Parenchyma

Parenchyma (Greek παρά para " beside", ἐγχεῖν enchein " pour ", literally " the next Infused " ) called in biology, a tissue that performs a specific function. The term was primarily known for Rudolf Virchow (1821-1902), who applied it in the context of its cellular pathology of animal and vegetable tissues.

The parenchymal tissue is formed by the more or less differentiated or specific parenchymal cells. In contrast, there are ( mesodermal connective tissue) in vertebrates, the cells that form the supporting tissues or carrier or scaffold tissue. It also speaks of the interstitium (or stroma), in which the parenchyma " poured " is.

In humans and vertebrates

Denotes the parenchyma tissue formed by the cells of an organ -specific function (for example, the nephrons of the kidney, the alveoli of the lungs, the white and red pulp of the spleen ). To this end, unlike stands the interstitium (also called stroma ), the untergliedernde connective tissue that makes no actual organ function, but contains the afferent and efferent vessels and nerves and what boundary between organs and its surroundings and keeps its shape and supports. The parenchyma is derived mostly from the ectoderm or endoderm from. Thus, for example, originate the nerve cells from ectoderm ( neural groove ).

Parenchymal tissue is usually distinguished from the mesodermal connective tissue. This is like to be placed subliminally expressed that this is derived from the mesoderm and is on a lesser degree of differentiation. But also from the mesoderm develop specific organ structures such as smooth and striated muscles. The evolutionary origin of a given cotyledon says so not necessarily something about differences of differentiation.

Both worms

In various worms such as flatworms parenchyma referred to as " an inner body fills the tissue into which the bodies are embedded ."

In plants

In general, the tissue -forming cells have no specific anatomical differentiation. Parenchyma cells are thin-walled cells of the ground tissue that make up the majority of non-woody ( herbaceous ) plant structures ( although in some cases their cell walls can be lignified ) and, for example, the storage of nutrients serve. There are differentiated several types.

Palisade parenchyma

The palisade parenchyma or palisade tissue is a plant tissue, that can be found in the leaves of higher plants below the upper epidermis. It consists of elongate, cylindrical cells and serves largely photosynthesis. Therefore Adjacent cells resemble palisades, when you look at a blade section with the light microscope. Borne in mind here, however, that the cells of the palisade parenchyma are not only arranged in a row, but also to a surface. Intercellular spaces are rare in this tissue. Parenchyma contained compared to the spongy parenchyma approximately three to five times as many chloroplasts.

Leaves that are frequently exposed to sunlight ( so-called sun leaves) have a multi-layered palisade parenchyma, while the palisade cells usually form only one layer in shade leaves, so that the cells of the spongy parenchyma also still use the low light intensity.

Spongy parenchyma

The spongy tissue or sponge is a vegetable tissue of the foliage leaf, which is bordered at the bottom of the lower epidermis and the top of the palisade parenchyma inside the leaf, or is surrounded with äquifazialen leaves of two palisade tissues. It consists of mostly irregularly shaped, often stellate cells ( then called Sternparenchym ) between which are larger intercellular spaces. Compared to the palisade parenchyma spongy parenchyma contains fewer chloroplasts. It is primarily for gas exchange during photosynthesis, which is favored by the intercellular system, as this results in the formation of large internal surfaces in the result sheet. When catalpa example 5100 m² interior surface were measured at only 390 sqm outer leaf surface.

Generally refers to a spongy only as such when a palisade parenchyma is provided in parallel.

Chlorenchym ( Assimilationsparenchym )

The Chlorenchym, also Assimilationsparenchym, is the specialist on photosynthesis parenchyma. It is a chloroplastenreiches leaf tissue ( the mesophyll ), which consists of the palisade layer and the spongy. The spongy parenchyma is also Chlorenchym and aerenchyma.

Speicherparenchym in the root of the herb Scharbock

Aerenchym

Under Aerenchym refers to a form of basic plant tissue in which the intercellular spaces are so far that a veritable " aerenchyma " arises. It occurs especially in marsh and aquatic plants and serves the gas exchange of the submerged plant organs.

Hydrenchym

Hydrenchym may also be referred to as " Wasserspeicherparenchym ". It mainly serves succulent plants for the storage of water and has cells with very large vacuoles.

Speicherparenchym

Speicherparenchym used to store nutrients such as starch, fats, proteins, and water.