Regeneration (biology)

Under regeneration is the ability of an organism to replace lost parts.

Plants are capable of doing, but also many invertebrates such as various cnidarians, ascidians, flatworms and the like. Among the vertebrates, the power has been largely lost to regenerate organs and tissues. Amphibians such as salamanders and axolotl are partly able to regenerate lost limbs, eyes and parts of internal organs. The ability of some reptiles such as lizards, to throw off its tail at a breaking point due to muscle contraction, and then to re-grow again ( in reduced form ), is rare among vertebrates.

In the arthropods is the ability to replace lost body parts at the next molt partially widespread. The input mode is molting one of each being replaced as in the previous moult, so that when a sufficiently large number of molts body parts can also be completely replaced. The number of molts is but in some groups of arthropods limited ( eg in insects ), so that in these cases, after the last, often the last molt, no further recovery is possible.

Types of regeneration

There are three types of regeneration:

In mammals, in addition to the regeneration of the hypertrophy is also very important for the recovery of particular parenchymatous internal organs. A key element of the internal organs hypertrophy is the increase of functional mass by cell enlargement rather than the recovery of the outer body shape. Typically occurs hypertrophy not only in case of damage or partial removal of an organ on, but especially increased functional stress.

Mechanism

The mechanisms that allow regeneration of entire limbs, organs, and even parts of the brain that are currently the subject of intensive research efforts. The Mexican axolotl salamander is in this respect a very popular subject of study because of its particularly extensive regenerative capacity. Contrary to the previous assumption that regress after an injury initially, the surrounding cells into so-called all-rounder cells ( pluripotent stem cells) and occur in the next step of this all new cells, recent research has here shown that develop new limbs or organs from cells that can only evolve each to certain tissue types. In other words, each produces a tissue precursor cells (English: progenitor cells), which have only a limited potential for reverse engineering. This surprising discovery, the researchers involved in the view important implications for regenerative medicine. To display the result, that complete dedifferentiation of the cells is required back to the pluripotent stage of development for the complex phenomenon of regeneration. Further, the presence of macrophages in the regeneration process is necessary.