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

Scanning Electron Microscope, Freeze Etching and Glycosaminoglycan Cytochemical Studies of the Cerebellar Climbing Fiber System

Mouse and teleost fish cerebelli were processed by the freeze-fracture methods for scanning and transmission electron microscopy in order to study the three-dimensional morphology and intramembrane features of climbing fiber-Purkinje spine synapses. In addition, Alcian Blue and ruthenium chloride stainings were applied to mouse cerebellar tissue to investigate the polyanion composition of these excitatory synapses under the transmission electron microscope. In the granular layer, tendril and glomerular collaterals of climbing fibers were observed. In the molecular layer climbing fibers exhibited a characteristic crossing-over or arborescence pattern type of bifurcation, Scheibel\u27s collaterals and multiple thorn synapses with Purkinje spiny dendrites. At the synaptic active zones of climbing fiber-Purkinje spine synapses the freeze-etching replicas showed focal aggregates of intramembrane particles at the E and P faces of the pre-and past-synaptic membranes. Membrane protuberances and pits were also observed at the pre-synaptic membrane. Ultracytochemical study of the climbing fiber synaptic varicosities revealed an Alcian Blue and ruthenium chloride positive material which appeared at the axoplasm surrounding the synaptic vesicles, at the pre-and post-synaptic densities and in the synaptic cleft. The axoplasmic material was sensitive to testicular hyaluronidase, therefore it would correspond to glycosaminoglycans (hyaluronic acid and/or chondroitin sulphates), which have been earlier reported in other cerebellar excitatory systems as those of mossy fiber-granule cell and parallel fiber-Purkinje dendritic spine

Contribution of Conventional and High Resolution Scanning Electron Microscopy and Cryofracture Technique to the Study of Cerebellar Synaptic Junctions

The cerebelli of teleost fishes, primates and humans were processed for conventional and high resolution scanning electron microscopy (SEM) to study the outer and inner surfaces of axo-dendritic, glomerular and axo-somatic synapses. The cryofracture technique, either by slow or fast freezing, exposed the hidden neuronal surfaces of synaptic connections, selectively removing the glial ensheathment. Axo-dendritic junctions of climbing fibers and Golgi axonal ramifications were studied in gold-palladium and chromium coated samples. Chromium coating showed different mass density and topographic contrast between axonal and dendritic profiles. Conventional SEM of cryofractured glomerular synapses exhibited the outer surface view of en passant mossy fibers glomeruli, in which granule cell dendrites appear surrounding the afferent mossy fibers. The cryo-fracture method also exposed the axosomatic contacts of basket axonal collaterals upon the Purkinje cell somatic surface and the climbing fiber bulbous endings upon tertiary Purkinje dendrites. Field emission high resolution SEM of parallel fiber-Purkinje cell dendritic spines showed the inner organization of pre-synaptic endings and the three-dimensional structure of the synaptic membrane complex. The spheroidal synaptic vesicles appeared embedded in a homogeneous axoplasmic substance. Round subunits, 15-20 nm in diameter, were observed as intrinsic components of the post-synaptic membrane and associated with the post-synaptic density. High resolution SEM offers SE-I images comparable in resolution to thin section electron microscopy and freeze-etching replicas at intermediate magnifications

Scanning Electron Microscopy of Vertebrate Cerebellar Cortex

In this study, the Golgi method for light microscopy, transmission and conventional scanning electron microscopy, the ethanol-cryofracturing technique, the freeze-fracture method for SEM, and the freeze-etching method have been used in conjunction to analyze the three-dimensional cytoarchitectonic arrangement and intracortical circuits of vertebrate cerebellar cortex. Approximately more than 100 specimens of mice, rat, teleost fishes and human cerebelli were processed by the above mentioned techniques. A chronological review of other methods for studying hidden surfaces of cerebellar nerve cell has been also described. The three-dimensional morphology, outer and inner surfaces of granule, Golgi, Purkinje and stellate cells were reviewed by means of a correlative and comparative study. The cerebellar circuits formed by mossy and climbing fibers with granule cell dendrites and Purkinje cell-granule cell synapses have been traced by ethanol-cryofracturing technique, freeze-fracture method for SEM and freeze-etching technique. These findings have been correlated with previous light and electron microscope findings published in the last century. Some advantages and limitations of each method are pointed out. The review emphasizes the paramount importance of correlating light microscope Golgi method with ethanol-cryofracturing and slicing techniques for SEM. The correlation between freeze-fracture method for SEM and freeze-etching technique provides a new approach for studying three-dimensional morphology of nerve cells at cellular and macromolecular levels. This modern methodology of three-dimensional analysis offers new potential areas for future experimental investigation in embryology and pathology of the central nervous system

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

Veterinaria en Córdoba: 150 años

La presente comunicación debe ocuparse de los aspectos del ejercicio y enseñanza del arte y ciencias veterinarias en el Mediodía de la Península Ibérica, en Homenaje al 150 aniversario del establecimiento de los estudios de Veterinaria en Córdoba, única ciudad andaluza donde se imparten tales estudios y que desde la reciente creación de la Facultad de Veterinaria de Murcia (1982) el área de influencia de la Facultad de Veterinaria de Cáceres (1983, Universidad de Extremadura), comparte con ellas tales responsabilidades en toda el área meridional

Contribución al estudio de la anemia infecciosa en los équidos

Comunicación presentada al XVIII Congreso Luso-Español de la Asociación para el Progreso de las Ciencias, Córdoba, 3-10, octubre, 194

Epifisiolisis de cadera

a epifisiolisis de cadera, aún no siendo una enfermedad muy frecuente, sigue siendo una de las afecciones de la cadera del adolescente que más contribuye al desencadenamiento de la degeneración artrósica. La etiopatogenia es desconocida. Sólo en algunos casos existen alteraciones endocrinas que pudieran alterar la resistencia de la fisis ante fuerzas de carga, la gran mayoría únicamente parecen evidentes factores puramente mecánicos y los recientes estudios anatomopatológicos así lo demuestran. El diagnóstico clínico, en su etapa inicial, sigue siendo la pieza clave para obtener un buen resultado. Por ello se insiste en la aparición de signos radiológicos precoces y que deben confirmarse mediante una adecuada exploración radiográfica. El tratamiento consiste en detener el posible desplazamiento epifisario, lo cual se consigue mediante la fijación de la epífisis, es reservando las osteotomías intra-articulares para los casos con desplazamiento grave. La mejoría en la técnica quirúrgica e indicaciones más precisas, han hecho bajar el porcentaje de complicaciones, en lo que se refiere a la condrolisis y necrosis. Hace falta más investigación para averiguar su etiopatogenia y llegar a conseguir la detección precoz de la enfermedad.Slipped capital femoral epiphysis is a relative infrequent entity but it is responsible for early degenerative arthritis. The aetiology still remains unknown. Only in a few cases, endocrine factors decreasing the resistance of the physis to shear strength can be detected. In most patients, mechanical factors seem to be implicated, and recent pathological studies have confirmed this hypothesis. At early stages, the clinical diagnosis continues to be essential in order to obtain a good outcome. The detection of radiological findings has been said to be crucial in the first stage of the disease, and therefore an adequate examination should be performed. The goal of treatment is to stop slipping of the femoral epiphysis which can be achieved by internal fixation with techniques. Intraarticular osteotomies should be reserved for cases with great displacement. The improvement of surgical techniques and a more precise indications have contributed to a lower rate of complications such as condrolysis and femoral head necrosis. Understanding of the aetiology and signs for early detection of the disease are demanding further research