what is the function of parenchyma?

Parenchyma (para - beside ;chyma - in filling) is a term used to describe a bulk of a substance. It is used in different ways in animals and in plants

The parenchyma are the functional parts of an organ in the body. This is in contrast to the stroma, which refers to the structural tissue of organs, namely, the connective tissues.

In cancer, the parenchyma refers to the actual mutant cells of a single lineage, whereas the stroma is the surrounding connective tissue and associated cells that support it.

Early in development the mammalian embryo has three distinct layers: ectoderm (external layer), endoderm (internal layer) and in between those two layers the middle layer or mesoderm. The parenchyma of most organs is of ectodermal (brain, skin) or endodermal origin (lungs, gastrointestinal tract, liver, pancreas). The parenchyma of a few organs (spleen, kidneys, heart) is of mesodermal origin. The stroma of all organs is of mesodermal origin.

IN PLANTS

Parenchyma cells are thin-walled cells of the ground tissue that make up the bulk of most nonwoody structures, yet sometimes their cell walls can be lignified. Parenchyma cells in between the epidermis and pericycle in a root or shoot constitute the cortex, and are used for storage of food. They are mainly present in the soft areas of the stems, leaves, root, flowers, fruits etc. Parenchyma cells within the center of the root or shoot constitute the pith. Parenchyma cells in the ovary constitutes the nucellus and are brick-like in formation. Parenchyma cells in the leaf constitute the mesophyll; they are responsible for photosynthesis and they allow for the interchange of gases.[2]

Parenchyma is the most common and versatile ground tissue. It forms, for example, the cortex and pith of stems, the cortex of roots, the mesophyll of leaves, the pulp of fruits, and the endosperm of seeds. Parenchyma cells are living cells and may remain meristematic at maturity, meaning that they are capable of cell division. They have thin but flexible cellulose cell walls, and are generally polygonal when close-packed, but approximately spherical when isolated from their neighbours. They have large central vacuoles, which allows the cells to store and regulate ions, waste products and water.