bluuebunny/crossref_metadata_2025_split huggingface dataset:
Morphology of the teeth of adult caudata and apoda: Fine structure and chemistry of enamel
Authors: Sato I. , Shimada K. , Sato T. 
Published: February 2005

AbstractRepresentative functional teeth from Cryptobranchus alleghaniensis (Cryptobranchidae), Amphiuma means (Amphiumidae), Dicamptodon ensatus (Dicamptodontidae), Necturus maculosus (Proteidae), and Dermophis sp. (Costa Rica) (Caeciliidae) were prepared for transmission electron microscope and electron microprobe analysis of the trace elements of the enamel layer. The enamel layer of these species is very thin and the arrangement of enamel crystals variable. In particular, the outer part of the enamel layer in which hydroxyapatite elements (Ca, P) and trace elements (e.g., F, Fe, Mg) are concentrated, is most heavily mineralized. The concentrations and alignment of crystals in the outer and inner parts of the enamel layer differ among these species.The presence of collagen fibers in the inner part of the enamel layer of Cryptobranchus and Dermophis indicates that it is enameloid rather than true enamel. The presence of trace elements may be related to the pattern of mineralization of enamel or enameloid, as suggested for tetra‐odontiform fishes by Suga et al. (J. Dent. Res. 68:1115–1123, 1989). © 1992 Wiley‐Liss, Inc.
The male reproductive system and mechanism of sperm transfer in Argulus japonicus (Crustacea: Branchiura)
Authors: Avenant‐Oldewage Annemarié , Swanepoel J. H. 
Published: February 2005

AbstractThe histomorphology of the male reproductive system and surface morphology of the “peg‐and‐socket” in Argulus japonicus are described from serial sagittal and transverse sections and scanning electron micrographs. The prostate complex consists of a glandular part, a reservoir for storing the secretion, and an efferent duct opening into the ejaculatory duct. The openings of both the vas deferens and the prostate duct into the ejaculatory duct are guarded by sphincters. The ejaculatory ducts, which are lined by tall columnar epithelial cells, do not open into the cuticle‐lined genital atrium but are blind‐ending tubes. This observation and results obtained from observing live specimens, as well as the fact that no spermatophores are formed, suggest that semen could leave the ejaculatory duct only after puncturing of its walls. It is suggested that sperm transfer is accomplished in the following manner: during copulation contraction of the muscular walls of the vas deferens and prostate duct causes semen to be pumped into the ejaculatory duct, which is then closed off by sphincters and a high internal pressure is developed. When a spermathecal spine penetrates the walls of the ejaculatory duct, semen flows from the ejaculatory duct into the spermathecal vesicle due to the higher pressure in the ejaculatory duct. This mechanism is analogous to the sucking up of fluid with a hypodermic syringe. © 1993 Wiley‐Liss, Inc.
Ultrastructural variations in the spermiogenesis of Triatoma infestans induced by temperature changes
Authors: Giojalas Laura C. 
Published: February 2005

AbstractThe reproductive process in insects may be affected by several factors, among which environmental temperature is one of the most important because of the poikilothermic condition of insects. To determine the effect of suboptimal temperature on the spermiogenic process of Triatoma infestans, males were exposed to 12°C for 10 days. In order to determine the reversibility of such alterations, males were returned to 28°C for 10 days after exposure to 12°C. Low temperature caused abnormal changes in the spermiogenic cells such as lack of spermatid orientation, general cyst disorganization, and asynchrony in the development of contiguous cysts. Highly vacuolized areas and pseudomyelinic bodies enclosing isolated or clustered vesicles of different electrodensity were also observed. At the end of the recovery time, cysts with spermatids developed synchronously. However, some presented isolated and clustered vesicles of different size and electrodensity. Some supernumerary organelles were also observed. These abnormal structures were related to processes of autophagy and phagocytosis of degenerating sexual cells. © 1993 Wiley‐Liss, Inc.
Ultrastructure of prothoracic glands during larval‐pupal development of the tobacco hornworm, Manduca sexta: A reappraisal
Authors: Hanton Wilma K. , Watson R. Douglas , Bollenbacher Walter E. 
Published: February 2005

AbstractThe structure of Manduca sexta prothoracic glands was investigated using a protocol that preserves membranes. During the last larval stadium, prothoracic gland cells increase in diameter, volume, protein content, and perhaps number, enhancing their capacity to produce ecdysteroids. The glands' strand‐of‐cells morphology, their in situ location, the presence of gap junctions between cells, and junctional foot‐like structures within cells support previous findings that prothoracicotropic hormone stimulates ecdysteroidogenesis via Ca2+‐induced Ca2+ release. A different method of tissue fixation from that previously used to investigate the ultrastructure of Manduca sexta prothoracic glands has revealed a significantly different ultrastructure. These new findings begin to define roles for endoplasmic reticulum and mitochondria in ecdysteroid synthesis and support the hypothesis that the glands secrete the steroid hormone via exocytosis. The structural dynamics of the glands are discussed in the context of the glands' function during Manduca sexta larvalpupal development. © 1993 Wiley‐Liss, Inc.
Ultrastructural localization of RNA in the chromatoid bodies of undifferentiated cells (neoblasts) in planarians by the RNase–gold complex technique
Authors: Auladell Carme , Garcia‐Valero Josep , Baguñà Jaume 
Published: February 2005

AbstractUndifferentiated cells of planarians (Platyhelminthes, Turbellaria), also called neoblasts, are totipotent stem cells, which give rise to all differentiated cell types, while maintaining their own density by cell proliferation. Neoblasts are the only somatic cells of planarians bearing chromatoid bodies in their cytoplasm; these organelles disappear as differentiation takes place. Studies on germinal cells of several groups of organisms have shown that chromatoid bodies contain substantial amounts of RNA. To test its presence in neoblasts, we have used an RNase–gold technique. We found chromatoid bodies labeled with RNase–gold particles. Heterogeneity in the density of the label, may be correlated with the functionality and complexity of these organelles. The gold marker was also present over the nucleus and rough endoplasmic reticulum, but mitochondria, secretory granules, and the extracellular space were devoid of label. This specific localization of RNA in planarian chromatoid bodies supports earlier findings on germ cells and embryonic cells in a variety of organisms, indicating that chromatoid bodies are information‐storage structures, essential during the process of cell differentiation. © 1993 Wiley‐Liss, Inc.
Osmoregulatory‐like mitochondria‐rich cells in the developing pancreatic ducts of young anuran tadpoles
Authors: de Zárate A. Ortiz , Villaro A. C. , De Rada O. Díaz , Montuenga L. , Etayo J. C. , Sesma P. , Vázquez J. J. 
Published: February 2005

AbstractPancreatic ducts of young posthatching Rana temporaria tadpoles are the main component of the developing pancreas. At this stage (free‐swimming tadpoles with internal gills), duct cells display a high degree of development of basal and lateral outfoldings of the cell membrane with extensive interdigitation, and numerous mitochondria are present throughout the cytoplasm. Wide intercellular spaces also exist, sometimes forming canaliculi‐like structures. Since these traits are characteristic of cells engaged in osmotic regulation, we suggest the possibility that this temporary duct system participates in such control. Duct cells in tadpoles with well‐developed hindlegs have diminished interdigitation, and mitochondria are localized apically. © 1993 Wiley‐Liss, Inc.
Ultrastructure of the cardiac and pyloric glands of the gastric mucosa of the South African hedgehog, Atelerix frontalis
Authors: Gregorowski M. Detken , Coetzee Heleen L. , Loots G. P. 
Published: February 2005

AbstractThe cardiac and pyloric glands in the gastric mucosa of the South African hedgehog, Atelerix frontalis, are described. The cardiac area of the stomach contains proper cardiac glands and lacks undifferentiated fundic glands. The cardiac glands are simple tubular, coiled, and lined with columnar cells ultrastructurally similar to those of the gastric surface epithelium. Secretory granules with varying electron densities fill the apical cytoplasm of these cells. In contrast to other mammals, these glands lack mucous neck cells. The neck of the pyloric glands contains only a single cell type, whereas the basal regions of these glands contain “light” and “dark” cells. The secretory granules in the “dark” cells and the pyloric neck cells have a moderate electron density and often contain an electron dense core. An electron‐lucent cytoplasm with numerous polysomes is characteristic of the “light” cells. Some “light” cells contain electron‐dense granules in the apical cytoplasm. The presence of only neutral mucins in the cardiac gland cells denotes the absence of mucous neck cells. The acidic mucins within the pyloric neck cells seem to indicate that these cells are mucous neck cells, whereas the neutral mucins within the basally located pyloric gland cells show at least a partial functional difference from the pyloric neck cells. © 1993 Wiley‐Liss, Inc.
Scaling of cursoriality in mammals
Authors: Steudel Karen , Beattie Jeanne 
Published: February 2005

AbstractData on limb bone lengths from 64 mammalian species were combined with data on 114 bovid species (Scott, '79) to assess the scaling of limb lengths and proportions in mammals ranging from 0.002 to 364 kg. We analyzed log‐transformed data using both reduced major axis and least‐squares regression to focus on the distribution across mammals of two key traits—limb length and metatarsal/femur ratio—associated with cursorial adaptation. The total lengths of both fore and hindlimbs scale in a manner very close to the M0.33 predicted by geometric similarity. Thus the relative limb lengths of large mammals, including bovids, generally regarded among the most cursorial of mammals, are very similar to those of the rodents and insectivores in this sample. Metatarsal/femur ratio also shows little change with changing mass, although bovids tend to have relatively longer metapodials than do other families in the sample. We argue that many of the remaining morphological traits associated with cursoriality (e.g., reduction in joint mobility and number of distal limb bone elements) promote cursoriality only at large body sizes. These results lead us to question the general perception that cursoriality is most widespread among large mammals. We also suggest that discussions of cursoriality should focus explicitly on the two partially independent aspects of performance that are otherwise confounded under this general term—speed and the ability to cover substantial distance. © 1993 Wiley‐Liss, Inc.
Electromyographic and kinematic studies of tail movements in dogs during treadmill locomotion
Authors: Wada Naomi , Hori Hiroko , Tokuriki Mikihiko 
Published: February 2005

AbstractElectromyographic (EMG) activities of three tail muscles, the extensor caudae lateralis (ECL), abductor caudae externus (ACE), and flexor caudae longus (FCL), were recorded bilaterally in seven adult dogs during walking, trotting, and galloping on a treadmill. Each dog's movements were recorded with a 16 mm high‐speed camera system, and angular movements of the tail were analyzed. During walking and trotting, reciprocal EMG bursts were observed between right and left tail muscles and corresponded with lateral movements of the tail.The tonic discharges that were observed in ECL and FCL seemed to maintain the position of the tail. During galloping, synchronized EMG activity of all tail muscles produced reactive torques to counter those generated by cyclic limb movements and kept the tail in a stable position. These results suggest that tail movements are important in maintaining body balance during locomotion in the dog. © 1993 Wiley‐Liss, Inc.
Spermathecal cytology of Ambystoma opacum (Amphibia: Ambystomatidae) and the phylogeny of sperm storage organs in female salamanders
Authors: Sever David M. , Kloepeer Natalie M. 
Published: February 2005

AbstractSperm storage glands, spermathecae, were examined from mated female Ambystoma opacum during the breeding season. No differences occur in the spermathecal ultrastructure of individuals sacrificed prior to oviposition and those sacrificed within 3 days of removal from tended clutches of recently oviposited eggs. The simple tubuloalveolar glands produce two types of secretory vacuoles. Apical secretory vacuoles contain glycosaminoglycans for export into the lumen to bathe stored sperm, perhaps providing the chemical/osmotic environment necessary for sperm quiescence. The other type of secretory vacuole contains an unsaturated lipid that is produced for export into the connective tissue surrounding the spermathecae. The role of this secretion may involve the contraction of myoepithelial cells, resulting in sperm expulsion. Some sperm undergo degradation in the spermathecal epithelium, and an interepithelial leukocyte was observed in one specimen. Apical secretory vacuoles and sperm are absent from the spermathecae of a specimen sacrificed 62 days after removal from a tended egg clutch. This is the first report on the spermathecal cytology of a salamander from the Ambystomatidae, and comparisons with salamanders from other families provide a morphological basis for considering spermathecae polyphyletic within the Caudata. © 1993 Wiley‐Liss, Inc.
Regionalization of eccrine and spermiophagic activity in spermathecae of the salamander Eurycea cirrigera (Amphibia: Plethodontidae)
Authors: Sever David M. , Brunette Nicole S. 
Published: February 2005

AbstractThe spermathecae of female Eurycea cirrigera are compound alveolar glands; narrow neck tubules connect the distal bulbs to a common tube that opens onto the roof of the cloaca. The common tube and neck tubules produce apical secretory vacuoles that contain a periodic acid‐Schiff (PAS)+ substance for merocrine export into the lumen. This substance is produced throughout the year, although secretory vacuoles are less numerous during the period of reproductive inactivity in the summer. When sperm are present, the product from the secretory vacuoles bathes sperm in the lumen. Sperm are in orderly arrays and never are embedded in the cytoplasm of the common tube or neck tubules. The distal bulbs do not produce PAS+ secretory vacuoles, and are actively spermiophagic as long as sperm are present. Sperm become embedded in the epithelium of the distal bulbs where lysosomes degrade sperm. © 1993 Wiley‐Liss, Inc.
Morphological analysis of tendinous structure in the American alligator jaw muscles
Authors: Shimada Kazuyuki , Sato I. , Ezure H. 
Published: February 2005

AbstractIn the American alligator, the jaw muscles show seven bundles of tendinous structure: cranial adductor tendon, mandibular adductor tendon, lamina anterior inferior, trap‐shaped lamina lateralis, lamina intramandibularis, lamina posterior, and depressor mandibular tendon (originating from the musculus depressor mandibulae, m. pseudotemporalis, m. adductor mandibulae posterior, m. adductor mandibulae externus, m. intramandibularis, m. pterygoideus anterior, and m. pterygoideus posterior). These tendinous structures are composed of many collagen fibrils and elastic fibers; however, the distributions and sizes of the fibers in these tendinous components differ in comparison with those of other masticatory muscles. The differences of these properties reflect the kinetic forces or the stretch applied to each tendon by the muscle during jaw movements in spite of the simple tendon‐muscle junctions. © 1993 Wiley‐Liss, Inc.
Rostrate pedicellariae: A morphologically distinct form of echinoid test appendage
Authors: Campbell A. C. , Jensen Margit 
Published: February 2005

AbstractThe term rostrate was introduced by Mortensen ('07) to describe a type of pedicellaria he found in spatangoids. These pedicellariae resemble tridentate ones but have arching valves. Unlike the main categories of echinoid pedicellariae, no clear diagnosis of the rostrate form exists. This work examines the detailed morphology of the valves of rostrate pedicellariae observed by light and scanning electron microscopy and compares the shapes and dimensions of their component parts with tridentate pedicellariae. The data reveal considerable differences between the two, which warrant the recognition of rostrate pedicellariae as a distinct form. A diagnosis is given. © 1993 Wiley‐Liss, Inc.
Distribution of calcium‐ATPase in developing teeth of embryonic American alligators (Alligator mississippiensis)
Authors: Sato Iwao , Shimada Kazuyuki , Ezure Hiromitsu , Sato Tooru , Lance Valentine A. 
Published: February 2005

AbstractLight microscopic and ultrastructural observations were carried out to evaluate the cell morphology and histochemistry (calcium‐ATPase activity) of developing teeth in embryonic American alligators (Alligator mississippiensis). Ca‐ATPase activity was observed in the distal and lateral cell membranes, rough endoplasmic reticulum (rER), mitochondria, vacuoles, and other organelles of the ameloblast, but only in the distal cell membrane and process of the odontoblast. Enzyme activity in the ameloblasts increased gradually during development. These sites of enzyme activity are related to mineralization of the enamel layer, similar to that in mammalian tooth development. Alligator teeth are heavily mineralized like mammalian teeth; however, alligator ameloblasts have undeveloped distal processes during mineralization in contrast to mammalian ameloblasts in which Tomes' processes are found near the distal portion of ameloblasts at maturation stage. The localization of intense enzyme activity in the distal and lateral ameloblast cell membrane suggests that these regions are the site of accumulation of calcium as enamel differentiates in the developing tooth. © 1993 Wiley‐Liss, Inc.
Developmental changes in cytochrome oxidase histochemistry in the main and accessory olfactory bulbs of embryonic and neonatal garter snakes (Thamnophis sirtalis spp.)
Authors: Holtzman David A. , Gordon Evan , Halpern Mimi 
Published: February 2005

AbstractDevelopmental studies examining the changes in oxidative metabolic activity are useful for understanding how and if the vomeronasal and olfactory systems respond to stimulation during embryogenesis. Garter snakes are good candidates for examining the potential functionality of the vomeronasal system in utero. In adult garter snakes, the vomeronasal system mediates many behaviors. Neonatal garter snakes exhibit these same behaviors, and the vomeronasal system has been shown to mediate feeding behavior in neonates. Using cytochrome oxidase histochemistry, we examined changes in the oxidative metabolic activity of main and accessory olfactory bulbs of embryonic and neonatal garter snakes (Thamnophis sirtalis sirtalis and T. s. parietalis). Cytochrome oxidase staining is greater in the accessory olfactory bulb than in the main olfactory bulb of embryonic garter snakes. However, neonates show no differences in the staining of the accessory and main olfactory bulbs, suggesting a change in the stimulation of the main olfactory bulb after birth. This is the first report of cytochrome oxidase histochemistry in reptiles and in the vomeronasal system of embryonic vertebrates. © 1993 Wiley‐Liss, Inc.
Spiral cleavage and cell position contribute to the specification of the dorsoventral axis in the embryo of the archaeogastropod Haliotis tuberculata
Authors: van den Biggelaar Jo A. M. , Faber Joop 
Published: February 2005

AbstractIn the embryo of Haliotis tuberculata spiral cleavage induces size differences between the quadrants in the 4‐cell embryo. These size differences, together with the formation of compact cell configurations, induce asymmetrical positions of equivalent cells in the 8‐ and 16‐cell embryo. The asymmetries in size and position influence the final specification of the dorsoventral asymmetry in the 32‐cell embryo, as well as formation of the mesentoblast. © 1994 Wiley‐Liss, Inc.
In vivo fluorescence imaging of the functional organization of trophotaenial placental cells of goodeid fishes
Authors: Kokkala I. , Wourms J. P. 
Published: February 2005

AbstractEmbryos of viviparous goodeid fishes undergo a 10 to 150 × increase in dry weight during gestation. Maternal nutrients are transferred across a trophotaenial placenta comprised of the ovarian lumenal epithelium and the trophotaeniae of the embryo. Trophotaeniae are externalized projections of the embryonic hindgut. Epithelial cells of the ribbon trophotaenia (Ameca splendens) resemble intestinal absorptive cells of suckling mammals and endocytose macromolecules. They possess an apical brush border, endocytotic complex, endosomal–lysosomal system, and apical and basal clusters of mitochondria. Cells of the rosette trophotaenia (Goodea atripinnis) lack an endocytotic apparatus, have small lysosomes, two mitochondrial clusters, and transport small molecules. Organelle‐specific fluorescent probes were employed to characterize the functional organization of the two types of trophotaenial cells. In A. splendens, Lucifer Yellow, a membrane‐impermeable tracer of vesicular transport, first appears in peripheral vesicles (15–45 sec), then passes into elongated tubular endosomes (1–3 min) and later appears in large central vacuoles (10–15 min). These vacuoles accumulate Acridine Orange, a classical probe for lysosomes, and have been shown to contain lysosomal enzymes. Endosomelysosome fusion was observed. In both A. splendens and G. atripinnis, Rhodamine 123 fluorescence was localized in two clusters of fine spots that corresponded to mitochondria. 4′,6‐diaminido‐2‐phenyl‐indole (DAPI) staining of nuclei established the positional relationships of cell organelles with respect to the nuclei. 3,3′‐dihexyloxacarbo‐cyanine iodide (DiOC6) revealed the perinuclear distribution of the endoplasmic reticulum. In order to compare in vivo fluorescence of Lucifer Yellow with previous ultrastructural observations, we employed fluorescence photoconversion and electron microscopy. © 1994 Wiley‐Liss, Inc.