Assembly of the glomerular filtration surface. Differentiation of anionic sites in glomerular capillaries of newborn rat kidney.
Assembly of the glomerular filtration surface. Differentiation of anionic sites in glomerular capillaries of newborn rat kidney.
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DOI：
10.1083/jcb.85.3.735
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发表时间：
1980-06
期刊：
影响因子：
--
通讯作者：
Farquhar MG
中科院分区：
文献类型：
--
作者：
Reeves WH;Kanwar YS;Farquhar MG
本文用电镜和细胞化学方法研究了新生大鼠肾脏肾小球的发育。不同发育阶段的肾小球结构与其组分的渗透性以及肾小球基底膜（GBM）和内皮细胞及上皮细胞表面阴离子位点的分化有关。阳离子探针（阳离子化铁蛋白，钌红，胶体铁）用于确定阴离子位点的出现和分布的时间，并与特定的酶（神经氨酸酶，肝素酶，软骨素酶，透明质酸酶）消化用于确定其性质。天然（阴离子）铁蛋白用于研究肾小球通透性。主要调查结果如下：（a）第一个内皮窗孔（在GBM完全组装之前出现）具有短暂的、带负电荷的隔膜，其结合阳离子化的铁蛋白并且对天然铁蛋白不可渗透。（B）。通过钌红染色可以识别两种类型的糖胺聚糖颗粒。大（30 nm）颗粒被视为只有在裂缝的S-形体时，间充质迁移到肾囊泡。它们由透明质酸和可能的硫酸软骨素组成。在最早的内皮和上皮基底膜（S形体阶段）中观察到较小的（10-15-nm）颗粒，在这两种膜融合形成GBM后，这些颗粒集中在稀有层中，并含有硫酸乙酰肝素。它们被认为是成熟GBM中富含硫酸乙酰肝素颗粒的前体。(c)在上皮细胞和内皮细胞表面都描绘了独特的富含唾液酸和缺乏唾液酸的质膜结构域。(d)上皮细胞表面唾液酸糖蛋白的出现与足突和滤过缝的发育一致。(e)最初，GBM组织松散，对天然铁蛋白渗透性很强;随着致密层变得更加致密，GBM对铁蛋白的渗透性越来越强。(f)随着GBM成熟，内皮窗孔和开放上皮狭缝的数量增加，并组织成天然铁蛋白通过的有效屏障。
Glomerular development was studied in the newborn rat kidney by electron microscopy and cytochemistry. Glomerular structure at different developmental stages was related to the permeability properties of its components and to the differentiation of anionic sites in the glomerular basement membrane (GBM) and on endothelial and epithelia cell surfaces. Cationic probes (cationized ferritin, ruthenium red, colloidal iron) were used to determine the time of appearance and distribution of anionic sites, and digestion with specific enzymes (neuraminidase, heparinase, chondroitinases, hyaluronidases) was used to determine their nature. Native (anionic) ferritin was used to investigate glomerular permeability. The main findings were: (a) The first endothelial fenestrae (which appear before the GBM is fully assembled) possess transient, negatively charged diaphragms that bind cationized ferritin and are impermeable to native ferritin. (b). Two types of glycosaminoglycan particles can be identified by staining with ruthenium red. Large (30-nm) granules are seen only in the cleft of the S-shaped body at the time of mesenchymal migration into the renal vesicle. They consist of hyaluronic acid and possibly also chondroitin sulfate. Smaller (10-15-nm) particles are seen in the earliest endothelial and epithelial basement membranes (S- shaped body stage), become concentrated in the laminae rarae after fusion of these two membranes to form the GBM, and contain heparan sulfate. They are assumed to be precursors of the heparan sulfate-rich granules present in the mature GBM. (c) Distinctive sialic acid-rich, and sialic acid-poor plasmalemmal domains have been delineated on both the epithelial and endothelial cell surfaces. (d) The appearance of sialoglycoproteins on the epithelial cell surface concides with the development of foot processes and filtration slits. (e) Initially the GBM is loosely organized and quite permeable to native ferritin ;it becomes increasinly impermeable to ferritin as the lamina densa becomes more compact. (f) The number of endothelial fenestrae and open epithelial slits increases as the GBM matures and becomes organized into an effective barrier to the passage of native ferritin.