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Parenchyma (/pəˈrɛŋkɪmə/)[1][2] is the bulk of functional substance in an animal organ such as thebrain orlungs, or a structure such as atumour. Inzoology, it is the tissue that fills the interior offlatworms. Inbotany, it is some layers in the cross-section of theleaf.[3]
The termparenchyma isNeo-Latin from theAncient Greek wordπαρέγχυμαparenchyma meaning 'visceral flesh', and fromπαρεγχεῖνparenkhein meaning 'to pour in' fromπαρα-para- 'beside' +ἐνen- 'in' +χεῖνkhein 'to pour'.[4]
Originally,Erasistratus and other anatomists used it for certain human tissues.[5] Later, it was also applied to plant tissues byNehemiah Grew.[6]
The parenchyma is thefunctional parts of anorgan, or of a structure such as atumour in the body. This is in contrast to thestroma, which refers to thestructural tissue of organs or of structures, namely, theconnective tissues.[citation needed]
The brain parenchyma refers to the functional tissue in thebrain that is made up of the two types ofbrain cell,neurons andglial cells.[7] It is also known to contain collagen proteins.[8] Damage or trauma to the brain parenchyma often results in a loss of cognitive ability or even death. Bleeding into the parenchyma is known asintraparenchymal hemorrhage.[9]
Lung parenchyma is the substance of thelung that is involved withgas exchange and includes thepulmonary alveoli.[10]
The liver parenchyma is the functional tissue of the organ made up of around 80% of theliver volume ashepatocytes. The other main type of liver cells are non-parenchymal. Non-parenchymal cells constitute 40% of the total number of liver cells but only 6.5% of its volume.[11]
Therenal parenchyma is divided into two major structures: the outerrenal cortex and the innerrenal medulla.Grossly, these structures take the shape of 7 to 18[12] cone-shapedrenal lobes, each containing renal cortex surrounding a portion of medulla called arenal pyramid.[13]
The tumor parenchyma, of a solidtumour, is one of the two distinct compartments in a solid tumour. The parenchyma is made up ofneoplastic cells. The other compartment is thestroma induced by the neoplastic cells, needed for nutritional support and waste removal. In many types of tumour, clusters of parenchymal cells are separated by a basal lamina that can sometimes be incomplete.[14]
Parenchyma is the tissue made up of cells and intercellular spaces that fills the interior of the body of aflatworm, which is anacoelomate. This is a spongy tissue also known as amesenchymal tissue, in which several types of cells are lodged in theirextracellular matrices. The parenchymal cells includemyocytes, and many types of specialised cells. The cells are often attached to each other and also to their nearby epithelial cells mainly bygap junctions andhemidesmosomes. There is much variation in the types of cell in the parenchyma according to the species and anatomical regions. Its possible functions may include skeletal support, nutrient storage, movement, and many others.[15]
The dictionary definition ofparenchyma at Wiktionary
