Cells In Inner Nuclear Layer Research Articles

Three types of GABA-immunoreactive cone horizontal cells in teleost retina.

Peroxidase-anti-peroxidase immunocytochemistry, applied on serial semithin epoxy resin sections, was used to examine the localization of endogenous GABA in horizontal cells in the retina of a marine teleost, the dragonet (Callionymus lyra L.). The immunostaining shows that not only the external H1 cone horizontal cells label with antibodies against GABA, but also the H2 and H3 cone horizontal cells in the inner nuclear layer. The distribution of the H1 cells corresponds to that of the single cones. They are square-patterned and in the dorsal retina their density equals 20,000 cells/mm2. The estimated density of the immunostained H2 and the H3 cells in the dorsal retina is 9500 and 1300 cells/mm2, respectively. The H2 and H3 cells are not geometrically arranged, but nearest-neighbor analysis shows that these horizontal cell types do have a very regular disposition. We suggest that GABA is the likely neurotransmitter substance used by all cone horizontal cell types in teleost retina.

Glutamate receptor expression in the rat retina

The expression of five genes (GluR A; B; C; D; GluR 5) encoding functional subunits of glutamate receptors was investigated in the rat retina using in situ hybridization with oligonucleotide probes. All five genes are expressed in the retina. All probes label cell bodies in the ganglion cell layer as well as somata in the inner third of the inner nuclear layer (INL), where the amacrine cells are located. In addition GluR 5, B and D, and to a lesser extent also GluR A are found in the middle and outer part of the INL, where bipolar and horizontal cells reside. Different subsets of retinal neurons may thus use glutamate receptors of different subunit composition.

Thyroid hormone receptors in chick retinal development: differential expression of mRNAs for α and N-terminal variant β receptors

Thyroid-hormone-dependent development of the neuroretina has principally been described in amphibia. Here, we show by in situ hybridisation that mRNAs coding for three distinct thyroid hormone receptors (TRs), TR alpha and two TR beta variants, are differentially expressed during chick retinal development. We isolated a cDNA for a novel N-terminal variant of chick TR beta (cTR beta 2) that is predominantly expressed in retinal development. Interestingly, in its N-terminal A/B domain cTR beta 2 is 70% homologous to the rat pituitary-specific TR beta 2. Expression of cTR beta 2 mRNA was high at embryonic day 6 (E6) in the retinal outer nuclear layer (ONL) and decreased to low levels at hatching. mRNA for the previously described chick beta receptor, cTR beta 0, was expressed at low levels in both the ONL and the inner nuclear layer (INL) after E10. In contrast, cTR alpha expression occurred in the ONL, INL and ganglion cell layer at intermediate and later stages. Finally, cTR beta 2 confers a stronger trans-activation of reporter gene transcription than cTR beta 0. The distinctive kinetics and localisation of TR alpha and beta gene expression suggest cell- and stage-specific functions for TRs, both individually and in combinations, in chick neuroretinal development.

Multiple nicotinic acetylcholine receptor genes are expressed in goldfish retina and tectum

cDNAs encoding a novel nAChR structural subunit (GFn alpha-3) and a ligand-binding subunit (GF alpha-3) have been isolated from a goldfish retina cDNA library. The protein encoded by GFn alpha-3 shares 88% amino acid similarity with that encoded by GFn alpha-2, a structural subunit gene previously identified to be expressed in this system (Cauley et al., 1989). The ligand-binding subunit (GF alpha-3) is likely the goldfish homolog of the rat alpha-3 gene (Boulter et al., 1986). Northern blots and S1 protection experiments show that GFn alpha-3 and GF alpha-3 genes are expressed in retina and brain. GFn alpha-3 identifies multiple RNAs differing in their 3' untranslated regions. In situ hybridization analysis demonstrates GFn alpha-3, GFn alpha-2, and GF alpha-3 expression by cells of the retinal ganglion cell layer. Unlike GFn alpha-2 and GF alpha-3, GFn alpha-3 is expressed at highest levels by cells of the retina's inner nuclear layer. In the optic tectum, both GF alpha-3 and GFn alpha-3 genes are expressed by cells of the periventricular zone, as well as more superficial layers. These results suggest the presence of multiple nAChR systems in retina and tectum. In addition, they indicate that tectal nAChRs may arise from remote (ganglion cell) as well as local (tectal cell) synthesis.

Retrograde transneuronal transport of Herpex simplex virus in the retina after injection in the superior colliculus, hypothalamus and optic chiasm

Immunocytochemistry was used to identify infected cells after injection of Herpes simplex virus (HSV) into the superior colliculus, hypothalamus and optic chiasm. Ganglion cells of the retina were labeled in a pattern consistent with known projections to retinorecipient nuclei. Cells of both inner and outer nuclear layer were labeled. If this represents retrograde transneuronal transport, then HSV may provide an important tool for studying the neuronal circuitry of the retina.

Cholinoceptive neurons in the retina of the chick: an immunohistochemical study of the nicotinic acetylcholine receptors.

Monoclonal antibodies directed against nicotinic acetylcholine receptors (nAChRs) were used to identify and characterize cholinoceptive neurons in the chick retina. Two monoclonal antibodies (mAbs), mAb 210 and mAb 270, stained many neurons in both the inner nuclear layer (INL) and ganglion cell layer (GCL). A class of large labeled cells in the inner INL were positioned at the INL/IPL (inner plexiform layer) border and resembled displaced ganglion cells (DGCs). Their identity was confirmed with injections of rhodamine-labeled microspheres into the ventral tectum and nucleus of the basal optic root (nBOR). Four days after the injection, large nAChR-positive neurons in the inner INL were labeled with beads. The distribution of these cells matched that reported for DGCs in the chicken and pigeon (Reiner et al., 1979; Fite et al., 1981). Many smaller cells in the INL also exhibited nAChR immunoreactivity. These cells were not retrogradely labeled after bead injections into retinal recipient areas. Their processes entered IPL where they arborized in a band comprised of the inner leaflet of lamina 1 and all of lamina 2. In some instances, a process continued inward to lamina 4. These neurons were tentatively identified as amacrine cells because of their position and branching pattern. Approximately 12-18% of the cells in the GCL exhibited nAChR immunoreactivity. Many of these cells could be classified as ganglion cells as their axons were also labeled following exposure to nAChR antibodies. Their distribution mirrored that of all ganglion cells with a higher density of cells in the central retina than in the periphery (Ehrlich, 1981). A "double label" technique was used to compare the distribution of nAChR-positive neurons with that of the choline acetyltransferase-positive (ChAT), cholinergic neurons in the chick retina. The two antigens were visualized with two different fluorophores: FITC and RITC. We were unable to find any cells in either the INL or GCL that exhibited both ChAT- and nAChR-like immunoreactivity. The nAChR-positive cells and the ChAT-positive cells both arborized in two bands within the IPL. The patterns were in perfect register in the inner IPL (lamina 4). But, in the outer IPL, the nAChR-positive dendrites were observed in the inner leaflet of lamina 1 and in all of lamina 2 while the ChAT-positive dendrites did not extend into the innermost portion of lamina 2.

Histochemical observations on unique rod-like cells in the developing retina of the normal rat.

Our previous immunohistochemical studies using specific anti-opsin antibodies have shown that in the normal postnatal rat retina, opsin-like immunoreactive materials can be seen not only in photoreceptor cells but also in some cells of the inner nuclear layer (INL). To characterize these ectopic opsin-like immunoreactive cells further, we have now studied developing rat retinae at the light and electron microscopic levels using both opsin immunocytochemistry and 5'-nucleotidase (5'-N) cytochemistry. Since photoreceptor cells are specifically stained in both methods, we investigated whether these methods would also stain some of the cells in the INL. Opsin-like immunoreactive cells in the INL always showed a characteristic nuclear structure, which was clearly distinguished from that of other INL cells and resembled rod cell nucleus because of the presence of conspicuous masses of condensed heterochromatin. Moreover, these opsin-like immunoreactive cells in the INL occasionally also displayed a ciliary process. They could only be seen in the INL until about day 25 of postnatal life. In the INL, 5'-N activity was found exclusively in cells showing rod-like nuclear features, and the timing of appearance and disappearance of 5'-N-positive cells in the INL was similar to that of the opsin-like immunoreactive cells. Numerous degenerating cells were observed in the INL at around day 10, some of which showed 5'-N reaction product at the cell surface. These results indicate that during postnatal development of the rat retina, some cells in the INL express several phenotypic properties characteristic of rod cells. It is suggested that these cells might undergo either cell degeneration or phenotypic conversion during the subsequent maturation of the retina.

Presence and distribution of histaminergic components in rat and bovine retina

The presence of histamine and its related enzymes, histidine decarboxylase and histamine N-methyltransferase and the subcellular distribution of the amine and of H 1-receptors were studied in the retina of two mammalian species. Histamine is present in rat and bovine retinas in concentrations (113 ± 10 and 72 ± 9 ng/g wet tissue, respectively) similar to those found in the brain. Histological examination and release experiments with Compound 48/80 performed in rat retina indicate a non mast cell location for the amine. Histidine decarboxylase and histamine N-methyltransferase activities in rat and bovine retinas were also comparable to those found in brain cortex suggesting that histamine can be synthesized and catabolyzed in situ. Subcellular fractionation of bovine retina showed that both the amine and H 1-receptors are concentrated in particulate fractions where small sized synaptosomes sediment, presumably derived from horizontal and amacrine cells. These results are in agreement with a neurotransmitter or neuromodulator role for histamine in cells of the retinal inner nuclear layer.

Experimental Chloroquine Retinopathy

Chloroquine retinopathy was produced experimentally in the eye of the albino corydoras (one of the tropical fish) by daily administration of chloroquine (0.1 mg per os). The enucleated eyes were examined from the 14th day to 3 months after the beginning of drug administration under light and electron microscopy. The first change of retina was the appearance of membraneous cytoplasmic body (MCB) in the cytoplasm of ganglion, amacrine, bipolar and horizontal cells. MCB might be degenerated lysosome. They showed lamellar figures or crystalline lattice-like structures. Secondarily, these MCB appeared in the inner segments of photoreceptor cells. The outer segments of rod cells disappeared, and then those of cone cells. Although photoreceptor cells were diminished in number in advanced degeneration, the cells of inner nuclear layer and ganglion cells were maintained in number. The presence of MCB dose not mean death of cells. The retinal pigment epithelial cells contained MCB in its cytoplasm only in severe degenerative cases, and did not show other remarkable changes. MCB also appeared in the cytoplasm of pericytes of retinal vessels. Chloroquine is considered to damage directly photoreceptor cells most severely.

Neuronal addition and retinal expansion during growth of the crucian carp eye.

Using standard paraffin technique the addition of new cells in crucian carp retinas was examined. Between eye diameters 4.4 and 10.0 mm the number of ganglion cells increases from 103,000 to 205,000, INL cells from 1.5 to 3 million, comes from 250,000 to 900,000, and rods from 2 to 9 million. Concomitantly retinal area increases fivefold and the cell densities decrease by 37% for the cones, 57% for the INL cells, and 58% for the ganglion cells, while the rod density remains stable. In relation to the rods the cell ratios at different retinal loci undergo marked changes during growth. The contributions to retinal growth by addition of new neurons and by expansion of the retina have been determined for the different retinal layers. The layer of rods grows exclusively by addition of new rod mosaic. In the cone layer 81% of growth is due to addition of new cone mosaic. In the inner nuclear layer (INL) 56% of growth is due to addition of new cells and in the ganglion cell layer 52% is due to cell addition. In each case retinal expansion accounts for the remainder of increase in retinal area. On morphological grounds six cone types can be found in the crucian carp retina. Their ratios are constant during retinal growth and at different retinal loci.

Retinal damage in scrapie mice.

Retinal damages in mice infected with scrapie are reported. The effects ranged from no histopathological changes, through partial loss of the outer nuclear layer (ONL) to the most severe changes with complete loss of ONL cells and photoreceptors. For the most part, cells of inner nuclear and ganglion layers were spared. These changes were found in 23% of C57BL/6J mice injected with the ME7 strain of scrapie and in 28.5% of VM mice injected with the 87 V strain, while no changes were found in 13 IM mice injected with the 87 V strain of scrapie. The possible relation of these changes to scrapie infection and to light induced retinopathy is discussed.

Ocular pathology of bovine GM1 gangliosidosis

Late-onset of disturbed vision is a clinical feature of bovine GM1 gangliosidosis. Studies on eight affected calves showed that ocular lesions were confined to the retinae and optic nerves. Myriad tiny white spots were visible by ophthalmic examination of the fundus. These spots were related to protuberances on the vitreal surface caused by distended retinal ganglion cells. The perikaryons of these were packed with dense aggregates of membranous cytoplasmic bodies (MCBs). Similar MCBs were present in the perikaryons of amacrine cells in the inner nuclear layer of the retina. Wallerian degeneration was present in the optic nerves. The lesions were compared with those described in gangliosidosis in man, cats, pigs and dogs. It is suggested that examination of the fundus is a useful clinical procedure in the diagnosis of bovine GM1 gangliosidosis.

Regional ischemic infarcts of the retina.

Macroscopic and light microscopic features of regional ischemic infarcts of retina in autopsy eyes are described. Lesions were found throughout life span, most patients having significant primary or secondary vascular disease (younger had systemic hypertension, rheumatic heart disease, vasculitis or sickle hemoglobinopathy; most older patients had arteriosclerosis). Diabetes mellitus and infarction of other organs (including brain) also were common. Topographically almost all lesions were found in posterior fundus; most were temporal and involved anatomical macula. Microscopically there was destruction of inner retinal layers with preservation of outermost cells of inner nuclear layer; occasionally ganglion cell layer was relatively spared.