Parenchyma

Parenchyma

[puh-reng-kuh-muh]
Parenchyma is a term used to describe a bulk of a substance. It is used in different ways in animals and in plants.

The term is New Latin, from Greek parenkhuma, visceral flesh, from parenkhein, to pour in beside : para-, beside + en-, in + khein, to pour.

In animals

The parenchyma are the functional parts of an organ in the body. This is in contrast to the stroma, which refers to the structural tissue of organs, being exactly, connective tissues.

In cancer the parenchyma refers to the actual mutant cells of a single lineage, while the stroma is the surrounding connective tissue and associated cells which support it.

The mesodermal layer of the embryo develops into a loose collection of cells known as parenchyma tissue. This tissue occupies the entire space between the outer body wall and the endoderm of the gut.

Examples include:

Organ Parenchyma
kidney nephron
lungs alveoli, respiratory bronchiole, alveolar duct and terminal bronchiole
spleen white pulp and red pulp
brain neuron
liver hepatocyte

In plants

Parenchyma cells are thin-walled cells of the ground tissue that make up the bulk of most nonwoody structures, yet sometimes their cell walls can be lignified. Parenchyma cells in between the epidermis and pericycle in a root or shoot constitute the cortex, and are used for storage of food. Parenchyma cells within the center of the root or shoot constitute the pith. Parenchyma cells in the ovary constitutes the nucellus and are brick-like in formation. Parenchyma cells in the leaf constitute the mesophyll; they are responsible for photosynthesis and they allow for the interchange of gases.

References

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