_{>> Cell Theory Section <<}

For the adressed purpose, the modification of the cell behavior by cell instruction via surfaces, a modular concept will be helpful. The modules cover the adhesion and the motility apparatus. It might appear somewhat selective but it is successful in the explanation of a member of different cell behaviors. Beneath the processes concerned there are migration, adhesion, phagocytosis and the cell communication by physical contact.

The figure introduces into the basic functional and structural components of the model. A simpler draft is given as long as Your mouse is over the image. The single modules are explained in higher detail in the topics on the page.

Click on the image for a higher resolution draft or click on the buttons to enter the topics.

Extracellular matrix (ECM) compounds cover the cell surface and fill the local environment. The ECM components are secreted by the cell. The ECM is a shield, a mechanical anchor, but also a reservoir for cell signal chemistry. Thus, with ECM one can stimulate a particular cell behavior. Vice versa, cells modify ECM composition and structure.

Actin pushes the front of a cell forward. This is the first of two different functions of the actin molecules. They form a gel consisting of numerous short fibres. This gel sucks water and swells up. The resulting volume increase pushes the cell border outwards. It would be interesting to know if gel formation can be stimulated with ECM compounds.

Adhesion sites stick the cell to the surface. On the outside they contact ECM molecules. Inside they are stay coupled to long protein fibers called the cytosceleton. This way they transduce forces produced during cell adhesion and movement into the ECM. Adhesions decide if the local environment is friendly. Also the cell shape is made here.

Pulls of contracting proteins, mainly Myosin I and II, along the actin fiber scaffold make cell movement happen. Also, the cell components are transported here along. Cell size and shape results from the pull activities. Last not least, the actin fibers interconnect the cell adhesion. As a result the actin cytosceleton reaaranges the adhesion pattern continuously.

Detachment of adhesion sites is of enormous importance. A cell which cannot detach from the environment is either impossible to move and to reshape or it will be ripped during migration because the cell front starts to move while the rest of the cell resides at the original position. Detachment is a highly dynamic process.