The mesophyll is a name given to two layers of cells inside of plant leaves. The first layer is above the second layer. The first layer is palisade parenchyma cells. This layer is inundated with loads of chloroplasts, making it the layer most directly responsible for photosynthesis.
Their chloroplasts absorb a major portion of the light energy used by the leaf.
Because they are surrounded by intercellular air pockets, the mesophyll cells are able to perform a gas exchange when the stomatal pores in the leaf's epidermis open