Retinal ganglion cells (GC) of the Lamprey were studied after in vitro labeling of these cells by iontophoretic deposition of horseradish peroxidase into the optic nerve. The majority of GC are located at the boundary between the inner nuclear layer and the inner plexiform layer; a small proportion (20%) lies in the vitreous portion of the inner plexiform layer. Four types of GC were identified.
Interplexiform cells (IPCs) have not been previously described as a component of the population of tyrosine hydroxylase (TH) immunoreactive (presumably dopaminergic) cells in the avian retina. In this study, carried out in both pigmented and imperfect albino mutant quails (Coturnix coturnix japonica), we initially describe TH immunoreactive cells in the inner nuclear layer whose internal dendritic arborization extends into strata 1 3 and 4/5 of the inner plexiform layer. Then, we describe ascending processes arising from the somata or proximal dendrites of these cells. These sclerally directed processes (100-1,000 μm long) run across the inner nuclear layer to terminate within the outer plexiform layer, sometimes even reaching the outer nuclear layer. Hence, the cells bearing such processes correspond well with the definition of IPCs. The number of scleral processes is higher in mutant (48 ± 19/retina) than in normal (12 ± 10/retina) quails and are distributed throughout the retina except the area surrounding the pecten. Comparison of biochemical assays for dopamine in the two strains reveals a significantly higher dopamine content in the mutant quails which could be related to its increased number of dopaminergic IPC processes.
The distribution of catecholaminergic amacrine cells has been investigated in rats by means of immunohistochemical labelling of wholemounted retinas. Two groups of catecholamine-containing cells could be distinguished on the basis of their catecholamine and biosynthetic enzyme content. Both groups could be stained with an anti-tyrosine hydroxylase (TH) antiserum. The first group was composed of large, strongly TH-immunoreactive stellate amacrine cells, located principally in the innermost row of the inner nuclear layer (INL) and sending processes to the outermost sublamina of the inner plexiform layer (IPL). Some were displaced in the IPL or in the ganglion cell layer (GCL). This first group of cells can be regarded as dopaminergic since they were also stained by an anti-dopamine (DA) antiserum. The second group was composed of small, weakly TH-positive cell bodies, located slightly more sclerad within the INL. Their processes were usually not labelled with anti-TH. Identical cells could be better visualized with an anti-phenylethanolamine-N-methyltransferase (PNMT) antiserum. Their processes were observed in the middle sublamina of the IPL. A great number of these cells were displaced in the GCL. They could be regarded as epinephrine cells. Concerning the density and distribution throughout the retina a striking difference was observed between the superior and inferior halves of the retina, whereas a lower difference was observed between the nasal and temporal regions. Almost all the PNMT-immunoreactive cells were located throughout the upper retina, whereas the DA-cells were especially concentrated in the upper temporal quadrant. The distribution of the DA cells parallels that of the ganglion cells whose density is also maximal in the upper temporal retina.
Choroidal and retinal neovascularization plays an essential role in various ocular diseases. In this study, we examined the role of nestin in this process. Nestin is an intermediate filament protein known to play several roles, including as a marker of neural progenitor and proliferating endothelial cells.We used Brown Norway rats, in which choroidal and retinal neovascularization was induced using intraocular laser impacts. The role of nestin was examined using angiography, western blot from the second to the 14th day after laser impacts, and intraocular injection of nestin siRNA. The localization of the protein was specified by co-immunoreactivity with glial fibrillary protein (GFAP), glutamine synthetase (GS), and von Willebrand factor (vWF).In the control retina, nestin was found principally in glial structures in the ganglion cell layer, as confirmed by nestin/GFAP immunolabeling. Two days after the laser impacts, the nestin expression extended to numerous radial processes at the site of the impacts. With Bruch's membrane ruptured, these processes penetrated into the choroid. Nestin immunolabeling remained high from the third to the seventh day but appeared reduced on the 14th day. The nature of these processes was not clearly defined, but co-immunolabeling with GFAP suggested that they were principally in activated Müller cells from the third day after the laser impacts. However, the co-immunoreactivity of nestin and GS, a marker of mature functional Müller cells, could be observable only from the seventh day. Nestin was also observed in some vascular cells, as demonstrated by the co-immunoreactivity of the protein with vWF in the choroid and retina. As observed on angiography, the numbers of choroidal and retinal blood vessels were significantly increased (principally on the seventh day) after the laser impacts. An intraocular injection of nestin siRNAs led to a significant decrease in the number of blood vessels.Our results confirmed the presence of nestin in glial (e.g., astrocytes), reactive Müller, and endothelial cells. They demonstrated their critical involvement in a rat model of retinal and choroidal neovascularization experimentally induced using ocular laser impacts.
