How do lymphatic capillaries help absorbed chemicals enter the circulatory system?

Lymphatic capillaries facilitate the entry of absorbed chemicals into the circulatory system by acting as a porous drainage network within the interstitial spaces.1

Unlike blood capillaries, the lymphatic capillaries feature significantly looser junctions between their endothelial cells. This increased porosity allows substances—including excess fluid, plasma proteins, and certain absorbed chemicals—to pass easily from the interstitial spaces into the lymphatic system. Once inside, these materials are transported as lymph through a series of larger vessels that eventually converge into lymphatic trunks, which connect to veins at the base of the neck, thereby returning the contents to the bloodstream. This pathway is particularly significant for substances like insoluble aerosols, which may enter the circulatory system indirectly after first being absorbed into these porous vessels.12