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A ground tissue of plants chiefly concerned with the manufacture and storage of food. The primary functions of plants, such as photosynthesis, assimilation, respiration, storage, secretion, and excretion—those associated with living protoplasm—proceed mainly in parenchymal cells. Parenchyma is frequently found as a homogeneous tissue in stems, roots, leaves, and flower parts. Other tissues, such as sclerenchyma, xylem, and phloem, seem to be embedded in a matrix of parenchyma; hence the use of the term ground tissue with regard to parenchyma is derived. The parenchymal cell is one of the most frequently occurring cell types in the plant kingdom. See Plant anatomy, Plant physiology

Typical parenchyma occurs in pith and cortex of roots and stems as a relatively undifferentiated tissue composed of polyhedral cells that may be more or less compactly arranged and show little variation in size or shape. The mesophyll, that is, the tissue located between the upper and lower epidermis of leaves, is a specially differentiated parenchyma called chlorenchyma because its cells contain chlorophyll in distinct chloroplastids.

This chlorenchymatous tissue is the major locus of photosynthetic activity and consequently is one of the more important variants of parenchyma. Specialized secretory parenchymal cells are found lining resin ducts and other secretory structures. See Photosynthesis, Secretory structures (plant)



(1) The fundamental tissue in plants. Parenchyma is composed of cells having a polyhedral shape, with the various diameters differing very little from each other. The cells form homogeneous aggregates in the plant body and fill the spaces between other tissues. They serve as part of the conductive and mechanical tissues. As a result of functional specialization of protoplasts, parenchyma cells may perform assimilative, excretive, and other functions. The presence of intercellular substances, especially in diffuse parenchyma with vacuoles, determines the tissue’s role in gas exchange. Parenchyma cells serving support functions may be elongated, branched, or stellate; their walls are thick and often lignified. Living parenchyma cells are capable of division. Phellogen (cork cambium) or, in unusually thick plants, cambium is formed (for example, in beets and certain lianas).

(2) In animals, parenchyma is the phylogenetic precursor of true tissue. It is divided into primary parenchyma and mixed parenchyma. The former is a bond of homogeneous cells without systematic organization. The cells are not fused in a syncytium or separated by interstitial matter (as in the embryos of certain hydroids in the morular stage). Mixed parenchyma is an aggregate of heterogeneous cells distributed randomly, as in the bodies of Acoela. At times, the term “parenchyma” is used to designate the principal functional tissue of the liver, spleen, lungs, and glands. It is also used to designate striated muscle tissue.


A tissue of higher plants consisting of living cells with thin walls that are agents of photosynthesis and storage; abundant in leaves, roots, and the pulp of fruit, and found also in leaves and stems.
The specialized epithelial portion of an organ, as contrasted with the supporting connective tissue and nutritive framework.
References in periodicals archive ?
Peroxisome proliferator-activated receptor alpha is restricted to hepatic parenchymal cells, not Kupffer cells: implications for the mechanism of action of peroxisome proliferators in hepatocarcinogenesis.
The composition of parenchymal cells in the processed bamboo residues is estimated at almost 80 percent (by weight).
On histochemistry, fat stains (oil red O, Sudan black) will usually show that the amount of intracellular fat is significantly less than it is in normal or suppressed parenchymal cells.
Jinyuan###A layer of barrier style of closely spaced parenchymal cells, with wall containing numerous irregular###Fig.
5] can easily reach alveolar parenchymal cells and can be internalized by alveolar epithelium and macrophages (Churg and Brauer 1997; Kim et al.
The classic 'triphasic' histology consists of 3 elements: very immature renal parenchymal cells (blastema), primitive tubules (epithelial cells) and supporting mesenchyme.
In heavy drinkers, however the liver's chief cells -- called parenchymal cells -- can suffer such a severe damage that scar tissue forms, resulting in a condition known as cirrhosis.
Further research led to the discovery of pattern-recognition receptors (PRRs) expressed in the liver, not only on Kupffer cells but also on other immune cells and parenchymal cells.
The liver is a highly metabolic, complex array of vasculature, endothelial cells and parenchymal cells that performs many functions in the body.
CP is synthesized primarily by the liver parenchymal cells.
Likewise, neurons are the parenchymal cells of the central nervous system.
Each tissue type has specific functions, and parenchymal cells, for example, perform many functions.