Michael H
Am J Physiol. 1978 Nov;235(5):F387-93. doi: 10.1152/ajprenal.1978.235.5.F387.
Differentiation of cell function should be studied in homogeneous cell populations. The differentiating mammalian kidney is a thoroughly heterogeneous organ. Consequently, the single epithelial segment was studied in situ and, particularly, by in vitro analysis of physical, chemical, and ultrastructural phenomena in perfused and nonperfused dissected nephrons.
The changes of hydraulic permeability in the proximal nephron appear to be important in utilizing extracellular forces for absorption, since cellular transport is restricted by low basolateral membrane area and by ion pump sites (Na+-K+-ATPase). Salt transport in the diluting segment, by contrast, changes at constant osmotic permeability and at increasing ion concentration gradients across the epithelium. Extracellular volume and osmotic homeostasis in the neonate testify to the competence of organ function, although cell structure and function differentiate. In the future, interactions between nephron cell functions will be studied by altering the natural sequence of phenomena during differentiation.
细胞功能的分化应在同质细胞群体中进行研究。正在分化的哺乳动物肾脏是一个完全异质的器官。因此，对单个上皮节段进行了原位研究，特别是通过对灌注和未灌注的离体肾单位的物理、化学和超微结构现象进行体外分析。
近端肾单位水通透性的变化在利用细胞外力进行吸收方面似乎很重要，因为细胞转运受到基底外侧膜面积小和离子泵位点（钠钾ATP酶）的限制。相比之下，稀释段的盐转运在恒定的渗透通透性和跨上皮离子浓度梯度增加时发生变化。尽管细胞结构和功能在分化，但新生儿的细胞外液量和渗透稳态证明了器官功能的能力。未来，将通过改变分化过程中现象的自然顺序来研究肾单位细胞功能之间的相互作用。
