Search results for " Plexiform"
showing 10 items of 26 documents
Synaptic ribbons, spheres and intermediate structures in the developing rat retina
1992
The present study was conducted to investigate the qualitative and quantitative development of synaptic bodies in retinae of Wistar rats during postnatal days 4-28. In addition, the effects of different light regimens and of eye pigmentation on SB numbers were studied. Synaptic bodies were counted and measured in the outer plexiform layer of retinal tissue fixed and processed by routine electron microscopical techniques. At postnatal days 4 and 5, retinae showed only few synaptic bodies. The main numerical development of synaptic bodies occurred between postnatal days 4 and 9, numbers remaining more or less constant thereafter. The intracellular location of synaptic ribbons changed from pre…
Tomographic reconstruction reveals the morphology of a unique cellular organelle, the aggregated macrotubules (Macrotubuli aggregati) of human retina…
2014
Abstract Horizontal cells of the human retina contain unique tubular organelles that have a diameter which is about 10 times larger than that of microtubules (∼230 nm). These macrotubuli in most cases form regular aggregates. Therefore we propose to introduce them as Macrotubuli aggregati in the Terminologia histologica. Tomographic investigation of the structures revealed that the walls of the tubules most probably consist of intermediate filaments running nearly parallel to each other and show somewhat regularly attached ribosomes on their inner and also outer surface. About 2% of the organelles exhibit double- to multiple layered walls and less than 1% resemble large scrolls. The tubules…
Strain differences in the ratio of synaptic body types in photoreceptors of the rat retina.
1993
In the retinal outer plexiform layer of seven different rat strains, synaptic bodies (SB) were counted and, according to their morphology, characterized as synaptic ribbons (SR), synaptic spheres (SS) or intermediate structures. It was found that absolute SB numbers showed relatively small variations while SR/SS ratios differed considerably between the strains investigated. These results are discussed with respect to retinal pigmentation and to formation and degradation, respectively, of synaptic ribbons.
PSA-NCAM immunocytochemistry in the cerebral cortex and other telencephalic areas of the lizard Podarcis hispanica: differential expression during me…
2002
The lizard medial cortex, a region homologous to the mammalian dentate gyrus, shows postnatal neurogenesis and the surprising ability to replace its neurons after being lesioned specifically with the neurotoxin 3-acetylpyridine. As the polysialylated form of the neural cell adhesion molecule (PSA-NCAM) is expressed during neuronal migration and differentiation, we have studied its distribution in adult lizards and also during the lesion-regeneration process. In the medial cortex of control animals, many labeled fusiform somata, presumably corresponding to migratory neuroblasts, appeared in the inner plexiform layer. There were also scattered immunoreactive granule neurons in the cell layer.…
Intrinsic organization of the medial cerebral cortex of the lizardLacerta pityusensis: A golgi study
1987
The morphology of cells and the organization of axons were studied in Golgi-Colonnier and toluidine blue stained preparations from the medial cerebral cortex of the lizard Lacerta pityusensis. In the medial cortex, six strata were distinguished between the superficial glial membrane and the ependyma. Strata I and II formed the outer plexiform layer, stratum III formed the cellular layer, and strata IV go VI the inner plexiform layer. The outer plexiform layer contained smooth bipolar neurons; their dendrites were oriented anteroposteriorly and their axons were directed towards the posterior zone of the brain. Five neuronal types were observed in the cellular layer. The spinous pyramidal neu…
Divergent distribution of cytoglobin and neuroglobin in the murine eye
2005
Neuroglobin (Ngb) and cytoglobin (Cygb) are two vertebrate globins with yet poorly defined functions. Previous studies had demonstrated a high expression level of neuroglobin in the mammalian retina, being in line with a respiratory function. Here we show that in the mouse eye, cytoglobin is localised in fibroblasts of the ciliary processes and the choroidea. In the neuronal retina, cytoglobin is expressed in a subset of neurons of the ganglion cell and inner nuclear layers. Cytoglobin is also present in the inner plexiform layer, but absent from the pigment cells. Neuroglobin is localised in photoreceptor inner segments, the plexiform layers and the ganglion cell layer. The divergent distr…
AAV-Mediated Clarin-1 Expression in the Mouse Retina: Implications for USH3A Gene Therapy
2015
Usher syndrome type III (USH3A) is an autosomal recessive disorder caused by mutations in clarin-1 (CLRN1) gene, leading to progressive retinal degeneration and sensorineural deafness. Efforts to develop therapies for preventing photoreceptor cell loss are hampered by the lack of a retinal phenotype in the existing USH3 mouse models and by conflicting reports regarding the endogenous retinal localization of clarin-1, a transmembrane protein of unknown function. In this study, we used an AAV-based approach to express CLRN1 in the mouse retina in order to determine the pattern of its subcellular localization in different cell types. We found that all major classes of retinal cells express AAV…
Impaired formation of the inner retina in an AChE knockout mouse results in degeneration of all photoreceptors
2004
Blinding diseases can be assigned predominantly to genetic defects of the photoreceptor/pigmented epithelium complex. As an alternative, we show here for an acetylcholinesterase (AChE) knockout mouse that photoreceptor degeneration follows an impaired development of the inner retina. During the first 15 postnatal days of the AChE-/- retina, three major calretinin sublaminae of the inner plexiform layer (IPL) are disturbed. Thereby, processes of amacrine and ganglion cells diffusely criss-cross throughout the IPL. In contrast, parvalbumin cells present a nonlaminar IPL pattern in the wild-type, but in the AChE-/- mouse their processes become structured within two 'novel' sublaminae. During t…
Identification of a β-Dystroglycan Immunoreactive Subcompartment in Photoreceptor Terminals
2005
PURPOSE Mutations in the dystrophin-associated glycoprotein complex (DGC) cause various forms of muscular dystrophy. These diseases are characterized by progressive loss of skeletal muscle tissue and by dysfunctions in the central nervous system (CNS). The CNS deficits include an altered electroretinogram, caused by an impaired synaptic transmission between photoreceptors and their postsynaptic target cells in the outer plexiform layer (OPL). The DGC is concentrated in the OPL but its exact distribution is controversial. Therefore, the precise distribution of beta-dystroglycan, the central component of the DGC, within the OPL of the mature chick retina, was determined. METHODS Double immuno…
Retinal ganglion cells projecting to the optic tectum and visual thalamus of lizards.
2002
Retinal ganglion cells projecting to the optic tectum and visual thalamus have been investigated in the lizard, Podarcis hispanica. Injections of biotinylated dextran-amine in the optic tectum reveal seven morphological cell varieties including one displaced ganglion cell type. Injections in the visual thalamus yield similar ganglion cell classes plus four giant ganglion cells, including two displaced ganglion cell types. The present study constitutes the first comparison of tectal versus thalamic ganglion cell types in reptiles. The situation found in lizards is similar to that reported in mammals and birds where some cell types projecting to the thalamus are larger than those projecting t…