SEARCH · PubMed Health

Results for “Retinal Horizontal Cells”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 901 records · Page 50Linked to original sources

PubMed1999

Functional anatomy of the photoreceptor and second-order cell mosaics in the retina of Xenopus laevis.

Mosaics of photoreceptors, and horizontal and bipolar cells of the Xenopus laevis retina were studied in whole-mount preparations applying lectin-cytochemical, immunocytochemical and intracellular labeling techniques. The combined density of all photoreceptor types was about 13700/mm2, of which rods represented 53%. Of the cones, the large long-wavelength-sensitive (86% of all cones) and the miniature ultraviolet-wavelength-sensitive (4%) ones could be labeled with peanut agglutinin, whereas the large short-wavelength-sensitive (10%) cones remained unlabeled. There were no significant regional differences in photoreceptor distribution. Bipolar cells were selectively labeled with antibodies against calretinin. Their density was between 4000 and 6000 cells/cm2, with slightly elevated numbers in the superior nasal quadrant. Two types of horizontal cell were injected intracellularly. The luminosity-type cells were more frequent (approximately 1000 cells/mm2) than the chromaticity cells (approximately 450 cells/mm2). The dendritic field size of the latter cell type was threefold bigger than that of the luminosity cells. The coverage factors were estimated to be 3.3 for the luminosity cells and 5.2 for the chromaticity cells. The luminosity cells contacted all photoreceptor types, whereas chromatic horizontal cells received their inputs from the short-wavelength-sensitive cones and from some, but not all, rods. Luminosity cells encounter about 50-60 potential synaptic partners within their dendritic fields, whereas chromatic horizontal cells only about 20. Chromatic horizontal cells form multiple synaptic contacts with the short-wavelength-sensitive cones. The results indicate that the overall photoreceptor to bipolar and bipolar to ganglion cell convergence in Xenopus retina is similar to that in the central retinal specialized regions of mammals, predicting comparable spatial resolutions.

Animals↗

PubMed2002

Somatostatin (SRIF) and SRIF receptors in the mouse retina.

In the retina, somatostatin (SRIF) acts as a neuromodulator by interacting with specific SRIF subtype (sst) receptors. The aim of this study was to detect mRNAs for sst(1-5) receptors by semiquantitative RT-PCR and to determine the cellular localization of either SRIF or individual SRIF receptor immunoreactivities. Size, density and absolute number of immunolabeled somata were measured using computer-assisted image analysis. With RT-PCR we found that all five sst receptor mRNAs were expressed, with highest levels of sst(2) and sst(4) receptors. SRIF immunolabeling was localized to sparse-occurring amacrine cells in the inner nuclear layer (INL) and to displaced amacrine cells in the ganglion cell layer (GCL). sst(2A) receptors were localized to protein kinase- (PKC) immunoreactive (IR) rod bipolar cells, calbindin- (CaBP-) IR horizontal cells, tyrosine hydroxylase- (TH-) IR amacrine cells and glycinergic amacrine cells. None of the sst(2A)-IR amacrine cells were found to express parvalbumin (PV) immunoreactivity. sst(4) receptor immunolabeling was localized to CaBP-IR and CaBP-non-IR cells in the GCL that originated long process bundles in the GC axon layer. These cells were not observed after optic nerve transection and they were therefore interpreted as ganglion cells. Quantitative analysis showed that all of the PKC-IR rod bipolar cells, CaBP-IR horizontal cells, and TH-IR amacrine cells and 5% of the glycinergic amacrine cells expressed sst(2A) receptors. In addition, 4-6% of the putative ganglion cells expressed sst(4) receptors. The localization of SRIF to sparse-occurring retinal neurons, together with the widespread expression of sst(2A) and sst(4) receptors suggests that SRIF acts at multiple levels of retinal circuitry. These results provide a database for investigations of the functional retinal networks in mice with genetic alterations of somatostatinergic transmission.

Amacrine Cells↗

PubMed1992

Squint-induced Modification of Visual Receptive Fields in the Lateral Suprasylvian Cortex of the Cat: Binocular Interaction, Vertical Effect and Anomalous Correspondence.

In this study, we investigated the receptive field properties of single cells in the lateral suprasylvian area of strabismic cats. More than three times as many cells could be driven by the non-operated than by the operated eye. Many more cells could be activated by the contralateral than by the ipsilateral eye. In both area 17 and the lateral suprasylvian area, more cells preferred horizontal rather than vertical or oblique orientations ('vertical effect'). In addition, a small percentage of cells in the lateral suprasylvian area showed an adaptive shift of spatial coordinates; this shift could provide the neural basis of anomalous retinal correspondence.

Journal Article↗

PubMed1995

Zinc downmodulates thf GABAc receptor current in cone horizontal cells acutely isolated from the catfish retina.

1. We studied the effect of zinc on the gamma-aminobutyric acid-C (GABAC) receptor in acutely isolated catfish cone horizontal cells using the whole cell patch-clamp technique. 2. GABA activates the GABAC receptor with a half-activation concentration (EC50) of 2.99 microM. The Hill coefficient is 1.32. Desensitization of the receptor is evident when GABA concentration is > 3 microM. 3. Zinc downmodulates the GABAc receptor current, elicited by 30 microM GABA, with a half-inhibition concentration (IC50) of 8.20 microM. 4. The inhibition of zinc is both competitive and noncompetitive. In the presence of 10 microM zinc, the maximum GABA response was reduced to approximately 60 percent of control and the EC50 increased to 17.32 microM, whereas the Hill coefficient (1.39) was not significantly altered. 5. The steady-state block by zinc is virtually voltage independent. 6. These results suggest that the GABAC receptor of horizontal cells can be modulated by endogenous zinc found in photoreceptors.

Animals↗

PubMed2000

The retinal determination gene, dachshund, is required for mushroom body cell differentiation.

The dachshund gene of Drosophila encodes a putative transcriptional regulator required for eye and leg development. We show here that dachshund is also required for normal brain development. The mushroom bodies of dachshund mutants exhibit a marked reduction in the number of (&agr;) lobe axons, a disorganization of axons extending into horizontal lobes, and aberrant projections into brain areas normally unoccupied by mushroom body processes. The phenotypes become pronounced during pupariation, suggesting that dachshund function is required during this period. GAL4-mediated expression of dachshund in the mushroom bodies rescues the mushroom body phenotypes. Moreover, dachshund mutant mushroom body clones in an otherwise wild-type brain exhibit the phenotypes, indicating an autonomous role for dachshund. Although eyeless, like dachshund, is preferentially expressed in the mushroom body and is genetically upstream of dachshund for eye development, no interaction of these genes was detected for mushroom body development. Thus, dachshund functions in the developing mushroom body neurons to ensure their proper differentiation.

Animals↗

PubMed2000

[Apoptosis in ischemic optic neuropathy].

PURPOSE: A study of human eyes with non-arteritic ischaemic optic neuropathy (NAION) to determine whether there is apoptosis and whether this is accompanied by cell necrosis mechanisms. METHODS: Transmission electron microscopy was used to examine the retinas of eyes with NAION. RESULTS: There was a large number of apoptotic ganglion cells. The lesion was not confined to this retinal layer but also affected the inner nuclear layer, where Müller glia with fagocytic capacity were detected. In this layer apoptosis alternated with necrosis in all of the cell types existing in this level: bipolar cells, amacrine cells and horizontal cells. The outer nuclear layer can also suffer lesion, essentially by induction of choroid ischaemia to that level. Again, apoptosis was observed at the photoreceptor level, where there was also death by heterophagy, although this was less frequent. CONCLUSIONS: The behaviour of NAION in humans is similar to that found in experimental models. Apoptosis mechanisms develop, alternating with cell necrosis in the nuclear level.

Aged↗

PubMed1996

[Density distribution of dopaminergic neurons in the retina of a marine teleost, Thamnoconus (Navodon) modestus].

By means of tyrosine hydroxylase immnocytochemical detection, regional densities of dopaminergic (DAergic) neurons were measured in 6 whole-mounted retinas of a marine teleost, Thamnoconus (Navodon) modestus. Isodensity lines of DAergic cells in the right retina were drawn to make a contour map. Depending upon the range of cell densities, the retinal field was divided into 3 regions: zone A, containing more than 300 per mm square; zone B, from 200 to 299; and zone C, below 200. Zone A was located in the small temporal (A1) and nasal (A2) areas as well as in the peripheral margin (A3). Zone B formed a horizontal streak-like band between regions A1 and A2. Low density areas (C) were located dorsally or ventrally to zone B. Where the densities were higher, soma sizes appeared to be smaller. DAergic neurons in the peripheral zone A3 were bipolar and the dendrites ran parallel to the retinal margin, while DAergic neurons in the other zones were multipolar and the dendrites ran in various directions. The presence of the small temporal (A1) and nasal areas (A2) with high densities of DAergic neurons, as well as the streak-like area (B) with a relatively high density, may correspond to similar areas in the isodensity contour map of ganglion cells.

Animals↗

PubMed1994

Horizontal cells and cone photoreceptors in human retina: a Golgi-electron microscopic study of spectral connectivity.

Connections of the three human horizontal cell (HC) types with overlying cone pedicles have been studied via electron microscopy (EM). Because blue cones (B-cones) can be recognized on distinctive morphological criteria, we could determine their presence by light microscopy (LM) in the mosaic overlying HC dendritic trees. Then we could confirm the presence or absence of dendritic contacts to B-cone pedicles by examining EM serial sections and making reconstructions of examples of the three HC types. Three HI cells have been reconstructed. Their dendritic terminals ended as lateral elements of ribbon synapses in green and red cone pedicles (G- and R-cones) primarily. B-cone pedicles in HI cell dendritic fields received no more than one or two contacts. Six reconstructed HII cells were found to contact all the pedicles within their dendritic field. However, their dendrites reached especially for B-cone pedicles and innervated them with disproportionately large numbers of terminals compared with G- and R-cones. HII axons appeared to contact B-cones exclusively. The four reconstructed HIII cells were found to avoid completely B-cones in their dendritic fields. Data have been collected on synaptic ribbon lengths at HI and HII lateral elements in the B-cone as compared with G- and R-cone pedicles. HII dendritic terminals end almost exclusively at the smaller ribbons and HI dendrites at the larger ribbons. The number of dendritic terminals provided by the three HCs to G- and R-cone pedicles as compared B-cone pedicles has been more accurately quantitated than was possible in the LM analysis (accompanying paper). New findings on the morphology of B-cone pedicles in peripheral retina have revealed that 1) B-cone pedicles end further vitread in the outer plexiform layer (OPL) than other cone pedicles, thereby forming a sublayer of the OPL neuropil, here named OPLb, in comparison to OPLa, where the G- and R-cone pedicles end; 2) B-cone pedicles have very few telodendrial connections; and 3) in peripheral retina (probably beyond 8 mm from the fovea to the ora serrata), they are bi- or trilobed, with each lobe containing separate synaptic invaginations. The vitread position and unique morphology of B-cone pedicles appear to relate directly to the unique morphology and unusual connectivity patterns of both their B-cone-specific bipolar and B-cone-related horizontal cell, the HII cell.(ABSTRACT TRUNCATED AT 400 WORDS)

Axons↗

PubMed1991

Number and distribution of retinal ganglion cells in anubis baboons (Papio anubis).

The number of retinal ganglion cells in Papio anubis was determined from light microscopic observations of wholemounted and vertically sectioned retinal tissue and electron microscopic examination of optic nerve cross sections. The total number of ganglion cells ranged from 1.41 to 1.81 million (mean 1.58 million, n = 6, SD = 169,927) per retina. The distribution of ganglion cells in cresyl violet stained wholemounts was also examined. Isodensity contours were almost circular perifoveally, but became horizontally elongated outside of the central retina, providing strong evidence for a visual streak. Ganglion cell somata within the streak were found to be significantly smaller than those outside of the streak in comparing regions of equal density. Finally, the distribution of blood vessels within the retina formed a watershed pattern with its crux centered on the ridge of this horizontally oriented high-density zone. Combined, these features indicate that anubis baboons possess a visual streak specialization as reported for lagomorphs, felines, and several primate species. Further, the visual streak appears more pronounced in anubis baboons than in any other primate species studied to date, with the possible exception of Homo sapiens, a similarly ground-dwelling/foraging and secondarily terrestrial species.

Animals↗

PubMed1989

Neurophysiological investigation of the pretectal nucleus lentiformis mesencephali in Rana pipiens.

Previous studies have demonstrated that the large-celled, optic pretectal nucleus lentiformis mesencephali (nLM) is essential for horizontal optokinetic nystagmus, yet little is known about its neurophysiology. In the present study, single-unit analysis of nLM utilized a large-field, patterned stimulus presented for 8 directions and 3 velocities of movement. All units localized in nLM were spontaneously active, motion sensitive, with response profiles that ranged from strongly directional and narrowly tuned to asymmetric and broadly tuned. Only about one-third of the units could be classified as directional, and no response bias for horizontal or temporal-to-nasal motion was observed. The majority of directional units showed greatest responsiveness at the lowest stimulus velocity, while the reverse occurred for many broadly tuned units. These low-velocity, highly directional units may be comparable to the 'retinal slip' neurons recently described in the large-celled pretectal nucleus of mammals. Directional information in the nLM of Rana pipiens thus appears to be represented in the activity of a large population of motion-sensitive units which includes both narrowly and broadly tuned individual response profiles. These results are consistent with the population-coding hypothesis recently advanced to account for directional coding in other sensorimotor systems, including primate motor cortex and superior colliculus.

Acceleration↗

PubMed2004

A strong correlation exists between the distribution of retinal ganglion cells and nose length in the dog.

The domestic dog, CANIS LUPUS FAMILIARIS, is a subspecies of the gray wolf, CANIS LUPUS, with almost identical mitochondrial DNA. The dog is the most diverse species on earth, with skull length varying between 7 and 28 cm whereas the wolf skull is around 30 cm long. However, eye size in dogs does not appear to vary as much. For example, small dogs such as the chihuahua appear to have very large eyes in proportion to the skull. Our aim was to examine eye size and retinal cell numbers and distribution to determine whether the dog eye exhibits as much variation as the skull. We found a correlation between eye radius and skull dimensions. However, the most surprising finding was that the distribution of ganglion cells in the eye varied tremendously from a horizontally aligned visual streak of fairly even density across the retina (as seen in the wolf) to a strong area centralis with virtually no streak (for example, as observed in a pug from the current series). This variation in ganglion cell density within a single species is quite unique. Intriguingly, the ratio of peak ganglion cell density in the area centralis to visual streak was highly negatively correlated with skull length (r = -0.795, n = 22) and positively correlated with cephalic index (r = 0.687, n = 22). The orientation of eyelid aperture was also correlated with cephalic index (r = 0.648, n = 22). Therefore, the genetic manipulation of selective breeding, which has produced an abnormal shortening of the skull and eyelids with less lateral apertures, has also produced a considerably more pronounced area centralis in the dog.

Animals↗

PubMed2003

Synaptic connections of starburst amacrine cells and localization of acetylcholine receptors in primate retinas.

Starburst amacrine cells in the macaque retina were studied by electron microscopic immunohistochemistry. We found that these amacrine cells make a type of synapse not described previously; they are presynaptic to axon terminals of bipolar cells. We also confirmed that starburst amacrine cells are presynaptic to ganglion cell dendrites and amacrine cell processes. In order to determine the functions of these synapses, we localized acetylcholine receptors using a monoclonal antibody (mAb210) that recognizes human alpha3- and alpha5-containing nicotinic receptors and also antisera against the five known subtypes of muscarinic receptors. The majority of the mAb210-immunoreactive perikarya were amacrine cells and ganglion cells, but a subpopulation of bipolar cells was also labeled. A subset of bipolar cells and a subset of horizontal cells were labeled with antibodies to M3 muscarinic receptors. A subset of amacrine cells, including those that contain cholecystokinin, were labeled with antibodies to M2 receptors. Taken together, these results suggest that acetylcholine can modulate the activity of retinal ganglion cells by multiple pathways.

Acetylcholine↗

PubMed1975

The distribution of the alpha type of ganglion cells in the cat's retina.

There is a distinct class of large ganglion cell bodies observable in whole-mount preparations of the cat's retina stained with cresyl violet. Measurements of perikaryal size and its variation with eccentricity from the central area support the identification of the large cells with the class of alpha cells previously defined in Golgi-stained preparations. A complete enumeration of alpha cells in one retina yielded a total of 6212. They were encountered in all parts of the retina and had a peak density within the central area ( 200/mm2). The retinal distribution was displayed as a contour map of alpha-cell density. Away from the central area, the lines of iso-density had the form of a 4-pointed star with rather blunt points corresponding to horizontal and vertical ridges of augmented density. Along horizontal, vertical and oblique strips through the central area, alpha-cell density was an approximately constant fraction of total ganglion cell-density. The average value of the fraction was 3.3% from which it has been calculated that the cat's retina may contain as many as 190,000 ganglion cells.

Animals↗

PubMed2006

Mosaic deletion of Rb arrests rod differentiation and stimulates ectopic synaptogenesis in the mouse retina.

The retinoblastoma gene (Rb) regulates neural progenitor cell proliferation and cell fate specification and differentiation. For the developing mouse retina, two distinct functions of Rb have been described: regulation of retinal progenitor cell proliferation and rod photoreceptor development. Cells that would normally become rods fail to mature and remain as immature cells in the outer nuclear layer in the adult. By using Chx10-Cre;Rb(Lox/-) mice, we generated a chimeric retina with alternating apical-basal stripes of wild-type and Rb-deficient tissue. This provides a unique model with which to study synaptogenesis at the outer plexiform layer within regions that lack differentiated rods. In regions where rods failed to differentiate, the outer plexiform layer (OPL) was disrupted. Horizontal cells formed, and their somata were appropriately aligned, but their neurites did not project laterally. Instead many horizonal cell neurites extended apically, forming ectopic synapses with photoreceptors at all levels of the outer nuclear layer. These ectopic photoreceptor terminals contained synaptic ribbons, horizontal cell processes with synaptic vesicles, and a single mitochrondrion characteristic of rod spherules. Rb-deficient bipolar cells differentiated normally, extended dendrites to the OPL, and formed synapses that were indistinguishable from adjacent wild-type cells. In contrast to OPL-positioned synapses, ectopic synapses did not contain bipolar dendrites. This finding suggests that horizontal cells and photoreceptors can form stable synapses that are devoid of bipolar dendrites outside the normal boundaries of the OPL. Finally, analysis of P4, P7, P12, and P15 retinae suggests that the apical horizontal cell processes result from their failure to establish their normal lateral projections during development.

Animals↗

PubMed1988

Kainic acid-induced eye enlargement in chickens: differential effects on anterior and posterior segments.

Intravitreal injections of kainic acid were used to examine the significance of normal retinal activity for eye growth in chickens, this acid being chosen because of its known, selective neurotoxic effects on cells in the chicken retina. A 6 nmole dose of kainic significantly reduces amacrine cell numbers when used in very young chickens, while higher doses of kainic acid also affect bipolar and horizontal cell numbers. The effects of intravitreal injection of kainic acid on eye growth were assessed 4 weeks after treatment. A 200 nmole dose of kainic acid, used with day-old and 14-day-old chickens, had opposing effects on the anterior and posterior segments of the eye; while growth of the anterior segment was inhibited, the posterior segment was enlarged, predominantly in the equatorial direction. A 20 nmole dose of this acid similarly affected growth in 14-day-old chickens, but in day-old chickens, the anterior segment was also enlarged and the overall eye enlargement had an axial bias. Myopia was the most common refractive error associated with both patterns of development. A 2 nmole dose of kainic acid was without effect on eye growth. Parallels are drawn between these eye enlargement phenomena and those described in chickens whose visual environments have been manipulated. Our results indicate that normal retinal activity is fundamental to normal eye growth in chickens, and furthermore, that growth of the anterior and posterior segments of the chicken eye are independently regulated.

Aging↗

PubMed1970

The representation of three-dimensional visual space in the cat's striate cortex.

1. Binocularly driven single units were recorded in the cat's striate cortex. For each neurone the two monocular receptive fields were stimulated simultaneously in order to assess the optimal positioning of the image in both eyes to give the best binocular response.2. The electrode was driven perpendicular to the surface of the brain to explore cortical columns, all the cells of which are known to have the same preferred target orientation.3. All orientation columns were found to fit into one of two classes according to their binocular organization.4. In a constant depth column the receptive fields of binocular neurones cover a small retinal area and they are laid out in almost identical arrays in the two eyes. Consequently, the horizontal disparity is practically the same for all the units. The depth column as a whole is viewing a thin sheet of visual space, a few degrees wide, floating at some distance from the cat. There may be about 0.6 degrees disparity difference between neighbouring depth columns.5. In a constant direction column the binocular units' fields are all super-imposed on the retina contralateral to the hemisphere containing the column. In the ipsilateral eye they are more scattered horizontally. Therefore the horizontal disparity varies enormously from cell to cell and the column as a whole is viewing a cylinder of visual space directed towards the contralateral eye. Neighbouring direction columns may vary by about 4 degrees in their oculocentric visual direction.6. This columnar arrangement is probably important for space perception in the cat. Activity in only one depth and one direction column would specify the orientation and the three-dimensional locus of an object in space.7. The two types of column may be involved in the control of disjunctive and conjugate eye movements.

Animals↗

PubMed2000

Distribution and developmental regulation of AMPA receptor subunit proteins in rat retina.

PURPOSE: To learn more about a possible functional role of alpha-amino-3-hydroxy-5-methyl-4-isoxasole-propionate (AMPA) receptors in retinal development, the spatial distribution and temporal regulation of all AMPA receptor subunit proteins was studied in rats. METHODS: Immunohistochemistry was performed on retinal sections between embryonic days (E)20 and E21 and the adult stage by using specific antibodies against AMPA subunits GluR1 to 4. RESULTS: All AMPA subunits were expressed in the ganglion cell layer from E21 on. In the inner plexiform layer (IPL), discernible bands of labeling appeared at distinct retinal ages for the different subunits. GluR1 immunoreactivity (IR) was concentrated in two broad bands by postnatal day (P)3, whereas three bands were visible beginning on P9. Two bands were located in a region of the IPL where off-cells terminate, and one band was found in the innermost part of the IPL where on-cells terminate. In contrast, two bands of GluR2/3- and GluR4-IR in the IPL were only discernible beginning on P14 and seemed to be located between the bands of GluR1-IR. GluR2/3 and GluR4 were observed both in horizontal cells and in the outer plexiform layer from early developmental stages on. GluR1 was not found in the outer retina, indicating that horizontal and bipolar cell processes in the rat express AMPA receptors composed of subunits GluR2 to 4. Double-labeling experiments with cell-specific markers revealed the expression of subunits GluR1 to 4 in cholinergic and AII amacrine cells. CONCLUSIONS: AMPA receptors are expressed before synapse formation, indicating a role not only in fast signal transmission but also in the establishment of inner retinal circuits. The differences in spatial and temporal subunit expression suggest that different retinal cell types selectively express distinct types of AMPA receptors during development of the rat retina.

Animals↗

PubMed1994

Threshold and chromatic sensitivity changes in fish cone horizontal cells following prolonged darkness.

The light-evoked responses of L-type cone horizontal cells in the teleost retina were studied following a prolonged period of complete darkness. Intact, isolated white perch retinas were superfused in complete darkness for more than 90 min, following which horizontal cells were impaled without the aid of any light flashes. Following this prolonged darkness, L-type cone horizontal cell light responses to dim and bright full-field stimuli were slow and small in amplitude and response duration to bright stimuli was considerably longer than stimulus duration. In addition, absolute threshold was 2 log units lower than typical for cone horizontal cells and spectral sensitivity to shorter wavelengths was increased. Following bright light stimulation, light responses became more transient and increased in amplitude, reaching 40-50 mV to bright flashes. Moreover, absolute threshold increased and responses to spectral stimuli were similar to those observed typically for L-type cone horizontal cells after light-sensitization. These results suggest that following prolonged darkness, cone input to cone horizontal cells is reduced and rod input is present.

Animals↗