mesofylli

Mesofylli refers to the mesophyll tissue of plant leaves, the internal tissue located between the upper and lower epidermis. It contains chlorenchyma cells rich in chloroplasts and is the primary site of photosynthesis. In many dicot leaves, the mesophyll is differentiated into two layers: the palisade mesophyll, a layer of elongated cells just beneath the upper epidermis where most light capture occurs, and the spongy mesophyll, a looser tissue with air spaces that facilitates gas exchange with stomata.

In monocot leaves, the mesophyll is typically a more uniform layer of chlorenchyma, though chloroplast-rich cells remain involved in photosynthesis and connect with intercellular air spaces. The mesophyll also contributes to gas exchange and water regulation, working with the stomatal apparatus in the epidermis. CO2 enters through stomata, diffuses through intercellular spaces, and is assimilated by photosynthetic reactions within mesophyll cells.

In C4 plants, mesophyll cells participate in initial CO2 fixation by phosphoenolpyruvate carboxylase and are arranged around bundle sheath cells in Kranz anatomy, which concentrates CO2 for efficient photosynthesis. In some xerophytes, the mesophyll may be reduced or arranged to minimize water loss, and in succulents it can become thickened or reduced. Developmentally, mesophyll originates from leaf ground tissue and differentiates into photosynthetic cells during leaf formation.

The term mesofylli is used in some languages to denote this tissue, equivalent to mesophyll in English.