bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantitative design of the skeleton in bird hatchlings: Does tissue compartmentalization limit posthatching growth rates?
Authors: Starck J. Matthias 
Published: February 2005

AbstractBased 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

AbstractPC12 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

AbstractTroglophilus 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

AbstractThis 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

AbstractCell 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

AbstractThe 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

AbstractLuteal 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

AbstractLongitudinal 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

AbstractThe 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

AbstractCephalometry 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

AbstractHomology 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

AbstractIntratendinous 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

AbstractThe 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

AbstractThe 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

AbstractThe 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.