bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spermathecae of Salamandrina terdigitata (Amphibia: Salamandridae): Patterns of sperm storage and degradation
Authors: Brizzi Rossana , Delfino Giovanni , Selmi Maria Gloria , Sever David M. 
Published: February 2005

AbstractThe spermathecae of female Salamandrina terdigitata were observed using light and transmission electron microscopy during the fallspring period of sperm storage and secretory activity and during the summer stasis. When sperm are stored inside the spermathecae, the product synthesized by spermathecal epithelial cells is exported into the lumen, where it bathes the sperm. During sperm storage some spermatozoa undergo degradation by the spermathecal epithelium. This process, which includes sperm capture by the apical microvilli, formation of endocytic vacuoles and production of lysosomes, becomes prominent shortly after oviposition. In many instances, cells filled with vacuolized spermatozoa and/or residual bodies undergo desquamation from the spermathecal epithelium and enter the lumen together with residual sperm. Desquamated cells, together with residual sperm, are a common feature in the spermathecal lumina at the end of the egg‐laying season.Concomitant to the activity of the spermathecal epithelium, macrophages move into the spermathecae from the stroma and contribute to the degradation of both the residual sperm and desquamated epithelial cells. As a result of this degradation activity, spermathecae observed during the short summer stasis appear devoid of secretory product and sperm. By late summer, however, the spermathecae already show early signs of an imminent resumption of biosynthetic activity. © 1995 Wiley‐Liss, Inc.
Mechanical properties of the skin of Xenopus laevis (Anura, Amphibia)
Authors: Greven Hartmut , Zanger Klaus , Schwinger Gerhard 
Published: February 2005

AbstractThe skin of the aquatic pipid frog, Xenopus laevis, was examined for specific biomechanical features: (1) thickness, (2) maximal strain at break (εf), (3) tensile strength (σm), (4) modulus of elasticity (E, stiffness), and (5) the area under the stress‐strain curve (W) (breaking energy, toughness). Skin freshly removed from dorsal, ventral, and lateral areas of the body was subjected to uniaxial tension. In both sexes, the dorsal skin is thicker than the ventral. The skin of male frogs was consistently thinner in all body regions than that of females. Most biomechanical parameters showed a considerable range of values in both males (εf = 59–63%, σm = 15–16.5 MPa, E = 33.5–38.4 MPa, W = 3.8–4.5 MJ/m3) and females (εf = 102–126%, σm = 11.5 MPa, E = 10.4–12 MPa, W = 5.2–6.7 MJ/m3). The disparate εf values in males (low) and females (high) might reflect sexual dimorphism. Static stress‐strain curves were typicxally J‐shaped; with the exception of “toe,” the curves rose approximately linearly with increasing strain. The skin of X. laevis, although heterogeneous in structure, possesses features similar to those found in tissues with aligned collagen fibers such as tendons or fish skin. However, in anurans, the skin seems to play a more passive mechanical role during locomotion than in fish. © 1995 Wiley‐Liss, Inc.
Superficial mandibular musculature and vocal sac structure in hemiphractine hylid frogs
Authors: Tyler Michael J. , Duellman William E. 
Published: February 2005

AbstractThree patterns of superficial mandibular musculature are described in hemiphractine hylid frogs. One of these is unique to the morphologically bizarre Hemiphractus. A second pattern is found in Flectonotus and also occurs in some species of Gastrotheca and Stefania. A third pattern involves a differentiated apical element of the m. intermandibularis and is found in Cryptobatrachus, many species of Gastrotheca, and one species of Stefania. Evidence supports the plesiomorphic state of an undifferentiated m. intermandibularis and two derived states of differentiation of that muscle. One of these is the development of supplementary posterolateral elements characteristic of the Phyllomedusinae, whereas the diferentiation of an apical element has occurred in at least six independent lineages—the entire Pelodryadinae, three unrelated genera of Hylinae, and two genera of Hemiphractinae. Gastrotheca and Stefania are the only anuran genera known to include species possessing, and others lacking, differentiation of the m. intermandibularis. Vocal sacs and apertures are absent in Cryptobatrachus, Hemiphractus, Stefania, and six species of Gastrotheca. © 1995 Wiley‐Liss, Inc.
Presence of interdigitating cells in thymus of the sea bass, Dicentrarchus labrax L. (Teleost)
Authors: Avilés‐Trigueros Marcelino , Quesada Juan A. 
Published: February 2005

AbstractInterdigitating cells in the thymus of the sea bass, Dicentrarchus labrax, occur principally in the internal zone and in the border with the external zone. Ultrastructurally, the most characteristic cytological features of these cells are their low electron density, complicated labyrinthine membrane‐membrane contacts, scantiness of cytoplasmic organelles, presence of Birbeck‐like granules, juxtanuclear tubulo‐vesicular complex, and phagocytic capacity. © 1995 Wiley‐Liss, Inc.
Morphology of the reflecting superposition eyes of larval oplophorid shrimps
Authors: Gaten Edward , Herring Peter J. 
Published: February 2005

AbstractThe eyes of larval and juvenile oplophorid shrimps are described for the first time. Variations in eye development occur depending on whether the zoeal stages are lecithotrophic or planktotrophic. In those genera where the first free‐living stage is planktonic, the eyes are of the transparent apposition type seen in other decapod zoeas. However, where the eggs hatch after completion of the lecithotrophic zoeal stages, the eyes are laready developing the superposition optics found in the adult. In Oplophorus spinosus the changeover from hexagonal to square facets, indicative of superposition optics, proceeds from anterior to posterior. In Systellaspis debilis the square facets appear first on the lateral face of the eye. Eventually, in both species, only the most dorsal ommatidia retain apposition optics. © 1995 Wiley‐Liss, Inc.
Morphology and ultrastructure of saccular otoliths from five species of the genus Coelorinchus (Gadiformes: Macrouridae) from the Southeast Atlantic
Authors: Lombarte Antoni , Morales‐Nin Beatriz 
Published: February 2005

AbstractThe morphology of the saccular otolith (sagitta) of five species of the genus Coelorinchus (grenadiers) from the southeastern Atlantic (C. coelorinchus, C. fasciatus, C. occa, C. braueri, and C. acanthiger) was analyzed macro‐ and ultrastructurally by digital image processing and scanning electron microscopy (SEM). Interspecies variations have been noted in the morphology and ultrastructure of the sulcus acusticus and are linked to differences in form of the entire otolith. This relationship may indicate a genetic regulation in the growth of the sulcus. Standard canonical analysis of biometric measurements of the otolith and acoustic sulcus has proved to be a good way to distinguish otoliths of the five species of Coelorinchus. © 1995 Wiley‐Liss, Inc.
Marginal tooth‐bearing bones in the lower jaw of the recent australian lungfish, Neoceratodus forsteri (Osteichthyes, Dipnoi)
Authors: Kemp A. 
Published: February 2005

AbstractDevelopmental studies of the Recent Australian lungfish, Neoceratodus forsteri, show that this species has two sets of functional tooth‐bearing bones in the lower jaw of young hatchlings. These coincide with an early stage in the life history when the fish is strictly carnivorous. In N. forsteri, a paired tooth‐bearing dentary and an unpaired symphyseal bone and tooth develop slightly later than the permanent vomerine, prearticular, and pterygopalatine tooth plates, which appear at stage 44 of development, and erupt with the permanent dentition between stages 46 and 48, when the hatchling first starts to feed on small aquatic invertebrates. At these stages of development, all of the teeth are long, sharp, and conical and help to retain prey items in the mouth. Disappearance of the transient dentition coincides with complete eruption of the permanent tooth plates and precedes the change to an omnivorous diet. Existence of a transient marginal dentition in this species of lungfish suggests that the presence of an apparently similar marginal dentition in adults of many species of Palaeozoic dipnoans should be considered in phylogenetic analyses of genera within the group, and when analysing the relationships of dipnoans with other primitive animals. © 1995 Wiley‐Liss, Inc.
Perinatal changes in avian muscle: Implications from ultrastructure for the development of endothermy
Authors: Eppley Zoe A. , Russell Brenda 
Published: February 2005

AbstractEndothermic heat production and the capacity to shiver develop soon after hatching in birds, permitting chicks to regulate their body temperature. Physiological studies have not clearly identified the developmental events causing this change in function. Here, we use electron microscopy to examine the development of structures involved in muscle activation, contraction, and metabolism coincident with the development of shivering thermogenesis. A stereological study was used to compare the ultrastructure of chicken iliofibularis before endothermic heat production was present (24 h before hatching) and 120 h later, when the iliofibularis had substantial capacity for shivering. Profound increases were found in the t‐tubule system and terminal cisternae, mitochondrial cristae, and lipids. The number of triadic profiles increased 3.8‐fold (7.6 ± 1.31/100 μm2 to 28.5 ± 2.90/100 μm2 fiber area). The surface area of cristae per mitochondrial volume doubled (12.0 ± 1.50 pm2/pm3 to 25.7 ± 1.84 μm2/μm3). Lipid droplets were rare in the iliofibularis of embryos about to hatch, but accounted for 4.4% of the muscle fiber volume in day 4 birds. We suggest that these ultrastructural changes more fully activate the iliofibularis, allow it to produce more heat both from calcium pumping and from contraction, and increase its endurance, thus permitting the muscle to be effective in thermogenesis. © 1995 Wiley‐Liss, Inc.
Sensory receptors on the adult labial and maxillary palpi and galea of Cicindela sexguttata (Coleoptera: Cicindelidae)
Authors: Baker Gerald T. , Monroe William A. 
Published: February 2005

AbstractFive types of sensilla are situated on the apical area of the labial and maxillary palpi and galea of Cicidela sexguttata. Large, conical, and peg‐like sensilla are in rows on the central region of each palpus. These sensilla have a hollow cuticular peg, with an apical pore and multi‐innervation. This central region of palpal sensilla is surrounded by campaniform sensilla that are disc‐shaped and small conical peg sensilla. A similar type of conical sensillum as the found in the palpal central region is situated around the periphery of the palpal apex and apex of the galea. This conical peg sensillum is located in a shallow depression and is structurally similar to the other peg sensilla, but it has a mechanoreceptor neuron attached to the cuticular base of the sensillum. A long, single, trichoid sensillum is situated in the center of the galea and is hollow, thick‐walled, porous, and multi‐innervated. The apices of the palpi and galea have a large number of dermal gland openings that actively secrete a substance during the feeding process of the tiger beetle. © 1995 Wiley‐Liss, Inc.
Microstructure, evolution, and ontogeny of scale surfaces in cordylid and gerrhosaurid lizards
Authors: Harvey Michael B. , Gutberlet Ronald L. 
Published: February 2005

AbstractThe distal oberhautchen and proximal beta layer of 41 species and every genus of cordylid and gerrhosaurid lizard were examined with a scanning electron microscope. Scale organs in these families are concentrated on the face, and scale organs occur singly or in pairs below the keel on the dorsals of cordylids but not gerrhosaurids. Most species examined possess primitive, lenticular scale organs. Unique and previously unknown, projecting scale organs occur in two species of Cordylus. Scale organs appear to be absent in species of Chamaesaura. The scale surfaces of cordylids are covered in macrohoneycomb. Individual compartments of cordylid macrohoneycomb are not intracellular structures but may be overlain by apparent oberhautchen cells. In some cordylid species, part of each cell is free and projects away from the scale surface as a pointed flap. Gerrhosaurids lack macrohoneycomb. Instead, their scale surfaces are covered in lamellae without dentate borders, 50–100 times as long as wide. The epidermis of Platysaurus is unique among cordylids in possessing lamellae 1–8 times as wide as long that overlap macrohoneycomb in some regions of the body. The scale surfaces of Cordylus cordylus undergo an ontogenetic change similar to that recently described for the xenosaurid genus Shinisaurus. Phylogenetic analysis of scale surface features allows the partitioning of Cordylus into three species groups and Chamaesaura into two species groups. Synapomorphies of the species of Chamaesaura, the species of Platysaurus, and the genera of the gerrhosaurids are also described. © 1995 Wiley‐Liss, Inc.
Spleen of the snake (Elaphe climacophora) and intrasplenic vascular architecture
Authors: Tanaka Yasukazu , Hirahara Yoshihiro 
Published: February 2005

AbstractThe spleen of the blue‐green snake (Elaphe climacophora) lies at the head of the pancreas and is separated from it by a fibrous capsule. A hilus is not clearly distinguished. Arteries and veins enter or leave the spleen through the capsule, but no collateral relationship is observed between these vessels. Histologically, the spleen consists of the capsule‐septal tissue, lymphoid tissue (the white pulp), and a fibrous zone (the perilymphoid fibrous zone: PLFZ) around the lymphoid tissue that includes many small veins. The PLFZ probably represents the involuted red pulp. The border between the white pulp and PLFZ is unclear in routine histological sections due to diffuse infiltration of lymphocytes into the latter region, but the border could be distinguished clearly in silver‐impregnated specimens.Arteries enter the spleen, run within the septa, and divide into terminal arteries in the lymphoid tissue that form end branches. There are no ellipsoids around the terminal arteries. The end branches communicate with veins of the PLFZ through transitional vessels within the lymphoid tissue (closed circulation). The veins of the PLFZ anastomose with drainage veins in the capsule.The snake spleen retains the basic histological characteristics of a spleen and is morphologically distinguishable from a lymph node. It may represent an extreme example of a spleen modified by the remodelling of the intrasplenic vasculatures during evolution. © 1995 Wiley‐Liss, Inc.
Contrast bone cement
Authors: Bargar William L. , Heiple Kingsbury G. , Weber Stephen , Brown Stanley A. , Brown Richard H. , Kotzar Geoff 
Published: February 2005

AbstractThe effects of adding 1.0 cc of aqueous methylene blue dye as a visual contrast agent to a standard 40 g pack of acrylic bone cement are determined. These cements are evaluated: Simplex P (Radiopaque), Zimmer Bone Cement, and Zimmer LVC Bone Cement. Seven tests were performed. Leach out is less than 2.0% and was undetectable after day 8. Biocompatibility using a rabbit model shows contrast and white cement to be equivalent. Tension, compression, and 3‐ and 4‐point bending strengths are not significantly altered except for a slight increase in 4‐point bending strength for contrast Zimmer (regular) bone cement. Dough, set, and working times are decreased by 30–150 s. The ASTM F451 intrusion standards are met for all three contrast cements. Viscosity increases more rapidly for contrast cement, but remains sufficiently low (less than 100 N‐s/m2) early after mixing to allow good penetration into bone. Ease of removal and visualization of contrast cement are shown by revision of cemented femoral total hip components in synthetic and cadaver femurs and by debriding cement particles from a soft tissue background coated with blood. The use of contrast bone cement appears to be both safe and efficacious for use in initial and revision total joint replacements. Because of the decreased working times, its use is recommended only by experienced surgeons.
Long‐term measurement of muscle function in the dog hindlimb using a new apparatus
Authors: Hargens Alan R. , Mortensen Wayne W. , Gershuni David H. , Crenshaw Albert G. , Lieber Richard L. , Akeson Wayne H. 
Published: February 2005

AbstractThe objective of this study was to develop an apparatus for reliable, reproducible, and minimally invasive measurements of long‐term, myoneural function. Twenty conditioned dogs were anesthetized and placed supine with one hindlimb secured in a boot apparatus. The hindpaw was attached to a force transducer that was connected to a recorder for continuous monitoring of torque. Muscles within the anterolateral compartment were stimulated by percutaneous electrodes over the peroneal nerve near the fibular head. This elicited isometric dorsiflexion of the hindpaw. Twitch and tetanic torques correlated positively with dog weight whereas other skeletal‐muscle function parameters (time to peak tension, one‐half relaxation time, and endurance) were independent of dog weight. Muscle function results were consistent with an overall compartmental composition of 30% Type I and 70% Type II fibers. Repetitive testing of twitch and tetanic torques in the dog legs yielded coefficients of variance of 3–4% (intraday) and 7% (interday). Thus, about onehalf of the interday variability may be accounted for by diet, exercise, and other physiological conditions that change daily. The apparatus was also used to detect myoneural degeneration following tourniquet ischemia. The results indicate that this procedure for evaluating muscle function yields reliable and quantitative results noninvasively, and thus allows long‐term testing of muscle function in normal and diseased hindlimbs of dogs.
Age‐related changes in bone in the dog: Calcium homeostasis
Authors: Williams E. Alan , Kelly Patrick J. 
Published: February 2005

AbstractTo explore the changes in the relationship between skeletal and Ca2+ homeostasis with age, we studied 50 dogs divided into four age groups. The skeletal uptake of 85Sr decreased markedly with age, and the immunoreactive parathyroid hormone (iPTH) level increased. There was a significant correlation between iPTH value and the calculated short‐term exchange of Ca in bone (r = −0.55; p < 0.001). Bone formation and bone resorption decreased with age except that in the oldest group of dogs the resorption increased (p < 0.001). We suggest that in aging dogs the skeletal exchange of Ca falls to a very low level that decreases the immediate effect of PTH and thus leads to a chronic net increase in circulating PTH. Concomitant with this is an increase in osteoclastic bone resorption and, over a long time, loss of skeletal mass.
In vitro growth of bovine articular cartilage chondrocytes in various capacitively coupled electrical fields
Authors: Brighton Carl T. , Unger Anthony S. , Stambough Jeffery L. 
Published: February 2005

AbstractIsolated articular cartilage chondrocytes from 1‐ to 3‐week‐old male Holstein calf knee joints were formed into pellets containing 4 × 106 isolated cells and were grown in tissue culture medium (minimum essential medium/NCTC 135) containing either 1 or 10% newborn calf serum (NBCS) in plastic Petri dishes in 5% CO2 and air at 37°C in saturation humidity. On the 4th postisolation day either [35S]sulfate or [3H]thymidine was added to the medium, and the pellets were exposed for 24 h to capacitively coupled electrical fields (10, 100, 250, and 1,000 V peak‐to‐peak, 60 kHz, sine wave signals). The pellets were then harvested, dialyzed, hydrolyzed, and assayed for DNA, protein, [35S]sulfate incorporation, and [3H]thymidine incorporation. Results indicated that at 250 V peak‐to‐peak there was a statistically significant increase in [35S]sulfate in 1% NBCS and a statistically significant increase in [3H]thymidine in 10% NBCS. At potentials above or below 250 V no changes were noted. Thus, articular cartilage chondrocytes grown in pellet form can be stimulated to increase glycosaminoglycan synthesis or to increase cell proliferation by an appropriate capacitively coupled electrical field. The importance of the serum concentration in the medium in evaluation of biosynthesis in vitro is noted.
The apparent elastic modulus of the juxtaricular subchondral bone of the femoral head
Authors: Brown Thomas D. , Vrahas Mark S. 
Published: February 2005

AbstractAn experiment was undertaken to obtain approximate values for the intrinsic elastic modulus of subchondral bone. Shallow spherical caps, with uniform and incrementally controlled thickness, were machined from subchondral bone in the weight‐bearing regions of 11 fresh‐frozen normal femoral head autopsy specimens. Under application of polar point loads, the measured deflections were compared with a corresponding analytical shell solution, thus allowing back‐calculation of the apparent modulus. Analogous tests were performed on similarly shaped specimens of stock Plexiglas® of known modulus in order to estimate the precision of the testing method. The aggregate results for subchondral bone showed that its intrinsic stiffness correlated inversely with nominal shell thickness, but even the thinnest (1.0 mm thick) of these shells had an apparent modulus (mean = 1.372 GN/m2, SD = 414 MN/m2) well below that generally accepted for “pure” cortical bone (about 14 GN/m2). This stiffness deficit was very likely due to the presence of histologically evident marrow spaces. However, the low apparent modulus values measured in this study may not be fully representative of complex in vivo behavior, because in the testing of excised shells there is no radial compressive stress transfer to underlying cancellous bone.
An epidemiologic study of lifting and twisting on the job and risk for acute prolapsed lumbar intervertebral disc
Authors: Kelsey Jennifer L. , Githens Penny B. , White Augustus A. , Holford Theodore R. , Walter Stephen D. , O'Connor Theresa , Ostfeld Adrian M. , Weil Ulrich , Southwick Wayne O. , Calogero John A. 
Published: February 2005

AbstractAn epidemiologic case‐control study undertaken in Connecticut during 1979–1981 indicated that persons with jobs requiring lifting objects of more than 11.3 kg (25 lb) an average of more than 25 times per day had over three times the risk for acute prolapsed lumbar intervertebral disc as people whose jobs did not involve lifting objects of this weight. If the body was usually twisted while the lifting was done, this elevation in risk was apparent with less frequent lifting. An especially high risk for prolapsed lumbar disc was associated with jobs involving lifting objects of more than 11.3 kg with the body usually twisted and the knees not bent while the lifting was done. Neither lifting objects of less than 11.3 kg nor twisting without lifting was associated with an increase in risk.
A system to measure the forces and moments at the knee and hip during level walking
Authors: Gilbert Jerome A. , Maxwell G. Maret , McElhaney James H. , Clippinger Frank W. 
Published: February 2005

AbstractThe forces and moments in the sagittal plane at the knee and hip were calculated using gait data collected during level walking. Accelerations were measured by accelerometers attached to the legs, and the force reactions at the foot were measured by a force plate. The recorded accelerations and the foot forces were used to determine the joint reactions through a Newtonian formulation modeling the leg as articulated, rigid links. Twelve normal subjects were included in this study along with nine lower limb amputees. Obvious differences were observed when comparing amputee data to normal data both at the knee and hip. Gait data obtained by this system can be readily used to form criteria for objective gait analysis and improved prosthesis design.