Andrews P
Georgetown University School of Medicine, Washington, DC 20007.
J Electron Microsc Tech. 1988 Jun;9(2):115-44. doi: 10.1002/jemt.1060090203.
The glomerular (visceral) layer of Bowman's capsule is comprised of a unique population of cells which have been termed "podocytes." Arising from these cells are large major processes and numerous smaller foot processes which completely surround underlying glomerular capillary loops. Podocyte foot processes interdigitate with each other and are separated by spaces (filtration slits) which are designed to facilitate flow of a large amount of filtrate across the glomerular wall. Podocytes exhibit dramatic morphological changes in response to the nephrotic syndrome and some forms of acute renal failure and may play an important role in the pathophysiology of these conditions. In vitro and in vivo studies have shown that a reduction in the sialic acid component of a thick anionic surface coat plays a major role in the morphological changes that these cells exhibit in the nephrotic syndrome. Also, it has been shown that filamentous actin concentrated mainly within podocyte foot processes are the contractile elements responsible for altering the shapes of these processes. There is evidence to suggest that by altering the shapes of their foot processes, podocytes in the normal kidney are able to alter the number of fully patent filtration slits and thereby actively regulate the rate of solute efflux across the glomerular wall. In vitro and in vivo studies have indicated that cytoplasmic microtubules are probably not involved in alterations of the podocyte foot processes but do appear important in maintaining the morphological integrity of podocyte cell bodies and their major processes. In the present paper, the morphological changes which glomerular podocytes exhibit in response to the nephrotic syndrome, various forms of acute renal failure, and during in vitro incubation are discussed along with studies of the possible roles of cytoplasmic microtubules, microtubules, and the glomerular anionic surface coat in these changes.
鲍曼囊的肾小球（脏层）由一类独特的细胞组成，这些细胞被称为“足细胞”。从这些细胞伸出的是大的主突和众多较小的足突，它们完全围绕着下方的肾小球毛细血管袢。足细胞的足突相互交错，其间有一些间隙（滤过裂隙），这些间隙有利于大量滤液穿过肾小球壁。足细胞在肾病综合征和某些形式的急性肾衰竭时会出现显著的形态变化，并且可能在这些病症的病理生理学中起重要作用。体外和体内研究表明，厚阴离子表面涂层中唾液酸成分的减少在这些细胞在肾病综合征中表现出的形态变化中起主要作用。此外，研究表明，主要集中在足细胞足突内的丝状肌动蛋白是负责改变这些足突形状的收缩元件。有证据表明，通过改变其足突的形状，正常肾脏中的足细胞能够改变完全开放的滤过裂隙的数量，从而积极调节溶质穿过肾小球壁的流出速率。体外和体内研究表明，细胞质微管可能不参与足细胞足突的改变，但在维持足细胞胞体及其主突的形态完整性方面似乎很重要。在本文中，将讨论肾小球足细胞在肾病综合征、各种形式的急性肾衰竭以及体外培养期间所表现出的形态变化，以及关于细胞质微管、微丝和肾小球阴离子表面涂层在这些变化中可能作用的研究。
