人胎视网膜发生的光镜和电镜观察

本文在光镜下观察40例人胎视网膜的发生,在电镜下观察15例人胎视网膜视细胞、双极细胞、节细胞的发育。结果表明:胚胎第9周时神经上皮可分内、外成神经细胞层。第10周时内、外成神经细胞层之间的Chievitz带消失;第11周时节细胞从内成神经细胞层内迁;第13周节细胞与内成神经细胞之间出现内网层;第16周始双极细胞从外成神经细胞层中内迁形成外网层和内核层。第20周后视网膜各层形成。而视细胞、双极细胞、节细胞的超微结构于胎儿8个月后才发育完善。其结构与成人基本相同。     

Matrix Metalloproteinase-2 and Tissue Inhibitor of Metalloproteinase-1 in the Retinal Pigment Epithelium and Interphotoreceptor Matrix: Vectorial Secretion and Regulation

Matrix metalloproteinases (MMPs) and the tissue inhibitors of metalloproteinases (TIMPs) play an essential role in both normal and pathological extracellular matrix degradation, and a TIMP has been associated with at least one type of retinal degeneration. We have studied expression of MMP-2 and TIMP-1 by zymography, immunocytochemistry, and immunoblotting in the retinal pigment epithelium (RPE) from normal, aged and diseased retinas. MMPs and TIMPs were found in the rat RPE, interphotoreceptor matrix (IPM), and in media conditioned by human and rat RPE in culture. In other polarized cells, MMPs and TIMP-2 are secreted vectorially towards the basal lamina. In the RPE, however, MMP-2 and TIMP-1 were secreted preferentially from the apical surface, the surface bordering the IPM. These findings provide new evidence that MMPs and TIMPs could play a role in the turnover of IPM components.Cell homogenates and conditioned media from RPE isolated from mutant Royal College of Surgeons (RCS) rats with inherited retinal dystrophy had similar amounts of MMP-2 and TIMP-1 as those from congenic control rats. The secretion of MMP-2 and TIMP-1 from RPE cell cultures isolated from young and aged human donors varied widely. However, with increasing cell passage number, secretion of MMPs and TIMPs from human RPE increased dramatically. Also, growing human RPE on bovine corneal endothelial cell-generated extracellular matrix instead of plastic reduced the secretion of both MMPs and TIMPs. These data suggest that the integrity of Bruch's membrane may serve to regulate RPE functions in MMP and TIMP secretion and that extracellular matrices contain signals that regulate MMP and TIMP synthesis and/or secretion by the RPE.     

地高辛标记核酸探针技术在家兔视网膜C－sis原癌基因检测中的应用

用ＡＧＰＣ法抽提幼年家兔视网膜总ＲＮＡ，并应用了地高辛标记核酸探针的方法。经斑点杂交显示幼年家兔视网膜出现Ｃ—ｓｉｓ原癌基因表达。对实验方法以及Ｃ－ｓｉｓ原癌基因表达的意义进行了探讨。认为此方法快速、灵敏，检测Ｃ－ｓｉｓ原癌基因表达对深入研究视网膜生长发育及肿瘤等病变有一定意义。     

视网膜分支静脉阻塞和新生血管形成

分析视网膜分支静脉阻塞240例245只眼(5人为双眼)，其中主干分支阻塞208只眼，黄斑分支阻塞37只眼。79只眼产生了新生血管，占总数的32.2%，占主干分支阻塞的37.9%．玻璃体出血39只眼，占分支阻塞的15.9%，占新生血管的49.4%。新生血管的危险因素是无灌注区形成、动脉灌注不良、阻塞处静脉严重受压．新生血管的发生随病程时间延长而增高，病程5年以上者高达83.3%。分支静脉阻塞盲目者20只眼占8.2%，其中因新生血管及并发症致盲者14只眼，占盲目的70%，占分支静脉阻塞的5.7%. （中华眼底病杂志，1994，10：67-70）     

玻璃体内注射庆大霉素致视网膜损伤的实验研究Ⅰ．组织病理学观察

为探讨庆大霉素对视网膜的毒性作用和评估玻璃体内注射庆大霉素的安全剂量，采用眼底镜观察及光镜、电镜技术对注射５种不同剂量庆大霉素的青紫蓝兔视网膜标本进行观察。结果：３０００μｇ庆大霉素注射后眼底表现为视盘水肿，后极部视网膜大片坏死，镜下视网膜组织形态严重破坏；５０～５００μｇ剂量注射引起后极部视网膜色素改变，组织损伤早期局限在视网膜内层，晚期全层受累。提示庆大霉素对视网膜的损伤程度随注入剂量增加而加重，即使５０μｇ的微小剂量仍可产生视网膜损伤。     

兔视网膜方向选择性神经节细胞树突的独特分枝模式及其生理意义

本实验研究了兔视网膜中的方向选择性神经节细胞 (direction selective retinal ganglion cells,DS cells)树突野的分枝模式。测量了视网膜中方向选择性神经节细胞和作为经典分枝模式神经元代表的α神经节细胞的树突直径。发现 ,方向选择性神经节细胞的树突在分枝后直径达到 0 .5 μm,进一步分枝树突直径仍保持在 0 .5 μm左右 ,这样 ,在方向选择性神经节细胞树突野中大多数树突直径在 0 .5μm左右。而作为经典分枝模式神经元代表的α神经元的树突每次分枝后都逐级变细 ,最终直径达到 0 .5μm左右 ,这样 ,α神经节细胞的树突直径大部分都大于 0 .5μm。我们应用程序“NEU RON”对在两种神经元模型中 ,抑制点落于兴奋点与胞体之间 (proximal)和抑制点不落于兴奋点与胞体之间 (distal)这两种情况进行模拟。我们发现 ,当抑制点不落于兴奋点与胞体之间时 ,在方向选择性神经节细胞的树突分枝模型中 ,抑制效果更强。那么 ,将使得方向选择性神经节细胞对抑制点落于兴奋点和胞体之间的要求变得不是那么迫切。所以 ,方向选择性神经节细胞的这种独特分枝模式 ,也许可以避免或至少减轻其在发育中可能会产生的连线的复杂性。并且 ,我们对得出的结论进行了电路分析 ,对方向选择性神经节细胞这种独特的分枝模式具有的?