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Parenchyma

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Definition

noun, plural: parenchymata

(anatomy) The essential or functional element of an organ (as opposed to the stroma or the connective tissue of an organ)

(botany) A fundamental type of tissue in plants characterized by cells with thin walls (as opposed to collenchyma and sclerenchyma)

(zoology) The spongy connective tissue in some invertebrates


Supplement

The term parenchyma comes from the Greek parénkhyma , which in turn is derived from parenkhein, meaning "beside" and "to pour in".

In anatomy, the parenchyma refers to the essential component of an organ. It is used to designate the functional elements of an organ, as distinguished from its framework or stroma. For example, the parenchyma of the brain includes the neurons and the glial cells.

In plants, the parenchyma is one of the three fundamental cell types. The other two are the collenchyma and the sclerenchyma. The thin wall of a parenchyma cell is one of the features that distinguish it from the other two. The thin wall is due to the absence of secondary cell wall (which is present in sclerenchyma). Collenchyma cell, in contrast, has only a primary cell wall as well but it is relatively thicker than that of parenchyma cell. Many of the collenchyma cells have an unevenly thickened primary cell wall.

The parenchyma remains a living cell at maturity. It is also the most common cell type, performing diverse functions, e.g. photosynthesis, storage, and secretion. A special type of parenchyma involved chiefly in photosynthesis is referred to as chlorenchyma. In vascular tissues, parenchyma cells are of two types: xylem parenchyma and phloem parenchyma.

In zoology, the parenchyma pertains to the spongy connective tissues in some invertebrates.


Word origin: Greek parénkhyma (“beside", "to pour in”)

See also:

Related term(s):

Related form(s):

  • parenchymatous, parenchymal (adjective, of, pertaining to, relating to, or characterized by parenchyma)