bluuebunny/crossref_metadata_2025 huggingface dataset:
Oocyte maturation triggered by the presence of male in the Blue Gourami, Trichogaster trichopterus
Authors: Jackson Karen , Abraham M. , Degani G.
Published: February 2005

Oocyte growth in females of Trichogaster trichopterus kept in solitary confinement or in groups of up to 20 specimens is arrested at the end of the vitellogenetic stage. In ∼ 60% of the pairs tested, a large number of oocytes mature during the first 2 days after pairing a female with a male. Mature oocytes contain a large apical lipid inclusion formed by coalescence of lipid droplets that were formed during the cortical alveolar stage. During maturation, the nucleus migrates toward the oocyte periphery. Five successive steps of the migration process have been recorded. After the arrival of the nucleus at the oocyte periphery, the nuclear membrane disintegrates and fragments of it appear in the cytoplasm surrounding the nucleus. At the same time, the vitelline membrane opposite the nucleus invaginates into the ooplasm. Within the invagination, a large follicular cell, i.e., the micropylar cell, appears, sending thin cytoplasmic processes into the zona radiata, thus forming the micropyle. These related maturation processes, i.e., formation of the apical vesicle, nuclear migration, disintegration of the nucleolemma, invagination of the vitelline membrane, appearance of the micropylar cell, and the formation of the micropyle, require the presence of a mature male in the same container with the female. © 1994 Wiley‐Liss, Inc.
Morphology and behavior of the feeding apparatus in Cryptobranchus alleganiensis (Amphibia: Caudata)
Authors: Elwood Jennifer R. Lorenz , Cundall David
Published: February 2005

Cine and high‐speed videographic analyses of feeding in Cryptobranchus alleganiensis demonstrate that prey are captured by either inertial suction or a strike combined with suction. Movements of cephalic elements during capture are generally similar to those of other suction‐feeding vertebrates but more variable than those of most aquatic salamanders. Following capture, prey frequently are manipulated and transported into and out of the buccal cavity across the teeth.

Specific features of the skull, mandibles, hyoid apparatus, and cephalic musculature of Cryptobranchus correlate directly with behavior. Although the skull is massive, sutures of the anterior braincase permit limited torsion, the maxillae move on their attachments to the braincase, and left and right mandibles are separated by elastic connective tissues. These features provide flexibility and permit asynchronous and asymmetric movements of the mandibles. Equivalent asymmetry and asynchrony of hyobranchial movements are also correlated with specific structural arrangements that may be neither paedomorphic nor primitive.

Its feeding mechanics suggest that Cryptobranchus represents a unique and highly derived condition among salamanders. Its ability to modulate movements of the left and right sides of its head argues strongly for the existence of bilaterally asynchronous motor patterns, and patterns of force generation, similar to but much faster than those employed in mammalian mastication. © 1994 Wiley‐Liss, Inc.
Central projections of ovipositor sense organs in the damselfly, Sympecma annulata (Zygoptera, Lestidae)
Authors: Gorb S. N.
Published: February 2005

Central projections of sensilla on different parts of the endophytic ovipositor of the lestid damselfly Sympecma annulata are traced. Sensilla include apical hairs of the stylus (STh), hair rows on the ventral part of the valvula (Vh), and distal campaniform sensilla of upper (ULc) and lower (LLc) ovipositor leaves. Backfilling of afferent fibers, using anterograde cobalt fills, reveals the presence of contralaterally projecting fibers for all organs. The main fiber bundle of the LLc enters the terminal ganglion laterally via the genital nerve, but the fibers from ULc enter via the posterior nerve. Main fiber bundles of both leaves end in a lateral part of the ganglion called the lateral neuromere; they demonstrate that sensory information from the two leaves has the same target area. It is hypothesized that the independent pathways of nerves from upper and lower ovipositor leaves (ULc and LLc) may indicate the phylogenetic origin of these appendages from different abdominal segments—the lower leaf from the 8th and upper from 9th. The convergence of afferent fibers from the sensilla of the different ovipositor parts (median, anterior, and lateral processes) in common ganglionic centers may provide the anatomical basis to account for coordination of the movements of different ovipositor parts during oviposition. © 1994 Wiley‐Liss, Inc.
Ontogeny of the Pectoralis muscle in the little brown bat, Myotis lucifugus
Authors: Schutt William A. , Cobb Matthew A. , Petrie Jacquelyn L. , Hermanson John W.
Published: February 2005

The ontogeny of a primary flight muscle, the pectoralis, in the little brown bat (Myotis lucifugus: Vespertilionidae) was studied using histochemical, immunocytochemical, and electrophoretic techniques. In fetal and early neonatal (postnatal age 1–6 days) Myotis, histochemical techniques for myofibrillar ATPase (mATPase) and antibodies for slow and fast myosins demonstrated the presence of two fiber types, here called types I and IIa. These data correlated with multiple transitional myosin heavy chain isoforms and native myosin isoforms demonstrated with SDS‐PAGE and 4% pyrophosphate PAGE. There was a decrease in the distribution and number of type I fibers with increasing postnatal age. At postnatal age 8–9 days, the adult phenotype was observed with regard to muscle fiber type (100% type IIa fibers) and myosin isoform profile (single adult MHC and native myosin isoforms). This “adult” fiber type profile and myosin isoform composition preceeded adult function by about 2 weeks. For example, little brown bats were incapable of sustained flight until approximately postnatal day 24, and myofiber size did not achieve adult size until approximately postnatal day 25. Although Myotis pectoralis is unique in being composed of 100% type IIa fibers, transitional fiber types and isoforms were present. These transitional forms had been observed previously in other mammals bearing mixed adult muscle fibers and which undergo transitional stages in muscle ontogeny. However, in Myotis pectoralis, this transition transpires relatively early in development. © 1994 Wiley‐Liss, Inc.
Electric organs in skates: Variation and phylogenetic significance (Chondrichthyes: Rajoidei)
Authors: Jacob Brian A. , McEachran John D. , Lyons Paul L.
Published: February 2005

A total of 63 species of skates (Chondrichthyes: Rajoidei) were surveyed, along with three species of the outgroup (Chondrichtyes: Rhinobatoidei) for electric organs along the sides of the tail. All skate specimens examined possessed what appeared to be functional electric organs, and the three species of the outgroup lacked evidence of electric organs. The electric organs were tail‐positive and arranged into horizontal columns divided by transverse septa. The electrocytes varied considerably within and among supraspecific taxa (subgenera and genera), but they could be broadly classified into cup‐shape, modified cup‐shape, intermediate‐shape, and disc‐shape cells, provided that the distinction was partially based on position of the electrocytes within their connective tissue chambers. The survey, in part, corroborates a phylogenetic hypothesis of skates and in some respects further resolves the hypothesis. The supraspecific taxa Atlantoraja and Rioraja have similar derived‐type electrocytes, as do the five supraspecific taxa of Rajini, and Cruriraja and Anacanthobatis, and to a lesser extent the supraspecific taxa Arhynchobatis, Psammobatis, and Sympterygia, and the supraspecific taxa Notoraja, Pavoraja, and Pseudoraja, corroborating the hypothesis. The supraspecific taxa Amblyraja, Rajella, Leucoraja, Breviraja, and Dactylobatus were unresolved in the phylogenetic hypothesis, but the electrocyte survey suggested that Leucoraja, Breviraja, and Dactylobatus were derived with respect to Amblyraja and Rajella. © 1994 Wiley‐Liss, Inc.
Ultrastructure and cytochemistry of the integument of Modiolicola gracilis, parasitic copepod in mussel gills (Mytilus galloprovincialis and Mytilus edulis)
Authors: Poquet Montserrat , Ribes Enric , Bozzo M. Gràcia , Durfort Merce
Published: February 2005

Of mussels taken from the Ebro Delta River (E. Spain), 3% have a nonmodified copepod, Modiolicola gracilis, in the gill tissues. The cuticle of different segments of the body has an epicuticle with two layers, which show external microvilli‐like projections. Weakly positive reactivity to the PTA technique has been detected in the external region. The procuticle has the helicoidal architecture of the chitinous tegument in arthropods, whereas the cuticle shows discontinuities in the regions of ducts in tegumental glands.

The integument is comprised of three types of cells. Epidermal cells are flat with numerous mitochondria. Muscle cells show well‐developed mitochondria with several longitudinally distributed cristae. A third and secretory cell shows a well‐developed rough endoplasmic reticulum and Golgi complex in the basal zone. Its apical portion is full of secretory granules. Through the cuticle, these integumental glands open directly to the cuticular surface via a short duct coated by epicuticle.

The composition and specializations of this complex cuticular architecture differ markedly from those shown by an endoparasitic copepod detected in the digestive gland of the mussel. It does not appear that the specializations detected in the cuticle of M. gracilis lead to any histopathological alteration in host tissues. © 1994 Wiley‐Liss, Inc.
Ultrastructure of the frontal sensory fields in the Lynceidae (Crustacea, Branchiopoda, Laevicaudata)
Authors: Cash‐Clark Cora E. , Martin Joel W.
Published: February 2005

The clam shrimp family Lynceidae is unusual in possessing paired fields of short setae on either side of the rostral carina. We describe the position of these fields relative to the direction of water movement in live animals as well as the external and internal structure of these setae. The majority of morphological features support a presumed chemosensory role for these sensilla. These features include the lack of a setal socket and the relatively short length of each seta. The low number of enveloping cells (three or four) is uncharacteristic of chemosensory setae and is more typical of mechanoreceptors, as is the absence of any pores on the setae; these characteristics indicate that these fields may have both functions. © 1994 Wiley‐Liss, Inc.
Noradrenergic and peptidergic innervation of lymphoid organs in the beluga, Delphinapterus leucas: An anatomical link between the nervous and immune systems
Authors: Romano Tracy A. , Felten Suzanne Y. , Olschowka John A. , Felten David L.
Published: February 2005

The presence of peptidergic and noradrenergic sympathetic nerve fibers in specific compartments of both primary and secondary lymphoid organs of the rodent is well established. These nerve fibers directly contact lymphocytes and macrophages, as well as vascular and trabecular smooth muscle. We investigated the noradrenergic and neuropeptide‐Y innervation of lymphoid organs in the cetacean, Delphinapterus leucas (beluga whale). The spleen, thymus, tonsil, gut‐associated lymphoid tissue, and assorted lymph nodes were collected from five belugas, obtained during sanctioned hunts, and processed for catecholamine fluorescence histochemistry and for tyrosine hydroxylase and neuropeptide‐Y immunocytochemistry.

Innervation studies revealed fluorescent nerve fibers, tyrosine hydroxylase, and neuropeptide‐Y positive nerve fibers in parenchymal lymphoid compartments, where they were closely associated with cells of the immune system, and in vascular and trabecular compartments. In lymphoid zones, tyrosine hydroxylase and neuropeptide‐Y positive nerve fibers were observed in the periarteriolar lymphatic sheath and marginal zone of the spleen; in the outermost portion of the cortex, the corticomedullary zone, and medulla of the lymph nodes; in the parafollicular zones, and diffuse lymphocyte layer below the epithelium of the tonsil; in the outermost portion of some thymic lobules; and in the lamina propria of the gut.

These findings are similar to those described for other mammals and substantiate an anatomical link between the nervous and immune systems in the beluga, whereby central nervous system activity may influence autonomic outflow to lymphoid organs and effect immunologic reactivity. © 1994 Wiley‐Liss, Inc.
Nervous system of Triatoma infestans
Authors: Insausti Teresita C.
Published: February 2005

The anatomy of the adult nervous system of the haematophagous bug Triatoma infestans has been studied by means of dissections and histology. The central nervous system comprises three nervous masses: the brain + suboesophageal ganglion, the prothoracic ganglion, and the posterior fused ganglion (meso + metathoracic + abdominal ganglia). The form of the brain is determined by the tubular head and the highly developed muscles of the pharyngeal pump. The prothoracic. ganglion is located near the posternum, the posterior ganglionic mass near the mesosternum. A significative variation of the branching pattern of abdominal nerves is reported. The innervations of mouth parts, salivary glands, muscles, retrocerebral complex, spiracles, rectum, reproductive organs, alary muscles, and peripheral nerves are described. © 1994 Wiley‐Liss, Inc.
Apical surface of hydrozoan nematocytes: Structural adaptations to mechanosensory and exocytotic functions
Authors: Golz Rainer
Published: February 2005

At the apical cell pole of the nematocytes of a hydrozoan (Hydra vulgaris), cytoskeletal elements of different molecular families (microfilaments, microtubules, cross‐striated rootlets) are combined in a complex framework. As determined by transmission and scanning electron microscopy, the stimulus‐transducing cnidocil apparatus of these mechanosensitive cells is forced into a lateral position, facilitating the close apposition of the nematocyst to the apical cell membrane. The nematocyst, a single, extraordinarily large, exocytotic organelle, is held in position by a microtubular basket. The cnidocil apparatus and microtubular basket are linked to an ellipsoid arrangement of pseudovilli, i.e., small surface protrusions containing cross‐striated rods. These nematocyte‐specific, cytoskeletal elements mediate the anchorage of the entire cytoskeletal framework to the apical cell membrane. The apical membranes of the nematocyte and nematocyst are separated by a distance of only ∼ 50 nm. Structural modifications on the external side of the cyst membrane resemble those of synaptic membranes. © 1994 Wiley‐Liss, Inc.
Quantitative design of the skeleton in bird hatchlings: Does tissue compartmentalization limit posthatching growth rates?
Authors: Starck J. Matthias
Published: February 2005

Based on a detailed description of hatchling skeletons of the precocial buttonquail (Turnix suscitator) and the altricial budgerigar (Melopsittacus undulatus), this report presents the hypothesis that the rate of avian posthatching growth is limited by the quantitative design (i.e., relative volumes of cartilage, bone, and marrow) of the hatchling skeletons. A Jarge portion of bone in the skeletal elements and fast growth are hypothesized to be mutually exclusive. This hypothesis is tested by morphometric techniques and by statistical comparison of morphometric and growth data. All predictions are met by the data, and the design of hatchling skeletons is described as determined by a tradeoff between tissue composition of skeletal elements and maximum rates of posthatching growth. The precocial design shows large bony areas that supposedly resist mechanical stress of locomotion; however, the relatively small cartilaginous areas exclude high growth rates. The altricial design shows the reverse relationship with small bony areas and a lack of locomotion on the one side but large cartilaginous areas and fast posthatching growth on the other side. © 1994 Wiley‐Liss, Inc.
Effects of anisosmotic conditions on the cytoskeletal architecture of cultured PC12 cells
Authors: Cornet Michèle , Isobe Yuji , Lemanski Larry F.
Published: February 2005

PC12 cells show a classical volume regulatory process when submitted to hypo‐osmotic conditions. The present study examined the effects of such osmotic shock on the structural organization of different cytoskeletal elements. Results were obtained by use of different light and electron microscopy techniques combined with immunostaining methods. It appeared that the osmotically induced changes in cell volume were concomitant with important modifications in the organization of the microfilament network. Microfilaments concentrated in the perinuclear area, leaving only radial extensions of poorly organized structures in the cytoplasm. The latter were the only actin structures immunologically stained in the cytoplasm and seemed to anchor to the plasma membrane. Measurements of the fluorescence intensity of PC12 cells treated with FITC‐labeled phalloidin indicated a progressive depolymerization, followed by a repolymerization of F‐actin. This occurs in parallel with microfilament reorganization and volume regulatory processes. The appearance of microfilament reorganization was a function of both the incubation period and the amplitude of the osmolarity changes. During the first minutes of osmotic shock, a decrease was observed in the density and length of microvilli, which normally cover the PC12 cell surfaces, suggesting an early reorganization of the underlying microfilament network. Microtubules and intermediate filament networks were not affected by the hypo‐osmotic conditions. © 1994 Wiley‐Liss, Inc.
Structure of atympanate tibial organs in legs of the cave‐living ensifera, Troglophilus neglectus (Gryllacridoidea, Raphidophoridae)
Authors: Jeram S. , Rössler W. , Čokl A. , Kalmring K.
Published: February 2005

Troglophilus neglectus (Gryllacridoidea, Raphidophoridae) is a nocturnal Ensifera which can be found in caves of Slovenia. The anatomy of the tibial organs in the fore‐, mid‐, and hindlegs, as well as the external morphology of the proximal fore‐tibia and the prothoracic tracheal system, is described comparatively. In the prothorax and in the forelegs, no sound‐conducting structures such as an acoustic trachea, enlarged spiracles, or tympana are developed. A group of 8–10 campaniform sensillae is located in the dorsal cuticle of the proximal tibia. In each leg, the tibial organ complex is built up by two scolopale organs, the subgenual organ and the intermediate organ; the structure and the number of scolopidia is similar in each leg. No structure resembling the crista acoustica is found. The subgenual organ contains around 30 scolopidia; the intermediate organ is subdivided into a proximal part containing 8‐9 scolopidia and a distal part with 5–6 scolopidia. The two groups of scolopidia are not directly connected to the tracheal system. The tibial organs in the forelegs are insensitive to airborne sound, and they appear to be more primitive compared to those found in members of the Tettigoniidae and the Gwllidae. The results indicate that the complex tibial organs in all legs of T. neglectus are primarily vibrosensitive. © 1995 Wiley‐Liss, Inc.
Skeletal morphogenesis in the urodele skull: II. Effect of developmental stage in thyroid hormone‐induced remodeling
Authors: Rose Christopher Stewart
Published: February 2005

This study investigates the effect of developmental stage on thyroid hormone (TH)‐mediated remodeling in the skeletal tissues of hemidactyliine plethodontid urodeles. Rate of morphogenesis was quantified in 17 metamorphic tissues for three different size‐age classes of Eurycea bislineata larvae immersed in a metamorphic dosage of T4. Extent of morphogenesis after a 3‐week immersion was also quantified in these tissues plus four larval ones for the full size range of E. bislineata larvae and for less complete size ranges of E. wilderae, E. longicauda guttolineata, Gyrinophilus porphyriticus, and Pseudotriton ruber larvae. Although all tissues respond more slowly with decreasing size/age, two tissue‐specific effects are evident in all species. Larval ossifications are less inducible than metamorphic ossifications, and progressive metamorphic events are more retarded and, in some cases, more prone to abnormal morphogenesis than regressive ones. The first effect agrees with the prediction that tissues that naturally remodel at metamorphosis are more responsive to a metamorphic dosage of TH than those that respond at a larval stage and lower TH. The second effect agrees with the prediction that progressive morphogenesis is more likely to be impaired at small size than regressive morphogenesis, although the frequent discrepancies between individuals of similar size implicate developmental age more than size in this effect. Collectively, these two effects provide only equivocal support for the hypothesis that direct development in plethodontids evolved via precocious TH activity. However, the unexpected transition from ceratobranchial replacement to ceratobranchial shortening in medium‐sized larvae suggests that the former pathway requires a longer period of cell specification at low TH. Since ancestral plethodontids appear to have been distinguished by an exceptionally long larval period with exceptionally low TH activity, this developmental prerequisite may in turn be partly responsible for their singular evolution of ceratobranchial replacement. © 1995 Wiley‐Liss, Inc.
Surface morphology of hamster (Mesocricetus auratus) decidual cells in vitro
Authors: Shukla Rajiv , Pande Shalini , Mehrotra P. K. , Maitra S. C. , Kamboj V. P.
Published: February 2005

Cell surface morphology of hamster decidual cells isolated from day 8 implantation swellings was studied, using both phase‐contrast and scanning electron microscopy. Two kinds of cells, fibroblastic and epithelioid, were identified in cultures examined by phase‐contrast microscopy. Fibroblastic cells were spindle‐shaped, having pointed or blunt terminals on one end and bifid or webbed projections at the other end. Epithelioid cells, on the other hand, were flat and discoid, having a distinctively ruffled plasma membrane. Further, the plasma membrane of epithelioid cells formed rope‐like or flange‐like processes. The significance of such adaptations is discussed. © 1995 Wiley‐Liss, Inc.
Atomic force microscopy of the morphology of the matrix and mineral components of the otolith of Hyperoglyphe antarctica
Authors: Gauldie R. W. , Xhie J.
Published: February 2005

The sagittal otolith of Hyperoglyphe antarctica (Centrolophidae: Teleostei) has a prismatic structure in which the anti‐sulcal growth axes of each prism consist of a series of nested cones each composed of a mineral layer followed by an organic matrix layer. Broken sections show the mineral layers to be composed of stacks of crystals. Otolith matrix that has been decalcified and air‐dried, or critical‐pont‐dried, retains a periodic structure of repeating high and low matrix density. At high magnifications, both broken whole crystal surfaces and decalcified matrix surfaces have a granular structure. Chloroxbleached whole otoliths also show a granular crystalline structure. At higher magnifications, the air‐dried matrix showed a parallel fiber structure with similar dimensions to keratin fibers. © 1995 Wiley‐Liss, Inc.
Formation and regression of the corpus luteum of the American alligator (Alligator mississippiensis)
Authors: Guillette Louis J. , Woodward Allan R. , You‐Xiang Qui , Cox M. Cathy , Matter John M. , Gross Timothy S.
Published: February 2005

Luteal morphology of the American alligator is unique when compared to other reptiles but is similar to that of its phylogenetic relatives, the birds. The theca is extensively hypertrophied, but the granulosa never fills the cavity formed following the ovulation of the ovum. The formation of the corpus luteum (CL) is correlated with elevated plasma progesterone concentrations, which decline dramatically after oviposition with the onset of luteolysis. Unlike those of most other reptiles, the central luteal cell mass is composed of two cell types; one presumably is derived from the granulosa, whereas the other is from the theca interna. Both cell types are present throughout gravidity but only one cell type is seen during mid to late luteolysis. A significant decline in luteal volume occurs following oviposition and continues throughout the post‐oviposition period. The fastest decline in luteal volume occurs in the month immediately after oviposition; this rate then slows. Luteolysis appears to continue for a year or more following oviposition, as distinct structures of luteal origin can still be identified in animals 9 months after oviposition. The size of persistent CL can be used to determine whether a given female oviposited during the previous nesting season. Females with CL having volumes greater than 0.2 cm2 or CL diameters greater than 0.4 cm were active the previous season. © 1995 Wiley‐Liss, Inc.
In vivo strain in the humerus of pigeons (Columba livia) during flight
Authors: Biewener A. A. , Dial K. P.
Published: February 2005

Longitudinal and principal strain recordings were made in vivo at three sites (dorsal, anterior, and ventral) on the humeral midshaft of pigeons executing five modes of free flight: Take‐off, level flight, landing, vertical ascent, and near‐vertical descent. Strains were also recorded while the birds flew carrying weights that were 33%, 50%, or 100% of their body weight. The relative distribution of strain measured at the three surface midshaft sites and across the bone's cortex was found to be similar for all flight modes. Principal strains recorded in the dorsal and ventral humerus indicated considerable torsion produced by aerodynamic loading of the wing surface posterior to the bone. Measured torsional shear strains (maximum: 2,700–4,150 μ ε during level flight) were 1.5 times greater than longitudinal strains. In addition to torsion, the humerus is also subjected to significant dorsoventral bending owing to lift forces acting on the wing during the downstroke. Analysis of the cross‐sectional distribution of longitudinal strains at the humeral midshaft cortex shows that the orientation of bending shifts in a regular manner during the downstroke, indicating that the wing generates progressively more thurst (vs. lift) later in the downstroke. This shift is less during take‐off and vertical ascent when greater lift is required. Peak principal and longitudinal strains increased by an average of only 50% from landing to vertical ascending flight and take‐off (e.g., dorsal humerus: −1,503 to −2,329 μ ε) and did not exceed −2,600 μ epsiv; at any site, even when the birds flew carrying twice their body weight. Strains recorded when birds flew at two times their body weight (100% BW load) were similar in magnitude to those recorded during vertical ascent and take‐off and likely represent those developed during maximal performance. Strains developed within the midshaft were maximal in the anterodorsal and posteroventral cortices, not at the dorsal, ventral, and anterior sites at which strain was recorded. Consequently, maximum strains experienced by the bone are probably 20–25% greater than those recorded (ca. 3,200 μ ε), indicating a safety factor of about 3.5 for compressive strain failure. The much higher shear strains, however, indicate a lower safety factor (1.9), in which the bone's torsional strength is its most critical design feature. Finally, the magnitude and distribution of strains developed in the humerus of pigeons are generally similar to those recorded in the humerus of large fruit‐eating bats during flight. © 1995 Wiley‐Liss, Inc.
Mechanics of the avian propatagium: Flexion‐extension mechanism of the avian wing
Authors: Brown Richard E. , Baumel Julian J. , Klemm Robert D.
Published: February 2005

The supporting elements of the avian propatagium were examined in intact birds and as isolated components, using static force‐length measurements, calculated models, and airflow observations. The propatagial surface supported between Lig. propatagiale (LP) and brachium‐antebrachium is equally resistant to distortion over the range of wing extension used in flight. The lengths LP assumes in flight occur across a nearly linear, low‐stiffness portion of the force‐length curve of its extensible pars elastica. In an artificial airflow, intact wings automatically extend; their degree of extension is roughly correlated with the airflow velocity. Comparisons between geometric models of the wing and the passive force‐length properties of LPs suggest that the stress along LP blances the drag forces acting to extend the elbow. The mechanical properties (stiffness) of the LP vary and appear to be tuned for flight‐type characteristics, e.g., changes in wing extension during flight and drag. Lig. limitants cubiti and LP combine to limit elbow extension at its maximum, a safety device in flight preventing hyperextension of the elbow and reduction of the propatagium's cambered flight surface. Calculations using muscle and ligament lengths suggest that M. deltoideus, pars propatagialis, via its insertions onto both the propatagial ligaments, controls and coordinates propatagial deployment, leading edge tenseness, and elbow/wing extension across the range of wing extensions used in flight. The propatagial ligaments and M. deltoideus, pars propatagialis, along with skeleto‐ligamentous elbow/carpus apparatus, are integral components of the wing's extension control mechanism. © 1995 Wiley‐Liss, Inc.
Cephalometric correlates of echolocation in the chiroptera: II. Fetal development
Authors: Pedersen Scott C.
Published: February 2005

Cephalometry was used to detect patterns of cranial growth in fetal bats that were stained differentially for bone and cartilage. Three developmental features distinguish embryos of taxa that echolocate nasally from embryos of taxa that echolocate orally: (1) the basicranium is retained ventral to the cervical axis, (2) the rostrum is retained below the basicranial axis, and (3) the lateral semicircular canals are rotated caudally. Together, the first two actions align the fetal nasal cavity with what will be the long axis of the adult body in flight. The third action aligns the lateral semicircular canals with the horizontal. In contrast, skulls of oral‐emitting taxa are constructed such that the oral cavity is aligned with the long axis of the body in flight. The evolution of head posture and skull form in microchiropteran bats has been constrained by the demands of vocalization, i.e., ultrasonic echolocation. Accordingly, the ontogeny of the microchiropteran skull has been canalized along two distinct developmental paths—oral‐emitting and nasal‐emitting Baupläne. © 1995 Wiley‐Liss, Inc.
Homology of facial structures in extant archosaurs (birds and crocodilians), with special reference to paranasal pneumaticity and nasal conchae
Authors: Witmer Lawrence M.
Published: February 2005

Homology of virtually all major components of facial anatomy is assessed in Archosauria in order to address the function of the antorbital cavity, an engimatic structure that is diagnostic for the group. Proposed functions center on its being a housing for a gland, a muscle, or a paranasal air sinus. Homology is approached in the context of the Extant Phylogenetic Bracket method of reconstructing unpreserved aspects of extinct organisms. Facial anatomy and its ontogeny was studied in extant archosaurs (birds and crocodilians) to determine the osteological correlates of each soft‐tissue component; resemblances between birds and crocodilians comprised the similarity test of homology. The congruence test of homology involved surveying phylogenetically relevant fossil archosaurs for these bony signatures. The facial anatomy of extant birds and crocodilians is examined in detail to provide background and to discover those apomorphic aspects that contribute to the divergent specialization of these two groups and thus obscure homologies. Birds apomorphically show enlarged eyeballs, expanded nasal vestibules, and reduced maxillae, whereas crocodilian faces are dorsoventrally flattened (due to nasal rotation) and elongated. Most facial attributes of archosaurs are demonstrably homologous and in fact characterize much more inclusive groups. Special emphasis has been placed on the nasal conchae and paranasal air sinuses. Within Amniota, the following conchal structures are homologous, and all others are neomorphs: Avian caudal concha, crocodilian concha + preconcha, Sphenodon caudal concha, squamate concha, and probably the mammalian crista semicircularis. The avian antorbital paranasal air sinus is homologous with the crocodilian caviconchal sinus; the maxillary sinus of placental mammals is not homologous with the archosaurian paranasal sinus. With regard to the function of the antorbital cavity, archosaurs possess homologous nasal glands, dorsal pterygoideus muscles, and paranasal air sinuses, but the osteological correlates of only the paranasal sinus involve the antorbital fenestrae and fossae. Thus, the antorbital cavity is best interpreted as principally a pneumatic structure. © 1995 Wiley‐Liss, Inc.
Intratendinous ossification in birds: A review
Authors: Berge James C. Vanden , Storer Robert W.
Published: February 2005

Intratendinous ossification (tenostosis; Tendo ossificans) is a distinct structural form feature of the avian musculoskeletal system with different definitions in terms of morphogenesis, resultant morphology, and functional role(s). Interpretation of these structural elements and their pattern(s) among avian taxa at different systematic levels is reviewed with regard to age‐related changes in tendon, form features in avian phylogeny, and adaptive features in biomechanics and kinematics of locomotion. Specific examples of patterns in the musculoskeletal elements of the head and hyolingual system, axial (vertebral) system, and the limbs in several avian taxa are given. A series of questions is formulated as a prospectus for further study. © 1995 Wiley‐Liss, Inc.
Mechanism of lung ventilation in the caecilian Dermophis mexicanus
Authors: Carrier David R. , Wake Marvalee H.
Published: February 2005

The pattern of lung ventilation in the terrestrial caecilian Dermophis mexicanus was investigated by recording pressure changes of buccal and pleuroperitoneal cavities and activity of the buccal musculature. This species uses a fairly typical sarcopterygian buccal pumping system to inflate its single lung. What distinguishes it from other amphibians is the large number of buccal pumping cycles that occur in each ventilatory cycle. Up to 29 buccal cycles were observed to occur in a single respiratory cycle, with a mean of 16.1 ± 3.0 buccal cycles. This long series of buccal cycles avoids the sarcopterygian pattern of rebreathing expired air because only the first buccal cycle pumps expired air back into the lung. The series of buccal cycles also generates pleuroperitoneal pressures that are three to ten times greater than those observed in other amphibians. We suggest that these high pleuroperitoneal pressures are necessary for the maintenance of body form and locomotor function in terrestrial caecilians. © 1995 Wiley‐Liss, Inc.
Anatomy of the feeding apparatus of the lemon shark, Negaprion brevirostris
Authors: Motta Philip J. , Wilga Cheryl A. D.
Published: February 2005

The anatomy of the feeding apparatus of the lemon shark, Negaprion brevirostris, is investigated by gross dissection, computer axial tomography, and histological staining. The muscles and ligaments of the head associated with feeding are described. The upper and lower jaws are suspended by the hyoid arch, which in turn is braced against the chondrocranium by a complex series of ligaments. In addition, various muscles and the integument contribute to the suspension and stability of the jaws. The dual jaw joint is comprised of lateral and medial quadratomandibular joints that resist lateral movement of the upper and lower jaws on one another. This is important during feeding involving vigorous head shaking. An elastic ethmoplatine ligament that unites the anterior portion of the upper jaw to the neurocranium is involved with upper jaw retraction. The quadratomandibularis muscle is divided into four divisions with a bipinnate fiber arrangement of the two large superficial divisions. This arrangement would permit a relatively greater force per unit volume and reduce muscle bulging of the jaw adductor muscle in the spatially confined cheek region. Regions of relatively diffuse integumental ligaments overlying the adductor mandibulae complex and the levator palatoquadrati muscle, interspersed with localized regions of longer tendonlike attachments between the skin and the underlying muscle, permit greater musculoskeletal movement relative to the skin. The nomenclature of the hypobranchial muscles is discussed. In this shark they are comprised of the unsegmented coracomandibularis and coracohyoideus, and the segmented coracoarcualis. © 1995 Wiley‐Liss, Inc.
Morphology of the tibial organs of acrididae: Comparison of subgenual and distal organs in fore‐, mid‐, and hindlegs of Schistocerca gregaria (Acrididae, Catantopinae) and Locusta migratoria (Acrididae, Oedipodinae)
Authors: Lin Yuzhen , Rössler Wolfgang , Kalmring Klaus
Published: February 2005

The structure of the complex tibial organs in the fore‐, mid‐, and hindlegs of two grasshopper species, Schistocerca gregaria (Acrididae, Catantopinae) and Locusta migratoria (Acrididae, Oedipodinae), is described. In each leg the tibial organs consist of two scolopale organs: the subgenual organ and the distal organ. Both organs are located in the hemolymph channel. The subgenual organ has a sail‐like structure, and its scolopidia are oriented perpendicular to the long axis of the leg. The number of scolopidia in the subgenual organs is lower in Locusta migratoria than in Schistocerca gregaria. The scolopidia of the distal organ are clearly spearated from those of the subgenual organ and lie parallel with the long axis of the legs. They insert distally on an attachment plate that lies in the hemolymph channel. The subgenual organs and the distal organs are smaller in the hindlegs than in the fore‐ and midlegs, and this difference is especially pronounced in Locusta migratoria. The complex tibial organ of Locusta and Schistocerca is very similar in structure and cellular composition with that of Periplaneta (Blattidae). In tettigoniids and gryllids the distal organ is differentiated into an intermediate organ and the crista acoustica. © 1995 Wiley‐Liss, Inc. © 1995 Wiley‐Liss, Inc.
Synovial factors and chondrocyte‐ mediated breakdown of cartilage: Inhibition by hydrocortisone
Authors: Steinberg James J. , Sledge Clement B.
Published: February 2005

Cartilage‐synovium interactions were explored in a model culture system. Bovine nasal‐cartilage discs were cocultured with minced rheumatoid synovium or synovium‐conditioned media (SCM) in the presence or absence of hydrocortisone. Cartilage breakdown was assessed by the release of proteoglycan (PG) and hydroxyproline, and matrix biosynthesis by [35S]sulfate incorporation during pulse labeling. Chondrocyte‐dependent breakdown in response to synovial factors (i.e., “catabolin” activity) was assessed by the difference in PG release between living and dead cartilages. Short‐term contact with minced synovial membrane or exposure to its products released at a distance was sufficient to induce cartilage degradation in coculture; continued exposure was not required for breakdown to persist. Conditioned media from short‐term synovial culture were similarly potent, and the induced breakdown was chondrocyte dependent. Matrix biosynthesis was inhibited in exposed cartilage but could be rapidly restored to normal on synovium removal despite the persistence of cartilage breakdown. Early hydrocortisone treatment suppressed the initiation of cartilage breakdown in cocultures and largely abolished the appearance of inductive factors in SCM. Later applications had little effect either in cocultures or in catabolin assays. We conclude that synovium‐induced breakdown is an early event and that chondrocyte catabolic mechanisms once they have been activated are sufficient to maintain breakdown at a high level. Hydrocortisone, as well as limiting proteolysis, inhibits early tissue interactions at the level of synovial catabolin production or release.
Use of lumbar trunk muscles in isometric performance of mechanically complex standing tasks
Authors: Schultz Albert , Haderspeck Karol , Warwick David , Portillo Deborah
Published: February 2005

Ten subjects performed 25 tasks isometrically while standing. Those tasks imposed substantial extension, lateral bending, and twisting moments on the lumbar spine. Mechanically complex trunk muscle actions were called for to resist those moments. Biomechanical model analyses were used to predict the trunk muscle contraction forces needed to perform those tasks, and surface myoelectric activities were measured to validate those predictions. Predictions and measurements were linearly well correlated.
Electrical osteogenesis by low direct current
Authors: Baranowski Thomas J. , Black Jonathan , Brighton Carl T. , Friedenberg Zachary B.
Published: February 2005

A constant direct current cathode was employed in the medullary canal of the rabbit tibia to investigate electrical osteogenesis at low current levels. Currents of 0.015 or 0.075 μA were delivered to the bone and the biological response was compared with contralateral controls receiving 20 μA. This investigation was performed to determine if electrical osteogenesis occurs at current levels below the previously studied range of 1–100 μA with stainless steel electrodes. New bone formed by 0.015 μA cathodes was statistically comparable with that found around inactive cathodes from an earlier pertinent study. The osteogenic response to 0.075 μA cathodes was significantly elevated above that to inactive ones, thus substantiating electrical osteogenesis for currents below 1 μA. However, it is evident that this does not demonstrate a further stimulatory range but that currents near 0.075 μA probably approach the lower significant limit for electrically induced bone growth with stainless steel electrodes.
Effect of postoperative immobilisation on the regrowth of the knee joint semilunar cartilage: An experimental study
Authors: Ghosh P. , Taylor T. K. F. , Pettit G. D. , Horsburgh B. A. , Bellenger C. R.
Published: February 2005

Bilateral total medial meniscectomy was undertaken in the knee joints of 12 adult greyhounds. One‐half of the animals had one meniscectomised joint immobilised by an external fixation system for 5 weeks following meniscectomy. All animals were sacrificed 6 months after surgery. The menisci (regrown and normal) were examined for collagen content and analysed histochemically to assess collagen assembly and glycosaminoglycan (GAG) distribution. Although the collagen content of regrown tissues was not statistically different from normal medial or lateral menisci, the fibre development and GAGs were abnormal. It is concluded that movement following meniscectomy is likely beneficial to the matrix formation in the regenerating tissue, but this together with weight bearing may have a detrimental effect on articular cartilage of the medial joint compartment.
Relationship of isokinetic torque to isometric torque
Authors: Otis James C. , Godbold James H.
Published: February 2005

Isokinetic muscle testing has become an increasingly popular method for measuring muscle performance. However, the relationship of isokinetic strength measurements to static strength measurements remains unclear. The relationship between maximal isokinetic and maximal isometric torque was investigated at angular velocities of 24, 48, 96, and 192°/s for both flexion and extension of the elbow joint. Twenty‐four subjects were tested bilaterally, and discrete torque values at the positions of 60 and 90° of flexion were obtained from the continuous isokinetic records for comparison with isometric torques recorded at the same two positions. Data were analyzed using an analysis of covariance with isokinetic torque, the dependent variable, expressed as a function of isometric torque and as a function of the design variables side and position. The results demonstrated significant effects of side and position and also demonstrated the dependence of isokinetic strength on velocity. Confidence intervals were determined for the prediction of isokinetic torque from observed isometric torque for normal individuals, providing a potentially useful tool to aid in the diagnosis of muscular disorders.
Natural history of healing in the repaired medial collateral ligament
Authors: Frank C. , Schachar N. , Dittrich D.
Published: February 2005

The purpose of this study was to assess morphologically the healing of repaired medial collateral ligaments (MCLs) in a rabbit model. Healing ligaments were examined grossly and histologically at various intervals, from 3 days to 2 ½ years after injury, and compared with the appearances of normal age‐, sex‐, and activity‐matched controls. Results show that all ligaments healed by bridging scar formation rather than true ligament regeneration. Increases in cellularity and temporary matrix disorganization along the entire length of the ligaments during healing suggest a combination of diffuse mechanical damage from their failure in tension and regional inflammatory injury (in excess of surgical exposure alone) from the processes of degradation and replacement. Substance that was not injured physically in this model demonstrated complete recovery, while that replaced by scar did not. Healing processes were similar to those of other highly specialized soft tissues (e.g., tendons), with short phases of hemorrhage and inflammation, an intermediate phase of proliferation, and a prolonged phase of remodeling. Failure of repairs to maintain anatomical apposition of torn ends may have contributed to the delay of these healing processes by increasing scar mass. Incomplete scar remodeling at 2 ½ years, however, suggests much slower MCL healing than previously reported and probably, therefore, a longer period for potential treatment influence.
Tendons and ligaments: A morphological and biochemical comparison
Authors: Amiel D. , Frank C. , Harwood F. , Fronek J. , Akeson W.
Published: February 2005

The purpose of this study was to compare selected rabbit tendons and ligaments morphologically and biochemically. Five representative structures from each of six age‐ and sex‐matched rabbits were compared. Biochemical analyses included total collagen, reducible collagen cross‐links, quantitative collagen typing, DNA, and glycosaminoglycans. Histological and chemical differences were demonstrated between the tendons and the ligaments. Smaller differences were also found between the individual ligaments (collateral and cruciate) and between the two tendons (patellar and Achilles) that were examined. These findings suggest that ligaments are more metabolically active than tendons, having more plump cellular nuclei, higher DNA content, larger amounts of reducible cross‐links, and the presence of more type III collagen, as compared with tendons. They also contain slightly less total collagen than tendons and more glycosaminoglycans. We conclude that the tendons and ligaments studied have unique histological and biochemical characteristics, despite their gross similarities. Relatively increased metabolic activity in ligaments, implied by our findings, may be species specific, age related (transient), or may truly represent a structural expression of functional need for more rapid adaptation. Further investigation of other similarities or differences between particular ligaments (or tendons) is indicated, and attention is directed toward the importance of such variables in development of models for tendon and ligament studies.