Parenchymen

Parenchymen is the plural form of parenchyma in German and is sometimes used in English-language contexts to refer to the functional tissue of an organ, as opposed to supportive or connective tissue (stroma). In anatomy and histology, parenchyma denotes the cells and tissues that carry out the essential functions of an organ.

In plants, parenchyma is the most common fundamental tissue. Parenchyma cells are typically living at maturity, with thin primary cell walls and the capacity to divide and differentiate. They form much of the plant’s cortex and pith, as well as the mesophyll of leaves. When specialized for photosynthesis, they are called chlorenchyma; when adapted for storage, they may store starch, oils, or water. Other specialized forms include aerenchyma, which contains large air spaces to aid buoyancy or gas exchange, and storage parenchyma that accumulates reserves in various organs.

In animals, parenchyma refers to the functional tissue of an organ, as distinct from its supportive framework (stroma). Examples include the liver parenchyma, composed mainly of hepatocytes responsible for metabolism and detoxification, and the renal parenchyma, which includes the functional units of the kidney. Parenchymal tissues perform the specific activities of their organs, while stroma provides structural support, blood vessels, and connective elements.

Developmentally, plant parenchyma arises from undifferentiated meristematic cells and can differentiate into other tissue types as needed. In animals, parenchymal cells originate from embryonic germ layers and can exhibit varying degrees of proliferative capacity, depending on the tissue and organism. Parenchymen thus encompasses the essential functional components across plant and animal organs, shaping both structure and physiology.