• Applied Microscopy
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• v.27 no.2
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• pp.131-144
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• 1997

The present study was carried out to investigate the processes of the ultrastructural differentiation and the acetylcholinesterase (AChE) activities of the developing rat retina. The results are as follows. The retina of fetal rat on the 13th day of gestation showed the early stage of differentiation. Briefly, there appeared dividing chromosomes, the plentiful free ribosomes, and the high ratio of nucleus to cytoplasm. The reaction products by AChE were localized at the membrane of endoplasmic reticulum and on the outer membrane of nucleus. Ultrastructures and AChE activities in the retina of the fetal rats on the 18th day of gestation were similar to those of the prior stages, except the appearence of rough endoplasmic reticulum and Golgi apparatus. According to the ultrastructural observations, the rat retina was still in immature state at birth, but the pigment epithelial cells were fully differentiated, e. g. the increase of melanin granules, the development of mitochondria and Golgi apparatus. The AChE activity was weekly detected. The differentiated retinal layers and the outer segment of photoreceptor cells were observed on the 7th postnatal day. And the pigment epithelium appeared to be fully differentiated. On the 14th postnatal day, rat retina were completely differentiated. In other words, the rat retina was characterized by the prominent outer segments, phagocytosed residues in the pigment epithelium, and the localization of reaction products by AChE in the synapses. In conclusion, the differentiation of rat retina is charaterized by the changes of cell shape, the increase of retinal layers, and the alterations of AChE activities. It seems that rat retina is to be functional from 2 weeks of birth onward, coinciding with the eye opening of the juvenile rats.

• Applied Microscopy
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• v.15 no.1
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• pp.59-70
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• 1985

Morphogenesis of rat retina was studied by light and electron microscope from day 14 of gestation to 55 days after birth. The results indicate as follows: 1. At the outer border of the neuroblastic layer at the 14th day of gestation, cells she wed active mitotic figures which result in the increases of thickness and differentiations of this layer. 2. At birth, rat retina is still in a premature state. But, it is begining to approach its adult condition in appearance till the 9th postnatal day. Particulary photosensitive cells are fully developed by the 14th postnatal day, so they are functional from now on. 3. It is observed that the pigment epithelium begins differentiation at the fetal period, but is not functional urtil birth 4. The pigment epithelium differentiates earlier than the neuroblastic layer. It is suggested that these two layers are so closely associated that the pigment epithelium takes part in the differentiations of the neuroblastic layer. In conclusion, rat retina is differentiated soon after the optic cup formation before the 14th day of gestation, but even new born rat retina is not functional, and then it has function as photoreceptors coincided with the eye opening.

• Animal cells and systems
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• v.15 no.2
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• pp.155-159
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• 2011

Doublecortin (DCX) is microtubule-associated protein and is required for neuronal migration, differentiation and plasticity. In the retina, it is highly expressed between embryonic day 18 (E18) and E20, and is poorly expressed postnatally. In this study, we investigated the expression and cellular localization of DCX in the rat retina following ischemia induced by transiently increasing the intraocular pressure. While DCX immunoreactivity in control retinas was restricted to the outer border of the inner nuclear layer, it appeared in horizontal cell somata and processes in affected retinas. Quantitative evaluation by immunoblotting confirmed that DCX expression continuously increased after ischemia-reperfusion and showed 370% of control protein levels at 4 weeks after ischemic insult. These results suggest that the DCX in horizontal cells might play a role in neurite remodeling or modulating other neurons in ischemic rat retinas.

• The Korean Journal of Physiology and Pharmacology
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• v.9 no.6
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• pp.347-352
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• 2005

The effects of nitric oxide (NO) on inhibitory neurotransmitter receptors and some types of inhibitory receptors in dissociated rod bipolar cell (RBC) were investigated. In the whole cell voltage-clamping mode, the gamma-aminobutyric acid (GABA) activated current showed both sustained and transient components. GABA activated transient current was fully blocked by bicuculine, a $GABA_A$ receptor antagonist. The cis-4-aminocrotonic acid (CACA), a $GABA_C$ receptor agonist, evoked the sustained current that was not blocked by bicuculline (BIC). Glycine activated the transient current. These results indicate that the RBCs possess $GABA_A$, $GABA_C$, and glycine inhibitory receptors. Sodium nitroprusside (SNP), a NO analogue, reduced the currents activated by $GABA_A$ receptor only, however, did not reduce the currents activated by either $GABA_C$ or glycine receptors. This study signifies further that only NO depresses the fast inhibitory response activated by $GABA_A$ receptor in RBC. We, therefore, postulate that NO might depress the light-on/off transient inhibitory responses in RBCs in the rat retina.

• The Korean Journal of Zoology
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• v.22 no.1
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• pp.1-10
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• 1979

From the experimental results of cellulose acetate membrane electrophoresis we concluded the followings in explaining the LDH isozyme patterns found in the retina and cerebrum of vertebrata. Lactate dehydrogenase of the retina and cerebrum of both Carassinus carassinus and Cyprinus carpio was found to have one diffused band located between $LDH_2$ and $LDH_1$. LDH isozyme patterns of heart, pectoral muscle, liver and stomach of the Cyprinus carpio had the same diffused band in all organs. LDH isozyme patterns of the cerebrum of Hynobius leechii and Rana nigromaculata were observed to be different, in Hynobius leeichi a single band moved to the negative pole and two bands of $LDH_5$ and $LDH_4$ were obtained in the Rana nigromaculata. The retina and cerebrum of Natrix tigrina lateralis were observed as one band but amyda maakii had different LDH isozymes of the retina and cerebrum. The retina of Amyda maakii had five distinct LDH isozyme bands which had decreasing activity in the order of $LDH_5, LDH_4, LDH_3, LDH_2 and LDH_1$. The cerebrum of Amyda maakii had one band like Natrix tigrina lateralis but it moved to the negative pole. LDH isozymes in the retina and cerebrum of Gallus gallus domesticus and Melopsittacus undulatus showed one band. Five characteristic LDH isozyme bands were obtained from the retina of mammals, Oryctolagus cuniclus, Canis familiaris, Sus scrofa bos taurus and in the cerebrum of mouse, albino rat, Rhinolophus ferrum-equinum kokai.

• Journal of Photoscience
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• v.9 no.2
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• pp.430-432
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• 2002

The changes in expression of copper-zinc superoxide dismutase (CuZn-SOD), manganese superoxide dismutase (Mn-SOD) and glutathione peroxidase (GPX) in light-damaged rat retinas were examined. Sprague-Dawley rats (male, 6-weeks-old) were maintained on a cyclic photoperiod (12 hours light and 12 hours darkness) for 2 weeks. The illumination intensity during the light period was 80 lux. To induce light damage to the retina, a high-intensity illumination (3000-lux) was applied to the animals for 24 hours. After light exposure, the animals were returned to cyclic lighting. Eyes were enucleated 12 and 24 hours after light exposure started or 1,3, and 7 days after light exposure ended. Eyes were fixed and embedded in paraffin wax. Tissues were cut into 4${\mu}{\textrm}{m}$-thick sections. Sections were immunostained using antibody against CuZn-SOD, Mn-SOD, GPX and 8-hydroxy-deoxyguanocine (8-OHdG) as oxidative stress marker. 8-OHdG was observed in the outer nuclear layer (ONL) and retinal pigment epithelium (RPE) during light exposure. In light-damaged retinas CuZn-SOD labeling was up regulated in the ONL and RPE. Mn-SOD labeling was up regulated in rod inner segments (RIS) during light exposure and that in the RPE was up regulated after exposure. GPX labeling was observed in rod outer segments (ROS) during light exposure. GPX labeling was also observed in the RPE during and after light exposure. All three enzymes were observed in the outer retina, which suffered light damage, but occurred in defferent layers except within the RPE, in which case all three were expressed. These enzymes may play complementary roles as protective factors in light-damaged retinas.

• Medical Lasers
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• v.10 no.1
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• pp.22-30
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• 2021

Background and Objectives Ocular alkali burns cause severe damage to the ocular tissues and vision loss. Solcoseryl is a standardized calf blood extract that normalizes the metabolic disturbance and aids in maintaining the chemical and hormonal balance and has been used to treat burns in various tissues. This study examined the effects of Solcoseryl on a rat corneal alkali burn model. Materials and Methods Twenty rats were assigned randomly to four equal groups, including alkali burn, hyaluronic acid, Solcoseryl eyedrop, and Solcoseryl gel. A corneal alkali burn was induced by a NaOH-soaked paper disc. The treatments were given twice a day, every day. The wound area was measured after 24 and 48 hours, and the degree of neovascularization and corneal opacity were scored every week. The rats were sacrificed after three weeks for immunohistochemistry (IHC) to compare the level of inflammatory cytokines, IL-1β, IL-6, and TNF-α. The thickness of the retinal layers was compared to observe any changes in the retina. Results The use of Solcoseryl on corneal alkali burn accelerated wound healing with less neovascularization, greater opacity, and less cataract. IHC showed that the inflammation of the cornea was controlled by both the hyaluronic acid and Solcoseryl treatments. On the other hand, the inflammation had spread to the retina. When the dosage forms were compared, eyedrops were more effective on corneal inflammation, while the gel-type had a greater effect on retinal inflammation. Conclusion Solcoseryl was effective in accelerating the wound healing rate on a corneal alkali burn but could not prevent the spread of inflammation from the cornea to the retina. Eyedrops were more effective on inflammation in the cornea, and the gel was more effective in the retina.

• Applied Microscopy
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• v.42 no.3
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• pp.142-146
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• 2012

Doublecortin (DCX) is a microtuble-associated protein that is required for the migration of immature neuroblasts within the chick and mammalian brain. Although it is generally thought that DCX is expressed only in the neuroblasts, some mature neurons maintain DCX expression; for example, horizontal cells in adult rat retina. In this study, we demonstrate that retinal neural progenitors in the early embryonic stage of the chick also expressed DCX, as do developing ganglion cells and horizontal cells in later stages of development. These findings raise the possibility of a role for DCX in retinal neural progenitors, before they become specialized into neuroblasts in the chick.

• Proceedings of the Zoological Society Korea Conference
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• 2003.08a
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• pp.172.1-172
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• 2003

No Abstract, See Full Text

• Applied Microscopy
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• v.23 no.2
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• pp.11-26
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• 1993

This experiment was performed to study the morphological responses of the pigment epithelial cell and the Bruch's membrane of the retina of rat following X-ray irradiation. Male rats were divided into normal and experimental groups. The heads of the rats, under sodium thiopental anesthesia, were exposed to 3,000 rads or 6,000 rads of radiation in a single dose, respectively. The source was a Mitsubishi Linear Accelerator ML-4MV. The target to skin distance was 80cm, and the. dose rate was 200 rads/min. The experimental groups were sacrificed on the 6th hour, 2nd and 6th day after X-ray irradiation. Under anesthesia, 1% glutaraldehyde-1% paraformaldehyde solution(0.1M Millonig's phosphate buffer, pH 7.3) was perfused through the left ventricle and ascending aorta. Pieces of the tissue taken from the posterior region of the retina were fixed in 2.5% glutaraldehyde-1.5% paraformaldehyde(0.1M Millonig's phosphate buffer, pH 7.3) and 1% osmium tetroxide(0.1M Millonig's phosphate buffer, pH7.3), and embedded in araldite mixture. The ultrathin sections contrasted with uranyl acetate and lead citrate were observed with JEM 100 CX-II electron microscope. The results were as follow; 1. The morphological changes of the pigment epithelial cells were not pronounced after exposure to 3,000 rads of X-ray. But on the 6th hour after exposure to 6,000 rads of X-ray, bulging nuclear membrane protruding into the cytoplasm and nuclear chromatin clumped into numerous masses along the nuclear membrane were observed. At the 2nd and 6th day post-irradiation, partial cytolysis or necrosis were seen. 2. The thickness of the Bruch's membrane of the experimental groups were increased in the time and dose range covered by this study, and splitting or diffusing basal laminae of the choriocapillary layer were observed frequently in the experimental group. Above results suggest that large amount(6,000 rads) of head irradiation induce direct hazardous effects on the pigment epitherial cells and Bruch's membrane of the retina of the rat, but pigment epithelial cells are more radioresistant than Bruch's membrane.