Water-soluble substances, like ions, cross the capillary wall through either water-filled spaces, called clefts, between the endothelial cells, or through large pores in the walls of fenestrated capillaries.

水溶性物质，如离子，通过内皮细胞间的充水空间（裂缝），穿过毛细血管壁或由有孔毛细血管壁的小孔穿过。