Intercellular clefts are important for allowing the transportation of fluids and small solute matter through the endothelium.

Plasma, the major component in blood, communicates freely with interstitial fluid through pores and intercellular clefts in capillary endothelium.

Exchange of macromolecules across the endothelium involves active vesicle formation, and transendothelial channels and intercellular clefts (Simionescu et al, 1976; Chien, 1978).

In continuous capillaries the endothelial cells are tightly spaced, allowing only small molecules like ions or water to diffuse through the intercellular clefts (the gaps between the endothelial cells).

Intercellular clefts are channels between cells which are tightly packed together, as in the case of some endothelial cells (including those endothelial cells which form the blood-nerve barrier surrounding nerves).

Water and solutes can pass between the interstitial fluid and blood via diffusion across gaps in capillary walls called intercellular clefts; thus, the blood and interstitial fluid are in dynamic equilibrium with each other.