Syncytium

As syncytium or syncytium (from ancient Greek σύν syn , German 'with, together' and κύτος kýtos "vessel", "cavity" or "cell"; plural: syncytia or syncytia ), also coenoblast ( κοινός koinós "together", βλάστη blástē "scion") or coenocyte (κοινός + κύτος), is a multinucleated (polyenergid) cell or a multinuclear organism without cellular subdivision. A syncytium can arise either through nuclear divisions without subsequent cell divisions or secondary through fusion of cells. The latter is the original and still predominant meaning of syncytium , while primarily multinucleated organisms are referred to as coenoblasts , siphonal or plasmodia .

As functional syncytia cells are referred, which are morphologically separated from each other, their cytoplasm but via gap junctions is connected.

Examples

Syncytia or coenoblasts are for example:

• The fibers of the striated skeletal muscles , whereby a muscle consists of many muscle fibers (syncytia). They are created by the fusion of the muscle-building cells ( myoblasts ).
• The early stages of superficial furrowing in insect eggs.
• The neodermis of tapeworms ( Cestoda ), roundworms ( Nematoda ) and suction worms ( Trematoda ).
• The early development stage of the endosperm , known as nuclear , of most flowering plants .
• The sieve tubes in the vascular tissue of many bed covers.
• The siphonal algae ( Caulerpa , Acetabularia and others).
• The yoke mushrooms and the egg mushrooms .
• The plasmodia of the slime mold .
• The giant amoeba of the genus Chaos .
• From the human respiratory syncytial virus infected ciliated cells in apes (ie incl. Humans)
• The syncytiotrophoblast , part of the placenta in higher mammals (placentalia).

Syncytia in evolutionary models

Occasionally, the special organization of the eyelash animals ( ciliata ) is discussed as a further developed syncytium. So here hypotheses and models for evolutionary processes play a role, which are sometimes even extended to the evolution of the metazoa as a whole . According to such assumptions, syncytial tissues appeared very early in the evolution of the Metazoa, but not through the fusion of cells, but rather arising from a polyenergid, unicellular precursor of the multicellular forms of life (detailed e.g. by Jovan Hadzi , Wolfgang Friedrich Gutmann ). The original multicellular Trichoplax adhaerens , but also some sponges , is sometimes referred to as a living model for this .

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1. ↑ Syncytiotrophoblast , on: DocCheck Flexikon
2. ↑ Nadja Podbregar: Secret Helpers - What Function Do Endogenous Retroviruses Have in Us? , on: scinexx.de from November 5, 2010
3. ^ K. Edlinger: Bilateral symmetry and evolution. In: W. Hahn, P. Waibel (Ed.): Evolutionary Symmetry Theory. Self-organization and dynamic systems. Hirzel Verlag, Stuttgart 1996, pp. 77-89.
4. ↑ J. Hadzi: The evolution of the metazoa. Pergamon Press, Oxford 1963.
5. ↑ K. Bonik, M. Grasshoff, WF Gutmann: The evolution of animal constructions. In: Nature and Museum. 106, 1976, pp. 129-143.