bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tooth replacement in the teleost fish Prionurus microlepidotus Lacépède
Authors: Wakita Minoru , Itoh Katsuhiro , Kobayashi Shigeo 
Published: February 2005

AbstractPrevious studies on tooth replacement in lower vertebrates have been plagued by a lack of common integrative approaches and methods, making it impossible to furnish a phylogenetic synthesis. This study is based on serial sections of the jaw of Prionurus microlepidotus. Each Toothgerm was characterized by its developmental stage and its position in the jaw. The relationship between the developmental stage of toothgerm and position in the jaw has been studied and expressed in several graphical illustrations. The following conclusions have been made: (1) The initiation of toothgerms in P. microlepidotus is governed by two Zahnreihen, which respectively initiate toothgerms on the lingual and labial side of the functioning teeth in an alternating pattern. (2) Therefore, functioning teeth in one locus are supplied by the alternate eruption of lingual and labial toothgerms. (3) Advancing of tooth replacement in each locus is independent of functioning teeth and their successors in adjacent loci. (4) The disorders of replacement patterns are caused by an alternated rate of eruption of successive toothgerms as a response to unusual shedding of the functioning teeth.
Arrangement and structure of sinus hair muscles in the big‐clawed shrew, Sorex unguiculatus
Authors: Yohro Takeshi 
Published: February 2005

AbstractThe arrangement and structure of sinus hair muscles in the snout of the shrew, Sorex unguiculatus, were studied by electron microscopy and serial section light microscopy. Both striated and smooth muscles are directly associated with sinus hair follicles. The striated muscle fibers originate from the base of a follicle and insert onto the superficial portion of adjoining caudally positioned follicles. Some fibers insert into the corium instead of inserting into a follicle. The fibers show a fine structure typical of red fibers. Smooth muscle cells form a network with elastic fibers beneath the corium. Some cells are directly attached to the capsule of the sinus, thus forming a type of M. arrector pili. Striated muscle fibers that appear to end in the corium are connected with the smooth muscle network through the elastic fibers which appear to function as the tendon of these two types of muscle cell.
Vascular follicle system of the sea cucumber, Stichopus moebii
Authors: Herreid Clyde F. , Defesi Charles R. , Larussa Vincent F. 
Published: February 2005

AbstractSea cucumbers, Stichopus moebii, have a unique specialization of their blood vascular system: The vascular follicle network is composed of numerous small chambers (follicles) interconnected by minute vessels. The fine structure of the follicle system was studied in detail. The follicles are composed of several layers: an external ciliated epithelium, neuromuscular layer and basement membrane, connective tissue, and a fenestrated endothelial lining. The follicle lumen is filled with coelomocytes and necrotic cells surrounding particles of iron. The follicle may function in coelomocyte production and destruction.
Ultrastructural study of the normal degeneration of the intersegmental muscles of Antheraea polyphemus and Manduca sexta (Insecta, lepidoptera) with particular reference to cellular autophagy
Authors: Beaulaton Jacques , Lockshin Richard A. 
Published: February 2005

AbstractIn studying ultrastructural changes in metamorphosis‐related degeneration of intersegmental muscles in Antheraea polyphemus, particular attention was directed to the mechanisms and timing of degradation of organelles and myofilaments. At emergence, the muscles are typical slowly contracting insect muscles, with a few dense body lysosomes and occasional autophagic vacuoles containing mitochondria. During the early phases of degradation the number of autophagic vacuoles, dense bodies, and lamellar bodies increases rapidly, along with an expansion of the Golgi system and the T system. Free glycogen particles and glycogenosomes are demonstrated by the PATAg test.Between 7 and 20 hours after ecdysis the T system continues to expand, the fibers subdivide, and the contractile system is degraded. Myofibrils fragment; myofilaments are not enclosed in isolating membranes at the time of their dissolution. The destruction of individual filaments occurs rapidly, with few intermediate stages being seen, while thick filaments tend to disappear earlier than thin filaments and Z‐line material. The process is generalized and not confined to specific regions of the fiber. Autophagy destroys cell organelles in apparent synchrony with the first signs of nuclear pycnosis.By 20 to 30 hours after emergence, the fibers are reduced to lamellae of polynucleate sarcoplasm containing no organized contractile material. The sarcoplasm is filled with autophagic vacuoles containing mitochondria, dense lamellar or residual bodies, and ribosome‐rich sarcoplasm. The number of mitochondria is drastically reduced at this time.In the final phases of involution (40–49 hours after emergence) shedding of the residual sarcoplasm precedes the expulsion of the pycnotic nuclei into the hemocoele.These results indicate that autophagy is responsible for the selective destruction of mitochondria, glycogen particles, ribosomes, and other organized sarcoplasmic structures. The one exception is the dissolution of the myofilaments, a process which remains undefined but which appears to be independent of lysosomal activity.
Oxytalan fibre organization in marsupial mandibular periodontal tissues
Authors: Sampson W. J. , Sims M. R. 
Published: February 2005

AbstractThe arrangement and distribution of oxytalan fibers in Australian marsupials has not previously been reported. Periodontal tissues of wombat, wallaby, possum, and marsupial mouse were examined to ascertain oxytalan fibre organization. Despite adaptation of the marsupial masticatory apparatus to different diets the oxytalan fibre organization in the periodontal ligament shows a basic pattern which corresponds with that reported in other animals. The oxytalan system forms a continuous meshwork of fine, branching fibres which completely invests each tooth root and connects adjacent teeth. Thick ribbon‐like apico‐occlusally orientated oxytalan fibres, thought to form by the coalescence of thinner fibres, are restricted to the periodontal ligament. The oxytalan fibres are embedded in cementum and attached to blood vessels in the periodontal ligament. Oxytalan fibres do not insert into alveolar bone. Histological evidence indicates functional remodelling of the oxytalan fibre system in continuously erupting teeth.
An electron microscopic study of early developmental stages, myogenesis, oogenesis and cnidogenesis in the anthomedusa, Podocoryne carnea M. Sars
Authors: Boelsterli Urs 
Published: February 2005

AbstractThis descriptive electron microscopic study of the blastogenetic medusa development of Podocoryne carnea focuses on the earliest stages of primordium formation, myogenesis, oogenesis and cnidogenesis. The events which take place at the cellular level prior to the formation of stage 1 (Frey, '68), which are characterized by ecto‐ and entodermal accumulations of undifferentiated I‐cells and the beginning of transdifferentiation of epithelial cells, have been subdivided into four distinct stages (U1‐U4). The genealogy of cells participating in medusa differentiation indicates that some cell types of the medusa are derived by transdifferentiation from the polyp's epithelial cells, while others originate by differentiation from I‐cells. The myogenesis of the subumbrellar muscle cells resembles vertebrate myocardiac differentiation in many respects.
Fine structural changes in the mandibular gland of the male spider crab, Libinia emarginata (L). Following eyestalk ablation
Authors: Hinsch Gertrude W. 
Published: February 2005

AbstractMandibular glands from destalked male spider crabs were fixed in glutaraldehyde‐paraformaldehyde, post‐fixed in 1% osmium in phosphate buffer, dehydrated in acetone and embedded in Spurr's low‐viscosity medium ('69). The glands hypertrophy and several changes occur in the subcellular cytoarchitecture following eyestalk ablation. These include loss of most of the smooth endoplasmic reticulum or its appearance as lamallae, appearance of numerous polysomes and a change in mitochondrial structure. Large vesicles with ribosomes spaced at intervals along their membranes are apparently formed by blebbing of the outer nuclear membrane and appear throughout the cytoplasm. Banded structures consisting of alternate granular and flocculent materials are found within the nucleus.
Fine structure of tarsal sensilla of Aedes aegypti (L.) (Diptera: Culicidae)
Authors: McIver Susan , Siemicki Roman 
Published: February 2005

AbstractThe tarsi of all three pairs of legs of both sexes of Aedes aegypti (L.) bear spine sensilla, five types of hair sensilla, which are designated A, B, C1, C2 and C3, and campaniform sensilla. Type A and B hairs, spines, and cam‐paniform sensilla are innervated by one neuron with a tubular body, a characteristic of cuticular mechanoreceptors. In particular the hairs and spines are tactile receptors and the campaniform sensilla are proprioceptors. The C1, C2, and C3 hair sensilla have the morphological features of contact chemoreceptors. Type C1 and C3 hairs are innervated by five and four neurons, respectively, which extend to the tip of the hair. Type C2 is innervated by five neurons, one of which terminates at the base of the hair in a tubular body while the remaining four extend to the tip of the hair. The role of the type C hairs in oviposition behavior, nectar feeding, and recognition of conspecific females is discussed. Presumed efferent neurosecretory fibers occur near the spine and hair sensilla.
Repair and reorganization of minced cardiac muscle in the adult newt (Notophthalmus viridescens)
Authors: Bader David , Oberpriller John O. 
Published: February 2005

AbstractStudies of the response of adult mammalian and amphibian ventricle to injury have indicated the formation of a connective tissue scar in the place of the wounded or amputated muscle. It has been demonstrated that amphibian myocytes adjacent to a wound surface, unlike mammalian myocytes, have a proliferative capacity. In the present study, a minced cardiac muscle graft was placed into the adult newt ventricle in order to increase the number of myocytes near a wound surface. With such an increased number of reactive myocytes, it was thought a new wall consisting primarily of muscle might be formed. One‐sixteenth to one‐eighth of the ventricular apex was removed, minced and returned to the amputation surface of the ventricle. General histological and autoradiographic studies were conducted on two sham‐operated animals and on five experimental animals which were killed at 5, 10, 20, 30, 50 and 70 days after surgery. Major events of the repair and reorganization of minced cardiac muscle included blood clot formation followed by necrosis of the blood clot and much of the muscle graft. By ten days, an apparent coalescence of muscle fragments and continuity of ventricular and graft lumina were observed, although the graft area never formed an integrated unit with the wounded ventricular wall. The peak of mitotic activity (3.19%) and thymidine labeling (28.1%) of graft cells, including many cells which resembled cardiac myocytes, was observed at 20 days. At 30 days, the graft was observed as a continuous wall composed primarily of muscle fibers. Several 30‐, 50‐ and 70‐day grafts had rhythmic contractions. These results suggest that amphibian cardiac muscle has histogenetic and proliferative capacities not attributable to mammalian cardiac muscle.
Cyclic changes in fine structure of the epithelium lining the ovary of the viviparous teleost, Cymatogaster aggregata (Perciformes: Embiotocidae)
Authors: Gardiner David M. 
Published: February 2005

AbstractThe most striking morphological feature of the ovarian epithelium of Cymatogaster is the presence of intercellular dilations during much of the year. These dilations increase markedly in volume during the several months prior to ovulation and fertilization, and decrease in volume during the months of embryogenesis and gestation. The epithelium then returns to its initial, relatively undifferentiated state. The extracellular material within the dilations likely is synthesized in the cells adjacent to or within the dilations. Apparently most of this material is released into the ovarian lumen when the apicolateral margins of adjacent epithelial cells pull apart; possibly it serves as nutrient for developing embryos.In addition to supporting embryogenesis, the ovarian epithelium also apparently is involved in sperm storage. Sperm are maintained within pockets in the ovarian epithelium for the several months between insemination and fertilization. The cells lining the sperm pocket do not develop the intercellular dilations characteristic of most of the ovarian epithelium, and sperm remain associated only with the sperm pocket cells.
Time‐lapse cinemicrographic analysis of superficial cell behavior during and prior to gastrulation in Xenopus laevis
Authors: Keller R. E. 
Published: February 2005

AbstractTime‐lapse cinemicrography was used to show what changes in the number, size, shape, arrangement and what movements of apices of superficial cells occur during epiboly, extension, convergence and blastopore formation in the blastula or gastrula of Xenopus laevis. Epiboly of the animal region occurs by apical expansion of superficial cells at a nearly constant rate from the midblastula to the midgastrula stage. Egression of deep cells into the superficial layer does not occur. Extension of the dorsal marginal zone begins in the late blastula stage with the rapid spreading of the apices of cells in this region and this continues until the onset of neurulation when rapid shrinkage begins. Extension and convergence of the dorsal marginal zone occurs by a rearrangement in which individual cells exchange neighbors and by a change in the shape of the cell apices. Regional differences in apical expansion are accompanied by differences in rate of anticlinal division of superficial cells such that cells in all sectors of the animal region and the marginal zone show similar patterns of decrease in apparent apical area. Shrinkage of the apices of bottle cells during blastopore formation is described. From this and other studies, a model of the cellular behavior of epiboly, extension and convergence is constructed and several hypotheses as to how these activities might generate the mechanical forces of the gastrulation movements are presented.
Re‐regeneration of lower jaws and the dental lamina in adult urodeles
Authors: Graver Heber T. 
Published: February 2005

AbstractTransverse amputations were carried out through one‐third fully regenerated jaw segments and through normal tissue of the mandible on the same and opposite sides of the jaw in adults of Notophthalmus viridescens. Collectively the results suggest that, in adult urodeles, the mandible and the dental lamina can be replaced in an identical manner more than one time. Although the major histological events are the same in jaw regeneration and re‐regeneration, regrowth is more rapid in re‐regeneration. Extensively dedif‐ferentiating muscle fibers and skeletal elements contribute to a rapidly forming blastema in re‐regeneration. It appears that recently differentiated tissues of the regenerate have a higher capacity for regeneration than normal tissues amputated for the first time. Re‐regeneration of the jaw occurs by growth of the original regenerate cartilage which has undergone reorganization. In re‐regeneration, the skeletal elements exhibit no polarity and regrowth occurs in both directions, while the dental lamina possesses an anterior‐posterior polarity and can regrow in an anterior direction only. Information concerning the mechanisms involved in the regenerative events remain to be determined.
The jelly envelopes and fertilization of eggs of the newt, Notophthalmus viridescens
Authors: McLaughlin Ellen W. , Humphries A. A. 
Published: February 2005

AbstractFertilization in Notophthalmus viridescens is internal and involves passage of the sperm through five layers of egg jelly (J5‐J1, from outermost to innermost), each of which is secreted by a discrete region of the oviduct. Polyspermy is normal. Passage of the sperm through the jelly and into the egg was studied by a technique of artificial insemination similar to natural insemination, in that undiluted fluid from the vas deferens was applied directly to eggs with various layers of jelly present, followed by flooding with water three to five minutes later. In general, successful fertilization increased as the number of jelly layers increased; jellyless coelomic eggs were not fertilizable. Sperm passage through the jelly and into the egg usually occurs within one to three minutes. Upon hydration of the jelly, barriers to sperm penetration develop in layers J5 and J3. Changes in the egg jelly thus seem to be involved in the restriction of polyspermy to a low level.
The pineal‐paraphyseal complex of sea turtles. I. Light microscopic description
Authors: Owens David W. , Ralph Charles L. 
Published: February 2005

AbstractThe pineal‐paraphyseal complex of sea turtles is an impressively large structure which projects dorsally and anteriorly above the prosencephalon. The complex was examined by light microscopy in several age classes of green sea turtles (Chelonia mydas) and from juvenile loggerhead turtles (Caretta caretta). The paraphysis is extensively fused to the distal portion of the pineal body, suggesting an interrelated function for these two tissues. No duct or canal was observed connecting the pineal lumen to the third ventricle. Two pineal cell types are described which appear to correspond to the neuroglial supportive cells and the secretory rudimentary photoreceptor cells of other amniotic vertebrates. A possible luminal secretion in the form of apical protrusions is produced by the latter cell type. No typical photoreceptive outer segments were observed.
Comparative analysis of the intrinsic leg musculature of the American cockroach, Periplaneta americana (L.)
Authors: Alsop D. W. 
Published: February 2005

AbstractThe American cockroach has a total of 368 muscles inserting on the post‐coxal segments of its legs. By using a narrow morphological definition for delimiting individual muscles, it is shown (i) that the protrochanteral musculatures (23 muscles/leg) differ from the essentially identical meso‐ and metatrochanteral musculatures (24 and 26 muscles/leg) in number and disposition of extensors and in having a completely different flexor composition, and (ii) that the musculatures of the more distal segments of the legs are completely serially homologous, there being 2 muscles for moving each femur, 23 for each tibia, 7 for each first tarsomere, and 5 for each of the paired pretarsal claws. In all six legs, the trochanteral and tibial musculatures each contain single slender muscles that may be acting proprioceptively to measure the angular displacements between, respectively, the coxas and trochanters, and the femurs and tibias. Neurological and phylogenetic considerations are used to demonstrate why a narrow morphological definition should be employed, and why the widely used functional definition of Snodgrass ('35) is not only fallacious on evolutionary grounds, but also leads to making erroneous conclusions regarding the manner in which insect musculature is controlled by the insect central nervous system. Finally, it is hypothesized that the physiological limitations imposed by having an open circulatory system and the problems inherent in the neural control of large muscles may have been major evolutionary factors in forcing insects to use many slender muscles to control their body movements.
Studies on fish scale formation and resorption. I. Fine structure and calcification of the scales in Fundulus heteroclitus (Atheriniformes: Cyprinodontidae)
Authors: Yamada Juro , Watabe Norimitsu 
Published: February 2005

AbstractFine structure of the scales of Fundulus heteroclitus was examined by scanning and transmission electron microscopy. The concentric ridges of the scale surface were characterized by the presence of minute, highly calcified, denticles or tooth‐like processes. Needle‐shaped crystals of hydrox‐yapatite were precipitated not only in the osseous layer but in the intimate lamellae of the fibrillary plate except in portions just below the grooves. The calcification of the osseous layer was observed to proceed by filling the matrix with patches of crystals. The fibrillary plate appeared to calcify by invasion of crystals from the upper calcified zone into spaces between collagen fibers.
The intranuclear helices of Euplotes: Their substructure, localization, and apparent migration to the cytoplasm
Authors: Ruffolo John J. 
Published: February 2005

AbstractStudy of the fine structure of the macronucleus in Euplotes eurystomus, a ciliate protozoon, during various stages of the cell division cycle has yielded new information about intranuclear helices. They are frequently observed at the periphery of chromatin bodies or next to the nuclear envelope, and they appear to be a constituent of nucleoli. The fibril that forms a helix is about 11–15 nm thick, and torus profiles of helices cut in cross section are about 35 nm in diameter. In substructure the helix is composed of a thin strand 3–5 nm thick which is coiled to form the 11–15 nm fibril; so the helix is a super‐coiled structure. The intranuclear helices are present in the macronucleus throughout the cell cycle. They do not show obvious changes of relative abundance nor changes of relative localization in the nucleus, with one exception: they were never observed in the diffuse zone of replication bands. Evidence is presented indicating that nuclear helices migrate to the cytoplasm through nuclear pores. Although the chemical composition of the Euplotes intranuclear helices is unknown, information in the literature on similar helices in Amoeba indicates that they contain RNA and not DNA. The observations on Euplotes helices are consistent with a concept of “packaged” RNA for transport to the cytoplasm.
The morphology of the central nervous system of the barnacle, Semibalanus cariosus (Pallas)
Authors: Gwilliam G. F. , Cole E. S. 
Published: February 2005

AbstractThe central nervous system of the sessile barnacle, Semibalanus cariosus (Pallas), has been studied with the particular aim of determining the locations of neuron somata in relation to peripheral nerves. This was accomplished by tracing peripheral nerves using dissection and methylene blue staining techniques, histological methods, and by permitting cobaltous chloride to diffuse via axons into ganglia (“backfilling”).The neuron maps resulting from the study reveal some well‐defined sub‐systems, a considerable degree of functional clumping of neuron somata, and some unexpected projections of neurons in the CNS. Neurophysiological studies based on these findings are in progress.