Ultrastructure of adult rd mouse retina
Ultrastructure of adult rd mouse retina
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DOI：
10.1007/s00417-003-0649-1
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发表时间：
2003-05-01
影响因子：
2.7
通讯作者：
Tanabe, T
中科院分区：
文献类型：
--
作者：
Gouras, P;Tanabe, T
目的：检查成年rd小鼠视网膜的超微结构，以确定哪些结构改变或丢失，从而更好地解释在该视网膜变性模型中感光细胞和/或视网膜移植产生的变化。方法：使用在视杆双极中表达LacZ报告基因的rd突变小鼠，以鉴定这些细胞及其过程。通过电子显微镜研究了6周龄至5个月大的小鼠，集中在通常放置视网膜移植的后极。结果如下：成年rd小鼠视网膜包括退化的视锥细胞、视锥细胞外节、具有突触囊泡的视锥细胞突触蒂和突触后接触。主要的异常发生在视网膜下腔，在那里所有的杆的痕迹都消失了，主要的结构是锥的内部部分。这些内节比正常的小，含有更少更小的线粒体，具有有组织的微管阵列，类似于锥体轴突过程中的微管阵列，并且完全被视网膜上皮顶端过程的大量增殖所吞没。视网膜下腔由玻璃体外界膜和视网膜脉络膜上皮明确界定。苗勒细胞向视网膜下间隙延伸球状突起而不是丝状突起，视网膜下间隙与上皮的顶端突起接触。视杆双极细胞存活并保留外丛状层中的突起。结论：成年rd小鼠保留了光传导和通过视锥系统将信号传递到视网膜内层所必需的结构元件。主要缺陷位于视网膜下腔，其中所有杆丢失，锥内节经历缓慢变性。杆双极细胞生存，但似乎是deafferented，有没有证据表明，他们接触残留的锥过程中的外部丛状层。rd小鼠是研究光感受器移植效果的合理模型，因为二阶和三阶视网膜神经元以及退化的视锥细胞在成年视网膜中存活。
Purpose: To examine the ultrastructure of the adult rd mouse retina in order to determine what structures are altered or lost and thus to better interpret changes produced by photoreceptor and/or retinal transplantation in this model of retinal degeneration. Methods: rd mutant mice expressing a LacZ reporter gene in rod bipolars were used in order to identify these cells and their processes. Mice of age 6 weeks to 5 months were studied by electron microscopy, concentrating on the posterior pole where retinal transplants are usually placed. Results: The adult rd mouse retina contains degenerating cones, cone outer segments, cone synaptic pedicles with synaptic vesicles and post-synaptic contacts. The major abnormalities occur in the subretinal space where all traces of rods are gone and the main structures are inner segments of cones. These inner segments are smaller than normal, contain fewer and smaller mitochondria, have organized arrays of microtubules, resembling those in cone axonal processes, and are completely engulfed by massive proliferation of apical processes of the retinal epithelium. The subretinal space is well defined by the external limiting membrane vitreally and the retinal epithelium choroidally. Muller cells extend globular rather than filamentous processes into the subretinal space which contact the apical processes of the epithelium. Rod bipolar cells survive and retain processes in the external plexiform layer. Conclusions: The adult rd mouse retains structural elements necessary for phototransduction and transmission of signals to the inner layers of the retina by the cone system. The major deficits are located in the subretinal space where all rods are lost and cone inner segments undergo a slow degeneration. Rod bipolar cells survive but appear to be de-afferented; there was no evidence that they contact residual cone processes in the external plexiform layer. The rd mouse is a logical model to study the effects of transplantation of photoreceptors because second- and third-order retinal neurons as well as degenerating cones survive in the adult retina.