Inoue S, Bendayan M
Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada.
Ultrastruct Pathol. 1995 May-Jun;19(3):175-85. doi: 10.3109/01913129509064219.
The ultrastructure of the glomerular basement membrane of the long-term diabetic and age-matched control rats was studied with the application of advanced high-resolution microscopy. By using the freeze substitution method for the preparation of the renal tissue, it was possible to observe that the glomerular basement membrane in control and diabetic animals is composed on only a single lamina densa without the presence of a lamina lucida interna or externa. High-resolution electron microscopy of the diabetic glomerular basement membrane showed significant alterations in its morphology and ultrastructure. First, the basement membrane in diabetic condition appeared to be split into two halves, endothelial and epithelial. In the epithelial half of the membrane, the network of distinct strands referred to as cords, which were clearly present in the glomerular basement membrane of age-matched control animals, became less distinct and showed a diffused appearance being evenly replaced by thin filaments. The openings of the network were filled with a granular material. In the endothelial half of the membrane, on the other hand, the cord network was variably lost in diabetic condition and, within the resulting vacant spaces, bundles of fibrils 12 nm in width, identified as basotubules, were deposited. Immunolabeling for type IV collagen was found to be enriched in the endothelial half of the basement membrane being associated with the bundles of basotubules. The ultrastructural changes reported by high-resolution microscopy could be related to the molecular alterations of the basement membrane components and to the loss in permselectivity occurring during diabetes.
应用先进的高分辨率显微镜研究了长期糖尿病大鼠和年龄匹配的对照大鼠肾小球基底膜的超微结构。通过使用冷冻置换法制备肾组织，观察到对照动物和糖尿病动物的肾小球基底膜仅由单一的致密层组成，不存在内透明层或外透明层。糖尿病肾小球基底膜的高分辨率电子显微镜显示其形态和超微结构有显著改变。首先，糖尿病状态下的基底膜似乎分裂为内皮侧和上皮侧两半。在膜的上皮侧，在年龄匹配的对照动物的肾小球基底膜中清晰可见的称为索的独特股线网络变得不那么清晰，并呈现出扩散的外观，被细丝均匀取代。网络的开口充满了颗粒物质。另一方面，在膜的内皮侧，糖尿病状态下索网络不同程度地消失，在形成的空隙中，沉积了宽度为12nm的纤维束，鉴定为基底微管。发现IV型胶原的免疫标记在内皮侧基底膜中富集，与基底微管束相关。高分辨率显微镜报告的超微结构变化可能与基底膜成分的分子改变以及糖尿病期间发生的选择通透性丧失有关。
