bluuebunny/crossref_metadata_2025_split huggingface dataset:
Renal tubule of dogfish, Scyliorhinus caniculus: A comprehensive study of structure with emphasis on intramembrane particles and immunoreactivity for H+‐K+‐adenosine triphosphatase
Authors: Hentschel H. , Mähler S. , Herter P. , Elger M. 
Published: February 2005

AbstractThe ultrastructure of renal tubule cells was studied in the European lesser spotted dogfish by the evaluation of thin sections and freeze fracture replicas. Computer‐assisted three‐dimensional reconstruction of entire nephrons was performed. The distinction of nephron segments and collecting tubule was made using results of previous histological work. The first proximal tubule segment (PI) consists of two subsequent portions, PIa and PIb. PIa is a component of the lateral countercurrent bundle, and PIb, which displays an apical tubulovesicular apparatus and an extended lysosomal compartment, is located in the vicinity of the glomeruli. Rod‐shaped intramembrane particles were detected in PIa. The second proximal tubule segment (PII) is a special segment in elasmobranch and teleost fish. PII differs largely from PI in cell morphology and function. The apical cytoplasm was filled with small clear vesicles, and an apical endocytic apparatus was lacking. In the apical cell membrane, rod‐shaped particles were revealed by freeze fracture. The apical tight junctions of PI and PII consisted of seven to ten meandering strands. The distal nephron was subdivided into two major segments: early distal tubule (EDT) in the lateral countercurrent bundles and late distal tubule (LDT) in the mesial tissue. The EDT showed marked amplification of basolateral cell membranes. The tight junctions displayed a low number of continuous parallel strands, which is also characteristically found in the diluting segments of other vertebrates. LDT cells showed cytoplasmic studs and rod‐shaped intramembraneous particles at the apical cell membrane, thereby resembling type A intercalated cells of collecting duct. The collecting tubule (CT) emerged from the LDT and was part of the countercurrent arrangement inside the lateral bundles. Tight junctions of LDT and CT consisted of many meandering strands in a honeycomb pattern. With immunohistochemistry, binding sites of a polyclonal antibody against an extraplasmic portion of rat gastric H+‐K+‐adenosine triphosphatase (ATPase) were observed at the apical cell membrane of PIa, PII, and LDT. From the colocalization of binding sites for the antibody against the transport enzyme with rod‐shaped intramembrane particles, we assume that these might be the morphological correlate of gastric H+‐K+‐ATPase‐like enzyme in the renal tubule. © 1993 Wiley‐Liss, Inc.
Basement membrane formation and re‐distribution of the β1 integrins in a human intestinal co‐culture system
Authors: Vachon Pierre H. , Durand Josée , Beaulieu Jean‐Francois 
Published: February 2005

AbstractWe have developed a co‐culture system suited for the study of epithelial‐mesenchymal interactions in the human fetal small intestine. As the epithelial component of this model, we used the human intestinal cell line Caco‐2 that is unique in its property to differentiate in vitro into a mature fetal enterocyte‐like cell type. A sheet of human intestinal mesenchymal cells, which we derived from an 18‐week‐old fetus, was used as mesenchymal element. Expression and distribution of cell‐specific markers (cytokeratin 18 and dipeptidyl peptidase IV), major basement membrane components, and β1 integrins were analyzed. In 14‐day co‐cultures, Caco‐2 cells formed a cytokeratin 18‐positive epithelial‐like sheet covering the vimentin‐positive HIM cell layers. As assessed by brush border dipeptidyl peptidase IV expression, co‐cultured Caco‐2 cells achieved cytodifferentiation as when cultured on plastic. A complete deposition of all known major human fetal intestinal basement membrane components occurred at the Caco‐2/HIM interface. Type IV collagen and tenascin were produced from the mesenchymal compartment, whereas laminin and fibronectin were contributed by both cell types. Interestingly, synthesis and deposition of basement membrane heparan sulfate proteoglycan were exclusively observed in co‐cultures, suggesting modulation of epithelial expression of this molecule by HIM cells. Finally, we observed that epithelial integrin‐β1 chains redistributed at the basal domain of co‐cultured Caco‐2 cells. Taken to gether, these observations indicate that the Caco‐2/HIM co‐culture model is a valuable system to study in vitro human basement membrane formation in the context of intestinal epithelial‐mesenchymal interactions. © 1993 Wiley‐Liss, Inc.
Monoclonal antibodies identifying subsets of ectodermal, mesodermal, and endodermal cells in gastrulating and neurulating avian embryos
Authors: Ellis Linda C. , Smith Alan M. , Alvarez Ignacio S. , Schoenwolf Gary C. 
Published: February 2005

AbstractThe goal of our laboratory research is to elucidate the mechanisms underlying gastrulation and neurulation, using the avian embryo as a model system. In previous studies, we used two approaches to map the morphogenetic movements involved in these processes: (1) we constructed quail/chick transplantation chimeras in which grafted quail cells could be identified within chick host embryos by the presence of nucleolarassociated heterochromatin, and (2) we microinjected exogenous cell markers. However, it would be advantageous to be able to detect endogenous markers to demarcate various subsets of cells within the unmanipulated embryo. To elucidate such a series of natural markers, we have used monoclonal antibodies to identify epitopes found on subsets of ectodermal, mesodermal, and endodermal cells. Antibodies were made by immunizing mice against either homogenized ectoderm (i. e., Prospective neural plate and surface ectoderm) or primitive streak, which had been microdissected from stage 3 chick embryos. Additionally, we screened a panel of antibodies made against soluble protein obtained from isolates of cell nuclei from late embryonic chick brain. Here, we describe the labeling patterns of three monoclonal antibodies, called MAb‐GL1, GL2, and GL3 (GL, germ layer), during avian gastrulation and neurulation. Our results show that labeling early avian embryos with monoclonal antibodies can reveal previously undetected distributions of cells bearing shared epitopes, providing new labels for subsets of cells in each of the three primary germ layers. © 1993 Wiley‐Liss, Inc.
Chronology of peroxidase activity in the developing rat parotid gland
Authors: Redman Robert S. , Field Ruth B. 
Published: February 2005

AbstractThe course of development of salivary peroxidase, an enzyme that has an important role in oral defense mechanisms, has been well documented in rat submandibular glands. However, the only report on salivary peroxidase activity in the other major salivary glands of the rat has been a cytochemical study of the adult parotid gland. In the present investigation, the accumulation of salivary peroxidase activity in developing parotid glands of rats was followed both biochemically and cytochemically. Specific activity (units per mg protein) attributable to salivary peroxidase began at 1 day after birth, then rose rapidly but unevenly, with peaks at 21 and 70 days, and no difference between the sexes at any age. Activity per gland increased progressively to 42 days in both sexes and was significantly higher in males at 70 days. The cytochemical observations on peroxidase activity localized to the rough endoplasmic reticulum and secretory granules of the developing acini were well correlated with the biochemical findings. Peroxidase‐negative cells occurred in immature acini at 1 and 7 days, but only in the intercalated ducts thereafter. This observation suggests that the acini are a source of some of the ductal cells, at least during early postnatal development. The developmental pattern of specific activity differed from those of other rat parotid secretory enzymes, indicating that control of their synthesis during development is noncoordinate. The patterns of specific activity of the parotid and submandibular glands were complementary, suggesting that their combined secretions may supply biologically significant peroxidase activity to the oral cavities of rats throughout postnatal development. © 1993 Wiley‐Liss, Inc.
Foveal topography in the optic nerve and primary visual centers in Falconiforms
Authors: Inzunza Oscar , Bravo Hermes 
Published: February 2005

AbstractThe topography of the retinal nasal and temporal foveal projections upon the optic nerve and primary visual centers was studied in diurnal bifoveate birds of prey by means of restricted tritiated proline intraocular injection.According to the degree of retinotopy, this study reveals that a single injection of tracer in the nasal or temporal fovea produces a well‐defined and complementary pattern of projections in the following contralateral nuclei: lateral anterior thalamus, lateroventral geniculate nucleus (glv), superficial synencephalic (ss), tectal grey (gt), and optic tectum. In the thalamic nucleus dorsolateral anterior, the nasal foveal projections are seen mainly in the lateral and rostrolateral subdivision, while temproal projections are seen mainly in the magnocellular subdivision. In the external and ectomammillary nuclei there is some evidence of retinotopic innervation. Finally, a discrete field of projection from the nasal or temporal fovea is detected in lateral hypothalamus, ventrolateral thalamus, lateral geniculate intercalated nucleus, and pretectal optic area.The nasotemporal axis of the retina is ventrodorsally oriented in the optic nerve with ganglion cell axons of the temporal fovea more dorsally placed than the nasal ones. In the primary visual centers this retinal axis is mediolaterally rpresented in the nuclei glv, ss, and gt, and dorsoventrally oriented in the optic tectum. © 1993 Wiley‐Liss, Inc.
Ultrastructure and innervation of neuroepithelial bodies in the lungs of newborn cats
Authors: Van Lommel Alfons T. L. , Lauweryns Joseph M. 
Published: February 2005

AbstractNeuroepithelial bodies (NEB) occur throughout the airway mucosa and alveolar parenchyma of kitten lungs. In the bronchi, they are often situated on top of a cartilage plate. They form compact corpuscles containing 10–20 corpuscular cells and appear covered with a layer of flattened Claracells. Kitten NEB are occasionally observed to display mitosis of the corpuscular epithelial cells. A prominent blood capillary lies at their basal pole. The corpuscular cells contain numerous dense core vesicles (DCV), whose number and diameter remain unchanged with age. Kitten NEB are innervated by nerve fibres that “loop” through the corpuscle and form morphologically afferent as well as efferent nerve endings. The nerve endings display afferent synaptic junctions with the corpuscular cells and sometimes run in clusters, so that they contact each other. Many nerve endings undergo spontaneous degeneration.We conclude that kitten NEB are well adapted to function as chemoreceptors and as endocrine or paracrine organs. Their chemoreceptor activity could be modulated by axon reflexes since their afferent nerve endings are often continuous with the efferent ones, as well as by interneural modulation since nerve endings often form clusters. In addition, kitten NEB innervation appears to involute rapidly soon after birth. This may indicate that their chemoreceptor function is only of primary importance during gestation and at birth. However, the secretory function of kitten NEB, as evidenced by the unchanged numbers and dimensions of their DCV, seems to remain steady throughout life.© 1993 Wiley‐Liss, Inc.
Chronic hyperoxia and hamster pulmonary neuroendocrine cell bombesin and calcitonin
Authors: Nylen Eric S. , Becker Kenneth L. 
Published: February 2005

AbstractHamsters were exposed to 60% hyperoxia for 1 week, 3 weeks, or 3 months. The exposed animals gradually failed to gain body weight as controls. The pulmonary neuroendocrine (PNE) cell peptides, mammalian bombesin (MB) and immunoreactive calcitonin (iCT), were determined in the lung and the serum. At 1 week and 3 weeks, lung MB was unchanged while the iCT levels were markedly depleted. In contrast, the lung levels of both MB and iCT were significantly elevated at 3 months. Serum levels of MB showed an initial decline at 1 week, which was followed by augmented levels at 3 weeks and at 3 months. In contrast, serum iCT showed considerable depletion at 1 week, and also at 3 weeks, followed by increased levels at 3 months.Thus, chronic exposure to hyperoxia causes profound perturbation of PNE cell peptides. In particular, the early depletion of lung and serum iCT appears to be a unique feature of the response to hyperoxia. The principal difference between the MB and the iCT responses was the lack of an initial depletion of lung MB, and the earlier rise of serum MB to supranormal levels. It seems likely that the early peptide effects of hyperoxia are related to oxygen toxicity upon the PNE cells, while the changes noted at 3 months reflect a hyperplastic accommodation of PNE cells to the prolonged oxygen exposure with resultant increases in MB and iCT. This response is distinctly different from that we have seen previously in hamsters exposed to hyperoxia combined with a nitrosamine, or a nitrosamine alone. © 1993 Wiley‐Liss, Inc.
Spatial distribution of muscle fibers in a lumbrical muscle of the rat
Authors: Gates H.‐J. , Betz W. J. 
Published: February 2005

AbstractThe spatial distributions of two differnt populations of muscle fibers were measured in cross‐sections taken from the mid‐belly of adult 4DL muscles. Muscle fibers belonging to a single motor unit (identified by glycogen depletion) were distributed randomly in most muscles. Muscle fibers which contained slow myosin (identified immunohistochemically) were distributed nonrandomly, being evenly distributed throughout most of the muscle cross‐section, but excluded from the edge of the muscle. Interpreted from a developmental perspective, the results are consistent with the proposals that slow myosin‐containing fibers in the adult represent the original population of primary myotubes, and that the adult pattern of motor unit fiber type is achieved by synapse elimination from mismatched fibers rather than by conversion of fiber type. © 1993 Wiley‐Liss, Inc.
Prolactin alters the expression of integumental glycoconjugates in the red‐spotted newt, Notophthalmus viridescens
Authors: Singhas Charles A. , Ward Demetrice L. 
Published: February 2005

AbstractProlactin (PRL)‐mediated changes in the texture and secretory activity of the skin in adult red‐spotted newts may involve alterations in the distribution and/or expression of structural and secretory epidermal glycoconjugates. To explore this possibility, skin samples were obtained from groups of conditioned animals that had received injections of either ovine prolactin or amphibian saline over a 14‐day period. Glycoconjugates within the epidermis and cutaneous glands were examined by means of lectin hitochemistry using a panel of eight HRP‐labelled lectins. PRL increased levels of sialic acid and n‐acetylglucosamine in the stratum corneum. In contrast, glycoconjugates containing fucose, galactose, n‐acetylgalactosamine, and galactose‐(1,3)‐n‐acetylgalactosamine were decreased by PRL within both glands and epidermis. These results suggest that the intergumental effects associated with prolactin in the red‐spotted newt are mediated, at least in part, through the alteration of epidermal and glandular glycoconjugates. © 1993 Wiley‐Liss, Inc.
Stretch induces non‐uniform isomyosin expression in the quail anterior latissimus dorsi muscle
Authors: Alway Stephen E. 
Published: February 2005

AbstractStretch‐overload has been shown to elevate muscle mass in the avian anterior latissimus dorsi (ALD) by increasing both fiber size and fiber number; however, it is not known if these adaptations result in uniform regulation of myosin isoform expression along the length of the fibers in this slow tonic muscle. When a weight was added to the left wing of 20 adult quail for 30 days, ALD mass was increased by 161%. ALDs were divided into proximal, middle, and distal portions. Tissue cross‐sections from each muscle portion were reacted against monoclonal antibodies for either fast (FM) or slow myosin (SM), or processed for identification of native myosin isoforms. The number of fibers expressing FM increased by 190% in the distal region after stretch; however, most of these were small fibers. Electrophoretic analyses of stretched muscles demonstrated an upregulation of SM2 in all regions of the ALD. SM1 was only down‐regulated in the proximal region of the ALD. FM isoforms had greater increases in the proximal region than other regions of the overloaded ALD. These data indicate that stretch‐induced hypertrophy induces a non‐uniform increase in fast myosin isoforms and SM1 along the length of the fibers of the ALD. © 1993 Wiley‐Liss, Inc.
Morphometric analysis of fetal rat lung development
Authors: Moschopulos Michael , Burri Peter H. 
Published: February 2005

AbstractApplying the zone concept described previously, we quantitatively analyzed fetal rat lung development. The zone concept allowed us to coherently define reference spaces in the developing lung, a prerequisite for morphometric analysis.The peripheral zone I corresponds to a zone of growth of yet undifferentiated tissues; zone II arises from zone I and represents a region of structural and cellular differentiation; zones III and IV comprise the conducting airways and vessels.Lungs of fetal rats aged 17–23 days and 20 hours postnatal were fixed with OsO4 and glutaraldehyde and processed for light and electron microscopic morphometry implemented by point and intersection counting.Fetal lung volume grew in proportion to body weight. Zone II being the largest compartment, its volume changes largely determined lung growth rates. Zone II increased in mass owing to differentiation processes at the interface to zone I where the proximal portions of zone I were continuously shifted into zone II by differentiation. New tissue was generated within zone I. Due to these combined processes zone I changed little in volume until it disappeared at the end of the canalicular stage. The presence in the pseudoglandular stage of half of the parenchymal epithelial mass available around birth indicated that parenchymal development started earlier than assumed so far.While the endothelial surface increased most at birth, the epithelial surface grew by more than 600% at day 21, reflecting the onset of canalisation.The study confirmed the usefulness of the zone concept for morphometry and provided some new insights into lung development. © 1993 Wiley‐Liss, Inc.
Acetylcholinesterase activity is associated with efferent endings in the sensory epithelia of the utricle and semicircular canals of the rainbow trout inner ear
Authors: Khan Khalid M. , Drescher Marian J. , Hatfield James S. , Drescher Dennis G. 
Published: February 2005

AbstractThe mechanosensory hair cells of the utricle and semicircular canals of the trout inner ear are morphologically similar to type II hair cells of the avain and mammalian vestibular end organs. These cells are innervated by two types of nerve terminals. The nonvesiculated terminals are considered to be afferent, and the vesiculated endings are presumed to be efferent. The presumptive efferent endings contain numerous clear, round vesicles and a few that are dense‐cored. Histocytochemical, electron microscopic analysis has localized acetylcholinesterase activity to plasma membranes of vesiculated, presumptive efferent nerve terminals in sensory epithelia of the utricle and semicircular canals. No reaction product was observed at the receptoneural synapse or found in nonvesiculated, presumptive afferent endings. Control specimens incubated in the presence of eserine sulfate, an inhibitor of acetylcholinesterase, were devoid of reaction product. These results support the tenet that vesiculated nerve endings in the sensory epithelia of the utricle and semicircular canals of the trout are cholinergic. © 1993 Wiley‐Liss, Inc.
Ribosomes in the skeletal muscle filament lattice
Authors: Gauthier Geraldine F. , Mason‐Savas April 
Published: February 2005

AbstractThe compartmentalization of myosin isoforms within a muscle cell (Gauthier: J. Cell Biol. 110:693–701, 1990) suggests that myosin might be assembled directly into thick filaments at sites where it is synthesized. We therefore examined myofibrils by immunoelectron microscopy to determine whether ribosomes are associated with thick filaments under conditions in which new myosin can be identified. We used the embryonic chick anterior latissimus dorsi (ALD), a slow muscle that is induced, by curare, to synthesize a fast myosin isoform that is not normally present. Myosin was localized in situ, using a gold‐labeled monoclonal antibody that recognizes the new isoform. The gold marker, as expected, was localized preferentially to the A band. There was an overall increase of fivefold in the number of gold particles per μm2 of A band in the curare‐treated compared to the normal ALD, indicating that the labeled isoform was largely newly formed. There was a corresponding preferential distribution of ribosomes at the A band, especially in the H‐band region, and the number of ribosomes per μm2 of A band was nearly twice as high in the curare‐treated as in the normal muscle. Ribosomes were located between thick filaments, often aligned in rows. We conclude that ribosomes are located within the filament lattice, and therefore that they are available for local myosin synthesis. © 1993 Wiley‐Liss Inc.
Sertoli cell cycle: A re‐examination of the structural changes during the cycle of the seminiferous epithelium of the rat
Authors: Ye Shi‐Jun , Ying Li , Ghosh Sushmita , De França Luiz Renato , Russell Lonnie D. 
Published: February 2005

AbstractSeminiferous tubules in mammals are composed of cell associations that show a cyclic pattern of renewal and development. The cyclic nature of germ cell development suggests that the cells supporting the spermatogenic process, the Sertoli cells, might also differ structurally during the spermatogenic cycle in terms of the quantity of their constituents. In the present study, cyclic differences in volumes, and surface areas were determined using a sampling technique at the electron microscope level that proportionally samples the Sertoli cell within the seminiferous tubule. Among the many parameters studied, only the surface area of the cell, the volume of lipid, and the volume and surface area of the rough endoplasm reticulum were shown by statistical analysis to vary cyclically. Regarding rough endoplasm reticulum, the volume and surface area of this organelle peaked at mid‐cycle and its low was recorded near the end of the cycle, exhibiting an approximate 15‐fold difference between extremes. The rough endoplasm reticulum parameters generally correlated with known patterns of protein secretion within the tubule and with the secretion of specific proteins as well as the factors important in controlling protein secretion. Many Sertoli cell structural parameters suggested to be influenced cyclically in the rat in other studies could not be confirmed by the present study. Methodological differences in the present study and past studies are discussed as potential sources of error for these discrepancies. © 1993 Wiley‐Liss Inc.