bluuebunny/crossref_metadata_2025 huggingface dataset:
Anatomy and histology of the cardiac conal valves of the adult dogfish (Scyliorhinus canicula)
Authors: Sans‐Coma Valentín , Gallego Alejandro , Muñoz‐Chápuli Ramón , De Andrés A. Victoria , Durán Ana C. , Fernández Borja
Published: February 2005

Background: Knowledge of the structural arrangement of the cardiac conal valves in Elasmobranchs is scarce. The present study was designed to assess the anatomical and histological features of the conal valves of the dogfish as a starting point for further investigation of the mechanical properties of these valves.

Methods: The sample examined consisted of 31 adult dogfishes. The study was carried out using scanning electron microscopy and histological techniques for light microscopy.

Results: In the dogfish, the conus arteriosus contains two transverse rows of valves. The anterior row lies at the level of the conus‐ventral aorta junction and is composed of three valves of similar size. The posterior row is near the conus‐ventricular junction and consists of four valves, one of them very reduced in size. Each valve shows two components, namely, the leaflet and its supporting structure, the sinus. In the anterior valves, the length of the leaflets between their lateral attachments to the sinus wall is remarkably longer than the straight‐line distance between the points of attachment. This allows each leaflet to close against the other two leaflets of the same row, even when the conus is relaxed. The leaflets of the posterior valves are anchored to the conus wall by means of tendinous cords and cannot practically bridge the lumen of the relaxed conus. Each leaflet has a stout central body in which the connective tissue is stratified in three layers: outer fibrosa, spongiosa, and inner fibrosa. The lateral parts of the leaflet mainly consist of a single fibrous layer that bifurcates into the outer and inner fibrosa layers of the central body. The sinus walls of the posterior valves are entirely made up of conal tissue, whereas those of the anterior valves incorporate an aortic component.

Conclusions: The present findings suggest that the inner fibrosa and the fibrous lateral portions of the leaflets mainly bear the stress of pressure generated by blood backflow. The stretching of the leaflets in the radial direction may basically depend on the spongiosa, whereas the outer fibrosa determines the radial stiffness of the leaflets. © 1995 Wiley‐Liss, Inc.
Parasympathetic preganglionic neurons in the spinal cord involved in uterine innervation are cholinergic and nitric oxide‐containing
Authors: Papka Raymond E. , McCurdy James R. , Williams Sonya J. , Mayer Bernd , Marson Lesley , Platt Kenneth B.
Published: February 2005

Background: The purpose of this study was to elucidate parasympathetic preganglionic neurons in the spinal cord that project axons in pathways to the uterus and to reveal their neurotransmitter phenotype.

Methods: “Uterine‐related” neurons were identified by using a combination of retrograde axonal tracers: (1) Fluorogold injected into the ganglia of termination of preganglionic fibers, and (2) a transganglionic axonal tracer (pseudorabies virus) injected into the uterus. Immunohistochemistry was used to reveal virus‐labeled neurons and their neurotransmitter marker.

Results: Double‐labeled (Fluorogold + pseudorabies virus) “uterine” preganglionic neurons were identified in the sacral parasympathetic nucleus of the rat lumbosacral spinal cord. Subpopulations of neurons in the sacral parasympathetic nucleus were shown to be immunoreactive for choline acetyltransferase or nitric oxide synthase. Double‐staining immunohistochemistry (for pseudorabies virus + neurotransmitter enzyme) revealed that some of the uterine‐related preganglionic neurons were cholinergic and some nitric oxide synthase‐containing.

Conclusions: These results demonstrate a subpopulation of pregauglionic parasympathetic neurons in the sacral parasympathetic nucleus that are involved in uterine innervation. In addition, both acetylcholine and nitric oxide could be used to modify activity in the postganglionic neurons, which directly innervate the uterus. © 1995 Wiley‐Liss, Inc.
Ultrastructural and histochemical studies of the epiphyseal plate in normal chicks
Authors: Takechi Masato , Itakura Chitoshi
Published: February 2005

Background: Chondrocytes in the epiphyseal plate undergo a series of well‐defined stages, each stage containing a morphologically homogeneous cell population. However, biochemical studies show that there are some functionally heterogeneous cell types in the calcifying zone of the chick epiphyseal plate.

Methods: We studied the sequence of chondrocytic maturation in the normal chick epiphyseal plate ultrastructurally and histochemically. Chondrocytes in the calcifying zone were of three distinct types, the appearance of each cell type being closely related to the stage of matrix calcification.

Results: Clear cells were observed in the upper calcifying region, stellate cells appeared in the middle calcifying region, and hypertrophic clear cells appeared in the lower calcifying region. Rough endoplasmic reticulum (RER) and lysosome‐rich cells were found, these being limited to the outermost layers of the calcifying zone and containing ACPase‐positive products. Osteoclasts were attached to the matrix near the RER and lysosomerich cells in the poorly calcified regions.

Conclusion: We hypothesized that each cell type played a different role in the initiation, progression, and maintenance of cartilage calcification. RER and lysosome‐rich cells may be responsible for the resorption of uncalcified cartilage matrix, this resulting in induction of the osteoclastic resorption of the calcified matrix. In addition, the fate of the chondrocytes was twofold: hypertrophic clear cells died, while the RER and lysosme‐rich cells survived, suggesting that these cells were transformed into osteogenic cells. © 1995 Wiley‐Liss, Inc.
Ultrastructural identification of the splenic follicular dendritic cells in the chicken
Authors: Gallego Margarita , del Cacho Emilio , Zapata Agustin , Bascuas Jose Antonio
Published: February 2005

Background: There is a need to identify the follicular dendritic cells (FDC) of the chicken spleen at the ultrastructural level during a secondary immune response.

Methods: The cells were identified after intravenous priming BSA and boosting with biotinylated BSA conjugated to colloidal gold particles. Monoclonal antibodies raised specifically either to chicken IgG or IgM were used to characterize these immune complex‐trapping cells.

Results: The FDC had an irregular morphology which varied through time, supporting the existence of two types of FDC in the chicken spleen, one showing filiform cell processes, the other provided with beaded dendrites. When the filiform dendrites were observed, the FDC bound the antigen on their surfaces. These dendrites showed an intrincate convoluted configuration, forming tightly wrapped networks near the cell body. The networks had the same features as those described in mammals as antigen retaining reticulum (ARR). In chickens, the ARR, which represents sites of antigen localization on FDC, reached maximum development on day 5 after the second injection of BSA and had disappeared by day 8. At this time FDC had beaded dendrites.

Conclusions: Antigen is retained on FDC in the chicken spleen for long periods of time. © 1995 Wiley‐Liss, Inc.
Appearance and distribution of laminin a chain isoforms and integrin α2, α3, α6, β1, and β4 subunits in the developing human small intestinal mucosa
Authors: Perreault Nathalie , Vachon Pierre H. , Beaulieu Jean‐François
Published: February 2005

Background: Laminin, a major component of basement membranes, is well known in its classical heterotrimeric form (B1‐A‐B2) to regulate diverse biological functions, including cell polarization and differentiation. However, the role of merosin, a laminin‐like molecule in which an M chain is substituted for its homologous A chain, remains largely unknown.

Methods: In the present study, we analyzed by indirect immunofluorescence the expression and distribution of these four laminin chains as well as the integrins α2β1, α3β1,α6β1, and α6β4, four potential recptors, at the epithelial‐mesenchymal interface of the developing human small intestine, with a panel of specific monoclonal antibodies.

Results: Beginning at 7 weeks of gestation and throughout mucosal organogenesis, the B1 and B2 chains were uniformly detected at the epithelial basement membrane. The A chain also was detected beginning at 7 weeks, and its distribution at the basement membrane remained uniform throughout villus (9+ weeks) and crypt (16+ weeks) formation. In contrast, M chain expression was not observed until 16 weeks; between 16 and 20 weeks, it was exclusively associated with the base of epithelial cells that comprised the forming crypts. Integrins α6β1 and α6β4, as determined by their subunit immunolocalization, appeared to be expressed by all enterocytes from 7 to 20 weeks. In contrast, the expression of the α2β1 and α3β1 integrins was found time‐ and site‐restricted. The α2 subunit was predominantly detected in the epithelial cells of the intervillous area and its derivative, the crypt, whereas the α3 subunit was strongly expressed by all epithelial cells except those located at the bottom of 19–20‐week‐old crypts.

Conclusions: Taken together, these observations demonstrate that both compositional changes in the basement membrane and differential expression of receptors occur during human intestinal organogenesis, suggesting that epithelial cell‐matrix interactions play a role during development. © 1995 Wiley‐Liss, Inc.
Satellite cell activation after muscle damage in young and adult rats
Authors: Jacobs S. C. J. M. , Wokke J. H. J. , Bär P. R. , Bootsma A. L.
Published: February 2005

Background: Level exercise leads to focal structural damage in muscle fibers and to an increase of creatine kinase in the blood. We questioned whether it also induces activation of young and adult muscle satellite cells toward proliferation.

Methods: Rats of two different ages, 6 and 16 weeks, were forced to run on a level treadmill and killed at different time intervals. The temporal profile, up to 3 weeks, of muscle damage was investigated by quantification of the focally disturbed fiber area in longitudinal sections of the m. soleus. Bromodeoxyuridine (BrdU) was injected before death to determine the labeling index of satellite cells. Labeled and unlabeled satellite cells, myonuclei, and fibers were counted in cross sections of the belly part of the muscles.

Results: The muscle fiber damage differed in both amount and temporal profile between young and older animals. Damage was already visible immediately after running. However, whereas in the younger animal the amount of damage increased gradually in time until 8% at 48 hours and disappeared to almost control levels at 1 week after running, in the older animals the amount of damage was lower but remained present for at least 2 weeks. The cell kinetic data on both groups showed a proliferation response of satellite cells throughout the muscle. The effects were most pronounced in the older rats. In these rats a large increase of the labeling index was found between 24 hours and 1 week, whereas the total number of satellite cells was consistently higher from 2 days on until 2 weeks after running. In the younger animals roughly the same time pattern was observed.

Conclusion: Since the damage differed in amount and time between the two age groups, we conclude that the quick and huge proliferation response is due to leakage of mitogenic factors through small membrane disruptions that are generated during the exercise itself. © 1995 Wiley‐Liss, Inc.
Comparison of left and right vertebral artery intracranial diameters
Authors: Mitchell Jeanette , McKay Alison
Published: February 2005

Background: The vertebral artery is vulnerable to mechanical injury, especially in the region of the first and second cervical vertebrae, with resultant thrombus and/or emboli formation, often found at the vertebro‐basilar junction. Such vascular injuries and associated neurological insults have been documented repeatedly in the literature as following cervical spine manipulation, when movements of the head and neck can cause compression and/or stretching of the vertebral artery and alterations in its blood flow. This has particular clinical relevance if a patient has a hypoplastic vertebral artery. Such persons may be considered at risk as regards vascular accidents following manipulation of the cervical spine. The aim of this study was to measure and compare the intracranial diameters of the left and right vertebral arteries in groups of black and white male and female South African subjects. Methods: Cadaver material from 58 specimens was processed for light microscopy, and measurements of inner (lumen only) and outer (lumen, tunica intima, and tunica media) diameters taken and compared, using the t‐test. Results: Data analysis revealed a significant difference between the left and right vertebral artery intracranial diameters in the white female group only (N=8). Conclusions: Such a statistically significant difference implies a difference of biological importance and it is suggested that this particular group of subjects may be a high‐risk group as regards vascular accidents following cervical spine manipulation. © 1995 Wiley‐Liss, Inc.
Macrophage‐lymphocyte cell clusters in the hypothalamic ventricle of some elasmobranch fish: Ultrastructural analysis and possible functional significance
Authors: Torroba M. , Chiba A. , Vicente A. , Varas A. , Sacedón R. , Jimenez E. , Honma Y. , Zapata A. G.
Published: February 2005

Background: Previous studies have demonstrated the existence of lympho‐haemopoietic tissue in the meninges and choroid plexuses of various primitive vertebrates, including the stingray Dasyatis akajei and in early human embryos. In the present study, we extend these results analyzing macrophage‐lymphocyte cell clusters found in the floor of the hypothalamic ventricle of several specimens of elasmobranchs.

Methods: After aseptical isolation of the brain from several specimens of smooth dogfish Triakis scyllia, cloudy dogfish Scyliorhinus torazame, gummy shark Mustelus manazo, and stingray Dasyatis akajei their hypothalamic regions were processed routinely by light, scanning, and transmission electron microscopy.

Results: The study of serial histological sections demonstrated that the macrophage‐lymphocyte cell clusters proceeded from the meningeal lymphohaemopoietic tissue, reaching the ventricular lumen along large blood vessels. In this tissue, macrophages, different sized lymphocytes, lymphoblasts, granulocytes, monocytes, and developing and mature plasma cells were closely packed among a meshwork of fibroblastic reticular cell processes. It never invaded the brain parenchyma. A cell layer of glial elements and a continuous basement membrane interposed between the lymphoid tissue and the neural elements although some macrophages had migrated across the ependymal cell layer. In the ventricular lumen very irregular macrophages with long cell processes and containing abundant engulfed material of unknown origin formed big cell clusters with neighboring lymphocytes, lymphoblasts, and plasma cells, similar to those described during the immune response. Moreover, electron lucent cells which resembled the antigen‐presenting cells of higher vertebrates established intimate surface cell contacts with the surrounding lymphocytes. In the third ventricle of several specimens of gummy shark, Mustelus manazo, morphologically similar cell clusters appeared but these were not connected to the meningeal lympho‐haemopoietic tissue. No intraentricular cell aggregates were found in the stingray brain.

Conclusions: Although we cannot rule out that these macrophage‐lymphocyte cell clusters represent a permanent structure in the elasmobranch brain they rather seem to be only established after specific stimulation for preventing the entrance of noxious, foreign materials into the elasmobranch brain parenchyma. © 1995 Wiley‐Liss, Inc.
Pulmonary lymphatics and their spatial relationship to venous sphincters
Authors: Aharinejad S. , Böck P. , Firbas W. , Schraufnagel D. E.
Published: February 2005

Background: Pulmonary lymphatics are critical to clearing lung fluid. Although their structure can be shown with light and transmission electron microscopy, scanning electron microscopy of their casts can better show their number, size, shape, distribution, and degree of filling. This technique has identified four forms of lung lymphatics, but these forms have not been fully evaluated by tissue microscopy. A most important site of pulmonary edema formation, the pulmonary capillary, is just upstream from small veins which have focal, smooth muscle tufts termed venous sphincters. Because of their constricting potential, these sphincters may control lung perfusion and cause edema.

Methods: With light and transmission electron microscopy of tissue and scanning electron microscopy of casts, the lymphatic forms were explored in relation to the tissue anatomy in rats without pulmonary edema and with mild‐to‐moderate edema caused by extended vascular rinsing.

Results: The edematous lungs had increased sacculo‐tubular lymphatics adjacent to the venous sphincters. These lymphatics were in the adventitial connective tissue and were partially endothelialized. As lymphatics became more tubular their endothelium became more complete. Collagen fibers traversed the lumen of these lymphatics even where endothelial cells were present and caused the lines on the surface of the lymphatic casts. Overlapping endothelial cells caused clefts on the casts.

Conclusions: Scanning electron microscopy of lymphatic casts better defines their ultrastructure and shows the spatial relationship of veins and their sphincters to venous lymphatics. Sphincter contraction may influence pulmonary lymph production which could affect other aspects of regional lung perfusion. © 1995 Wiley‐Liss, Inc.
Central cardiovascular shunts in the perinatal marsupial
Authors: Runciman S. I. C. , Gannon B. J. , Baudinette R. V.
Published: February 2005

Background. Marsupials are born at an early stage of development after a short period of gestation. In this study the nature and timing of closure of the central cardiovascular shunts was investigated.

Methods. Light and scanning electron microscopy were used to determine changes in central cardiovascular shunts in eight marsupial species with gestation periods of between 12.5 and 36.5 days and birth weights ranging from 12.5 mg to 740 mg. Laboratory mice with a birth weight of about 1,000 mg and a gestation period of 21 days were included for comparison.

Results. Marsupials have a ductus arteriosus and an interatrial communication. The former closes rapidly after birth in the marsupial; however the interatrial communication is in the form of a fenestrated septum, which closes as result of tissue proliferation over a period of days after birth. An additional central shunt, an interventricular foramen, was found to persist in three species for a short time after birth. In one species, the eastern native cat, Dasyurus viverrinus, which has a gestation period of about 19 days and low birth weight of about 12.5 mg, in addition to the two common shunts there was a large interventricular communication and septation of the outflow tract was incomplete.

Conclusion. In adapting from intra‐uterine life, it seems that marsupials have adopted different, but equally effective strategies, with regard to the circulatory system. © 1995 Wiley‐Liss, Inc.
Growth of the myocardial volumes of the individual cardiac segments in the rat embryo
Authors: Knaapen M. W. M. , Vrolijk B. C. M. , Wenink A. C. G.
Published: February 2005

Background: Although the growth of the developing heart in relation to an increase of ventricular systolic pressure and the growth of the entire embryo during development has been described, no data are available on the growth of the individual segments and intersegmental junctions. Because these different portions are known to function differently, the need for data on their individual development is obvious.

Methods: We have measured the volumes of these different compartments by Cavalieri's point counting method in rat embryos from 11 to 17 days.

Results: It is shown that sinus venosus and sinu‐atrial junction as well as the main compartments atrium, inlet, and proximal outlet segment grow roughly proportional to the total myocardial volume. Atrio‐ventricular canal and distal outlet segment show a restricted growth and their proportional volumes decrease in time. The inlet segment is the most important part of the ventricular mass at 11 days of gestation, when it is still larger than the proximal outlet segment and, thus, takes the greater part in systolic action of the ventricular mass. The growth of the primary fold increases from day 13 onwards and can be considered as part of the wall of the inlet segment which gives rise to the main part of the ventricular septum.

Conclusions: The timing of the septal volume increase fits with qualitative descriptions of ventricular septation. The atrio‐ventricular canal and distal outlet segment have an important constrictive function in early stages, when valves are not yet present. Slow conduction and contraction patterns have been reported to be a characteristic feature of these portions of the embryonic heart. With development of valves these segments are loosing their mechanical function and, thus, their proportional volume declines. © 1995 Wiley‐Liss, Inc.
Integrin distribution during heart development in the long ‐ tailed macaque (M. fascicularis)
Authors: Pow Craig S. T. , Hendrickx Andrew G.
Published: February 2005

Background: Cardiogenesis appears to require cellular and extracellular matrix interactions for normal development. Although numerous matrix components have been identified within embryonic heart tissue, the distribution, and function of their respective integrin receptors, implicated as mediators of cell‐matrix interaction, remain unknown in primates.

Methods: Using immunocytochemistry, the localization of integrin subunits α1, α5, α6, and β1 were examined in hearts of macaque embryos during early septation and trabeculation, and compared to the distribution of the integrin ligands laminin, collagen IV, and fibronectin.

Results: At stage 11, α5 reactivity was limited to endothelial cells in the primitive heart. At stage 13, α1 and α5 were additionally detected on mesenchymal cells within the endocardial cushions. On myocardial cells at this stage, α5 stained weakly in all regions, but α1 was not expressed. The α6 subunit appeared more prominent in both stages, being present on myocardial cells throughout the heart, particularly on the basal surface of myocardial cells adjacent to the myocardial basement membrane. Inconsistent reactivity occurred on endothelial cells however, and no staining for α6 was detected on cushion mesenchymal cells. At both stages, β1 reactivity was present on all cardiac cell population and overlapped that of the α‐subunits examined. Laminin, collagen IV, and fibronectin were detected at each stage and their distribution correlated with that described for the subunits.

Conclusions: These results show specific selective patterns of expression for the subunits which are comparable to the localization of their known glycoprotein ligands and suggest defined roles for individual integrins during heart development in primates. © 1995 Wiley‐Liss, Inc.
Type VI collagen in mouse masseter tendon, from osseous attachment to myotendinous junction
Authors: Senga Katsuhiro , Kobayashi Miya , Hattori Hisashi , Yasue Kazuki , Mizutani Hideki , Ueda Minoru , Hoshino Takeshi
Published: February 2005

Background and Methods: The association of masseter tendon type VI collagen with other extracellular matrix (ECM) components was examined from osseous attachment to myotendinous junction by immunohistochemistry and transmission electron microscopy with ATP treatment and enzyme digestion.

Results: In the tendon proper, fibrocytes extended their processes among bundles of striated collagen fibrils and associated with adjacent cells through amorphous materials, thus forming a three‐dimensional network. The amorphous or filamentous material was observed around the fibrocyte cell body and along the cell processes, where the localization of type VI collagen was confirmed by immunohistochemistry using anti‐type VI collagen antibody. After treatment with 20 mM adenosine 5′‐triphosphate (ATP), 100 nm periodic fibrils, an aggregated form of type VI collagen, were formed in the place where amorphous or filamentous material was present before the treatment. In myotendinous junction, the ATP‐aggregated periodic fibrils were observed to associate with the external lamina of the muscle cells as well as among junctional tendon collagen fibrils. In the tendonbone boundary, ATP‐aggregated periodic fibrils were observed around fibrocartilage‐like cells in the uncalcifying area but not in the calcification front. Prolonged ATP treatment or hyaluronidase predigestion caused the formation of type VI collagen periodic fibrils in the area near the calcified matrix.

Conclusions: The distribution of type VI collagen in mouse masseter tendon is different in different anatomical position. This may reflect the different functional demand for this collagen. © 1995 Wiley‐Liss, Inc.
Exocytosis of secretory granules in the juxtaglomerular granular cells of kidneys
Authors: Ogawa Kazushige , Yamasato Maki , Taniguchi Kazuyuki
Published: February 2005

Background: There is little agreement as to the secretory process of renin granules in juxtaglomerular granular cells (JG cells) of kidneys, although a large number of studies of the regulation of renin secretion have been reported.

Methods: The structural correlation between the stimuli and the secretory process was examined in mouse JG cells on renal cortical slice incubated with the beta‐adrenergic agonist, isoproterenol; the loop diuretic, furocemide; the Ca2+ chelator, EGTA; and the actin filament‐disrupting agent, cytochalasin B.

Results and Conclusions: Treatment with isoproterenol (10−5−10−3 M) or furocemide (10−3M) in Ca2+‐containing medium did not significantly affect the ultrastructure of JG cells. In slices incubated with isoproterenol or furocemide in the Ca2+‐free medium, JG cells occasionally contained a few electron‐lucent granules at the cell periphery in addition to the electrondense mature granules observed in the control slices. On rare occasions, the JG cells displayed omega‐shaped cavities with electron‐lucent matrices, a feature similar to the contents of electron‐lucent granules. Cytochalasin B markedly promoted the effects of these stimulants in Ca2+‐free medium. These findings suggest the participation of actin filament disassembly in the exocytotic process of the mature granules in JG cells. © 1995 Wiley‐Liss, Inc.
Satellite cells and myonuclei in long‐term denervated rat muscles
Authors: de Castro Rodrigues Antonio , Schmalbruch Henning
Published: February 2005

Background: The percentage of satellite cells rapidly decreases in aneurally regenerating soleus muscles of rat. Also denervation of intact muscles causes fiber loss and regeneration, but the fate of satellite cells is unknown; myonuclei have been suggested to undergo changes resembling those in apoptotic cells.

Methods: Rat soleus and extensor digitorum longus (EDL) muscles were denervated at birth or at age 5 weeks and investigated after periods of up to 38 weeks. At least 400 myonuclei in each muscle were assessed by electron microscopy, and satellite cell nuclei were counted. In sity nick translation and tailing were performed after 30 weeks denervation in order to demonstrate DNA breaks associated with apoptosis.

Results: Myotubes indicating regeneration were prominent in the adult denervated soleus and deep layers of EDL muscles after 7 weeks and in the superficial parts of EDL muscle after 16 weeks. The percentage of satellite cell nuclei slowly decreased to less than one fifth of normal after 20–30 weeks. Almost all satellite cells had vanished 10 weeks after neonatal denervation. Degenerating myonuclei in adult, but not in neonatally denervated muscles, remotely resembled apoptotic nuclei of lymphocytes, but no evidence of DNA breaks was found.

Conclusion: Denervation of rat skeletal muscles causes, in addition to fiber atrophy, loss of fibers with subsequent regeneration. Proliferation of satellite cells under aneural conditions may lead to exhaustion of the satellite cell pool. This process is more rapid in growing than in adult muscles. Myonuclei in denervated muscles do not show DNA breaks which can be demonstrated by in situ nick translation. © 1995 Wiley‐Liss, Inc.
Microvasculature of the rabbit urinary bladder
Authors: Hossler Fred E. , Monson Frederick C.
Published: February 2005

Background: The urinary bladder requires a rich blood supply to maintain its functions, the storage and release of urine. Specialized properties of the bladder vasculature might be anticipated to ensure the integrity of this blood supply, because it is known that blood flow is reduced by distension during bladder filling. However, the bladder vasculature has been described in detail only at the gross level. A comprehensive, threedimensional view of the blood supply to the bladder wall is presented here.

Methods: The microvasculature of the bladder of male New Zealand white rabbits was described using the combination of vascular corrosion casting, alkali digestion, light microscopy, and scanning and transmission electron microscopy. Following administration of an anticoagulant and an overdose of anesthetic, the abdominal aorta was cannulated just above the inferior mesenteric artery to permit flushing of the distal vasculature. The bladder vasculature was cleared of blood with buffered saline and then either perfuse‐fixed with buffered 2% glutaraldehyde and sectioned, or filled with “Mercox” resin to prepare vascular corrosion casts. Casts were cleaned with NaOH, formic acid, and water. In some cases fixed bladders were partially digested with NaOH to expose the mucosal capillary plexus.

Results: The bladder is supplied with blood by single, left and right vesicular branches of the internal or external iliac arteries. The serpentine vesicular arteries extend along the lateral borders of the bladder from base to apex just deep to the serosal surface and send dorsal and ventral branches to supply the dorsal and ventral bladder walls. Veins accompany the arteries and exhibit numerous valves. A very dense complex of vessels at the apex of the bladder apparently serves to accommodate bladder distension. The muscularis and submucosa contains few vessels, but the mucosa is well vascularized. An especially dense capillary plexus is present in the lamina propria at its junction with the transitional epithelium. In the relaxed bladder these capillaries lie in grooves formed by the basal layers of the epithelium. The endothelial cells of these capillaries display few cytoplasmic vesicles and are continuous or fenestrated. These capillaries are often invested with pericytes. The mucosal capillary plexus may be associated with an epithelial transport function or may be necessary for urothelial metabolism or maintenance of the barrier function of the urothelium. Unusual capillary tufts, possibly associated with vascular lymphatic tissue, are found associated with the main vessels on the lateral walls in the basal half of the bladder.

Conclusions: These methods present a clear, comprehensive, three‐dimensional view of the microvasculature of the bladder wall. They also identify several unique features of this vasculature and provide a basis for studies of the response of this vasculature to pathologic states and experimental manipulation. © 1995 Wiley‐Liss, Inc.
Mathematical model of influenza A virus production in large‐scale microcarrier culture
Authors: Möhler Lars , Flockerzi Dietrich , Sann Heiner , Reichl Udo
Published: February 2005

A mathematical model that describes the replication of influenza A virus in animal cells in large‐scale microcarrier culture is presented. The virus is produced in a two‐step process, which begins with the growth of adherent Madin‐Darby canine kidney (MDCK) cells. After several washing steps serum‐free virus maintenance medium is added, and the cells are infected with equine influenza virus (A/Equi 2 (H3N8), Newmarket 1/93). A time‐delayed model is considered that has three state variables: the number of uninfected cells, infected cells, and free virus particles. It is assumed that uninfected cells adsorb the virus added at the time of infection. The infection rate is proportional to the number of uninfected cells and free virions. Depending on multiplicity of infection (MOI), not necessarily all cells are infected by this first step leading to the production of free virions. Newly produced viruses can infect the remaining uninfected cells in a chain reaction. To follow the time course of virus replication, infected cells were stained with fluorescent antibodies. Quantitation of influenza viruses by a hemagglutination assay (HA) enabled the estimation of the total number of new virions produced, which is relevant for the production of inactivated influenza vaccines. It takes about 4–6 h before visibly infected cells can be identified on the microcarriers followed by a strong increase in HA titers after 15–16 h in the medium. Maximum virus yieldVmaxwas about 1 × 1010virions/mL (2.4 log HA units/100 μL), which corresponds to a burst size ratio of about 18,755 virus particles produced per cell. The model tracks the time course of uninfected and infected cells as well as virus production. It suggests that small variations (<10%) in initial values and specific rates do not have a significant influence onVmax. The main parameters relevant for the optimization of virus antigen yields are specific virus replication rate and specific cell death rate due to infection. Simulation studies indicate that a mathematical model that neglects the delay between virus infection and the release of new virions gives similar results with respect to overall virus dynamics compared with a time delayed model. © 2005 Wiley Periodicals, Inc.
Prevention of naphthalene‐induced pulmonary toxicity by glutathione prodrugs: Roles for glutathione depletion in adduct formation and cell injury
Authors: Phimister A. J. , Nagasawa H. T. , Buckpitt A. R. , Plopper C. G.
Published: February 2005

Naphthalene is metabolized in the lung and liver to reactive intermediates by cytochrome P450 enzymes. These reactive species deplete glutathione, covalently bind to proteins, and cause necrosis in Clara cells of the lung. The importance of glutathione loss in naphthalene toxicity was investigated by using the glutathione prodrugs (glutathione monoethylester or cysteine–glutathione mixed disulfide) to maintain glutathione pools during naphthalene exposure. Mice given a single intraperitoneal injection of naphthalene (1.5 mmol/kg) were treated with either prodrug (2.5 mmol/kg) 30 min later. Both compounds effectively maintained glutathione levels and decreased naphthalene–protein adducts in the lung and liver. However, cysteine–glutathione mixed disulfide was more effective at preventing Clara cell injury. To study the prodrugs in Clara cells without the influence of hepatic naphthalene metabolism and circulating glutathione, dose‐response and time‐course studies were conducted with intrapulmonary airway explant cultures. Only the ester of glutathione raised GSH in vitro; however, both compounds limited protein adducts and cell necrosis. In vitro protection was not associated with decreased naphthalene metabolism. We conclude that (1) glutathione prodrugs can prevent naphthalene toxicity in Clara cells, (2) the prodrugs effectively prevent glutathione loss in vivo, and (3) cysteine–glutathione mixed disulfide prevents naphthalene injury in vitro without raising glutathione levels. © 2005 Wiley Periodicals, Inc. J Biochem Mol Toxicol 19:42–41, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20052
Effects of nickel poisoning on expression pattern of the 72/73 and 94 kDa stress proteins in rat organs and in the COS‐7, HepG2, and A549 cell lines
Authors: Hfaiedh N. , Allagui M. S. , Feki A. El , Gaubin Y. , Murat J. C. , Soleilhavoup J. P. , Croute F.
Published: February 2005

The present study deals with the effects of Ni on the expression level of three stress proteins, namely, the cytosolic HSP72 and HSP73, and the reticulum‐associated GRP94. Experiments were carried out on “Wistar'' female rats daily injected with 4 mg NiCl2 per kg body weight for 1, 3, 5, and 10 days. Another set of experiments were carried out using cell lines, derived from the monkey kidney (COS‐7), and from human tumors of the lung (A549) and liver (HepG2). Cells were cultured for 4 days in the permanent presence of 100, 200, or 400 µM NiCl2. In control rats, stress proteins pattern was found to be tissue specific: two protein bands of 96 and 94 kDa were immunodetected with the anti‐GRP94 antibody in kidney and liver extracts, whereas only the 96 kDa band was present in ovary extracts. HSP73 was present in kidney, liver, and ovary whereas HSP72 was only found in kidney. In kidney of nickel‐treated animals, HSP73 and the 96 kDa proteins were overexpressed whereas HSP72 was strongly down regulated. No such effect was observed in liver or ovary. Similarly, in nickel‐treated cell lines, HSP72 was downregulated and GRP94 (96 kDa protein) was overexpressed. HSP73 expression appeared moderately increased in A549 cells but decreased in COS‐7 cells. Because long‐term caloric restriction was reported to reduce free radical generation in cells, the effect of 1 month food restriction (50%) was tested in rats as a possible way to lower oxidative damages induced by Ni. No significant effect on HSP expression was observed. © 2005 Wiley Periodicals, Inc. J Biochem Mol Toxicol 19:12–18, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20056
Cell Division: Pressure‐induced reversal of the antimeiotic effects of heavy water in the oocytes of the starfish, Asterias forbesi
Authors: Marsland Douglas , Hiramoto Yukio
Published: February 2005

Meiotic activity in the öcytes of the starfish, Asterias forbesi, may be blocked by immersion in deuterated sea water (60% or more) as is judged by a stoppage in the breakdown of the germinal vesicles and a failure of the cells to form persistent polar bodies. These anti‐meiotic effects of heavy water were reversed in significant degree by application of suitable intensities (3,000 to 6,000 psi) of hydrostatic pressure. In this regard meiosis resembles mitosis, as studied previously in the first cleavage division of the sea urchin, Strongylocentrotus purpuratus.

In studying germinal vesicle breakdown, immersion of the öcytes in deuterated (60, 70 and 80% D2O) sea water was initiated ten minutes after shedding and pressurization was established six minutes later. None of the non‐pressurized deuterated cells showed complete breakdown of the germinal vesicle, whereas complete breakdown was observed in a significant percentage of the pressurized deuterated specimen.

In studying their capacity to form and maintain polar bodies, the öcytes were deuterated 60 minutes after shedding and pressurized six minutes later. Maximum release from deuterational blockage, as judged by the percentage of persistent polar bodies after one hour of treatment, was as follows: 85% at 2,000 psi for 50% D2O; 65% at 2,500 psi, for 60%; 77% at 3,000 psi for 70%; 55% at 3,500 psi for 80% and 65% at 3,500 psi for 90%. Persistence of polar bodies in the non‐pressurized deuterated cells did not exceed 15% in any medium containing 60% or more of D2O and the average persistence in such media was only 2.5%.

Basic mechanisms which may account for the observed effects are discussed.
Temperature regulation in the echidna (Tachyglossus aculeatus)
Authors: Schmidt‐Nielsen Knut , Dawson T. J. , Crawford E. C.
Published: February 2005

The echidna (Tachyglossus aculeatus) maintained a body temperature of 30.7°C ± 1.03 s.d. (N = 23) at ambient temperatures (TA) between 0 and 25°C. It may, however, also become hypothermic at low TA. At TA = 30°C or above the echidna became hyperthermic. The thermoneutral range was about 20–30°C. At low TA the metabolic rate might be increased several fold. The thermal conductance was at a minimum at TA = 20°C, and was not further reduced at lower TA. At higher TA the thermal conductance increased up to five‐fold. The evaporation showed little change with increasing TA. At the highest TA we used (33°C) the evaporation on the average accounted for the dissipation of only about one‐third of the metabolic heat produced. These findings suggest that the echidna, although it can maintain its body temperature at low ambient temperature, cannot rely upon evaporation as the major avenue for heat loss at high ambient temperature.
A circadian rhythm of mating type reversals in Paramecium multimicronucleatum, syngen 2, and its genetic control
Authors: Barnett Audrey
Published: February 2005

Two new alleles, C and c, involved in mating type expression were demonstrated. A dominant allele, C(cycler), must be present for the expression of the rhythm involving a sequential alternation of the two complementary mating types (III and IV). Cultures can be entrained with light‐dark cycles. The phase of each clone can be characterized by its III to IV and IV to III transitions in relation to the zero hour of a given light‐dark cycle. Phase is a stable phenotypic trait during asexual reproduction, but following sexual reproduction it does not display Mendelian segregation. Instead phase is determined through nuclear differentiation, i.e., the trait is controlled by differently determined macronuclear alagen (caryonidal inheritance) which normally segregate at the second cell division after conjugation. The phase of a clone within its genetic limits is a function of the photofractions and the light intensities used in the entraining treatment. By examining a number of clones a variety of phase angles between the mating type cycle and the entraining light‐dark cycle are found. Dividing cells which are sexually unreactive and therefore do not express the rhythm can be entrained and following entrainment, phase is inherited through repeated cell replications at a rate greater than one fission a day in continuous darkness or continuous dim light. This result unique to this system indicates that the cellular processes underlying the phase and period of this circadian rhythm persist (unexpressed: sexual reactivity requires slight starvation) through repeated cell replications even when the division cycle is considerably shorter than the expressed circadian period. The rhythm has a circadian period in continuous darkness or light (tested for six days) of less than 24 hours. The reversal of mating type ceases in continuous light at higher intensities. Cells homozygous for the recessive allele, c(acyclic), do not reverse mating type but are either mating type III or IV, again as a consequence of nuclear differentiation. Since individual cells with the dominant allele express both mating types, differentiation for mating type can not involve the absence in the macronucleus of mating type determining factors.
Neural responses in the inferior colliculus of echolocating bats to artificial orientation sounds and echoes
Authors: Friend J. H. , Suga N. , Suthers R. A.
Published: February 2005

The responses of single units and evoked potentials to a pair of artificial sounds, mimicking theorientation sound and echo, and to tape recorded actual orientation sounds were studied in terms of recovery cycle. the recovery cycle of single units could be classified into four groups: (1) short suppression (4%), (2) delayed inhibition (11%), (3) temporal recovery with or without a supernormal phase (7%), and (4) undelayed inhibition (78%) lasting 4 to 26 msec. therefore the majority of neurons were not excited by the second sound (echo) of a pair when it was delivered within several milliseconds after the first (out‐going orientation sound). the duration of the recovery cycle was a function of the intensity of a pair of sounds. the weaker the first tone pulse relative to the second, the more rapid the recovery to the second. therefore, the reception of echoes is probably improved by contraction of middle ear muscles resulting in attenuation of self‐stimulation by the out‐going pulse.

The collicular evoked potential consisted of two components, a fast one mainly due to the incoming fibers from lower levels and a slow one due to the main body of the inferior colliculus. The slow component showed slow recovery cycles as did the majority of single units while the fast one recovered very quickly. No noticeable difference in recovery cycles was found between awake and anesthetized animals. The functional meaning of inhibitory periods in the recovery cycle and role of the inferior colliculus in echo‐location are discussed.
The metabolism of L‐glutamate and L‐5‐Carboxypyrrolidone by mouse cells (NCTC clone 929) under conditions of defined nutrition
Authors: Kitos Paul A. , Waymouth Charity
Published: February 2005

The utilization of L‐glutamate by clone 929 mouse cells growing in a synthetic medium, MAL 294/2, was studied with the aid of carbon‐14 labeled L‐glutamate. The rate of consumption of extracellular glutamate was rapid even though the extracellular concentration of this substance has been found to remain constant or to increase. The rate of uptake during an interval of otpimal growth was calculated to be approximately 42 mμmoles/mg of cell protein per hour.

Among the metabolic products that are derived from the carbon of glutamate and secreted from the cells are carbon dioxide, lactic acid, proline, alanine, alpha‐ketoglutaric acid and 5‐carboxypyrrolidone. Aspartic acid, although produced by the cells in amounts sufficient to meet the needs for growth, does not appear as an extracellular product of glutamate metabolism. Extracts of L cells were found to exhibit four times as much glutamic‐oxaloacetic as glutamic‐pyruvic transaminase activities. Failure to secrete aspartic acid must not be due to a deficiency in the transaminase. The transaminase concentrations are apparently not affected by variations in the concentrations of aspartic acid and alanine in the medium, both of which are absent from MAL 294/2.

5‐Carboxypyrrolidone, although produced from L‐glutamate by L cells, is metabolically inert in this system. Likewise, mouse fetal lung cells, cultured in a similar way, use glutamic acid as extensively as L cells and fail to metabolize exogenous 5‐carboxypyrrolidone.
The effect of phytohemagglutinin on glucose‐U‐C14 oxidation by peritoneal and blood white cells of the rat
Authors: Hrachovec Josef P.
Published: February 2005

Incubation of washed white cells with phytohemagglutinin (PHA) had a stimulatory effect on the rate of C14O2 evolution from uniformly C14‐labeled glucose by the cells. The intensity of this effect depended not only on the concentration of PHA, but also on the duration of soaking of the cells in protein‐free medium for tissue culture before PHA was added and on the length of incubation of the soaked cells with PHA before glucose‐U‐C14 was added. This effect of PHA on the rate of glucose‐U‐C14 oxidation by the cells was essentially the same, whether white blood cells or peritoneal white cells were used.