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R Anadón

Publications and source records attributed to R Anadón.

At least 73 records · Page 4Linked to original sources
PubMed1992

GOLGI cells of the cerebellum of the dogfish, Scyliorhinus canicula (elasmobranchs): a GOLGI and ultrastructural study.

GOLGI cells of the dogfish cerebellum were studied using both GOLGI methods and electron microscopy. The arborization of their dendrites and axonal processes is limited to the granular layer, which in this species forms characteristic granular eminences. The dendrites are rather simple. However, the various axons of a GOLGI cell form a dense plexus of thin beaded processes whose complexity approaches that observed in the mammalian cerebellum. Electron microscopy shows that the GOLGI cells are medium-sized neurons whose processes contact cerebellar glomerulus of the granular layer. The GOLGI cell perikarya are also contacted by mossy fibres.

Animals↗
PubMed1992

Light- and electron microscopic study of oligodendrocytes in the lateral line area of the medulla in Chelon labrosus (Teleostei).

The oligodendrocytes of the medullary lateral line area of the teleost Chelon labrosus were studied with light and electron microscopy. Oligodendrocytes are sharply differentiated from neurons or other class of glia cells from their ultrastructural characteristics. The three subtypes of oligodendrocytes (light, medium and dark) that have been recognized are not homogeneously distributed but have preferential locations related to the size of nearby myelinated fibres. No perineuronal oligodendrocytes are present in this medullary center. Oligodendrocytes show a variety of dense bodies, sometimes of bizarre shapes, in addition to characteristic mitochondria and endoplasmic reticulum. Three types of intercellular junctions were observed in these cells: gap junctions, tight junctions and puncta adhaerentia. Gap junctions and puncta adhaerentia link oligodendrocyte somata and astrocytic processes. Tight junctions were observed both between oligodendrocytes and between oligodendrocytes and astrocytic processes. The significance of these results is discussed in relation to the maturation and function of oligodendrocytes and the characteristics of fish brains.

Animals↗
PubMed1992

The structure and development of the 'plana semilunata' of the labyrinth of the trout.

Five plana semilunata consisting of tall epithelial cells were found in the semicircular canal ampullae of the trout labyrinth. All these areas began to develop after hatching. Their cells were cuboid at fry stages and prismatic in juveniles and adults. Cell outlines were smooth, with no basal infoldings of the plasma membrane or apical microvilli. The cell nucleus occupied basal locations in juveniles but migrated centrally in adults. The most conspicuous organelle, the smooth endoplasmic reticulum, was continuous with a well-developed vacuolar system. These cells stored numerous glycogen granules. The ultrastructural features of the plana semilunata strongly suggest their involvement in endolymph secretion.

Animals↗
PubMed1991

Specialized presynaptic dendrites in the stratum cellulare externum of the optic tectum of an elasmobranch, Scyliorhinus canicula L.

Electron microscopy of the stratum cellulare externum of the optic tectum of an elasmobranch revealed the presence of two types of presynaptic dendrites in the neuropil as well as axo-dendritic synapses. In the dendro-dendritic or dendro-axonic synapses, the presynaptic process was a beaded dendrite. These findings support the view that the synaptic organization of the tectum in elasmobranchs is basically similar to that of higher vertebrates, rather than the classical opinion that it is less highly organized.

Animals↗
PubMed1991

The fine structure of lamellate cells in the brain of amphioxus (Branchiostoma lanceolatum, Cephalochordata).

The lamellate cells of amphioxus have round nuclei, and cytoplasm with many mitochondria and a large amount of glycogen. Each of these cells projects a highly modified, branched cilium into the central canal, where it characteristically forms lamellar structures. Primary branches and secondary lamellae often contain accessory microtubules that are not derived from the axonema. The functional and evolutionary significance of this cell type is discussed in relation to the ciliary photoreceptors found in other chordates.

Animals↗
PubMed1990

A freeze-fracture study of the soma membranes of monoaminergic neurons in the hypothalamic nucleus recessi posterioris of the rainbow trout (Salmo gairdneri Rich.).

Monoaminergic neurons in the hypothalamic nucleus recessi posterioris of the rainbow trout were studied by freeze-fracturing. The size and distribution of intramembrane particles in the nuclear and plasma membranes and the density of nuclear pores in the nuclear envelope were determined. The density of nuclear pores in these cells was significantly greater than in the non-granulated neurons of this nucleus. The density of IMPs in the P face of the inner nuclear membrane was significantly greater than in the P face of the outer nuclear membrane; however in the E faces the density is greater in the outer nuclear membrane but the differences are not statistically significant. In both membranes, the proportion of large particles (greater than 9.6 nm) was greater in the E than in the P faces. The coefficient of partition between the plasma membrane faces was 1.97 +/- 0.24 while in non-granulated neurons was 4.45 +/- 0.51. There are significant differences among these values. Interestingly, the coefficient of partition of the plasma membrane in monoaminergic neurons was lesser than in some other types of neurons. Postsynaptic areas or other membrane specializations were not found on the cell body plasma membrane, which corroborates the results of conventional transmission electron microscopy.

Animals↗
PubMed1990

The development of the diencephalon of the rainbow trout (Salmo gairdneri Richardson). Thalamus and hypothalamus.

This article describes a study of the development of the thalamus and hypothalamus of the rainbow trout from the embryo to the juvenile fish. The areas from which the various nuclei derived are reported together with the order of their appearance, the earliest being the nucleus geniculatus lateralis, the nucleus pretectalis, the nucleus of the torus lateralis hypothalami, the nucleus preglomerulosus and the nucleus diffusus of the lateral lobes, all of were beginning to be distinguishable in 9 mm embryos. The lateral lobes of the hypothalamus developed mainly after hatching, and medial regions generally developed later than lateral areas, though certain periventricular structures appeared very soon. Cell proliferation persisted in 35 mm juveniles, especially in the walls of the lateral and posterior recesses.

Animals↗
PubMed1990

Freeze-fracture study of synaptic contacts in the neuropil of the tuberal hypothalamus of the rainbow trout (Salmo gairdneri Rich.).

Synaptic contacts in the neuropil of the tuberal hypothalamus of the rainbow trout were examined by the freeze-fracture technique. Three types of synaptic boutons, rounded, flattened and cup-shaped were characterized. In addition, a fourth type of nerve bouton did not exhibit membrane active sites. The round and cup-shaped synaptic boutons had vesicles of 50 nm in size, but flattened boutons contained both small (50 nm) and large sized (100 nm) vesicles. The active sites at the presynaptic membrane showed pits in the P-face and craters in the corresponding E-face; the postsynaptic membranes showed clusters of IMPs in both P- and E-faces. The postsynaptic cytoplasms had clustered particles directly apposed to the active sites corresponding to the postsynaptic density; sometimes, other particle clusters appeared in the presynaptic cytoplasm corresponding here to the presynaptic grid. There also were particles in the synaptic clefts that seemed to connect the pre- and postsynaptic membranes.

Animals↗
PubMed1990

Primary nerve projections and primary nuclei of the octaval nerve in the teleost Chelon labrosus. An HRP study.

The medullary nuclei and the primary projections of the octaval nerve have been studied in the Teleost Chelon labrosus, using argentic impregnations, NISSL stains and anterograde marking with peroxidase. The octaval nerve enters the medulla in two separate branches, the anterior and posterior. In its intramedullary traject it originates ascendent and descendent bundles. Its fibres end principally in the ventral part of the octavo-lateral area, with practically no overlapping with the terminals of the lateral line nerves. Three neuronal groups appear in this zone: the magnocellular vestibular nucleus, the tangential nucleus and the descending octaval nucleus. The magnocellular nucleus, formed by large neurons, receives thick fibres from the anterior branch of the octaval nerve. The tangential nucleus can be subdivided into three parts: Dorsal, intermediate and ventral depending upon its afferents and efferents. The dorsal part receives fibres from the posterior root of the octaval nerve. Fibres from the anterior branch end in the intermediate and ventral parts. The descending octaval nucleus, formed by polymorphous neurons, receives descending fibres from the octaval nerve branches. These fibres form a peculiar neuropil. A few fibres from both branches end in the medial nucleus of the octavolateral area. No primary projections of the octaval nerve have been found to the cerebellar crests.

Animals↗
PubMed1989

Ganglion cells and retinopetal fibers of the larval lamprey retina: an HRP ultrastructural study.

The ultrastructure of ganglion cells and centrifugal fibers of the larval lamprey retinas were studied using horseradish peroxidase (HRP) as a marker. Larval ganglion cells were found both in the inner nuclear layer and the inner plexiform layer of the differentiated retina, and also were present in the undifferentiated retina. Direct photoreceptor-ganglion cell contacts and the presence of centrifugal fibers are described for the first time in the lamprey. The centrifugal fibers contact directly with ganglion cells in this species.

Animals↗
PubMed1989

HRP study of the central components of the trigeminal nerve in the larval sea lamprey: organization and homology of the primary medullary and spinal nucleus of the trigeminus.

The medullary and spinal connections of the trigeminal nerve of larval sea lampreys Petromyzon marinus were studied by anterograde and retrograde HRP transport after application into the orbit. Three components were found, all of them ipsilateral: 1) The motor nucleus was undivided in the larva, and its neurons possessed a rich dendritic tree. The single motor root was well separated from the sensory root. 2) The descending root was laterally located, and its fibers ran compactly to spinal levels. 3) Most medullary and many rostral spinal dorsal cells were labeled. Dorsal cells, which were mostly multipolar, had numerous mutual contacts. Some dorsal cell processes contacted the fourth ventricle. The name "primary medullary and spinal nucleus of the trigeminal nerve" (PMSV) is proposed for these dorsal cells. Medullary dorsal cells were not labeled by applying HRP at the level of spinal nerves, but application to the vagus nerve did label some. The possible relationship of this nucleus with the mesencephalic trigeminal nucleus of jawed vertebrates is discussed.

Animals↗
PubMed1989

Some observations on the fine structure of the Rohde cells of the spinal cord of the amphioxus, Branchiostoma lanceolatum. (Cephalochordata).

The fine structure of ROHDE neurons of the amphioxus spinal cord has been studied using transmission electron microscopy. ROHDE cells are segmentary giant multipolar neurons with a large nucleus and nucleolus. The cytoplasm has a large amount of neurofilaments and numerous mitochondria, dictyosomes, and other organula. The ROHDE cells cross the central canal and send to it cilia and numerous microvilli. The cell surface is mostly covered by glial laminar processes which can also accompain to deep invaginations of the neuron plasma membrane. Chemical synapses were not found over the cell perikaryon or their dendrites, but contacts resembling "gap junctions" were common. Giant axons of ROHDE cells have large amounts of neurofilaments and are ensheathed by glial processes. ROHDE axons make small "en passant" synapses with other neuronal processes. The functional and evolutionary significance of these findings is discussed.

Animals↗
PubMed1987

The cerebellum of the dogfish, Scyliorhinus canicula: a quantitative study.

This quantitative study on neuron populations of the dogfish cerebellum reveals noticeable differences in cell size and density between its portions. A remarkable result was the large proportion of granule, Golgi and stellate cells as regards to the Purkinje cells, with some values higher than in many mammals. These results indicate that the complexity level of this Selachian cerebellum is not far from cerebella of some primitive mammals.

Animals↗
PubMed1987

The development of retina and the optic tectum of petromyzon marinus, L. A light microscopic study.

Morphological evolution of the retina and optic tectum along the stage of ammocoete, transformation and young adult of sea lampreys (Petromyzon marinus L.) was studied using light microscopic techniques and quantitative morphometry. A retinal differentiated zone surrounding the optic nerve head with a kind of differentiated photoreceptors is present through all the stages studied until stage VI of transformation and its extension is almost unchanged since 60 mm. larve. From this length larval retina grows by extension of the lateral undifferentiated retina, that in large larvae subdivides in a lateral germinal zone and an intermediate differentiating zone more thickened were ganglion cells and the optic fibre layer differentiate early. In the largest larvae outer and inner neuroblastic layers were also recognized in these intermediate zone except in the most lateral retina. Mitotic activity was observed both in germinal and intermediate differentiating zones near the optic ventricle. The germinal zone disappears after the formation of an irideal retina in transforming stages and, with the exception of the photoreceptor layer, retinal layers were differentiated since stage III along the neural retina. The photoreceptor layer develops in the early stage VI along the retina. Adult pattern of retinal pigmentation is found in these stage. A periventricular and a lateral region were recognizable in the optic tectum of the larval period. Tectum of large larvae shows an outline of laminar organization. In the stage III of transformation the tectal lamination is the same of the young adults: the periventricular cell layer is subdivided by fibre bands and in the lateral region a stratum cellulare centralis and a stratum cellulare et fibrosum externum were distinguishable. A comparison between retinal and tectal growths was made. Most retinal and tectal growth and differentiation occurs before adult photoreceptors develop.

Aging↗
PubMed1986

Ciliated neurons of the nucleus praeopticus magnocellularis and nucleus lateralis tuberis of an advanced teleost, Chelon labrosus (Risso, 1826).

Large groups of cilia are found on certain nucleus praeopticus magnocellularis (NPOM) and nucleus lateralis tuberis (NLT) neurons in the hypothalamus of a higher teleost, Chelon labrosus. They normally appear in an invaginated area of the perikaryon in the proximity of large numbers of synapsis buttons, and often close to unfenestrated capillaries. It is suggested that these ciliosynaptic groups act as osmoreceptors.

Animals↗
PubMed1985

Colonization antigens and haemagglutination patterns of human Escherichia coli.

The haemagglutinating properties of 223 (35 enterotoxigenic and 188 non-enterotoxigenic) Escherichia coli strains with nine erythrocyte types were investigated; 153 strains were also tested for beta-haemolysis and colicin production and for the presence of CFA/I, CFA/II, K88 and K99 antigens. A selected group of strains was also examined by electron microscopy to determine the presence of fimbriae or fibrils and to establish the relationship between these, the haemagglutinating properties and the presence of colonization antigens. Generally, the haemagglutinating patterns yielded by the same strains grown in Mueller Hinton broth and on CFA agar differed considerably. Mannose-sensitive haemagglutinating (MSHA) patterns were more homogeneous than mannose-resistant haemagglutinating (MRHA) patterns. Forty-seven percent of the non-enterotoxigenic MRHA+ strains were haemolytic while only 6% of the remaining strains were (chi2 correction = 34.01; p less than 0.001). CFA/I was only detected in the four enterotoxigenic MRHA+ strains which were positive only with human and calf erythrocytes when grown on CFA agar. CFA/II was detected in three of a total of six enterotoxigenic strains which were MRHA+ only with calf erythrocytes when grown on CFA agar. K88 and K99 antigens were not detected. All strains in which bacteria with fimbriae or fibrils were observed showed haemagglutinating activity. Thus, 18 (66.7%) of the 27 haemagglutinating strains grown on CFA agar showed fimbriae or fibrils while none of the 19 non-haemagglutinating strains did (chi2 correction = 18.10; p less than 0.001).

Agglutination Tests↗