Haptotaxis

Under haptotaxis ( "touch" of gr haptein, " tack " and taxis "order", " march " ) is understood in biology and medicine, the movement of cells and cell processes that appeal to a concentration gradient of a structure-bound signaling substance ( Haptotaxin ) orient. In contrast to the haptotaxis in chemotaxis is the concentration gradient ( the chemotactic gradient ) of a dissolved substance signal ( chemotaxin ), the movement direction. For complex living organisms ( metazoans ) of the signal stimulus causes most cell migration towards the higher concentration of the signaling substance (positive haptotaxis or chemotaxis), but the opposite is also possible (negative haptotaxis or chemotaxis).

Chemotaxis and haptotaxis are essential organizational elements in the morphogenetic movements during embryonic development, but also later in growth, transformation and healing processes, eg in the outgrowth of nerve cell processes ( Axogenese ) or vessels (angiogenesis ). Even the immune system or bacterial cells ( eg, Escherichia choli ) orient yourself with such stimuli.

Haptotactic signals can emanate from specific structures of the cell surface as well as the intercellular substance (eg, connective tissue fibers ). An example of a molecule that exerts a haptotactic stimulus neutrophils in the blood stream, the PECAM 1 receptor ( CD31 ) is upregulated on endothelial cells of the site of inflammation in inflammation. His increasing density towards the cell periphery derives an adherent granulocytes to the edge of the cell where it can leave at the contact point to the next cell the blood stream ( diapedesis ).