The spongy mesophyll is full of air pockets (hence the name spongy) that allow \(\ce{CO2}\) to move into the leaf to the palisade mesophyll, as well as allowing oxygen to diffuse from the palisade mes...The spongy mesophyll is full of air pockets (hence the name spongy) that allow \(\ce{CO2}\) to move into the leaf to the palisade mesophyll, as well as allowing oxygen to diffuse from the palisade mesophyll through the spongy mesophyll and out the stomata. The xylem is transporting water and dissolved minerals from the roots up to the leaf, while the phloem is transporting sugars made in the leaf to other regions of the plant.