Parenchyma (/pəˈrɛŋkɪmə/)[1][2] is the bulk of functional substance in an animal organ or structure such as a
tumour. In
zoology, it is the name for the tissue that fills the interior of
flatworms. In
botany Parenchyma is used to refer to some layers in the cross-section of the
leaf.[3]
Etymology
The term parenchyma is
Neo-Latin from the
Ancient Greek word παρέγχυμαparenchyma meaning 'visceral flesh', and from παρεγχεῖνparenkhein meaning 'to pour in' from παρα-para- 'beside' + ἐνen- 'in' + χεῖνkhein 'to pour'.[4]
Originally,
Erasistratus and other anatomists used it to refer to certain human tissues.[5] Later, it was also applied to plant tissues by
Nehemiah Grew.[6]
Structure
The parenchyma is the functional parts of an
organ, or of a structure such as a
tumour in the body. This is in contrast to the
stroma, which refers to the structural tissue of organs or of structures, namely, the
connective tissues.[citation needed]
Brain
The brain parenchyma refers to the functional tissue in the
brain that is made up of the two types of
brain cell,
neurons and
glial 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 as
intraparenchymal hemorrhage.[citation needed]
The liver parenchyma is the functional tissue of the organ made up of around 80% of the
liver volume as
hepatocytes. 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.[10]
Kidneys
The
renal parenchyma is divided into two major structures: the outer
renal cortex and the inner
renal medulla.
Grossly, these structures take the shape of 7 to 18[11] cone-shaped
renal lobes, each containing renal cortex surrounding a portion of medulla called a
renal pyramid.[12]
Tumors
The tumor parenchyma, of a solid
tumour, is one of the two distinct compartments in a solid tumour. The parenchyma is made up of
neoplastic cells. The other compartment is the
stroma 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.[13]
Flatworms
Parenchyma is the tissue made up of cells and intercellular spaces that fills the interior of the body of a
flatworm, which is an
acoelomate. This is a spongy tissue also known as a
mesenchymal tissue, in which several types of cells are lodged in their
extracellular matrices. The parenchymal cells include
myocytes, and many types of specialised cells. The cells are often attached to each other and also to their nearby epithelial cells mainly by
gap junctions and
hemidesmosomes. 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.[14]
^LeMone, Priscilla; Burke, Karen; Dwyer, Trudy; Levett-Jones, Tracy; Moxham, Lorna; Reid-Searl, Kerry; Berry, Kamaree; Carville, Keryln; Hales, Majella; Knox, Nicole; Luxford, Yoni; Raymond, Debra (2013).
"Parenchyma". Medical-Surgical Nursing. Pearson Australia. p. G–18.
ISBN978-1-4860-1440-8.
Archived from the original on 2015-11-30. Retrieved 2015-05-21.
^Virchow, R.L.K. (1863). Cellular pathology as based upon physiological and pathological histology [...] by Rudolf Virchow. Translated from the 2nd ed. of the original by Frank Chance. With notes and numerous emendations, principally from MS. notes of the author. 1–562. [Cf. p. 339.]
linkArchived 2021-04-27 at the
Wayback Machine.
^Gager, C. S. 1915. The ballot for names for the exterior of the laboratory building, Brooklyn Botanic Garden. Rec. Brooklyn Bot. Gard. IV, pp. 105–123.
linkArchived 2017-11-10 at the
Wayback Machine.
^Kmieć Z (2001). "Introduction — Morphology of the Liver Lobule". Cooperation of Liver Cells in Health and Disease. Advances in Anatomy Embryology and Cell Biology. Vol. 161. pp. iii–xiii, 1–151.
doi:
10.1007/978-3-642-56553-3_1.
ISBN978-3-540-41887-0.
PMID11729749.
^Walter F. Boron (2004). Medical Physiology: A Cellular And Molecular Approach. Elsevier/Saunders.
ISBN978-1-4160-2328-9.
^Connolly, James L.; Schnitt, Stuart J.; Wang, Helen H.; Longtine, Janina A.; Dvorak, Ann; Dvorak, Harold F. (2003).
"Tumor Structure and Tumor Stroma Generation". Holland-Frei Cancer Medicine. 6th edition.
Archived from the original on 2020-12-19. Retrieved 2019-10-01.
^Conn, D (1993). "The Biology of Flatworms (Platyhelminthes): Parenchyma Cells and Extracellular Matrices". Transactions of the American Microscopical Society. 112 (4): 241–261.
doi:
10.2307/3226561.
JSTOR3226561.
External links
The dictionary definition of
parenchyma at Wiktionary