Parenchyma

Parenchyma (pale grey) in a plant stem, with scattered veins (darker red)

Parenchyma (/pəˈrɛŋkɪmə/)^[1][2] is the bulk of a substance. In animals, a parenchyma comprises the functional parts of an organ and in plants parenchyma is the ground tissue of nonwoody structures.

Etymology

The term parenchyma is New Latin from Greek παρέγχυμα parenkhyma, "visceral flesh" from παρεγχεῖν parenkhein, "to pour in" from παρα- para-, "beside", ἐν en-, "in" and χεῖν khein, "to pour".^[3]

Animals

The parenchyma is 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 the brain, the parenchyma refers to the functional tissue in the brain that is made up of the two types of brain cell, neurons and glial cells.^[4] Damage or trauma to the brain parenchyma often results in a loss of cognitive ability or even death.

Lung parenchyma is the substance of the lung outside of the circulation system that is involved with gas exchange and includes the alveoli and respiratory bronchioles.^[5]

In cancer, the parenchyma refers to "The portion of a tissue that lies outside the circulatory system and is often responsible for carrying out the specialized functions of the tissue".^[6]

Plants

In plants, "parenchyma" is one of the three main types of ground tissue, and the most common. It can be distinguished through their thin cell wall as compared to other cells. Parenchyma cells make up the bulk of the soft parts of plants, including the insides of leaves, flowers and fruits (but not the epidermis or veins of these structures).^[7]

References

External links

• The dictionary definition of parenchyma at Wiktionary