Immunochemical changes of calbindin, calretinin and SMI32 in ischemic retinas induced by increase of intraocular pressure and by middle cerebral artery occlusion

Jong-Hyun Lee,Ji Man Shin,Yoo-Jin Shin,Myung-Hoon Chun,Su-Ja Oh 대한해부학회 2011 Anatomy & Cell Biology Vol.44 No.1

The reaction of neuroactive substances to ischemic conditions in the rat retina evoked by different methods was immunochemically evaluated in adult Sprague-Dawley rats. Ocular ischemic conditions were unilaterally produced by elevating intraocular pressure (EIOP) or by middle cerebral artery occlusion (MCAO). Two EF-hand calcium binding proteins, calbindin D28K (CB) and calretinin (CR), in the normal retina showed similar immunolocalization, such as the amacrine and displaced amacrine cells, the ganglion cells, and their processes, particularly CB in horizontal cells. CB immunoreactive neurons in the ganglion cell layer in both types of ischemic retinas were more reduced in number than CR neurons compared to those in a normal retina. The CB protein level in both ischemic retinas was reduced to 60-80% of normal. The CR protein level in MCAO retinas was reduced to about 80% of normal but increased gradually to the normal value, whereas that in the EIOP showed a gradual reduction and a slight recovery. SMI32 immunoreactivity, which detects a dephosphorylated epitope of neurofilaments-M and -H, appeared in the axon bundles of ganglion cells in the innermost nerve fiber layer of normal retinas. The reactivity in the nerve fiber bundles appeared to only increase slightly in EIOP retinas, whereas a moderate increase occurred in MCAO retinas. The SMI32 protein level in MCAO retinas showed a gradual increasing tendency, whereas that in the EIOP showed a slight fluctuation. Interestingly, the MCAO retinas showed additional SMI32 immunoreactivity in the cell soma of presumed ganglion cells, whereas that of EIOP appeared in the Müller proximal radial fibers. Glial fibrillary acidic protein (GFAP) immunoreactivity appeared in the astrocytes located in the nerve fiber layer of normal retinas. Additional GFAP immunoreactivity appeared in the Müller glial fibers deep in EIOP retinas and at the proximal end in MCAO retinas. These findings suggest that the neurons in the ganglion cell layer undergo degenerative changes in response to ischemia, although EIOP retinas represented a remarkable Müller glial reaction, whereas MCAO retinas had only a small-scaled axonal transport disturbance.

EST analysis of regenerating newt retina

Hisatomi, Osamu,Hasegawa, Akiyuki,Goto, Tatsushi,Yamamoto, Shintaro,Sakami, Sanae,Kobayashi, Yuko,Tokunaga, Fumio Korean Society of Photoscience 2002 Journal of Photosciences Vol.9 No.2

A vertebrate retina is an organ belonging to the central nerve system (CNS), and is usually difficult to regenerate except at an embryonic stage in life. However, certain species of urodele amphibians, such as newts and salamanders, possess the ability to regenerate a functional retina from retinal pigment epithelial (RPE) cells even as adults. After surgical removal of neural retinas from adult newt eyes, the remaining RPE cells lose their pigment granules, transdifferentiate into retinal progenitor cells, which further differentiate into various retinal neurons, and then finally reform a functional neural network. To understand the molecular mechanisms of CNS regeneration, we attempted to investigate the genes expressing in regenerating newt retina. mRNAs were isolated from regenerating retinas at 18-19 days after the surgical removal of the normal retina, and a cDNA library (regenerating retinal cDNA library) were constructed. Our EST analysis of 112 clones in the regenerating cDNA library revealed that about 70% clones are closely related to the genes previously identified. About 40% clones are housekeeping genes, and about 15% clones encode proteins related to the regulation of gene expression and to the proliferation of the cells. Sequences similar to neural retina- and RPE-specific genes were not detected at all. These results led us to suppose that the regenerating retinal cells are in a state considerably different from those of neither neural retina nor RPE cells.

Disruption of the polyubiquitin gene <i>Ubb</i> causes retinal degeneration in mice

Lim, Daehan,Park, Chul-Woo,Ryu, Kwon-Yul,Chung, Hyewon Elsevier 2019 Biochemical and biophysical research communication Vol.513 No.1

<P><B>Abstract</B></P> <P>We have previously demonstrated that a reduction in ubiquitin (Ub) levels via disruption of the polyubiquitin gene <I>Ubb</I> results in reactive gliosis and hypothalamic neurodegeneration in mice. However, it is not known whether other neural tissues, apart from the brain, can also be affected by <I>Ubb</I> disruption. We examined the retina, which, being derived from the diencephalon, has the same developmental origin as the hypothalamus. We found that expression levels of <I>Ubb</I> were much higher than those of the other polyubiquitin gene <I>Ubc</I> in the retina. In retinal tissues from <I>Ubb</I> knockout (KO) mice, we found that <I>Ubc</I> expression was upregulated to compensate for the loss of <I>Ubb</I>; however, the Ub pool remained disrupted, with reduced levels of free Ub. To directly demonstrate whether the disrupted Ub pools affect neural integrity in retinal tissues, we investigated retinal layers in control and <I>Ubb</I> KO mice. Using optical coherence tomography and histological analysis, we demonstrated that the thickness of the outer nuclear layer of the retina was decreased in <I>Ubb</I> KO mice compared to control mice, suggesting that retinal degeneration was induced by Ub deficiency. Furthermore, the mRNA and protein levels of rhodopsin decreased and those of glial fibrillary acidic protein increased in <I>Ubb</I> KO mouse retinas. Therefore, the maintenance of Ub pools in the retina appears to be crucial for the survival of photoreceptor cells and the prevention of excessive glial cell activation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ub pools fluctuated due to reduced levels of free Ub in the retinas of <I>Ubb</I> KO mice. </LI> <LI> A compensatory upregulation of <I>Ubc</I> was observed in the retinas of <I>Ubb</I> KO mice. </LI> <LI> Degeneration of the ONL occurred in an age-dependent manner in <I>Ubb</I> KO retinas. </LI> <LI> Altered expression levels of rhodopsin and GFAP were observed in <I>Ubb</I> KO retinas. </LI> <LI> Overt signs of photoreceptor layer degeneration were observed in adult <I>Ubb</I> KO mice. </LI> </UL> </P>

발생중인 흰쥐 망막의 분화 및 Acetylcholinesterase 활성에 관한 연구

김완종,최준섭,Kim, Wan-Jong,Choi, Jun-Sub 한국현미경학회 1997 Applied microscopy Vol.27 No.2

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.

닭 배자 망막에서 희소돌기아교세포의 기원

서제훈(Je Hoon Seo),조사선(Sa Sun Cho) 대한해부학회 2004 Anatomy & Cell Biology Vol.37 No.5

망막을 구성하는 대부분의 세포는 망막의 미분화세포에서 기원하지만, 조류 망막에서 희소돌기아교세포는 셋째뇌실의 배쪽 신경상피에서 기원하여 시각신경을 거쳐 발생 10일경에 망막으로 이주하는 것으로 알려져 있다. 그러나 최근 희소돌기아교세포의 뭇기원(multiple origin)에 대한 연구가 활발하고, 희소돌기아교세포의 형성에 중요한 역할을 하는 sonic hedgehog이 망막에서 발현되는 것이 보고되어 희소돌기아교세포가 망막에서 기원할 가능성이 있다. 본 연구에서는 망막에서 기원하는 희소돌기아교세포의 존재를 세포유래연구(cell lineage study)에 유용한 역전사바이러스운반체(retroviral vector)인 LZ12를 이용하여 규명하고자 하였다. 희소돌기아교세포의 특이전사물(specific transcripts)인 plp/dm-20과 pdgfr-α는 망막 발생의 초기인 발생 5일에 이미 발현하였다. 발생 3일에 LZ12에 감염된 망막의 미분화세포는 분열하여 발생 9, 10일에 부챗살 형태로 망막의 전 층에 걸쳐 동일세포무리(clone)를 형성하였다. 특히 일부 동일세포무리의 신경섬유층에는 신경아교세포로 판단되는 작은 세포가 관찰되었으며, 희소돌기아교세포의 표지자와 이중염색되었다. 셋째뇌실 주변의 미분화세포 중 일부도 희소돌기아교세포로 분화하여 시각신경을 거쳐 망막으로 이주하는 것을 확인하였다. 이상의 결과는 망막의 희소돌기아교세포가 셋째뇌실 주변의 미분화세포에서 유래하는 동시에 망막의 미분화세포에서도 기원함을 보여주는 최초의 보고이다. Unlike other retinal cells, oligodendrocytes originate from the ventral midline of the third ventricle, and migrate to the retina at embryonic day 10 (E10) through the optic chiasm and the optic nerve in the bird. Recent studies have demonstrated that sonic hedgehog (shh), a differentiation factor for oligodendrocytes, was secreted by ganglion cells in the developing retina, indicating that microenvironment of the retina is sufficient for the generation of oligodendrocytes. Furthermore, it was revealed that uncommitted progenitors could differentiate into all cell types in the murine retina. On the basis of these reports, we proposed that a subpopulation of oligodendrocytes might generate in the retina in situ of the chick embryo. In order to verify our hypothesis, we injected the intraretinal space of chick embryos with a replication-defective retroviral vector (LZ12), and identified oligodendrocytes among LZ12-incorporated cells. Plp/dm-20 and pdgfr-α, oligodendrocyte specific transcripts were already expressed in the E5 retina. The expression of shh transcripts was also detected in the same stage. Analysis of the retina with intraretinal space injection demonstrated many clones consisting of various cell types arranged vertically through the retina. In addition, we found a few clones that had O4± oligodendrocytes. In case of third ventricle injection, we found that LZ12-incorporated cells occurred in rows, the typical shape of interfascicular oligodendrocytes in the optic nerve, and were located in the nerve fiber layer adjacent to the ganglion cells in the retina. These cells were also labeled with TfBP antibody. These results indicate that retinal oligodendrocytes of birds are differentiated from retinal precursor cells, together with undifferentiated cells adjacent to the third ventricle.

척추동물 망막의 신호 전달 경로 시뮬레이터 개발 및 분석

백승범(Seungbum Baek),장영조(Young-Jo Jang),조경록(Kyoungrok Cho) 한국콘텐츠학회 2018 한국콘텐츠학회논문지 Vol.18 No.11

망막은 눈을 통해 입력되는 빛을 수용하여, 이를 전기신호로 변환한 후 뇌의 시각 피질에 전달하는 역할을 수행한다. 망막을 하드웨어로 구현하기 위해서는 망막의 구조와 동작에 대한 이해가 필요하며, 이를 위해 망막의 모델링이 유용할 수 있다. 본 논문에서는 척추동물의 망막을 구성하는 신경세포와 시냅스의 신호 전달 경로를 포함하는 2-D 망막 네트워크 모델을 소개한다. 또한 수치해석을 기반으로 다양한 조건에서 망막 모델을 해석하기 위해 시뮬레이터를 개발하였다. 이를 통해 다양한 세기의 빛이 망막에서 흡수되었을 때, 기존의 연구와 대비하여, 각 세포와 시냅스 노드 단위로 입출력 반응을 정밀하게 검증하여 인공망막 장치 개발에 기여하였다. Retina transforms the external light into electrical signal that stimulates visual cortex of the brain. Electrical modeling of the retina is useful to understand its structure and action that is a prerequisite to implement the retina as a hardware device. This paper introduces a 2-D electrical network model of vertebrate’s retina considering signal pathway of retinal cells and synapses. We implemented a simulator of the retina based on the electrical network model to analyze its operation under various circumstances. Compared to the prior studies, It might contribute designing of artificial retina device in terms of that this study specifically observed input and output reactions of each cell and synapse node under various light intensity on the retina.

초광각안저촬영을 통한 시간경과에 따른 망막진탕의 변화에 대한 고찰

이안나(Anna Lee),홍승우(Seung Woo Hong),나 호(Ho Ra),김은철(Eun Chul Kim),강남여(Nam Yeo Kang),백지원(Jiwon Baek) 대한안과학회 2020 대한안과학회지 Vol.61 No.3

목적: 초광각안저촬영을 통하여 시간경과에 따른 망막진탕의 면적 변화 및 소실 속도를 분석하였다. 대상과 방법: 망막진탕으로 진단받은 환자의 33안을 대상으로 첫 내원 시, 수상 후 3일, 1주 그리고 4주째 초광각안저촬영(ultra-wide field color fundus photography)을 시행하여 망막진탕의 면적 및 소실 속도를 계산하였다. 결과: 평균 관찰기간은 10.8 ± 12.1주(4-44주)였으며, 수상 후 4주째 모든 환자에서 망막 진탕이 합병증 없이 소실되었다. 수상 후 3일에 측정한 관찰 가능한 총 망막의 면적에 대한 망막 진탕 면적의 평균비(8.51 ± 9.66%)는 첫 내원 시(12.23 ± 10.39%)와 비교하여 의미 있는 감소를 보였고(p<0.001), 수상 후 1주째(1.04 ± 2.75%)와도 유의한 차이를 보였다(p<0.001). 그러나 4주째(0.00 ± 0.00%)에는 1주째에 비해 망막진탕 면적의 유의한 감소를 보이지 않았다(p=0.219). 망막진탕의 소실 속도는 첫 3일간, 수상 후 3일에서 1주 사이, 수상 후 1주에서 4주 사이에 각각 12.97 ± 13.44%/day, 19.62 ± 9.22%/day, 0.87 ± 1.87%/day였으며 1주째 회복 속도가 가장 빨랐다(p=0.192, p<0.001). 결론: 초광각안저촬영은 망막진탕의 변화를 정량적으로 분석할 수 있는 검사이며 망막진탕 환자에서 백색화 병변의 감소는 수상 후 1주일까지 대부분 안정화되어 1달째 후유증을 남기지 않고 모두 자연 회복되었다. Purpose: To quantify the size of commotio retinae and investigate its spontaneous resolution over time using ultra-wide field(UWF) color fundus photography. Methods: We analyzed serial UWF color fundus photographs of 33 eyes of 33 ocular trauma patients with commotio retinae. Total visible retinal areas and the areas of commotio retinae were measured at baseline, 3 days, 1 week, and 4 weeks from the initial traumatic event. Results: The median time of observation was 10.8 ± 12.1 (4-44) weeks. Spontaneous resolution of commotio retinae was observed in all patients, and no patients experienced any complications during the follow-up period. The mean percentage of commotio retinae at 3 days significantly decreased compared to the baseline (8.51 ± 9.66% versus 12.23 ± 10.39%; p < 0.001), and more decreased at 1 week (1.04 ± 2.75%; p < 0.001), but no significant differences were observed between 1 week and 4 weeks(0.00 ± 0.00%; p = 0.219). The spontaneous resolution percentages during the first 3 days, between 3 days and 1 week, and during the next 4 weeks were 12.97 ± 13.44%/day, 19.62 ± 9.22%/day, and 0.87 ± 1.87%/day, respectively (p = 0.192 and p < 0.001, respectively). The resolution rate was higher during the first 1 week. Conclusions: We quantified the size of commotio retinae using UWF color fundus photography. Most patients with commotio retinae resolved spontaneously during the first 1 week following trauma, and all cases completely resolved at 1 month without any complications.

전기생리학적 기전에 근거한 망막 모델의 제안과 시공간적 응답의 분석

이정우,채승표,조진호,김명남,Lee, Jeong-Woo,Chae, Seung-Pyo,Cho, Jin-Ho,Kim, Myoung-Nam 대한전자공학회 2002 電子工學會論文誌-SC (System and control) Vol.39 No.6

본 논문에서는 망막의 전기생리학적 기전을 바탕으로 실제 망막과 유사한 기능 및 응답 특성을 갖는 망막 모델을 제안하였다. 시세포에서 양극세포까지는 기존에 연구된 여러 망막 모델들을 종합하여 모델링하였고, 3 NDP 기전을 이용하여 움직임 정보를 검출한다고 알려져 있는 아마크린세포와 양극세포 터미널에 관한 새로운 모델을 제안하였다. 이 모델의 평가를 위하여, 공간상의 동적 자극과 정지 자극에 대한 응답 특성을 비교 분석을 하였을 뿐만 아니라 자극의 움직임 속도에 따른 특성에 대한 분석도 수행하여 제안한 망막 모델을 검증하였다. 본 연구결과는 움직임 정보를 검출하기 위한 비전 시스템에 대한 인간 시각 시스템의 적용 및 생체에 이식할 수 있는 인공 망막의 개발을 위한 기초 연구에 이용될 수 있을 것이다. Based on electrophysiological retina mechanism, a retina model is proposed, which has similar response characteristics compared with the real primate retina. Photoreceptors, horizontal cells, and bipolar cells are modeled based on the previously studied retina models. And amacrine cells known to have relation to movements detection, and bipolar cell terminals are newly modeled using 3 NDP mechanism. The proposed model verified by analyzing the spatial response characteristics to stationary and moving stimuli, and characteristics for different speeds. Through this retina model, human vision system could be applied to computer vision systems for movement detection, and it could be the basic research for the implantable artificial retina.

당뇨병성 망막증에 있어서 Captopril에 의한 VEGF 발현 저하 효과

배춘식,임슬기,박민정,한호재,김계엽,정수영,윤경철,박수현,Bae, Chun-Sik,Lim, Seul-Ki,Park, Min-Jung,Han, Ho-Jae,Kim, Kye-Yeop,Jeong, Soo-Young,Yoon, Kyung-Chul,Park, Soo-Hyun 한국현미경학회 2009 Applied microscopy Vol.39 No.2

당뇨병성 망막증의 당뇨병 합병증의 주요한 증상중의 하나로 망막의 구조적 기능적 변화를 초래한다. 레닌-안지오텐신 시스템은 당뇨병성 망막증의 발병에 주요한 역할을 담당하며 angiotensin I을 angiotensin II로 전환하는 데 담당하는 안지오텐신 전환 효소 (ACE)는 레닌-안지오텐신 시스템의 주요한 요소이다. VEGF는 실명을 일으키는 당뇨병성 망막증의 신생혈관 생성에 관여하는 주요한 인자로 알려져 있다. 따라서 본 연구에서는 당뇨병성 망막증의 발생 기전 중 하나로 최근 연구가 진행되고 있는 VEGF의 발현과 안지오텐신 전환 효소 억제제를 이용한 VEGF 발현 억제효과의 규명을 통해 당뇨병성 망막증의 예방에 ACE 억제제가 효과가 있는지 ACE 억제제인 captopril을 이용하여 알아보고자 하였다. 본 연구에서는 streptozotocin 처리시 혈청내 VEGF 농도는 증가하였으나 captopril (65 mg/kg) 치료에 의해 감소하지 않았다. 망막에서 관찰한 결과 당뇨군에서 VEGF mRNA 및 단백질 발현이 증가하였으며, 안지오텐신 전환 효소인 capto-pril에 의해서 차단되는 것으로 나타났다. 결론적으로 captopril은 1형 당뇨에 있어서 망막의 VEGF 발현 억제를 통해 망막 보호효과를 나타내고 있음을 알 수 있었다. Diabetic retinopathy is one of major complications of diabetes mellitus, which is associated with the dysfunction of retina. It has been reported that the onset of diabetic retinopathy is related to the activation of renin-angiotensin system (RAS). Angiotensin converting enzyme (ACE), which converts angiotensin I into angiotensin II, is a key component of RAS. Among many growth factors, vascualr endothelial growth factor (VEGF) is an important cytokine in the neovasculization of retina, which is a characteristics of diabetic retinopathy. However, the relationship between ACE and VEGF was not elucidated in diabetic retinopathy. Thus, this study was conducted to examine the protective effect of captopril, an ACE inhibitor, in the retina of streptozotocin (STZ)-treated diabetic rats. In present study, STZ-treated diabetic rats exhibited the increase of VEGF levels in serum and retina. The serum levels of VEGF in STZ-treated diabetic rats was not blocked by the treatment of captopril. However, the retina levels of VEGF in STZ-treated diabetic rats was blocked by the treatment of captopril, suggesting the local action of captopril in retina. Immunohistochemical analysis also revealed that the retina of STZ-treated diabetic rats manifested the increase of ganglion cell layers, outer nuclear layers, and inner nuclear layers, which were also prevented by the treatment of captopril. In conclusion, captopril prevented the expression of VEGF in the retina of STZ-treated diabetic rats.

CD44 Expression in Microglia of the Retina and Cerebellum of Developing and Adult Chicken

Ji Young Kim(김지영),Hyun Joon Sohn(손현준),Je Hoon Seo(서제훈),Eun Young Lee(이은영) 대한체질인류학회 2017 대한체질인류학회지 Vol.30 No.1

CD44는 막관통단백질로서 히알루론산에 대한 막 표면 수용체로 작용한다고 알려져 있다. CD44가 발현되는 세포 종류 및 세포 내에서의 역할에 대하여 많은 연구가 시행되고 있으나 모든 결과들이 일치하지는 않는다. 본 연구에서는 발생 중 및 성체 조류의 망막과 소뇌에서 CD44가 발현되는지 확인하고 CD44가 발현되는 세포의 종류와 그 분포를 알아보고자 하였다. 본 연구에서는 발생 14일과 부화 후 90일 (성체) 된 닭의 망막과 소뇌를 사용하였다. 면역화학염색을 위해 CD44, RCA-1 그리고 GFAP 항체를 사용하였다. CD44 면역반응 세포들은 모든 시기의 망막과 소뇌에서 관찰되었다. 발생 14일 망막에서 CD44 면역반응 세포들은 주로 신경섬유층에서 관찰되었다. 성체에서도 대부분의 CD44 면역반응 세포들이 신경섬유층에서 관찰되었고 몇몇은 망막의 다른 층에 흩어져서 보였다. 발생 14일 소뇌의 CD44 면역반응 세포들은 바깥 및 속과립층을 포함한 소뇌 겉질에서 관찰되었다. 성체 소뇌의 CD44 면역반응 세포들은 소뇌 전체 층에 흩어져 존재하였으며, 발생 14일 때보다 더 많은 세포들이 관찰되었다. 고배율에서 관찰한 결과, CD44 면역반응 세포들은 세포체로부터 분지한 세포질돌기를 나타내었다. 미세아교세포 표지자인 RCA-1과 이중형광 염색을 한 결과, 발생 중과 성체의 망막과 소뇌에서, 대부분의 CD44 면역반응물은 RCA-1에 면역 염색성을 보이는 세포에 함께 존재하였다. 그러나 GFAP와 CD44 면역반응은 동일한 세포 내에서 관찰되지 않았다. 성체 망막에 LPS로 자극을 주었을 때 CD44 면역반응은 증가하였으며, 이 세포는 RCA-1에도 면역염색성을 나타내었다. 따라서, 결과를 종합하면, 정상 환경에서도 CD44는 발생 중 및 성체 조류의 망막과 소뇌의 미세아교세포에서 발현되었으며, 이는 LPS 자극에 의해 발현이 증가하였음을 보여줌으로써, 미세아교세포의 역할에 CD44가 중요하리라는 가능성을 시사하였다. CD44 is a transmembrane protein that acts as a receptor for an adhesion molecule, hyaluronic acid. The type of cells expressing CD44 and roles of CD44 are still controversial and need to be elucidated. The aim of the present study was to examine the type of cells expressing CD44 and the changes in their distribution in the retina and the cerebellum of the developing and adult chicken. Embryonic day 14 (E14) and post-hatch day 90 (P90) chickens were used in this study. CD44-immunoreactive (ir) cells were observed both in the retina and the cerebellum of the two developmental stages examined. In the retina of E14, CD44-ir cells were mainly located in the nerve fiber layer. In adults, most of the CD44-ir cells were in the nerve fiber layer and some were dispersed in other layers of the retina. In the cerebellum of E14, CD44-ir cells were distributed throughout the cerebellar cortex, including the external and internal granular layers. CD44-ir cells were more frequently found in the cerebellum of P90 adult chickens than in that of E14 embryos. At higher magnification, CD44-ir cells showed ramified cytoplasmic processes irradiating from their cell bodies. In the retina and in the cerebellum of all ages examined, double staining showed that most of the CD44-ir cells also expressed RCA-1, a marker of microglia. In contrast to that, at the same locations, GFAP and CD44 were not co-expressed in cells. When the adult retina was stimulated by LPS, CD44 immunoreactivity increased, and CD44-ir cells were also RCA-1-positive. The present results indicated that CD44 was expressed in microglia of the retina and the cerebellum of the developing and adult chicken even in normal conditions, and microglial CD44 expression was increased upon LPS stimulation.