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，皮胞水空（裂缝），穿毛血管壁或由有孔毛血管壁小孔穿。