It is a strategy used by multicellular organisms to selectively move material between two different environments while maintaining the distinct compositions of those environments. Cells have other strategies not involving membrane vesicles to selectively move smaller cargo (ions and small solutes) across cellular barriers. Paracellular transport, the movement between adjacent cells, is accomplished by regulation of tight junction permeability, and transcellular transport, the movement of ions and small molecules through a cell, is accomplished by the differential distribution of membrane transporters/carriers on opposite sides of a cell. Together, these three processes contribute to the success of multicellular organisms. Follow @world_of_medics Credit for this amazing Animation- @3dforscience ❤️