Sameshima M, Uehara F, Ohba N
Department of Ophthalmology, Faculty of Medicine, Kagoshima University, Japan.
Exp Eye Res. 1987 Dec;45(6):845-63. doi: 10.1016/s0014-4835(87)80101-x.
The binding sites of two lectins, peanut agglutinin (PNA) and wheat germ agglutinin (WGA), in the interphotoreceptor matrix (IPM) and photoreceptor plasma membranes of the Japanese monkey (Macaca fuscata) retina were localized using a pre-embedding staining method with ferritin-conjugated (Fer) lectins as well as a postembedding staining method with fluorescence-labeled (FITC) lectins. FITC-PNA, but not WGA, stained cylindrical domains of the IPM around cone outer and inner segments, while the IPM around rods stained with FITC-WGA but not PNA. When the intact (not detached) retinal tissues were incubated with Fer-lectin, the lectin generally labeled neither the IPM nor photoreceptor plasma membranes, but labeled only those structures in detached portions occurring at the edges of occasional retinal tissue blocks. Thus, the neural retinas physically isolated from the retinal pigment epithelium (RPE) were utilized principally here. Ultrastructurally, the IPM in the intact retina consisted of granular and filamentous materials; the IPM in the isolated neutral retina also retained those components, although somewhat loosely organized, and the IPM around cones appeared to be preserved better than did the IPM around rods. Fer-PNA bound to the IPM associated with cones, but not rods; Fer-WGA bound to the rod- but not cone-associated IPM. The ferritin particles were found to lie close to the granular and filamentous materials. Those photoreceptor-associated IPMs extended to the apical surface of the RPE in detached portions or to the apical villi of the RPE which were frequently found in the isolated neural retinas. Also, Fer-PNA labeled the cone, but not rod, plasma membranes; Fer-WGA bound heavily to the plasma membranes of rod and cone outer segments, but sparsely to those of their inner segments. These results suggest that the IPM comprises chemically and physically differential domains specialized for cone and rod photoreceptor cells, and that these specialized IPM are structurally so stable that may be involved in isolating photoreceptor cells physicochemically from each other and in the interactions between the photoreceptors and the RPE, such as retinal adhesion.
利用铁蛋白偶联（Fer）凝集素的包埋前染色方法以及荧光标记（FITC）凝集素的包埋后染色方法，对日本猕猴（食蟹猴）视网膜光感受器间基质（IPM）和光感受器质膜中两种凝集素，即花生凝集素（PNA）和麦胚凝集素（WGA）的结合位点进行了定位。FITC-PNA可对视锥细胞外段和内段周围的IPM柱状区域进行染色，而WGA则不能；FITC-WGA可对视杆细胞周围的IPM进行染色，而PNA则不能。当完整（未分离）的视网膜组织与Fer-凝集素孵育时，凝集素通常既不标记IPM也不标记光感受器质膜，而仅标记偶尔出现的视网膜组织块边缘分离部分的那些结构。因此，这里主要使用从视网膜色素上皮（RPE）物理分离的神经视网膜。超微结构上，完整视网膜中的IPM由颗粒状和丝状物质组成；分离的神经视网膜中的IPM也保留了这些成分，尽管组织有些松散，并且视锥细胞周围的IPM似乎比视杆细胞周围的IPM保存得更好。Fer-PNA与视锥细胞相关的IPM结合，但不与视杆细胞相关的IPM结合；Fer-WGA与视杆细胞相关的IPM结合，但不与视锥细胞相关的IPM结合。发现铁蛋白颗粒靠近颗粒状和丝状物质。那些与光感受器相关的IPM在分离部分延伸到RPE的顶端表面，或延伸到分离的神经视网膜中经常发现的RPE的顶端绒毛。此外，Fer-PNA标记视锥细胞质膜，但不标记视杆细胞质膜；Fer-WGA大量结合到视杆细胞和视锥细胞外段的质膜上，但稀疏地结合到它们内段的质膜上。这些结果表明，IPM包含专门为视锥细胞和视杆细胞光感受器细胞的化学和物理差异区域，并且这些专门的IPM在结构上非常稳定，可能参与光感受器细胞之间的物理化学隔离以及光感受器与RPE之间的相互作用，如视网膜粘连。
