Kriz W, Kretzler M, Provoost A P, Shirato I
Institut für Anatomie und Zellbiologie, Universität Heidelberg, Germany.
Kidney Int. 1996 Jun;49(6):1570-4. doi: 10.1038/ki.1996.227.
The complex architecture of the glomerular tuft is stabilized by several mechanisms. The basic system consists of the GBM and the mesangium maintaining the branching pattern of the capillary network. Superimposed are the podocytes, which appear to take effect by two mechanisms. First, podocytes contribute to the stabilization of the capillary folding pattern by supporting the angles between neighboring capillaries. Second, podocyte foot processes fixed to the outer aspect of the GBM probably function as contractile patches counteracting the elastic distension of the GBM. Simultaneously, the pattern of foot process interdigitation underlies the elaboration of a filtration slit and is thus pivotal for the high hydraulic permeability and the specificity of the glomerular filter. The loss of this pattern-commonly termed "foot process effacement" or "foot process fusion"-is frequently found in pathological situations and results in a decrease in permeability and impairment in specificity. On the other hand, foot process effacement is associated with prominent hypertrophy of the contractile apparatus of podocytes, suggesting an increased ability to generate forces counteracting capillary expansion. Thus, foot process effacement appears as an adaptive change in podocyte phenotype giving priority to the support function of podocytes for the prize of reducing the specific permeability.
肾小球丛的复杂结构通过多种机制得以稳定。基本系统由肾小球基底膜（GBM）和系膜组成，它们维持着毛细血管网络的分支模式。此外还有足细胞，其发挥作用似乎有两种机制。首先，足细胞通过支撑相邻毛细血管之间的夹角，有助于稳定毛细血管的折叠模式。其次，固定在GBM外侧的足细胞足突可能起到收缩斑的作用，抵消GBM的弹性扩张。同时，足突相互交错的模式构成了滤过裂隙的精细结构，因此对于肾小球滤过器的高水渗透性和特异性至关重要。这种模式的丧失——通常称为“足突消失”或“足突融合”——在病理情况下很常见，会导致通透性降低和特异性受损。另一方面，足突消失与足细胞收缩装置的显著肥大有关，这表明产生抵消毛细血管扩张力的能力增强。因此，足突消失似乎是足细胞表型的一种适应性变化，优先考虑足细胞的支撑功能，代价是降低特定通透性。
