Parenchyma


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Parenchyma

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)

Parenchyma

 

(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.

parenchyma

[pə′reŋ·kə·mə]
(botany)
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.
(histology)
The specialized epithelial portion of an organ, as contrasted with the supporting connective tissue and nutritive framework.
References in periodicals archive ?
Another type of axial parenchyma cell dimorphism can be found with respect to strands of small crystal-bearing cells ("chambered crystals").
Routine ultrasound of the abdomen can detect distorted renal parenchyma and presence of calculus.
From base to top portion of bamboo culm, the parenchyma lumen diameter in the nodal area decreased from 30.92 to 23.98 [micro]m, which was significantly larger than that at the internode, which was in the range of 19.07 to 23.43 [micro]m.
Sucrose partitioning between vascular bundles and storage parenchyma in the sugarcane stem: a potential role for the ShSUT 1 sucro se transporter.
The results of the present study showed that the testis of the African ostrich is composed of a capsule and parenchyma, and the parenchyma includes tubular compartments and interstitial tissue, this structure is similar to that reported in other animal species (Wang et al., 2000, 2011; Fu et al., 2009; Yu et al., 2010; Bai et al., 2009; Zhang et al., 2002; Lebelo and Horst, 2017).
In addition, single-slice ROIs were drawn in the liver parenchyma and the HCC lesion(s) of each patient.
But only a few cases point to direct rupture of the lung parenchyma [12-14].
In vivo, numbers of mitochondria in the lung parenchyma of ARDS rats treated with SW plus mitochondrial transfusion (SW + Mito) were significantly higher than those in the lungs of untreated ARDS animals or ARDS animals treated with Mito alone (Figure 2).
We calculated the mean and 95% confidence interval ( CI ) of the intrahepatic cyst volume, hepatic parenchyma volume, liver volume (cysts plus parenchyma), volume reduction rate of the liver, and circumference of the abdomen, before TAE as the baseline and at 3, 6, 12, 18, 24, and 36 months after TAE.
Their algorithm can reduce the occurrence of over segmentation of the abdomen and the mediastinum area which ispresented very adjacent to the lung parenchyma. Their algorithm has been analyzed their algorithm an approximate of 20 slices.
Following intratracheal delivery, amphotericin B was present in lung parenchyma at concentrations above the targeted MIC of 1 [micro]g/g for up to 9 days postadministration; however, distribution of the drug was uneven, with the majority of the drug concentrated in 1 lung lobe.