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At least 19 recordsLinked to original sources

PubMed1991

Morphogenesis and territorial coverage by isolated mammalian retinal ganglion cells.

Identified retinal ganglion cells were isolated from postnatal cat retinas and their dendrites were removed by trituration and centrifugation. The denuded cells were placed in a cell culture system and allowed to reexpress dendritic arbors in the absence of afferent input, target tissue, and interactions with neighboring ganglion cells. The retinal ganglion cells were grown above a feeder layer of astrocytes on glass coverslips equipped with paraffin pedestals. The spatial patterns of the reexpressed neurites were quantitatively analyzed using a number of measures, including an estimate of the Hausdorff dimension, H, which was used as a scale-independent metric for how well the neurite patterns filled in a restricted spatial domain. As assessed by the estimation of the Hausdorff dimensions, the neurites from a single cell achieve uniform coverage of a restricted territory independent of the total neurite length or the total number of inter-branch-point segments. A comparison with H values of ganglion cells from the intact retina revealed a similar trend. These results suggest that these cultured ganglion cells can express an intrinsic growth strategy for the uniform coverage of a restricted territory. The arbors expressed in the culture system displayed a limited range of diameters and exhibited morphology similar to the alpha-, beta-, and gamma-ganglion cells of the intact retina in the absence of afferent input or the influences of neighboring cells and target tissue. Time-lapse video data revealed that individual cultured cells showed extensive dendritic remodeling during their growth; however, after about 3 d in culture, this remodeling did not appreciably affect the territorial coverage of a cell. In the intact retina, the existence of dendritic sheets that independently and uniformly sample visual space may result from this intrinsic ability to elaborate dendrites that uniformly cover or fill in a restricted territory.

Animals↗

PubMed1989

Early differentiation of retinal ganglion cells: an axonal protein expressed by premigratory and migrating retinal ganglion cells.

A monoclonal antibody, RA4, was developed that recognizes retinal ganglion cell axons in the mature retina. Between embryonic days 3 and 9, the RA4 antigen was associated with cell bodies in certain regions of the retina in addition to the ganglion cell axons. The RA4-positive cells were of 3 types: an apolar cell adjacent to the ventricular surface, a bipolar cell that spanned the thickness of the retina, and a monopolar cell in the ganglion cell layer. Evidence suggests that these cells are premigratory and migrating retinal ganglion cells. The expression of the RA4 antigen is the earliest indicator of ganglion cell differentiation yet reported. The existence of RA4-positive apolar cells along the outer surface of the retina suggests that the ganglion cell phenotype is expressed as soon as the cell becomes postmitotic. Approximately 20% of the migrating ganglion cells were in pairs. The paired cells most likely arose from the terminal division of a germinal cell. One possibility suggested by these data is that a ganglion cell-specific germinal cell arises from a pluripotent germinal cell. Immunoblots and other analyses revealed the RA4 antigen to be a 140 kDa cytoplasmic protein in the retina. RA4 also recognized many long tract axons in the brain. In the brain, the RA4 epitope was observed on proteins with at least 7 different molecular weights. Evidence suggests that different cell types may express the RA4 antigen with slightly different molecular weights.

Animals↗

PubMed1990

Localization of laminin B1 mRNA in retinal ganglion cells by in situ hybridization.

In the nervous system, neuronal migration and axonal growth are dependent on specific interactions with extracellular matrix proteins. During development of the vertebrate retina, ganglion cell axons extend along the internal limiting (basement) membrane and form the optic nerve. Laminin, a major component of basement membranes, is known to be present in the internal limiting membrane, and might be involved in the growth of ganglion cell axons. The identity of the cells that produce retinal laminin, however, has not been established. In the present study, we have used in situ hybridization to localize the sites of laminin B1 mRNA synthesis in the developing mouse retina. Our results show that there are at least two principal sites of laminin B1 mRNA synthesis: (a) the hyaloid vessels and the lens during the period of major axonal outgrowth, and (b) the retinal ganglion cells at later development stages. Müller (glial) cells, the major class of nonneuronal cells in the retina, do not appear to express laminin B1 mRNA either during development or in the adult retina. In Northern blots, we found a single transcript of approximately 6-kb size that encodes the laminin B1 chain in the retina. Moreover, laminin B1 mRNA level was four- to fivefold higher in the postnatal retina compared to that in the adult. Our results show that in addition to nonneuronal cells, retinal ganglion cells also synthesize laminin. The function of laminin in postnatal retinas, however, remains to be elucidated. Nevertheless, our findings raise the possibility that neurons in other parts of the nervous system might also synthesize extracellular matrix proteins.

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PubMed1975

A quantitative analysis of the cat retinal ganglion cell topography.

A retinal ganglion cell distribution map has been prepared for the cresyl violet stained cat retina. It differs from previously published maps in revealing the visual streak to be more substantial and in showing a higher peak density of 9-10,000 ganglion cells/mm2 at the presumed visual pole. The map was used to obtain a minimum estimate of the retinal ganglion cell population as 217,000 cells, more than double the total previously reported. The problem of classifying the cells of the ganglion cell layer is discussed in detail and examples of criterion cells illustrated. The paper also includes an account of retinal mensuration (dimensions, area, etc.) and a discussion of the visual streak orientation.

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PubMedDate not supplied

The neurotensin-related hexapeptide LANT6 is found in retinal ganglion cells and in their central projections in pigeons.

Previous biochemical and immunohistochemical studies have shown that the neurotensin-related hexapeptide LANT6 is widespread and abundant in the avian nervous system. In the present study, immunohistochemical techniques were used to show that LANT6 is present in numerous cells of the retinal ganglion cell layer in pigeons. Consistent with the possibility that these LANT6+ retinal cells might be retinal ganglion cells, it was found that (1) the distribution of LANT6+ fibers and terminals in the central retinal target areas matched the distribution of central retinal projections; (2) the LANT6+ fibers and terminals are eliminated from retinal target areas by transection of the contralateral optic nerve; and (3) LANT6+ retinal cells in the ganglion cell layer can be retrogradely labeled by injections of fluorogold in the tectum. These results suggest that LANT6 may be utilized as a neuroactive substance by the central terminals of numerous retinal ganglion cells in birds. Similar anatomical findings have been previously reported for members of several other vertebrate groups, giving rise to the possibility that LANT6 (or its homologues in nonavians) may be a phylogenetically ubiquitous neuroactive substance used by retinal ganglion cells.

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PubMed1991

Cryopreservation of postnatal rat retinal ganglion cells: persistence of voltage- and ligand-gated ionic currents.

Established methods for cryopreservation of living cells were modified for freeze-storage of postnatal retinal ganglion cells from rat. Retinal cell suspensions containing fluorescently labeled ganglion cells were frozen after addition of 8% dimethyl sulfoxide and stored at -80 degrees C for up to 66 days. Viability of identified retinal ganglion cells was assessed by their ability to take up and cleave fluorescein diacetate to fluorescein. No significant difference was found in the number of living retinal ganglion cells when cells obtained from the same dissociation were counted before and after freezing (6.65 +/- 2.37 x 10(4) vs 7.05 +/- 3.67 x 10(4) retinal ganglion cells per ml, respectively; mean +/- S.D., n = 4). In culture following cryopreservation, the cells appeared morphologically normal, and developed neurites and growth cones similar to their freshly dissociated counterparts. Since very little is known about the electrophysiology and membrane properties of neurons after cryopreservation, we used the whole-cell configuration of the patch-clamp technique to study voltage- and ligand-gated conductances in cryopreserved retinal ganglion cells. The cryopreserved retinal ganglion cells studied under current-clamp maintained resting potentials of -60.9 +/- 6.6 mV (n = 10) and upon depolarization fired action potentials. During voltage-clamp in the whole-cell mode, depolarizing voltage steps activated Na(+)-(INa), Ca(2+)-(ICa), and K(+)-currents in all cells tested (n = 122). INa could be reversibly blocked by 1 microM tetrodotoxin added to the external solution. ICa was blocked by external 250 microM Cd2+ or 3 mM Co2+. In some cells, ICa consisted of both a transient and prolonged component. The outward K(+)-current consisted of Ca(2+)-dependent and -independent components. The Ca(2+)-insensitive portion of the K+ outward current was separated into four distinct components based upon pharmacological sensitivity and biophysical properties. In many cells, a rapidly inactivating current similar to the A-type K(+)-current (IA) observed in freshly cultured retinal ganglion cells was isolated by its greater sensitivity to 4-aminopyridine (5 mM) than to tetraethylammonium (20 mM). A tetraethylammonium-sensitive current with a more prolonged time course reminiscent of IK, the delayed rectifier, was also found. When the 4-aminopyridine- and tetraethylammonium-insensitive portions of the outward current were further analysed with voltage protocols, an additional slowly decaying potassium current became apparent. The inhibitory amino acids, GABA (20 microM) and glycine (100 microM), activated chloride-selective currents that were selectively blocked by bicuculline methiodide (10 microM) and strychnine (5 microM), respectively.(ABSTRACT TRUNCATED AT 400 WORDS)

Acetylcholine↗

PubMed1989

A single-cell analysis of early retinal ganglion cell differentiation in Xenopus: from soma to axon tip.

Intracellular injections of Lucifer yellow (LY) were made into the cell bodies of Xenopus retinal ganglion cells from the earliest stages of axonogenesis to the beginning of target innervation. Embryos were intact during the injection so that the entire cell (cell body, dendrites, axon, and growth cone) could be visualized. The purpose of the study was 3-fold: (1) to characterize the early steps in retinal ganglion cell differentiation before the axon reaches its target; (2) to determine whether guidepost cells exist as possible navigation cues in the vertebrate optic pathway; and (3) to investigate whether the morphology of early retinal ganglion cell growth cones varies in a position-dependent manner along the primordial optic pathway. Axons were generally initiated before dendrites and followed a well-defined course along the primordial optic pathway without branching. Surprisingly, at least 5% of the retinal ganglion cells sent more than one axon into the optic pathway. Sister axons from the same parent cell traveled separately in the pathway, indicating that their growth cones navigated independently. Examination of dendrite genesis showed that dendrites usually begin to emerge from the cell body well before the axon tip reaches the target. This observation argues against the possibility that target contact influences dendrite initiation. Nascent dendrites were commonly tipped with pronounced varicosities that did not resemble axon growth cones. Their number and branching correlated well with axon length, indicating that the age of the retinal ganglion cell itself, rather than the age of its presynaptic cells or local environment, is the strongest influence on dendrite genesis. Examination of LY-filled growth cones at varying points in the pathway showed no evidence of dye transfer to adjacent cells. This indicates that gap junctional contacts probably do not form during axonal pathfinding and suggests that direct intercellular communication between growing axons and other cells in the pathway does not play a major role in axon guidance. Growth cone morphology was analyzed quantitatively and found to vary at different positions along the pathway. Growth cones entering the optic nerve head were the largest and most complex; those on the retinal surface were the smallest and showed a simple morphology. Growth cones in the chiasm and optic tract showed a degree of complexity similar to those in the optic nerve head but were smaller.(ABSTRACT TRUNCATED AT 400 WORDS)

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PubMed1991

[Purification and survival of retinal ganglion cell].

We had used a specific anti-Thy 1.1 antibody binding method and a nylonmembrane sieve method to isolate and purify retinal ganglion cells from neonatal rats in order to compare the effect of tectal extract on these purified cells retinal ganglion cells. Isolated retinal cell suspension with retinal ganglion cells retrograde-prelabelled with Fast Blue were seeded on culture dishes coated with the specific anti-Thy 1.1 antibody for 30 minutes before nonadherent cells were removed. The percentage purity of the adherent retinal ganglion cells determined microscopically to be 95%. However, the percentage purity of the Fast Blue-labelled retinal ganglion cells recovered using the nylon membrane of pore size 15 microns was only 60 +/- 5%. Retinal ganglion cells purified by both methods could survive and grow into large, active neurons with neurite outgrowths in the presence of tectal extract. A MTT colorimetric microassay was used to quantify the survival growth activity of these purified retinal ganglion cells after culture for 24 hours. The result showed that the optical density ratio (+Te/-Te) of the retinal ganglion cells purified by anti-Thy 1.1 antibody binding method was 12.3 (0.111/0.009) and by the nylon membrane method was 6.4 (0.102/0.016), and the optical density ratio of the non-purified retinal cells was 3.8 (0.095/0.025), p less than 0.01 for all 3 sets of results. It was concluded that in the absence of other cells, the purified retinal ganglion cells responded specifically to the trophic activity in tectal extract, the purer the retinal ganglion cells and the clearer the effect.

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PubMed1992

Lucifer yellow, retrograde tracers, and fractal analysis characterise adult ferret retinal ganglion cells.

The dendritic morphology of retinal ganglion cells in the ferret was studied by the intracellular injection of lucifer yellow in fixed tissue. Ganglion cells were identified by the retrograde transport of red or green fluorescent microspheres that had been injected into different target nuclei, usually the lateral geniculate nucleus or superior colliculus. This approach allows the comparison of dendritic morphologies of ganglion cells in the same retina with different central projections and also identifies cells with branching axons. The digitised images of dendritic arbors were analysed quantitatively by a variety of measures. Dendritic complexity was assessed by calculating the fractal dimension of each arbor. The ferret has distinct alpha, beta, and gamma morphological classes of cells similar to those found in the cat. The gamma cell class was morphologically diverse and could be subdivided into "sparse," "loose," and "tight" groups, reflecting increasing dendritic complexity. Whereas the beta cell projection was limited to the lateral geniculate nucleus alone, alpha and gamma cells could project to either or both nuclei. Retinal ganglion cells labelled from the pretectal nuclei formed a morphologically distinct class of retinal ganglion cells. The ipsilateral projection lacked alpha cells and the most complex, "tight" gamma cells. However, ipsilaterally projecting "loose" gamma cells overlapped alpha cells in both soma and dendritic dimensions. Different morphological classes of retinal ganglion cells hence show characteristic axon behaviour both in their decussation at the chiasm and in which targets they innervate. Fractal measures were used to contrast variation within and between these identified classes.

Animals↗

PubMed1991

Regenerated synapses persist in the superior colliculus after the regrowth of retinal ganglion cell axons.

Synapse formation by retinal ganglion cell axons was sought in the superior colliculus of four adult rats 16-18 months after the optic nerve was transected and replaced by a peripheral nerve graft that guided regenerating RGC axons from the eye to the superior colliculus. The terminals of retinal ganglion cell axons were labelled by intravitreal injections of tritiated amino acids and studied by light and electron microscopic autoradiography. We found that (i) retinal ganglion cell axons had extended from the tips of the peripheral nerve grafts into the superior colliculus for approximately 350 microns; (ii) within the superior colliculus, some regenerated retinal ganglion cell axons became ensheathed by CNS myelin; (iii) retinal ganglion cell terminals formed asymmetric synapses with dendrites of neurons in the superficial layers of the superior colliculus, mainly the stratum griseum superficialis. Regenerated (n = 418) and normal retinal ganglion cell terminals (n = 1775) in the superior colliculus were compared in terms of their size (area, perimeter, and maximum diameter), contacts per terminal, contacts per 10 microns terminal perimeter, and post-synaptic structure contacted (dendritic spine, shaft, or soma). No statistically significant differences in the ultrastructural characteristics of the pre-synaptic profiles were apparent between the two groups. The post-synaptic structures contacted by axon terminals were similar in regenerated and control animals, although there were quantitative differences in the distributions of these contacts among dendritic spines and shafts. These results suggest that the regeneration of retinal ganglion cell axons in adult rats can lead to the formation of ultrastructurally normal synapses in the appropriate layers of the superior colliculus. The re-formed connections appear to persist for the life-span of these animals.

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PubMed1990

Survival of retinal ganglion cells in vitro: the effect of conditioned medium from retinal cell aggregates.

The time course of degeneration of retinal ganglion cells was studied in vitro. We used the retinae of newborn hooded rats retrogradely labeled with horseradish peroxidase injected bilaterally into the superior colliculus to permit the identification of retinal ganglion cells in culture. We tested the effect of conditioned medium either from aggregates or from explants of retinal cells on the survival of the ganglion cells. Both conditioned media approximately doubled the survival of ganglion cells after 48-72 h in culture. Our data are consistent with the hypothesis that retinal cells produce soluble trophic factors that influence ganglion cell survival.

Animals↗

PubMed1991

[A morphological classification of retinal ganglion cells in Chinese hamsters].

Retinal ganglion cells in Chinese hamsters were morphologically classified into alpha, beta and gamma cells by the horseradish peroxidase labeling method. The alpha cells had large somatic and dendritic fields. The beta cells were small to medium in somatic size and had small dendritic field size. The gamma cells had small to medium somatic and large dendritic fields. Each cell type had either symmetrical or asymmetrical dendrites arising from the soma. The dendrites of alpha, beta and gamma cells extended into either the internal or external stratum of the inner plexiform layer.

Animals↗

PubMed1991

Rat retinal ganglion cells in culture.

A stable cell culture system of identified retinal ganglion cells would facilitate the investigation of cellular mechanisms of damage from glaucoma and other disorders. We have developed a reliable technique to culture retinal ganglion cells on a glial cells monolayer which extends viability and promotes extensive neurite outgrowth. Dissociated retinal cells from 5-7-day-old Sprague-Dawley rats were cultured on glial monolayers derived from rat cerebral hemispheres. Retinal ganglion cells were labeled with retrograde fluorescent markers injected into the superior colliculus or in culture with monoclonal antibody to Thy-1 antigen. Since Thy-1 antigen is not entirely specific for retinal ganglion cells, and fluorescent markers fade in older cultures, the identity of Thy-1 marked cells was confirmed with whole-cell electrophysiologic recordings. Labeled, physiologically intact retinal ganglion cells were identified for at least 31 days in culture. Many retinal ganglion cells showed neurite elongation of 2 mm or more and developed complex intercellular networks. This cell culture system may be used to form the basis for future studies of the electrophysiology and transport properties of retinal ganglion cells under normal culture conditions and under adverse conditions such as those that mimic ischemia or mechanical deformation.

Action Potentials↗

PubMed1992

Synapse formation and preferential distribution in the granule cell layer by regenerating retinal ganglion cell axons guided to the cerebellum of adult hamsters.

To investigate constraints and preferences for synaptogenesis in the injured mammalian CNS, regenerating retinal ganglion cell (RGC) axons of adult hamsters were guided through a peripheral nerve (PN) graft to a target they do not usually innervate: the cerebellum (Cb). When identified by the presence of HRP anterogradely transported from the retina 2-9 months later, such RGC axons were found to have extended into the cerebellar cortex for up to 650 microns. Most of this growth was in the granule cell layer (GCL) and only a few axons entered the molecular layer. The preference for the GCL could not be explained by the position of the PN graft in the Cb, a selective denervation of the GCL, local damage to other neurons, or the distribution of reactive gliosis in the vicinity of the graft. Furthermore, by EM, more than 95% of the labeled retinocerebellar terminals and synapses were in the GCL. Retinocerebellar terminals were larger and contained more synapses than the regenerated RGC terminals previously studied in the superior colliculus. These results indicate that regenerating axons of CNS neurons can form persistent synapses with novel targets. The preferential synaptogenesis in the GCL suggests that such unusual connections are not formed randomly in the CNS of these adult mammals.

Animals↗

PubMed1991

A chondroitin sulfate proteoglycan may influence the direction of retinal ganglion cell outgrowth.

In the developing retina, retinal ganglion cell (RGC) axons elongate toward the optic fissure, even though no obvious directional restrictions exist. Previous studies indicate that axon-matrix interactions are important for retinal ganglion cell axon elongation, but the factors that direct elongation are unknown. Chondroitin sulfate proteoglycan (CS-PG), a component of the extracellular matrix, repels elongating dorsal root ganglion (DRG) axons in vitro and is present in vivo in the roof plate of the spinal cord, a structure that acts as a barrier to DRG axons during development. In this study, we examined whether CS-PG may regulate the pattern of retinal ganglion cell outgrowth in the developing retina. Immunocytochemical analysis showed that CS-PG was present in the innermost layers of the developing rat retina. The expression of CS-PG moved peripherally with retinal development, always remaining at the outer edge of the front of the developing axons. CS-PG was no longer detectable with immunocytochemical techniques when RGC axon elongation in the retina is complete. Results of studies in vitro showed that CS-PG, isolated from bovine nasal cartilage and chick limb, was inhibitory to elongating RGC axons and that RGC growth cones were more sensitive to CS-PG than were DRG neurites tested at the same concentrations of CS-PG. The behavior of retinal growth cones as they encounter CS-PG was characterized using time-lapse video microscopy. Filopodia of the RGC growth cones extended to and sampled the CS-PG repeatedly. With time, the growth cones turned to avoid outgrowth on the CS-PG and grew only on laminin. While numerous studies have shown the presence of positive factors within the retina that may guide developing RGC axons, this is the first demonstration of an inhibitory or repelling molecule in the retina that may regulate axon elongation. Taken together, these data suggest that the direction of RGC outgrowth in the retina may be regulated by the proper ratio of growth-promoting molecules, such as laminin, to growth-inhibiting molecules, like CS-PG, present in the correct pattern and concentrations along the retinal ganglion cell pathway.

Animals↗

PubMed1991

Formation of the retinal ganglion cell and optic fiber layers.

The early development of retinal ganglion cell and the optic fiber layers has been studied by examining the morphology of differentiating retinal ganglion cells using immunoelectron microscopy and a monoclonal antibody against neuron-specific beta-tubulin. This antibody identified retinal ganglion cells during the stages of their most active differentiation and axonogenesis prior to maturation of other retinal neurons. The changing morphology of retinal ganglion cells during these early stages is consistent with a differentiation sequence in which axonogenesis and translocation of the cell body to the vitreal surface occur while the cell is still attached to the vitreal margin through its vitreal endfeet. Thus, the mechanism of retinal ganglion cell axon generation and soma migration to the vitreal surface appears to involve maintenance of this attachment which may act as both a focus for axon differentiation and an anchor for directed nuclear translocation to the vitreal margin.

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PubMed1976

Conduction velocity groupings among axons of cat retinal ganglion cells, and their relationship to retinal topography.

Three unresolved issues in the conduction velocity groupings among the axons of cat retinal ganglion cells have been investigated. These are (i) the degree of separation of the velocity ranges of the axons of X-and W-type ganglion cells; (ii) the question whether the velocities of X-and Y-cell axons (i.e. of t1 and t2 axons have faster velocities than contralaterally projecting axons. Evidence is presented that the velocity ranges of W- and X-cell axons are almost completely separate; that the velocities of X- and Y-cell axons are not graded with retinal eccentricity (except in the immediate vicinity of the area centralis) and that ipsilaterally projecting axons are not faster conducting that contralaterally projecting axons. These results provide a context for summarising present understanding of conduction velocity groupings among the axons of cat retinal ganglion cells.

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PubMed1989

GABA-activated single channel currents in outside-out membrane patches from rat retinal ganglion cells.

gamma-aminobutyric acid (GABA) evokes large whole-cell currents in solitary mammalian retinal ganglion cells studied by the patch-clamp method. This evidence suggests that GABA acts directly on the retinal ganglion cells as an inhibitory transmitter as it does elsewhere in the mammalian central nervous system. Here, single-channel recordings of the currents underlying the GABA-induced responses were studied in outside-out patches of cell membrane. In some other preparations, single GABAA channels recorded in the excised patch configuration have been shown to have altered properties in comparison to responses elicited during whole-cell recording. For example, in cortical neurons single GABA-activated channels in excised patches display accelerated desensitization kinetics as well as rapid rundown of the response. Therefore, in retinal ganglion cells, responses generated by GABA in cell-free patches were compared to whole-cell responses. After determining that the responses to GABA in acutely isolated outside-out patches were indeed similar to those of the whole-cell currents in retinal ganglion cells, the unitary conductances were studied. It was determined that these single-channel events resemble those reported in other nervous tissues with 4 elementary conductances of approximately 10 pS, 19-22 pS, 30-33 pS, and 45-50 pS at 33-35 degrees C.

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