66 research outputs found
Electron Microscopy and Glycosaminoglycan Histochemistry of Cerebellar Stellate Neurons
The stellate neurons of the cerebellar molecular layer have been mostly studied by light and transmission electron microscopy (TEM). However, the freeze-fracture scanning electron microscopy (SEM) and glycosami noglycan histochemistry of these inhibitory microneurons have not been explored thus far. The freeze-etching technique, the freeze-fracture method for SEM and the conventional techniques for TEM were applied to cerebellar samples of Swiss albino mice and Arius spixii teleost fishes. In addition, Alcian Blue (AB) staining was applied to mouse cerebellar tissue in order to study glycosaminoglycan histochemistry. At the SEM level, the stellate neurons showed a short axonal plexus extending to the nearby secondary and tertiary Purkinje dendritic branches, and 2 to 4 conical dendrites receiving typical axo-dendritic synapses on their shafts. The fractured stellate neurons showed compact nuclear heterochromatin masses and the three dimensional interrelationship of ER and Golgi complex (Novikoff\u27s GERL complex). The surface of the scarce endoplasmic reticulum was observed as strands extending from the nuclear envelope to the inner surface of the plasma membrane. At the TEM level, axosomatic endings of parallel and climbing fibers were distinguished. The cytochemical study revealed a homogeneous alcianophylic cytoplasmic substance, sensitive to hyaluronidase. This was particularly evident around and within the nucleus. The AB results indicated the presence of hyaluronic acid. A complex neuropil formed by Purkinje cell spiny branches, bundles of parallel fibers, spine synapses and Bergmann astrocytic cytoplasm was seen adjacent to the stellate neurons
Three-Dimensional Morphology of Cerebellar Protoplasmic Islands and Proteoglycan Content of Mossy Fiber Glomerulus: A Scanning and Transmission Electron Microscope Study
The present review summarizes the outer and inner surface features of mossy fiber glomeruli in vertebrate cerebellar granular layer as seen by conventional scanning electron microscopy (SEM) and SEM freeze-fracture method. The intracortical trajectory of mossy fibers and their synaptic contacts with granule cell dendrites were traced by the slicing and freeze-fracture techniques revealing the radial distribution of granule cell dendrites around the central mossy rosette. The en passant nature of mossy fiber synaptic contacts and the participation of Golgi cell axonal ramifications were demonstrated. The results obtained were compared with available light and transmission electron microscopy data. The freeze-etching technique disclosed the true extension of glomerular neuroglial investment. The proteoglycan content of mossy fiber rosette has been also studied by Alcian Blue staining, enzymatic digestion with testicular hyaluronidase and neuraminidase and Os-DMEDA staining method resulting in the presence of an electron dense material at the mossy fiber axoplasmic matrix and some synaptic vesicles, pre-and postsynaptic densities and cleft substance. The axoplasmic material appears to be constituted by proteoglycans with hyaluronic acid or chondroitin sulphate in their composition. The possible role of proteoglycans in synaptic functions is also discussed. Scanning electron microscopy is a promising methodology for analysis of short intracortical circuits and for the study of complex multisynaptic arrangements
Three-Dimensional Morphological Analysis of Nerve Cells by Scanning Electron Microscopy. A Review
The present review provides a rational and new approach to study the three-dimensional morphology of nerve cells in situ at both cellular and macromolecular levels, by means of conventional (SEM) and high resolution scanning electron microscopy (HRSEM). The slicing and ethanol-cryofracturing methods, the freeze-fracture SEM method and tissue preparation for HRSEM have been described. Nerve cell outer surface, axon hillock and initial axon segment, axonal collateral ramifications and dendritic processes were visualized either by the slicing technique or the cryofracture method displaying neuronal geometry in situ. The cleavage plane occurred at the satellite neuroglial sheath exposing somatic hidden surfaces of unfractured neurons and the outer surface synaptic morphology. En passant axospinodendritic junctions, glomerular synapses and axosomatic contacts were examined in vertebrate cerebellar cortex. The SEM and cryofracture techniques could be applied as the Golgi light microscope technique to trace short neuronal circuits. The nerve cell inner surfaces were also studied by means of freeze-fracture SEM method and HRSEM. HRSEM provided information at both cellular and macromolecular levels. Topographic contrast of glycocalyx-like substance, synaptic junctions and myelin sheath was obtained. A comparison could be made between Au/Pd and chromium coated nerve cells. HRSEM provided SE-1 images of lipoprotein domains at the myelin sheath and globular subunits at the level of the postsynaptic membrane. This latter observation offers new potential areas for future studies on receptor morphology
Electron Bernstein waves emission in the TJ-II Stellarator
Taking advantage of the electron Bernstein waves heating (EBWH) system of the
TJ-II stellarator, an electron Bernstein emission (EBE) diagnostic was
installed. Its purpose is to investigate the B-X-O radiation properties in the
zone where optimum theoretical EBW coupling is predicted. An internal movable
mirror shared by both systems allows us to collect the EBE radiation along the
same line of sight that is used for EBW heating. The theoretical EBE has been
calculated for different orientations of the internal mirror using the TRUBA
code as ray tracer. A comparison with experimental data obtained in NBI
discharges is carried out. The results provide a valuable information regarding
the experimental O-X mode conversion window expected in the EBW heating
experiments. Furthermore, the characterization of the radiation polarization
shows evidence of the underlying B-X-O conversion process.Comment: 21 pages, 14 figure
Exponentially small heteroclinic breakdown in the generic Hopf-zero singularity
In this paper we prove the breakdown of an heteroclinic connection in the
analytic versal unfoldings of the generic Hopf-Zero singularity in an open set
of the parameter space. This heteroclinic orbit appears at any order if one
performs the normal form around the origin, therefore it is a phenomenon
"beyond all orders". In this paper we provide a formula for the distance
between the corresponding stable and unstable one dimensional manifolds which
is given by an exponentially small function in the perturbation parameter. Our
result applies both for conservative and dissipative unfoldings
Clinical study of cervicogenic headache
The cervicogenic headache was studied to get a deeper insight into the pathogenetic mechanisms, and clinical
presentation forms. Material and Methods. Eleven female patients, ranging from 34 to 81 years-old, with cervicogenic headaches, were studied and correlated with NMR images of the cervical spine. Results. Intense neck pain irradiated to parietal, occipital, temporal regions, and shoulders were correlated with NMR images of the degenerated cervical spine. Also, lumbar spine pathology, osteoporosis, gallstones, and cholecystitis were found. The following associated neurological, neurobehavioral, and metabolic diseases comorbidities were observed, such as blood hypertension, diabetes,
obesity, hypothyroidism, partial epilepsy, tremor, familial stress, memory, sleep disorders, and dizziness. Also, we found mixed cervicogenic headaches and migraines in 50% of cases studied. Conclusion. The headache and the associated images of cervical pathology have been clinically interpreted as cardinal signs of cervicogenic headache. A mixed cervicogenic mixed type was observed
Micro-computed tomography and histology to explore internal morphology in decapod larvae
Traditionally, the internal morphology of crustacean larvae has been studied using destructive
techniques such as dissection and microscopy. The present study combines advances in microcomputed
tomography (micro-CT) and histology to study the internal morphology of decapod larvae,
using the common spider crab (Maja brachydactyla Balss, 1922) as a model and resolving the individual
limitations of these techniques. The synergy of micro-CT and histology allows the organs to be easily
identified, revealing simultaneously the gross morphology (shape, size, and location) and histological
organization (tissue arrangement and cell identification). Micro-CT shows mainly the exoskeleton,
musculature, digestive and nervous systems, and secondarily the circulatory and respiratory systems,
while histology distinguishes several cell types and confirms the organ identity. Micro-CT resolves a
discrepancy in the literature regarding the nervous system of crab larvae. The major changes occur in
the metamorphosis to the megalopa stage, specifically the formation of the gastric mill, the shortening
of the abdominal nerve cord, the curving of the abdomen beneath the cephalothorax, and the
development of functional pereiopods, pleopods, and lamellate gills. The combination of micro-CT and
histology provides better results than either one alone.Financial support was provided by the Spanish Ministry of Economy and Competitiveness through the INIA
project (grant number RTA2011-00004-00-00) to G.G. and a pre-doctoral fellowship to D.C. (FPI-INIA)
Towed sensors and hydrodynamic model evidence the need to include submarine in coastal lagoons water balance, the Mar Menor example (SE Spain).
The use of radionuclide tracers to determine the submarine groundwater
discharges has been used widely but in areas highly anthropized as the Mar Menor
surface water tributaries can carry high concentration of Radon, making very difficult
to distinguish the radionuclide origin. In this paper a combined approach was
applied in the Mar Menor, a towed system was designed to enable the continuous
measurement of Radon and Nitrate and a hydrodynamic model was used to establish
the influence areas of the surface discharge to the lagoon. The areas were Radon
was detected and was out from the area located with the model could be establish
as a submarine groundwater discharge point.Peer Reviewe
Calculation of the bootstrap current profile for the TJ-II stellarator
Calculations of the bootstrap current for the TJ-II stellarator are
presented. DKES and NEO-MC codes are employed; the latter has allowed, for the
first time, the precise computation of the bootstrap transport coefficient in
the long mean free path regime of this device. The low error bars allow a
precise convolution of the monoenergetic coefficients, which is confirmed by
error analysis. The radial profile of the bootstrap current is presented for
the first time for the 100_44_64 configuration of TJ-II for three different
collisionality regimes. The bootstrap coefficient is then compared to that of
other configurations of TJ-II regularly operated. The results show qualitative
agreement with toroidal current measurements; precise comparison with real
discharges is ongoing
Ipomoea batatas (L.) Lam.: a rich source of lipophilic phytochemicals
The lipophilic extracts from the storage root of 13 cultivars of sweet potato (Ipomoea batatas (L.) Lam.) were evaluated by gas chromatography-mass spectrometry with the aim to valorize them and offer information on their nutritional properties and potential health benefits. The amount of lipophilic extractives ranged from 0.87 to 1.32% dry weight. Fatty acids and sterols were the major families of compounds identified. The most abundant saturated and unsaturated fatty acids were hexadecanoic acid (182-428 mg/kg) and octadeca-9,12-dienoic acid (133-554 mg/kg), respectively. β-Sitosterol was the principal phytosterol, representing 55.2-77.6% of this family, followed by campesterol. Long-chain aliphatic alcohols and α-tocopherol were also detected but in smaller amounts. The results suggest that sweet potato should be considered as an important dietary source of lipophilic phytochemicals.info:eu-repo/semantics/publishedVersio
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