Parenchyma

Parenchyma is an ambiguate term for different forms of tissues in botany and zoology.

Zoological organisms in the phylum Platyhelminthes possess a loose, sponge-like tissue which fills the unused pockets of the body that is referred to as parenchyma. It is referred to as a “filler” tissue which makes up the remainder of the platyhelminth.

In botany, plants possess parenchyma tissue, a tissue found in the ground tissue system. Parenchyma is a simple tissue composed of parenchyma cells. When mature, parenchyma cells are living cells with evenly thin primary cell walls and a middle lamella. They are usually isodiametrically shaped, or cuboidal; in some cases, they are elongate, such as when they are in leaf tissue. They have approximately 25 micrometers of air space between them and neighboring cells in order to maintain gas exchange.

Parenchyma cells are primarily used in photosynthetic and metabolic processes. In leaves, when they are a part of mesophyll, they contain chloroplasts and produce sugars for the plant. In other organs, such as the roots, they aid in cell respiration. Parenchyma cells are versatile and can also be used for storage, cell growth, or to maintain turgor pressure. They can even revert to a meristematic state to divide and produce new cells, such as if wounds in the plant need to be repaired.