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.

性物质，如离子，通内皮胞间的充空间（裂缝），穿血管壁或由有孔血管壁的小孔穿。