Mesophyll is the main part of the leaf anatomy; it forms bulk of tissue that is extending from the upper epidermis to the lower epidermis. It is developed from the ground meristem.
The mesophyll is differentiated into; i. upper palisade, ii. lower spongy tissue.
The cells of the palisade tissue are columnar in shape and present below the upper epidermis and arranged right angle to it. The palisade tissues have large number of chloroplast and the cells are compactly arranged. The palisade tissue is arranged as a single layer in the certain plants and it may vary from plants to plants. As the palisade tissue is well developed in the xerophytic plants. The plant with the centric leaves possess chloroplast around the periphery of the leaf.
The spongy tissues have parenchymatous thin cells which are loosely arranged with large inter cellular space. Hence it is known as the spongy tissue; It is present below the palisade tissue. The water plants possess well developed intercellular space and spongy tissue will be similar to the aerenchyma. The presence of the chloroplast is lesser than the palisade tissue.