction times and were more fatigable in the fox squirrel than in the opossum or in the raccoon. The data suggest that the musculoskeletal characteristics of the forelimbs of climbers vary according to behavioral, and possibly phylogenetic, differences.
Feeding mechanism of Epibulus insidiator (Labridae; Teleostei): Evolution of a novel functional system
Authors: Westneat Mark W. , Wainwright Peter C.
Published: February 2005

The feeding mechanism of Epibulus insidiator is unique among fishes, exhibiting the highest degree of jaw protrusion ever described (65% of head length). The functional morphology of the jaw mechanism in Epibulus is analyzed as a case study in the evolution of novel functional systems. The feeding mechanism appears to be driven by unspecialized muscle activity patterns and input forces, that combine with drastically changed bone and ligament morphology to produce extreme jaw protrusion. The primary derived osteological features are the form of the quadrate, interopercle, and elongate premaxilla and lower jaw. Epibulus has a unique vomero‐interopercular ligament and enlarged interoperculo‐mandibular and premaxilla‐maxilla ligaments. The structures of the opercle, maxilla, and much of the neurocranium retain a primitive labrid condition. Many cranial muscles in Epibulus also retain a primitive structural condition, including the levator operculi, expaxialis, sternohyoideus, and adductor mandibulae. The generalized perciform suction feeding pattern of simultaneous peak cranial elevation, gape, and jaw protrusion followed by hyoid depression is retained in Epibulus. Electromyography and high‐speed cinematography indicate that patterns of muscle activity during feeding and the kinematic movements of opercular rotation and cranial elevation produce a primitive pattern of force and motion input. Extreme jaw protrusion is produced from this primitive input pattern by several derived kinematic patterns of modified bones and ligaments. The interopercle, quadrate, and maxilla rotate through angles of about 100 degrees, pushing the lower jaw into a protruded position. Analysis of primitive and derived characters at multiple levels of structural and functional organization allows conclusions about the level of design at which change has occurred to produce functional novelties.
Postcranial skeleton of the marine catfish arius tenuispinis (osteichthyes: Siluriformes, Ariidae)
Authors: Lakshmi K. , Rao K. Srinivasa
Published: February 2005

The axial skeleton and the skeletal supports of median and paired fins of Arius tenuispinis, a marine catfish, are described. Particular attention is given to the description of the complex vertebra, the Weberian ossicles, and the articulations between the fin spines and their respective radials and girdle elements.
Functional morphology of the “tongue‐bite” in the osteoglossomorph fish Notopterus
Authors: Sanford Christopher P. , Lauder George V.
Published: February 2005

Osteoglossomorph fishes are characterized by having three sets of jaws: a mandibular jaw apparatus (MJA) anteriorly, a pharyngeal jaw apparatus (PJA) posteriorly, and a tongue‐bite apparatus (TBA) associated with basihyal and parasphenoid teeth. The TBA is a novel complex feature of the head that characterizes osteoglossomorph fishes and provides a case study in the origin of novel functions and roles in the vertebrate musculoskeletal system.

The function of the tongue‐bite in the osteoglossomorph fish Notopterus was characterized by using high‐speed cinematography and electromyography. The tongue‐bite is used during intraoral prey processing to shred and disable prey. Two distinct uses of the TBA were defined on the basis of kinematic and electromyographic profiles: raking and open‐mouth chewing. During raking behavior, the prey is held fixed in the MJA, the neurocranium is elevated, and the pectoral girdle is retracted. The adductor mandibulae, hypaxialis, epaxialis, and posterior intermandibularis muscles are all highly active, but only very low activity is observed in the sternohyoideus muscle. During open‐mouth chewing behavior, the prey is located within the oral cavity, posterior pectoral girdle rotation is less than during raking, and the levator operculi muscle shows relatively high activity.

We propose that a shearing action of the basihyal (moved anteroposteriorly by the posterior intermandibularis and hypaxial muscles) with respect to the neurocranium (elevated by epaxial muscles) is the critical aspect of the tongue‐bite in Notopterus. The body muscles (epaxials and hypaxials) provide the main power for the tongue‐bite. We hypothesize that lack of sternohyoideus activity during intraoral prey processing, posterior pectoral girdle rotation, and a long‐fibered posterior intermandibularis muscle are novel structures associated with the tongue‐bite apparatus within osteoglossomorph fishes.
Changes in the fine structure of the endocrine dorsal body cells of Helisoma duryi (mollusca) induced by mating
Authors: Khan Hamid R. , Ashton Mary Lou , Saleuddin A. S. M.
Published: February 2005

The morphology and the organization of the endocrine dorsal bodies (DB) of non‐reproducing virgin and castrated, and reproducing mated Helisoma duryi have been examined using serial sectioning. The DB cells occur in two masses on the mid‐dorsal side of the cerebral commissure, each of which has a cortical zone containing the cell bodies and a medulla where cell processes terminate. The cell bodies measure 10–15 μm in diameter, and are arranged in lobules of 6–12 cells. The complex cell processes are winding and terminate at various distances from their cell bodies in both reproducing and non‐reproducing snails. Few 70–90‐nm membrane‐bound granules are found in the cell bodies and many are seen in the cell processes, which seem to penetrate the perineurium of the cerebral ganglia and make close contacts with neurosecretory cells. In reproducing snails the DB cells display a significantly larger amount of plasma membrane sproutings in the form of loops and circles compared to that in reproductively inactive virgin or castrated snails. Images of thin‐sections and freeze‐fracture replicas of these membranes suggest that they are gap junctions, which join the DB cells with each other. It is likely that gap junction‐mediated cell to cell communication is involved in the activation of the DB cells for their role(s) in reproduction.
Embryonic and neonatal development of the vomeronasal and olfactory systems in garter snakes (Thamnophis spp.)
Authors: Holtzman David A. , Halpern Mimi
Published: February 2005

Newborn, unfed garter snakes (Thamnophis spp.) respond preferentially to aqueous extracts of natural prey items, and these responses are mediated by the vomeronasal system (VNS). Since the VNS, and possibly the olfactory system (OS), are functional at birth, we examined the ontogeny of VNS and OS structures in four embryonic stages and two postnatal ages in garter snakes. The results of this study show (1) significant changes in thickness of the receptor epithelia for both systems; (2) temporal differences in the innervation of the telencephalon for each system; and (3) concurrent development of primary and secondary projection sites in both systems. Possible interactions between different cell populations and their significance for morphogenesis are discussed.
Ontogeny of the limb skeleton in Alligator mississippiensis: Developmental invariance and change in the evolution of archosaur limbs
Authors: Müller Gerd B. , Alberch Pere
Published: February 2005

Crocodilians and birds are the extant representatives of a monophyletic taxon known as archosaurs. Their limbs are highly derived in terms of reduction in number of skeletal elements in both the carpus and the tarsus. It is necessary to have a detailed description of crocodilian limb ontogeny to address the evolutionary issue dealing with the origin and organization of the avian limb. In this paper, we present an analysis of the early development of the crocodilian limb skeleton. Contrasting with earlier observations, we redefine the number and composition of carpal, tarsal, and phalangeal elements. This ontogenetic information is then used to introduce a revision of the homologies of the skeletal elements in the crocodilian limb. Some invariances are pointed out in the developmental organization of tetrapod limbs and this evidence serves to readdress several issues concerning the evolution of the avian limb. We present further embryological data in support of the hypothesis that digits 2–3–4 are the components of the wing skeleton in birds. In general, our comparative survey indicates that the elements that appear late in ontogeny are the ones lost in phylogeny. By comparing turtle (primitive) limb development with crocodilian and bird development, we propose a hypothesis in which the derived skeletal patterns found in crocodilians and birds have originated by a heterochronic process of paedomorphosis.
Extrusion of the residual body in spermatids of Ancylostoma caninum (nematoda, strongyloidea)
Authors: Ugwunna Sydney C.
Published: February 2005

Transmission electron microscopy reveals that the spermatocytes of the hookworm Ancylostoma caninum contain an abundance of Golgi complexes, ribosomes, specialized membranous organelles, and long strands of smooth endoplasmic reticulum. These organelles remain abundant until the early spermatid stage of sperm development, when they reach their maximum abundance and maturity and the production of new ones ceases. Golgi complexes, ribosomes, and excess SER, which are not functional after this stage, become segregated and confined to the posterior portion of the spermatid in a polar lobe. Later, the polar lobe together with excess cytoplasmic matrix is bound by a membrane and dissociated from the spermatid as a residual body. The spermatid is then devoid of Golgi complexes and ribosomes. Formation of residual bodies as sperm cells mature may be considered a type of cell excretion.
Golgi study of the anterior dorsal ventricular ridge in a lizard. I. neuronal typology in the adult
Authors: Díaz C. , Yanes C. , Medina L. , Trujillo C. M. , Monzón M. , Puelles L.
Published: February 2005

Using Golgi techniques we have studied neuronal cell types in the anterior dorsal ventricular ridge (ADVR) of the adult lizard Gallotia galloti. Multipolar, bitufted, and juxtaependymal neuronal forms were found. The multipolar and bitufted neurons are present in both the periventricular and central ADVR zones. Multipolar neurons can be subdivided into multipolar neurons with polygonal somata and four to six main dendritic trunks and multipolar neurons with pyramidal somata and three or more dendritic trunks. The former are the cells most frequently impregnated in the ADVR. In the population of bitufted neurons, we distinguish subtypes I, II, and III according to the number of dendritic trunks that emerge from the somata. Juxtaependymal neurons are restricted to a cell‐poor zone, adjacent to ependymal cells. Their dendrites either are orientated parallel to the ventricular surface or extend into the periventricular zone. The dendrites of ADVR neurons have pedunculated spines with knob‐like tips. However, such spines do not appear on the somata or on the primary dendritic trunks. The number of spines is scarce or moderate. The periventricular neuronal clusters contain two to five cells. The morphology of these neurons is mainly multipolar, but we also found some bitufted neurons.
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

The 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

The 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

While 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

The 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

A 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

The 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

Ultrastructural 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

The 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

The 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

Development 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

The 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

The 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

Studies 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

The 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.
The morphology of the intrinsic tongue musculature in snakes (Reptilia, ophidia): Functional and phylogenetic implications
Authors: Smith Kathleen K. , Mackay Kathleen A.
Published: February 2005

Tongue musculature in 24 genera of snakes was examined histologically. In all snakes, the tongue is composed of a few main groups of muscles. The M. hyoglossus is a paired bundle in the center of the tongue. The posterior regions of the tongue possess musculature that surrounds these bundles and is responsible for protrusion. Anterior tongue regions contain hyoglossal bundles, dorsal longitudinal muscle bundles and vertical and transverse bundles, which are perpendicular to the long axis of the tongue. The interaction of the longitudinal with the vertical and horizontal muscles is responsible for bending during tongue flicking. Despite general similarities, distinct patterns of intrinsic tongue musculature characterize each infraorder of snakes. The Henophidia are primitive; the Scolecophidia and Caenophidia are each distinguished by derived characters. These derived characters support hypotheses that these latter taxa are each monophyletic. Cylindrophis (Anilioidea) is in some characters intermediate between Booidea and Colubroidea. The condition in the Booidea resembles the lizard condition; however, no synapomorphies of tongue musculature confirm a relationship with any specific lizard family. Although the pattern of colubroids appears to be the most biomechanically specialized, as yet no behavioral or performance feature has been identified to distinguish them from other snakes.
Mastication in springhares, Pedetes capensis: A cineradiographic study
Authors: Offermans Marc , de Vree Frits
Published: February 2005

Analysis of lateral and dorsoventral radiographic films shows that ingestion, transport, and mastication in Pedetes capensis (Rodentia) are cyclic and their movement patterns are essentially similar for the three food types offered. During the ingestion cycle, closing of the mouth is accompanied by a backward translation of the condyles, so that movement is predominantly orthal. During the opening stage, the extent of the anterior condylar translation is smaller. As a result the mandibular incisors move ventrally and posteriorly. During the ingestion cycles, food is transported to the back of the tongue, with the transverse rugae and the folds of the upper lip playing important roles.

Springhares show a bilateral masticatory pattern; food is chewed on both sides simultaneously. During chewing, the condyles lie in their most forward position at maximum opening of the mouth. The mouth is closed by rotation of the lower jaw around the temporomandibular joint coupled with posterior condylar translation. At the beginning of the slow‐closing stage, the upward rotation of the mandible slows and the jaw slowly shifts forward. During the grinding stage, the mandible is shifted forward with both toothrows in occlusion. During the opening stage, the jaw returns to its starting position.

Comparison of kinematic and anatomical data on rodent mastication suggests that some dental characteristics form the most important factors regulating the masticatory pattern and consequently allow reasonably reliable prediction of rodent masticatory patterns.
Surface ultrastructural changes in the gills of sockeye salmon (teleostei: Oncorhynchus nerka) during seawater transfer: Comparison of successful and unsuccessful seawater adaptation
Authors: Franklin Craig E.
Published: February 2005

Sockeye salmon were transferred rapidly from freshwater to seawater and the changes in gill morphology, in particular the distribution and sizes of chloride and mucous cells on the afferent filamental surface examined. Salmon that successfully adapted to seawater were compared with salmon that did not adapt to seawater and died as a consequence of osmoregulatory failure. The number of mucus cells (density), determined from scanning electron microscopy, increased significantly after seawater challenge. A greater increase in mucus cell density occurred in the salmon that failed to adapt to seawater. Light microscopy of transverse sections of gills detected no difference in mucus cell numbers after seawater challenge. It is proposed that mucus cells that lie just beneath the gill epithelium are activated in response to the seawater challenge, and migrate and open onto the epithelium. Freshwater‐adapted salmon that had low densities of chloride cells prior to the seawater challenge failed to adapt, whereas salmon that had high densities of chloride cells adapted successfully to seawater. In the latter, the density of chloride cells on the afferent surface decreased after 30 days in seawater. The apical surface of the chloride cells of freshwater‐adapted sockeye were either smooth or covered with microvilli. A greater proportion of microvilli‐covered chloride cells occurred in the freshwater‐adapted salmon that subsequently adapted to seawater.
Ultrastructure of nuchal organs in some marine polychaetes
Authors: Rhode Birgit
Published: February 2005

Polychaetes normally possess one pair of nuchal organs at the posterior edge of the prostomium or peristomium. They have been regarded as chemosensory organs. The nuchal organs of four marine polychaete species with different habits were investigated by electron microscopy.

Although the shapes of nuchal organs can vary greatly from simple ciliary bands (Scolelepis squamata, Spionidae) to retractile tongue‐like, piston‐ or finger‐shaped forms (Eteone longa, Anaitides mucosa, Phyllodocidae; Heteromastus filiformis, Capitellidae), the structural components, including the ciliated supporting cells, sensory cells, and nuchal epidermal cells, are essentially similar. The differences basically concern 1) the position of the sensory cells with relation to the ciliated supporting cells, 2) the location and structure of the nuchal nerve, and 3) the structure of the nuchal cuticle.

The diverging nature of this modified cuticle is described and discussed in detail. Comparisons are made with the fine structure of nuchal organs of other polychaete species. Similarities of cellular components of nuchal organs are found not only in the four species studied here but also in all nuchal organs investigated so far. This is hypothesized to be due to the fact that the polychaete stem species already possessed nuchal organs with the respective cell types. Differences in the number and distribution of cellular components and in the overall shape of nuchal organs are thought to have evolved in correlation with the equipment of other cephalic appendages and with different habits and modes of nutrition.
Observations and comments on the reliability of muscle reconstruction in fossil vertebrates
Authors: Bryant Harold N. , Seymour Kevin L.
Published: February 2005

InCanisandUrsusthe largest proportion of attachments of muscles of the shoulder and brachium on the scapula and humerus is direct; fewer attachments are aponeurotic or tendinous. In both genera most attachments can be associated with superficial osteological features (scars or delimitable surfaces); attachments that lack such features are direct. Most aponeurotic attachments are associated with rugose scarring whereas tendinous attachments are often associated with smooth surfaces. Although most attachments can be associated with osteological features the areal extent of attachment is often not inferrable from the bone. The inference of muscle size or functional significance from osteological features is problematic. The amount of myological information that can be deciphered from the osteology inCanisandUrsusis greater than that reported for particular members of other vertebrate groups which suggests that there may be differences in the degree to which muscles can be reconstructed from superficial osteology alone. Nonetheless, even in mammals such as the Carnivora, detailed muscular reconstructions in extinct taxa cannot be achieved without reference to the musculature of extant relatives. Such reconstructions rely on assumptions, that often have not been adequately tested, regarding the similarity of musculature in closely related taxa. This testing and well corroborated hypotheses of phylogenetic relationship are essential for the evaluation of the accuracy of reconstructions of the musculature in fossil vertebrates.
Changes in the arrangement of the extracellular matrix, larval shape, and mesenchyme cell migration during asteroid larval development
Authors: Crawford Bruce J.
Published: February 2005

When fixed in the presence of alcian blue, extracellular matrix (ECM) in the embryonic asteroid blastocoel can be visualized by light and electron microscopy as a fibrous meshwork encrusted with alcianophilic material. In early to mid‐gastrulae, the ECM is associated with the basal laminae underlying the ectoderm and endoderm. It also forms a fibrous meshwork between them in the posterior part of the blastocoel. In early larvae, when mesenchyme cells arrive at the esophagus to differentiate into smooth muscle, very little ECM is associated with the stomach region. In contrast, a meshwork of long ECM strands radiates from the esophageal basal lamina which connects to a dense ECM web associated with the inner aspect of the dorsal ectoderm. This dorsal web is associated, in turn, with numerous long ECM strands which run parallel to the stomodeum. The strands located between the esophagus and the ectoderm appear when the mouth and coeloms form and may be responsible for a constriction of the ectoderm that forms in this region. During late gastrula one population of mesenchyme cells becomes associated with the esophageal region and differentiates into muscle. Most of the other mesenchyme cells stop migrating through the esophageal web at this time. Less alcianophilic material is associated with the esophageal basal lamina, and the ECM adjacent to the esophagus in the late gastrula and early bipinnaria larvae. The arrangement of the ECM elements suggests that they could be involved in controlling the migration of mesenchyme cells, particularly those destined for the esophagus.
Ultrastructural study of hemocytes and phagocytes associated with hemolymphatic vessels in the hepatopancreas of Palaemonetes zariquieyi (Crustacea, Decapoda)
Authors: Sagristà E. , Durfort M.
Published: February 2005

Ultrastructural and cytochemical studies of the hepatopancreatic hemal space of Palaemonetes zariquieyi revealed the presence of three cell types: 1) hemocytes containing spherical and elongated granules, also localized in heart and the branchial hemal space; 2) cells containing lipidic inclusions and sub‐polyhedric granules with a paracrystalline component; and 3) phagocytic cells surrounding hemal vessels, exhibiting positive acid phosphatase reactivity in the Golgi complex and lysosomes. Possible functions of these cell types are discussed.