Internal Nuclear Layer Research Articles

Paracentral acute middle maculopathy as the first sign of internal carotid artery dissection

Purpose: It is proposed to present a clinical case of a patient with a paracentral acute middle maculopathy (PAMM) as the first sign of presentation of severe internal carotid artery (ICA) dissection.Methods: An initial basic ophthalmologic examination of the patient was performed, followed by an optical coherence tomography (OCT) and an OCT‐angiography (OCT‐A) of each eye. Finally, the patient was evaluated by a neurologist, performing a cerebral and supra‐aortic trunks (SAT) computed tomography (CT) angiography.Results: We present a 54‐year‐old patient who came to the emergency room complaining of central blurred vision in his left eye (OS) during 24 h. On ophthalmological examination, it is remarkable a visual acuity (VA) of counting fingers at 1 m in OS. Eye fundus (EF) of OS showed small oval whitish macular lesions. Macular OCT of OS revealed hyperreflective bands in the internal nuclear layer (INL) and OCT‐A showed areas with low flow at deep capillary plexus (DCP) and macular vascular density (MVD) parameters decreased compared to the right eye (OD). During the examination, the patient began to feel a slight loss of strength in his right hemibody with dizziness, so he was explored by a neurologist and a cerebral and SAT CT angiography was performed, which reported severe left ICA dissection with an area of hypoperfusion in the territory of the left middle cerebral artery, but without intracranial vascular occlusion. Since there was no image of occlusion and given the mild neurological symptoms, endovascular treatment was rejected and anticoagulation with enoxaparin was established. Two months later, VA of OS improved to 1, with no significant lesions in the EF. The OCT of OS showed a slight thinning of the INL and the OCT‐A revealed a greater flow in the DCP with better MVD values.Conclusions: This entity should be considered in patients with visual disturbances. PAMM may be the first sign of ICA pathology.

In utero alcohol exposure impairs retinal angiogenesis and the microvessel-associated positioning of calretinin interneurons.

In addition to brain disorders, which constitute a devastating consequence of prenatal alcohol exposure (PAE), eye development is also significantly affected. Given that the retina is a readily accessible part of the central nervous system, a better understanding of the impact of ethanol on retinal development might provide ophthalmological landmarks helpful for early diagnosis of foetal alcohol syndrome. This study aimed to provide a fine morphometric and cellular characterization of the development of retinal microvasculature and neurovascular interactions in a mouse model of foetal alcohol spectrum disorder. The data revealed that PAE impaired superficial vascular plexus development. In particular, progression of the vascular migration front was significantly decreased in PAE retinas, supporting a delay in plexus progression. Moreover, a significant decrease in the vessel density and number of perforating vessels was quantified in PAE mice, supporting less angiogenesis. The present study provides also the first evidence of a close interaction between migrating calretinin-positive interneurons and perforating microvessels in the inner nuclear layer of the developing retina. This neurovascular association was significantly impaired by PAE. Moreover, projections of amacrine cells were abnormally distributed and densified in stratum S1 and S2. In humans, comparison of a 5-month-old control infant with a 3-month-old alcohol-exposed case revealed a similar mispositioning of calretinin-positive interneurons. This opens new research avenues regarding a neurovascular contribution in the deleterious effects of alcohol in the developing retina and support that ophthalmological examination could become a promising approach for early detection of alcohol-exposed infants presenting with neurovascular brain defects.Significance StatementIn the developing brain, prenatal alcohol exposure (PAE) has been shown to disorganize cortical vasculature leading to defective layering of interneurons which use radial microvessels to enter the neocortex. Using a murine model of FASD, here we show that PAE impairs the retinal microvasculature development and neuronal organization. In particular, migrating calretinin-positive interneurons of the internal nuclear layer are associated with perforating microvessels. PAE reduces the number of vessel-associated calretininergic cells and impairs their positioning. The mispositioning of calretinin-positive interneurons is also observed in a human FAS infant. These findings provide new evidence that PAE-induced cortical impairments are found in retina. They offer promising tools for the early diagnosis of brain impairments in infants in utero exposed to alcohol.

The Incidence and the Clinical Course of Retinal Complications of Intracameral Cefuroxime in Cataract Surgery

Aim. To determine the incidence and the clinical course of retinal complications of intracameral administration of cefuroxime in minimally invasive cataract surgery.Methods. From 2016 to 2021, a prospective clinical study was conducted at the Volga District Medical Center of the Federal Medical and Biological Agency of Russia, which included patients with cataract in one or two eyes to be surgically treated. All patients received 1 mg of cefuroxime injected into the anterior chamber at the end of surgery. All patients underwent ophthalmological examination including evaluation of best corrected visual acuity with determination of logarithm of minimum angle of resolution (logMAR), tonometry, biomicroscopy, and ophthalmoscopy. Each patient before and the day after surgery underwent optical coherence tomography of the retina on a spectral optical tomograph RTVue-100 (Optovue). The dynamics of the condition was evaluated on days 3 and 7 after surgery.Results. Five cases of retinal complications of intracameral cefuroxime injection were identified during the 5-year study period. According to data of optical coherence tomography, retinal edema was localized in the internal nuclear layer of the retina, and the height of serous retinal detachment in the fovea area on the next day after surgery was 315.0 ± 11.0 µm and reduced statistically significantly to 59.8 ± 42.3 µm on the 3rd day after the intervention (p = 0.043). One week later, all patients had complete retinal adherence and recovery of visual function. Retinal edema did not recur in the long term after surgery.Conclusion. Serous retinal detachment with macular edema is the most common clinically relevant complication of intracameral antibiotic prophylaxis, which develops both in compliance with the dilution protocol and in overdose, and has a favourable prognosis.

Retinal Flow Density Changes in Early-stage Parkinson’s Disease Investigated by Swept-Source Optical Coherence Tomography Angiography

ABSTRACT Background: Parkinson’s Disease (PD) is the second-most common neurodegenerative disease affecting the elderly population. The eye has been referred to as a window to the brain due to its inseparable relationship with the central nervous system. The development of Swept-Source Optical Coherence Tomography (SS-OCT) and Optical Coherence Tomography Angiography (OCTA) technologies has offered us a better imaging modality to study the impact of PD on the retina. Method: Seventy-five eyes of 42 early-stage PD patients and 150 eyes of 75 matched healthy controls were enrolled in the current study. We performed SS-OCT and SS-OCTA to assess retinal nerve fiber layer (RNFL), ganglion cell layer (GCL) + inner plexiform layer (IPL), internal nuclear layer (INL) thickness, and retinal flow density and flow ratio. Results: Our study indicates decreasing superficial and deep flow density in most regions of the retina. Superficial and deep flow parameters were also associated with RNFL, GCL+IPL, and INL thickness. ROC analysis reveals superficial flow density demonstrated an Area Under Curve (AUC) of 0.688, which is greater than deep flow density and retinal thickness measurements. Conclusion: To the best of our knowledge, we are the first study using SS-OCT and SS-OCTA to study superficial and deep retinal flow changes in early-stage PD patients. Our study suggests decreasing retinal flow density provides greater diagnostic power than retinal thickness measurements in the early stage of PD. SS-OCTA parameters could potentially serve as imaging biomarkers in PD diagnosis and staging.

Cystic maculopathy of the inner nuclear layer in glaucoma patients

The study aimed to detect and describe glaucoma-related pseudocystic abnormalities at the internal nuclear layer (INL) of the macula using OCT, in relation with visual field defects and other clinical data. Primary open-angle glaucoma patients presenting for a follow-up visit were consecutively included over 5 months and underwent clinical examination, OCT imaging, and central 10-2 visual field testing. OCT measures included the thickness of the peripapillary retinal nerve fiber layer (RNFL) and macular ganglion cell complex (GCC), together with an analysis of B-Scans and en-face images. All data provided by OCT were analyzed and compared with the visual field testing. Fourteen patients out of 216 showed pseudocysts in the INL of the macula. These cysts were hyporeflective, fusiform, and of variable size (15 to 25μm) and were always associated with a thinning of both the RNFL and GCC. En-face OCT showed evidence of a distribution of cysts in the macular region, based on the appearance of numerous, dense hyporeflective pits whose localization matched precisely with the vision loss as assessed by central 10-2 visual field testing. No other correlations were found. Pseudocysts of the internal nuclear layer of the macular region are found in some cases of chronic glaucoma. Their presence is always associated with a scotoma in the visual field and appear to constitute a marker for glaucoma progression. Glaucoma-related central pseudocysts could result from Müller cell changes, excitotoxicity, and/or trans-synaptic retrograde degeneration. The presence of pseudocysts could be a marker of a particular subpopulation whose features remain to be determined.

Microcystic Changes in the Retinal Internal Nuclear Layer Associated with Optic Atrophy: A Prospective Study

Purpose. This study aimed at assessing the prevalence of pathologies presenting retinal inner nuclear layer (RINL) microcystic perimacular changes associated with optic nerve atrophy (OA). The charts of patients presenting a significant defect of the Retinal Nerve Fiber Layer (RNFL) were included prospectively in this study. Patients were classified according to the etiology of the RNFL defect. Two hundred and one eyes of 138 patients were enrolled in this analysis. Retinal images obtained showed the typical hyporeflective perifoveal crescent-shaped lesion composed of small round hyporeflective microcysts confined to the RINL in 35.3% of the eyes. Those findings were found in 75% of eyes presenting hereditary OA, 50% of eyes presenting ischemic optic neuritis, 50% of eyes with drusen of the optic nerve (ON), 44.4% of eyes presenting a compressive OA, 32% of eyes presenting inflammatory optic neuropathy from multiple sclerosis, 18.5% of eyes presenting OA from undetermined origin, and 17.6% of eyes having primary open-angle glaucoma. This study demonstrates that microcystic changes in RINL are not specific to a disease but are found in OA of various etiologies. Moreover, their incidence was found to be dependent upon the cause of OA, with the highest incidence occurring in genetic OA.

RETINAL INNER NUCLEAR LAYER MICROCYSTIC CHANGES IN OPTIC NERVE ATROPHY

Optic atrophy constitutes the final stage in the evolution of optic neuropathy. The aim of this study was to describe the presence of macular microcystic changes or pseudocysts in patients with advanced optic atrophy. The medical records of 24 patients who had retinal pseudocysts in association with optic atrophy have been analyzed. All patients underwent a complete neuro-ophthalmologic assessment; peripapillary retinal nerve fiber layer thickness and macular screening with spectral-domain optical coherence tomography and optical coherence tomography "en face" imaging analysis were also performed. A total of 36 eyes were included in the study. Patients' mean age was 37 years. The major cause of optic atrophy was glaucoma (12 cases). The retinal pseudocysts were observed as hyporeflective lesions in the internal nuclear layer. Infrared images revealed a hyporeflective circular or semilunar shape corresponding to the location of the pseudocysts in all cases. In eyes with pseudocysts, mean thickness of the peripapillary retinal nerve fiber layer was statistically significantly less than that of fellow eyes (P = 0.0003), whereas macular thickness was statistically significantly higher compared with fellow eyes (P < 0.005). The presence of pseudocystic lesions always associated with severe optic nerve fiber loss is reported. The reason why pseudocystic lesions develop within the retina is not well understood. They might constitute the translation of degeneration of Muller cells in severe optic nerve fiber loss. Recognizing these pseudocysts is crucial because they may be confused with cystoid macular edema. Their prognostic value and role in the therapeutic process need to be further evaluated with prospective studies and molecular experiments in vivo.

Histological Studies on the Retina of the Falcon "S Eye Ball (Circus Cyaneus C.) Under Light and Electron Microscopy

The histological study showed that the retina of falcon"s eyeball was thin at the peripheryand ranges between 0.6-0.8 μ but it was thick at center 1.68-2.64 μ. The retina consists fromten layers: pigmented epithelium, rods and cons layer, external nuclear layer, externalplexiform layer, internal nuclear layer, internal plexiform layer, Gangilionic cells layer,neurofibres layer and internal limiting membrane layer. The ultra-structural study stated thatthe rods and cons layers contained single rods with single and double cons. The retinacharacterized by lacking of the oil droplets in the internal segments of rods with narrowexternal plexiform layer in order to form network connecting rods and cones, horizontal cells,bipolar cells and Muller's cells.

Platelet-Derived Growth Factor Receptor Alpha Is Associated with Oxidative Stress-Induced Retinal Cell Death

The purpose of this study was to investigate the role played by platelet-derived growth factor-α (PDGFRα) in oxidative stress-induced retinal cell death. A previous proteomic study from our laboratory showed that expression of PDGFRα is elevated considerably in the retinas of an animal model of glaucoma-the excitatory amino acid carrier (EAAC) 1-deficient (EAAC1-/-) mouse. Retinal sites and expression patterns of PDGFRα were determined by immunohistochemistry in the retinas of EAAC1-/- and control CRL:CD1(ICR) mice. A retinal cell line was exposed to hydrogen peroxide, and expression PDGFRα determined by Western blot analysis. Effects of PDGF-AA and PDGFRα-siRNA on hydrogen peroxide-induced retinal cell death were examined. PDGFRα was detected in the retinal ganglion cell layer (RGL) of both EAAC1-/- and ICR mice, and was also localized in the internal nuclear layer (INL) of EAAC1-/- mice. While treatment with excess PDGF-AA had no additional effect on retinal cell death, expression of PDGFRα increased with exposure to hydrogen peroxide. Hydrogen peroxide-induced retinal cell death was inhibited by exposure to PDGF-AA via phosphatidylinositol 3 kinase (PI3K); cell death was promoted by PDGFRα-siRNA. PDGFRα is expressed in mouse retina, where it is essential for retinal cell survival under conditions of oxidative stress.

Toxicidade retiniana do gás hexafluoreto de enxofre, líquido perfluorocarbono, ar e solução salina balanceada em olhos de coelhos

To determine retinal toxicity after intravitreous balanced salt solution, sulfur hexafluoride gas, and perfluorocarbon liquid injection in rabbit eyes. Twenty-two eyes of sixteen New Zealand albino rabbits were divided into groups: balanced salt solution (7 eyes); sulfur hexafluoride gas (4 eyes); and perfluorocarbon liquid (5 eyes). After the introduction of a needle through the sclera the vitreous was aspirated (0.3 ml), balanced salt solution, sulfur hexafluoride gas 100% and perfluorocarbon liquid (0.3 ml) were injected into rabbit vitreous cavity. The control group (6 eyes) was not submitted to any procedure. After three weeks the vitreous was aspirated and submitted to biochemical analysis and the eyes prepared for histological analysis. The eyes submitted to perfluorocarbon liquid and sulfur hexafluoride gas injection showed a greater L-glutamate increase in the vitreous compared to balanced salt solution and control groups (p<0.05). Histological results confirmed small changes in the sulfur hexafluoride group and important lesions in perfluorocarbon liquid group, such as external photoreceptor segment disruption, external and internal plexiform layer thinning, ganglionar and internal nuclear layer decrease of nucleus number, edema, and presence of macrophages in the superficial layers. No major histological changes were observed with balanced salt solution and in control groups. Liquid intravitreous injection of sulfur hexafluoride gas and perfluorocarbon are potentially toxic to rabbit retina, compared to control and balanced salt solution groups.

Neuronal Intermediate Filament in the Developing Rat Retina

The distribution of peripherin mRNA in adult rat retinal ganglion cells revealed by in situ hybridization was relevant to the distribution of immunoreactivity to anti-peripherin. Peripherin positive ganglion cells began to differentiate from the 13th gestational day. These peripherin positive ganglion cells expressed α-internexin from the early phase of differentiation and majority of the peripherin positive ganglion cells completed their migration by the 17th gestational day. The optic nerve layer was gradually enlarged during the 15-17th gestational day. However, unlike adult retina, neurofilament triplets were not revealed in the prenatal optic nerve. A different group of neurons with α-internexin without peripherin increased during the 15-19th gestational day and neurons of the internal nuclear layer seemed to transiently express α-internexin because they were seen in the internal nuclear layer above horizontal cells on the 19th gestational day. Although horizontal cells were clearly identified in the retina on the 19th gestational day, calbindin 28KD was not revealed in this stage.

Diversification of brain and sense organ morphology in Antarctic dragonfishes (Perciformes: Notothenioidei: Bathydraconidae).

In the subzero shelf waters of Antarctica, fishes of the perciform suborder Notothenioidei dominate the fish fauna and constitute an adaptive radiation and a species flock. The 16 species of dragonfishes of the family Bathydraconidae live from surface waters to nearly 3,000 m and have the greatest overall depth range among notothenioid families. We examined the anatomy and histology of the brain, retina, and cephalic lateral line system of nine bathydraconid species representing 8 of the 11 known genera. We evaluate these data against a cladogram identifying three clades in the family. We provide a detailed drawing of the brain and cranial nerves of Gymnodraco acuticeps and Akarotaxis nudiceps. Bathydraconid brain morphology falls into two categories. Brains of most species are similar to those of generalized perciforms and some basal notothenioids (Class I). However, brains of deep-living bathydraconids (members of the tribe Bathydraconini minus Prionodraco) have a reduced telencephalon and tectum that renders the neural axis visible - the stalked brain morphology (Class II). All bathydraconids have duplex (rod and cone) retinae but there is considerable interspecific variation in the ratio of cones:rods and in the number of cells in the internal nuclear layer. Retinal histology reflects habitat depth but is not tightly coupled to phylogeny. Although the deep-living species of Bathydraconini have rod-dominated retinae, the retinae of some sister species are photopic. An expanded cephalic lateral line system is also characteristic of all members of the Bathydraconini as exemplified by Akarotaxis. This morphology includes large lateral line pores, wide membranous canals, hypertrophied canal neuromasts, and large anterodorsal lateral line nerves, eminentia granulares, and crista cerebellares. The saccular otoliths are also enlarged in members of this tribe. Neural diversification among bathydraconids on the Antarctic shelf has not involved the evolution of sensory specialists. Brain and sense organ morphologies do not approach the specialized condition seen in primary deep-sea fishes or even that of some secondary deep-sea fishes including sympatric non-notothenioids such as liparids (snailfishes) and muraenolepidids (eel cods). The brains and sense organs of bathydraconids, including the deep-living species, reflect their heritage as perciform shorefishes.

Early postnatal Müller cell death leads to retinal but not optic nerve degeneration in NSE-Hu-Bcl-2 transgenic mice

Topographically localized over-expression of the human Bcl-2 protein in retinal glial Müller cells of a transgenic mice (line 71) leads to early postnatal apoptotic Müller cell death and retinal degeneration. Morphological, immunohistological and confocal laser microscopic examination of transgenic and wild-type retinas were achieved on paraffin retinal sections, postnatally. Apoptosis occurs two to three days earlier in the internal nuclear layer of transgenic retinae, than in wild-type littermates. In parallel there was a progressive disappearance of transgenic Hu-Bcl-2 over-expression, as well as of the Müller cell markers, cellular retinaldehyde-binding protein and glutamine synthetase. This phenomenon led to retinal dysplasia, photoreceptor apoptosis and then retinal degeneration and proliferation of the retinal pigment epithelium. The optic nerve, however, remains intact. Two complementary observations confirm the pro-apoptotic action of Bcl-2 over-expression in Müller cells: (i) in the peri-papillary and peripheral regions where the transgene Bcl-2 is not expressed, cellular retinaldehyde-binding protein or glutamine synthetase immunostaining persist and Müller glia do not die; and (ii) the retina conserves a normal organisation in these two regions inspite of total retinal degeneration elsewhere. We conclude that retinal dysplasia and degeneration are linked to primary Müller cell disruption. Besides its generally accepted anti-apoptotic function, over-expression of Bcl-2 also exerts a pro-apoptotic action, at least in immature Müller glia. One may suppose that Bcl-2 translocation resulting in its over-expression in retinal Müller cells could be a putative mechanism for early retinal degeneration.

Immunochemical Analysis of the Sodium Channel in Rodent and Human Eye

The presence of the amiloride-sensitive sodium channel (ASSC) in ocular tissues was studied with the aid of a polyclonal antiserum raised against the 14 amino acid peptide QGLGKGDKREEQGL. This sequence corresponds to the region 44–58 of the α subunit of the channel, termed ENaC, cloned from rat colon. The antibody titers, measured by the ELISA technique, rose to 1:2560 4 weeks after immunization, and this bleed was used in all subsequent experiments. Immunoblotting with the polyclonal anti-αENaC serum, revealed a major band of 82–86 kDa in extracts prepared from whole bovine or rat retina; a minor component of 92 kDa in the extract from bovine ciliary body may represent a glycosylated species. Immunohistochemistry, using the αENaC-specific antiserum, revealed strong fluorescence in specific areas of the rat and human eye. Pronounced labelling was observed in the epithelial cell layer of the retina, the lens, as well as both the pigmented and the nonpigmented epithelium of the ciliary body and the iris. All of the cell layers (epithelium, endothelium and fibroblasts) in the cornea, the blood vessels in the iris, and iris epithelium, were also strongly immunopositive. The somatic body of the photoreceptor cells (cones and rods) in the inner and outer segments could be traced to forming a synapse in both the internal and external portions of the internal nuclear layer. The bipolar cells and ganglia in the neuronal compartment also exhibited occasional immunofluorescence. The method of fixation and the source of the tissue were important parameters for the immunochemical localization of the ENaC. The resolution was very poor when rat eye was fixed in Bouin's solution but this method was satisfactory for human tissues. For rat eye, optimum resolution was obtained with AMeX fixation. This widespread distribution of the ENaC generally colocalizes with the previously observed immunopositivity for the mineralocorticoid receptor such that steroid hormone-mediated ion regulation would appear to add a new parameter to the functional expression of ocular tissues.

Centrifugal Phe-Met-Arg-Phe-NH 2-like immunoreactive innervation of the retina in a non-teleost bony fish, Lepisosteus osseus

In all teleosts studied, Phe-Met-Arg-Phe-NH 2- (FMRFamide-) like immunoreactive fibers originating from structures related to the olfactory system project to the retina. A complete report on this olfacto-retinalis projection in fish that are phylogenetically older than teleosts is still missing. We have visualized FMRFamide-like immunoreactive fibers in the optic nerve, the optic chiasm and in the retina of the longnose gar, Lepisosteus osseus. They terminate on amacrine or horizontal cells in the internal nuclear layer. Additionally, some of them appear to contact retinal ganglion cells.

Comparative study of astrocytes in human and rabbit retinae

Immunohistochemical location of Glial Fibrillary Acidic Protein (GFAP) was used to compare the morphology of astrocytes in vascularized and partially vascularized retinae (human and rabbit, respectively). Astrocytes in human and rabbit retinae were found in the same regions as the blood vessels. These cells in partially vascularized retinae differed from those in vascularized retina in several respects. Firstly, there were six morphological types in rabbit retina and only two in human retina. Secondly, in rabbit retinae there were astrocytes only related to blood vessels called “perivascular astrocytes” which were absent in human retinae. Thirdly, the astrocytes were located in the nerve fiber layer and ganglion cell layer in both types of retinae, but in human retinae these cells could also be seen in the internal nuclear layer. These observations demonstrate that there are many differences between astrocytes in human and rabbit retina, suggesting that rabbit retina could be used with caution as an experimental model in comparative studies with human retina.

Localization of heme oxygenase in rat retina: effect of light adaptation

Heme oxygenase-2 isozyme is the predominant form of heme oxygenase in rat brain by western blot analysis. Heme oxygenase-1 isozyme is not induced by light adaptation in rat retina by western blot analysis. Immunocytochemistry localizes heme oxygenase-2 in three areas of the retina: the retinal pigment epithelium, inner segment and external nuclear layers of the rat retina. Ganglion cells and cell bodies of the internal nuclear layer of the retina and Müller cells were largely unstained for heme oxygenase-2. The localization of heme oxygenase-2 in the retina implies that its function is not associated with phototransduction. Also, light adaptation does not appear to induce heme oxygenase; 1, a measure of oxidative injury.

Immunohistochemical study of human retinal astroglia

Immunocytochemical localization of glial fibrillary acidic protein (GFAP) has been used to study astrocyte distribution and morphology in whole mounted human retinas and vertical sections. Two types of astrocytes can be distinguished: elongated astrocytes are located in the nerve fibre layer (NFL); and star-shaped astrocytes are found in the ganglion cell layer (GCL). Astroglial processes join to form bundles. The bundles formed by the elongated astrocytes lie along and separate the nerve fibre bundles. Processes from star-shaped astrocytes reach towards other star-shaped astrocytes and towards the vessels to form a morphologically honeycombed plexus. These astrocytes also send other processes towards the internal nuclear layer (INL), forming an irregular plexus which accompanies the GCL capillaries that extend into the INL. Often, the cell bodies of the star-shaped GCL astrocytes lie over vessels and form cell clusters. Finally, none of the retinas examined for this study evidenced the "perivascular astrocytes" described by Wolter in the human retina.

Development of gamma-aminobutyric acid-immunoreactive neurons in normal and intracranially transplanted retinas in rats

Retinas from embryonic day 14 Sprague-Dawley rats were transplanted intracranially to the midbrain or cortex of newborn (P0) rats with right eyes enucleated at the time of transplantation and the gamma-aminobutyric acid (GABA) immunoreactivity in developing retinal transplants, host as well as normal retinas, was studied. The results showed that GABA-immunoreactive neurons were identified in retinas of normal and host rats from the day of birth (P0) onward and that their somata were distributed primarily in the inner half of the internal nuclear layer and in the ganglion cell layer. The adult pattern of GABA immunoreactivity was first observed at P16 when several immunoreactive sublaminae were clearly identifiable in the inner plexiform layer. In contrast, gamma-aminobutyric acid-immunoreactive somata could not be identified in retinal transplants until P4, with a significant reduction in the density and number of GABAergic neurons detected by P12. Moreover, only two immunoreactive sublaminae were observed in the inner plexiform layer in all transplants at P12, as well as in more mature stages. These results suggest that significant changes occurred in the GABA system of the transplanted retina, despite the fact that the overall pattern of organization of the GABAergic neurons and their processes in the retinal transplants was comparable to that of the normal retina.

Lactate dehydrogenase activity and its isoenzymes in concentric layers of adult bovine and calf lenses.

The activity of lactate dehydrogenase (LDH) and its isoenzyme pattern were studied in four concentric layers of adult bovine and calf lenses. In both groups the specific activity of the total LDH diminished progressively toward the internal nuclear layer; the decrease was greater in the adult lenses. The enzyme activities in the cortical layers of the calf lens were lower than in the adult lens, but in the inner nuclear layers, the opposite was found. All of the 5 LDH isoenzymes were found in each layer. In both groups of animals the LDH1 isoenzyme prevailed, followed by LDH2. No differences were found in the percentage of each isoenzyme in the different lens layers. The differences in the activitie(s) of LDH found may be due to post-translational or post-synthetic modifications which may occur during the aging process.