bluuebunny/crossref_metadata_2025_split huggingface dataset:
Secretory activity in the floor plate neuroepithelium of the developing human spinal cord: Morphological evidence
Authors: Tanaka Osamu , Yoshioka Takafumi , Shinohara Haruo 
Published: February 2005

AbstractThe developing spinal cord at the cervical and thoracic levels in 14 human embryos ranging from Carnegie stages 14 to 20 were examined with the electron microscope. The floor plate‐forming cells contained numerous cytoplasmic organelles, such as rough endoplasmic reticulum (ER), Golgi apparatus, and well‐developed junctional complexes between the adjacent cells. Microvilli and cilia were numerous at the apical surface of neuroepithelial cells in the floor plate, but few were found in the lateral walls. Periodic acid‐Schiff‐positive substances were predominantly present in the neuroepithelial cells of the floor plate. In all specimens examined, multivesicular structures were observed in the floor plate neuroepithelium, but not in other regions of the spinal cord. The number of multivesicular structures appeared to increase with embryonic age. These structures contained numerous small and translucent vesicles within an electron‐dense matrix; most vesicles were 40–70 nm in diameter. It appeared that the envelope of the multivesicular structures was first formed by the fusion of smooth ER‐like cisterns, followed by invagination of the envelope by the vesicular contents. Presumably, the mature multivesicular structures were subsequently translocated to peduncular processes and their contents released into the central canal lumen in an exocytotic manner. This morphological evidence suggests that the floor plate cells of the spinal cord may have secretory activity during embryonic development.
Radioautographic demonstration of receptors for epidermal growth factor in various cells of the oral cavity
Authors: Cho Moon‐Il , Lee Yu Lin , Garant Philias R. 
Published: February 2005

AbstractMouse iodinated epidermal growth factor (EGF) was localized by light and electron microscopic radioautography in basal cells of oral epithelium, papillary cells of the enamel organ, periodontal ligament fibroblasts, preodontoblast precursor cells, and preosteoblasts of the alveolar bone of 13‐day‐old Sprague‐Dawley rats. The specificity of binding in these cells was suggested by an observed reduction of about 90% in the labeling when excess unlabeled EGF was injected along with the 125I‐EGF. In contrast, fully differentiated cells, such as ameloblasts, odontoblasts, and osteoblasts, were only poorly labeled. Quantitative analysis of the light microscopic radioautographs revealed that the papillary cells had the highest level of labeling (5.5 grains per 100 μm2 of cell area). The significance of the rather high labeling of the preosteoblasts of the alveolar bone and the fibroblasts of the periodontal ligament is unknown. However, the well‐known effect of EGF in producing precocious eruption of teeth may be a consequence of an effect on these two cell types.
Ultrastructural localization of the 9‐kilodalton vitamin d‐dependent calcium‐binding protein in the murine intraplacental yolk sac
Authors: Riad Nahad H. , Bruns M. Elizabeth H. , Fares Nagui H. , Bruns David E. , Herr John C. 
Published: February 2005

AbstractThe calcium‐binding protein (CaBP) calbindin has been implicated in the molecular mechanism of placental calcium transfer. Previous light microscopic studies have identified CaBP in visceral (but not parietal) endodermal cells of the yolk sac with the most intense immunocytochemical signal observed in the intraplacental yolk sac. In the present studies, electron microscopy was used to study the localization of CaBP in placenta.Placentas of 17‐day pregnant mice were fixed by perfusion in 0.5% gluteraldehyde, embedded in low‐temperature Lowicryl K4M, and examined in thin section for specific labeling with a polyclonal antiserum. Antibody to CaBP was localized by using protein A‐gold particles which were quantified for subcellular compartmentation by using a Videoplan computer system. A high signal for CaBP was found in the visceral endodermal cells of the intraplacental yolk sac. In these cells, gold particles indicating the location of CaBP were observed over (1) the cytoplasmic matrix where the average number of gold particles per μm2 was 33; (2) the microvilli (17/μm2); (3) the mitochondria (17/μm2); and (4) the nucleus (43/μm2). Sections from antigen‐absorbed controls, by contrast, showed few gold particles: cytosol, 2/μm2; microvilli, 5/μm2; mitochondria, 5/μm2; and nucleus, 4/μm2. Electron‐lucent profiles of the Golgi and endoplasmic reticulum contained no particles in the controls and a low particle count (4/μm2) in the stained sections. Parietal endodermal cells of the intraplacental yolk sac showed a relatively low signal for CaBP compared with the visceral endodermal cells (5 particles/μm2 vs. 39). Only low numbers of gold particles were observed in trophoblasts (6/μm2), lymphocytes (5/μm2), and erythrocytes (5/μm2). These findings indicate that 9 kd CaBP is located predominantly in cytoplasmic matrix, nucleus, and mitochondria within the visceral endodermal cells of the intraplacental yolk sac.
Ileal band in northwest Indian subjects
Authors: Jit Indar 
Published: February 2005

AbstractThe incidence of the ileal band was recorded in 1,040 northwest Indian subjects varying in age from 1 day to 100 years on whom a medicolegal postmortem had been performed by the author. The band was present in 31.8% of male and 17.5% of female subjects (P < .05) and was either quadrilateral (60%) or triangular in shape. In addition 25 foetuses, each above 250 mm in crown‐rump length, 25 neonates, 25 monkeys (Macaca mulatta), and an equal number of dogs, rabbits, guinea pigs and rats were also dissected, but the band was found to be absent. In all the foetuses dissected and in 24 out of 25 newborns the caecum was found to be either in the subhepatic or right lumbar region. The earliest age at which the band was found was 7 months. As the band was absent in the animals and the newborns, it appears that it develops in man on account of attaining an erect posture.
Presence and distribution of vimentin in cynomolgus monkey trabecular cells
Authors: Ken James , Wolf Paul 
Published: February 2005

AbstractThe role of the trabecular meshwork in the ocular outflow tract has made it the object of considerable study. Recent work has examined the presence and function of microfilaments and microtubules in the cytoskeleton of cultured cynomolgus monkey trabecular cells. In this study, we used an indirect immunofluorescence technique to investigate the presence and distribution of the intermediate filament vimentin in cultured cynomolgus monkey trabecular cells. The cytoskeletal active agents cytochalasin B, Colchicine, nocodozole, and taxol were also employed to investigate the role of vimentin in these cells. Vimentin formed a network of filaments that radiated throughout the cytoplasm from the nucleus to the cellular projections and cell membrane. The extensiveness of the vimentin network, and the cell shape, were observed to vary according to the degree of cell confluence, the degree of cell spread, and the degree of cell/cell contact. Cells in the less‐confluent periphery had extensive vimentin networks and greater cell spreading and were polygonal in shape. Cells in the more confluent areas had a less‐extensive vimentin network, underwent less cell spreading, and were primarily fusiform in shape. The change in cellular morphology induced by colchicine, nocodozole and taxol was proportional to the extensiveness and the degree of change of the vimentin network. Our observations have identified a proportional association between the extensiveness of the vimentin network, changes in the vimentin organization, and alterations in cellular morphology that is suggestive of a role for vimentin in determining cellular structure and shape. Because reports have suggested that alterations in trabecular cell morphology are related to changes in ocular outflow, our work suggests a role for vimentin in ultimately regulating the ocular outflow tract through the vimentin network's effects on trabecular cell structure and morphology.
New technique for differential staining of myelinated fibers and nerve cells on paraffin sections
Authors: Tolivia J. , Tolivia D. , Navarro A. 
Published: February 2005

AbstractA simple, rapid method for the differential staining of myelinated nerve fibers and nerve cell bodies, applicable to sections of central nervous system pieces embedded in paraffin, is described, Experimental material fixed by perfusion with mixed aldehydes or necropsy material fixed in formaldehyde can be used. Constant and homogeneous results are obtained with this technique, and the most important characteristic is the absence of differentiation in either of the steps: staining of myelinated fibers and staining of nerve cell bodies. Sections 15 μm thick were attached to slides, dewaxed, and hydrated. After hydration, sections are mordanted (30 min) in 2.5% iron alum (SO4)2FeNH4, and rinsed (1 min) in distilled water. Staining is for 180 min in the following solution: 5 ml freshly made 20% alcoholic hematoxylin diluted with 25 ml of distilled water and 25 ml of absolute ethanol to which 10 ml of 1% Li2CO3 is added. The sections are washed in distilled water (5 min) and stained during 5 min in the following solution: 0.2% pyronine, 20% formaldehyde in distilled water. The sections are dehydrated through 96% and absolute ethanol, cleared in eucalyptol, and mounted in Eukitt.Myelinated fibers appear dark blue, whereas nerve cell bodies are stained red and the cell nucleoli dark blue. This procedure provides an adequate contrast for observation and photography.
Site‐specific regulation of osteogenesis: Maintenance of discrete levels of phenotypic expression in vitro
Authors: McCulloch Christopher A. G. , Tenenbaum Howard C. , Fair Catherine A. , Birek Catalena 
Published: February 2005

AbstractIntrinsic differences in bone formation rate, cell numbers, and the percentages of cells expressing alkaline phosphatase activity were studied in explants of chick calvaria periosteum cultured for 4 days and 6 days. Proliferation, differentiation, and bone production were examined in radioautographs of plastic sections and by using whole‐culture biochemical assays of protein and alkaline phosphatase. Ectocranial explants at both 4 days and 6 days exhibited more alkaline phosphatase‐positive cells and significantly more bone formation than endocranial cultures. There were no detectable differences in cell numbers or 3H‐thymidine labeling indices. The volume of bone synthesized per osteoblast was significantly higher in the ectocranial group. Examination of bone stripped of periostea and then cultured for 4 days revealed that large areas of bone were covered by osteoblasts, indicating that the periosteal explant cultures were composed almost exclusively of osteoprogenitor cells and fibroblasts. The data suggest that the level of expression of predetermined osteogenic phenotypes can be maintained in vitro for 6 days following explantation and that variations in the rate of osteogenesis are programmed into progenitor cells prior to their differentiation into osteoblasts.
Immunogold distribution of actin during spermiogenesis in the rat, hamster, monkey, and human
Authors: Fouquet Jean‐Pierre , Kann Marie‐Louise , Dadoune Jean‐Pierre 
Published: February 2005

AbstractThe localization of actin during spermiogenesis in the rat, hamster, monkey, and human was examined at the ultrastructural level using postembedding immunogold methods. Results revealed a similar pattern of actin distribution in these four species, although the staining intensity was higher in rodent spermatids than in those obtained from primates. Gold particles were first detected in the nascent subacrosomal space of round spermatids. This subacrosomal labeling extended as the acrosome spread over the nucleus during the elongation phase, remained unchanged during the first steps of the maturation phase, and disappeared completely before spermiation. Thus, using antiactin probes (present results) and other specific probes, actin appears to be a consistent component of the subacrosomal layer of spermatids during the greater part of spermiogenesis in many mammals.
Cytoplasmic stress fibers in the developing heart
Authors: Sumida Hiroshi , Ashcraft Robert A. , Thompson Robert P. 
Published: February 2005

AbstractRhodamine‐conjugated phalloidin staining was used to study the distribution of filamentous actin in the developing heart of embryonic chicks and rats during the morphogenetic period of cardiac septation. In the chick, intense fluorescence indicative of abundant filamentous actin was observed along the myocardium and in the mesenchymal condensations that formed within the aorticopulmonary septum at day 5. Such cellular condensations and concentration of filamentous actin were not seen in the atrioventricular cushions nor in the preseptation outflow tract. Similar results were found in the 14‐day rat embryo. In electron micrographs, microfilament bundles with irregular dense bodies were seen in elongated mesenchymal cells between the valve sites of both species. Cell‐cell contacts were observed between such elongated cells and myocyte processes protruding from the nearby myocardial sheath. These histochemical and ultrastructural observations suggest that such mesenchymal condensations serve a specialized mechanical tensile role during embryonic septation of cardiac outflow channels.
Distribution of 35S‐Sulfate within the transseptal ligment of the mouse
Authors: Johnson Roger B. 
Published: February 2005

AbstractThe distribution of 35S‐sulfate‐labeled macromolecules was examined within three regions of the transseptal ligament: the (1) mesial, (2) middle and (3) distal thirds. Swiss mice, 6 weeks of age, were injected with 35S‐sulfate and killed after 1, 6, and 12 hours and 1,2,3,4,5, and 7 days. Silver grains and cell nuclei were counted on autoradiographs which had been counterstained by the Van Gieson method, and mean counts were analyzed statistically. Analysis of variance revealed no significant differences in mean number of cell nuclei between regions throughout the course of the experiment. 35S‐sulfate was rapidly incorporated into the transseptal ligament macromolecules. Grain counts were highest 6 hours after injections: counts were higest over the middle and lowest over the mesial thirds of the ligament. The rate of grain removal was significantly higher in the middle third compared to the mesial or distal thirds (P<0.001) and was significantly lower in the mesial third compared to the middle or distal thirds (P<0.001). The half‐life of labeled macromolecules was significantly greater in the mesial and distal thirds than in the middle third (P<0.005). The data demonstrates significantly higher rates of turnover of 35S‐sulfate‐labeled micromolecules in the middle region of the transseptal ligament. Since cellular density was similar throughout the transseptal ligament, higher turnover rates of 35S‐sulfate‐labeled macromolecules peobable indicate higher rates of cellular activity in this region, possibly a result of tissue remodeling coincident to stresses generated by occlusal forces and physiologic drift of the adjacent teeth.
Granule formation and polarity of the Golgi apparatus in neutrophil granulocytes of the rat
Authors: Tang R. Xue Ming , Clermont Yves 
Published: February 2005

AbstractThe formation of granules in neutrophil (heterophil) progenitor cells was examined with the electron microscope in sections of rat bone marrow fixed in 2% glutaraldehyde and postfixed with reduced osmium (Karnovsky:Proceedings of the 11th Meeting, American Society of Cell Biologists, Abstr. 284, p. 146, 1971). The cells were also osmicated in 2% osmium tetroxide for 36 hours at 37%C to outline the osmiophilic element usually observed on the cis‐face of the stacks of saccules of the Golgi apparatus of various cell types. In myeloblasts, which do not produce granules, the cis‐osmiophilic element (CE) was found on the concave face of the C‐shaped Golgi stacks, while the primary (azurophilic) granules fromed in relation to elements on the concave aspects of the stacks. In myleocytes, the situation was reversed: the CE was found on the concave face of the Golgi stacks, while the secondary (specific) granules were seen forming in relation to elements on the convex aspect of the stacks. Finally, in metamyelocytes and mature neutrophils in which no granule formation took place, the appearance on Golgi stacks varied: they were either flat or C‐shaped. The CE was indiscriminately found on one face or the other of the flat Golgi stacks of metamyetocytes and on the convex or concave faces of the C‐shaped Golgi stacks of mature neutrophis.Using the cis‐osmiophilic‐element as a marker of the cis‐face of the stackedGolgi elements, it thus appeared that despite marked changes in the configuration and orientation of the stacks the cis‐trans polarity of the stacked elements was maintained throughtout granulopoiesis. In addition the primary and secondary granules that appeared sequentially in promyelocytes and myelocytes were both seen to form in relation to trans‐elements of the Golgi apparatus.
Ultrastructural cytochemistry of aortic microfibrils in the arctic lamprey, Lampetra japonica
Authors: Isokawa Keitaro , Takagi Minoru , Toda Yoshihisa 
Published: February 2005

AbstractIn the ventral aorta of lamprey, microfibrils are major components of the extracellilar matrix. With special refeence to these microfibrils, we have cytochemically exmined the ventral aorta, utilizaing the tannic acid (pH 7.0)‐uranyl acetate (TA‐UA) method, elastase en bloc digestion, Thiéry's periodis acid‐thiocarbohydrazide‐silver proteinate (PA‐TCH‐SP) method, and ferritin‐ or horseradish peroxidase‐labeledd concanacalin A (Con A) methods. The lamprey microfirils were strongly stained with PA‐TCH‐SP and both Con A methods, but did not show TA‐UA staining nor elastase sensitivity. These cytochemical properties of lamprey microfibrils are identical with those of mammalian elastin‐associated microfibrils. On the other hand, in spite of extensive examination, TA‐UA positive and elastase‐sensitive extracellular components were not found, so that lamprey ventral aorta does not appear to contain elasin. These results indicate that lamprey lamprey aortic connective tissue contains microfibrils as elastic components, but deposition of amorphous elastin dose not occur.
Effect of selected denervations on glycoconjugate composition and tissue morphology during the initiation phase of limb regeneration in adult Ambystoma
Authors: Young Henry E. , Dalley Bernell K. , Markwald Roger R. 
Published: February 2005

AbstractThis study was undertaken to assess the effects of various quantities of neural tissue on the temporal relationship of matrix glycoconjugates to the regeneration morphology. 1) Denervation before amputation revealed that a threshold level of nervous tissue was necessary to activate a regeneration response from the tissue, i.e., appearance of regeneration‐specific morphologies and glycoconjugates. 2) Denervation after amputation demonstrated that the level of neural tissue necessary to maintain these responses was below the level necessary to activate the regeneration response. If neural tissue was completely removed there was a concomitant loss of regenerate morphologies and glycoconjugates. 3) Bilateral amputation of a neurogenically intact limb and its completely denervated contralateral limb revealed that the regeneration response was a localized phenomenon during the first 30 days after amputation. After 30 days the regeneration response appeared within the previously degenerated denervating limb. The results suggest that the factors controlling the regenerative response in adult Ambystoma are large diffusible substances that can be transported by the circulation and can affect the regenerative response in remote, previously activated, tissues.
Effects of aging on the neurons within area 17 of rhesus monkey cerebral cortex
Authors: Vincent Stephen L. , Peters Alan , Tigges Johannes 
Published: February 2005

AbstractA light and electron microscopic examination of area 17 of the visual cortex in well‐fixed young (5‐6 years) and old (25–35 years) rhesus monkeys was carried out to determine the effects of age on neurons. The analyses were made in a portion of area 17 on the lateral surface of the hemisphere just caudal to the lunate sulcus. Light microscopic measurements of the mean cortical depth in vertically oriented 1‐μ‐thick sections reveal no obvious thinning with age, and the mean diameters of neuronal nuclei do not change with age. On the basis of counts of neuronal profiles containing nuclei in 250‐μ‐wide strips of 1‐μ‐thick sections passing through the entire depth of the cortex, no significant neuronal loss could be detected. These findings are consistent with our electron microscopic observations on this area of the cortex, for in the old monkeys the neurons show little cytological evidence of advanced age beyond the presence of a few lipofuscin granules, although the neuropil contains some profiles of degenerating small‐caliber dendrites, myelinated axons, and a few axon terminals. Large vacuoles, some 10 μm or more in diameter, are present in the neuropil of the old animals. Some of these vacuoles appear to represent a late stage in the degeneration of myelinated axons, for they are bounded by a thin, laminated sheath. Other large vacuoles, of unknown origin, often contain membranous debris and have an attenuated limiting membrane. It is concluded that the cell bodies of neurons in area 17 of old rhesus monkeys do not show singificant structural changes due to age, although some of the neuronal processes in the neuropil are affected.
Foveal regions of bird retinas correlate with the aster of the inner nuclear layer
Authors: Inzunza Oscar , Bravo Hermes , Smith Ricardo L. 
Published: February 2005

AbstractA radiate specialization, the aster, has been found in whole‐mount retinas of birds and is associated to each one of the temporal and nasal fovea, with the one related to the convexiclivate nasal fovea more evident. This radial arrangement extends uniformly in all directions from the foveal pit. Transverse sections of the retina show that this structure is formed by bands of cells and bundles of fibers from the inner nuclear layer.
Acridine orange‐RNA fluorescence of maturing neurons in the perinatal rat brain
Authors: Topaloglu Haluk , Sarnat Harvey B. 
Published: February 2005

AbstractCytoplasmic RNA was demonstrated in neurons of the developing rat brain using acridine orange (AO) as a histochemical marker. Fetuses of 18 days and postnatal rats of 1, 7, 14, and 21 days as well as adults several months old were studied. Neuroblasts of the germinal matrix exhibited minimal or no orange‐red AO‐RNA fluorescence, but immature nerve cells in migration within the cerebral hemispheres of the rat showed a weak but definite orange colour. This finding contrasts with the absence of AO‐RNA fluorescence in migrating human neuroblasts. Neurons of the neocortical plate showed uniformly strong fluorescence. In the hippocampus, the most pronounced increase in AO‐demonstrated RNA was in pyramidal and granule cells during the first postnatal week. The cerebellum showed a paradoxically stronger fluorescence of granule cells in the 18‐day fetus than at birth, and almost no AO‐RNA fluorescence of granule cells at 21 days of age or in adults. Motor neurons showed the strongest fluorescence of all neurons. It is likely that the increase in cytoplasmic RNA in neurons corresponds to the onset of neurotransmitter biosythesis, but transitory fetal neuropeptides may explain stronger fluorescence of some neurons in young individuals. The reliable and simple AO method provides a supplementary means of studying one aspect of neuronal maturation.