Regeneration (physiology)
| Parent |
| Morphogenesis |
| Subordinate |
| Regeneration of organs tissue cell processes |
| Gene Ontology |
|---|
| QuickGO |
Under regeneration is the ability of an organism to replace lost parts.
Plants are able to do this, but also a great many invertebrates such as various cnidarians , ascidia , flatworms and the like. Ä. Among the vertebrates, the ability to regenerate organs and tissues has largely been lost. Amphibians such as B. the newts or axolotls are partly able to regenerate lost limbs, eyes and parts of internal organs. The ability of some reptiles, such as lizards , to shed their tail at a predetermined breaking point by muscle contraction and then let it grow back (in a reduced form) is rather rare among vertebrates.
In the arthropods , the ability to partially replace lost body parts during the next molt is widespread. In this case, one more piece is replaced per molt than in the previous molt, so that with a sufficiently large number of molts, body parts can also be completely replaced. However, the number of moults is limited in some groups of arthropods (e.g. insects ), so that in these cases no further regeneration is possible after the last, often the imaginal, moult.
Types of regeneration
There are three types of regeneration:
- Epimorphosis
- During epimorphosis, the lost parts are completely reshaped by the organism through cell proliferation . Examples of epimorphosis are the newts and starfish .
- Morphallaxis
- In morphallaxis, the lost parts are re-formed by rearranging the existing cells . So no new cells are formed. The freshwater polyp Hydra vulgaris is a classic example of morphallaxis.
- induction
- Induction regeneration is a largely experimental approach that dates back to the late 1930s. The tissue-specific regeneration is achieved through the application of tissues (e.g. finely ground bones ) or materials (e.g. trypan blue ) with specific inductive properties.
In mammals , in addition to regeneration, hypertrophy is also very important for the restoration of parenchymal internal organs in particular . A key element of internal organ hypertrophy is the increase in functional mass through cell enlargement rather than the regaining of the external organ shape. Typically, hypertrophy occurs not only when an organ is damaged or partially removed, but also when there is increased functional stress .
mechanism
The mechanisms that enable regeneration of entire limbs, organs and even parts of the brain are the subject of intense research. The Mexican salamander axolotl is a very popular study object due to its particularly extensive ability to regenerate. Contrary to the previous assumption that after an injury, the surrounding cells initially regress into so - called all-rounder cells (pluripotent stem cells ) and in the next step all new cells arise from these, recent research has shown that new limbs or organs develop from cells that can only develop into certain types of tissue. In other words, each tissue produces progenitor cells ( english progenitor cells ), which have only a limited potential for reverse engineering. According to the researchers involved, this surprising discovery has significant consequences for regenerative medicine . The result shows that the complex phenomenon of regeneration does not require complete dedifferentiation of the cells back to the pluripotent stage of development. The presence of macrophages is also necessary during the regeneration process.
literature
- Bruce Martin Carlson: Principles of Regenerative Biology. Academic Press, Oxford 2007, ISBN 978-0-12-369439-3 ( preview in Google Book Search).
Web links
- Regeneration ability ( memento from October 18, 2016 in the Internet Archive ). In: geodz.com (The regeneration and regenerative capacity in landscape ecology - schematic representation using the forest as an example)
Individual evidence
- ↑ a b L. V. Polezhaev: Methods of regeneration . In: The Soviet journal of developmental biology . 5, No. 2, 1975, ISSN 0049-173X , pp. 134-139. PMID 1124421 .
- ↑ a b Bruce Martin Carlson: Principles of Regenerative Biology. Academic Press, Oxford 2007, ISBN 978-0-12-369439-3 , 21-23 ( preview in Google Book Search).
- ↑ Elly M. Tanaka et al: Cells keep a memory of their tissue origin during axolotl limb regeneration. In: Nature . 460, July 2, 2009, pp. 60-65, doi: 10.1038 / nature08152 , PMID 19571878 .
- ↑ hda / dpa: Salamander: Researchers reveal the secret of regrowing limbs. In: spiegel.de. Spiegel Online , July 2, 2009, accessed January 26, 2015 .
- ↑ James W. Godwin, Alexander R. Pinto, Nadia A. Rosenthal: Macrophages are required for adult salamander limb regeneration. In: Proceedings of the National Academy of Sciences. 110, 2013, pp. 9415-9420, doi: 10.1073 / pnas.1300290110 .