pass through cell walls and facilitate connections with adjacent cells. Plasmodesmas are highly dynamic in both strucutural modifications and biogenesis. They are able to organize cells in domains, serving as basic developmental units for plants, as well as mediate the intracellular movement of a variety of proteins and nucleic acids. Cell–extracellular matrix signaling The extracellular matrix is composed of glycoproteins (proteins and mucopolysaccharides (glycosaminoglycan)) produced by the organism's cells. They are secreted not only to build a supportive structure but also to provide critical information on the immediate environment to nearby cells. Indeed, the cells can themselves interact by contact with extracellular matrix molecules and as such, this can be considered an indirect cell / cell communication. Cells use mainly the receptor integrin to interact with ECM proteins. Integrins are a family of receptor proteins that integrate the extracellular and intracellular structures, allowing them to perform together. This signaling can influence the cell cycle and cellular differentiation by directing which cells live or die, which cells proliferate, or which cells are able to exit the cell cycle and differentiate. Cellular differentiation involves a cell changing its phenotypical or functional type. See also Cell adhesion, mechanical adhesion between cells and/or the extracellular matrix Role of cell adhesions in neural development Cell adhesion molecules Pannexin, vertebrate proteins used to form conduits between the intracellular and extracellular space Autocrine signalling Paracrine signalling Endocrine system References External links "Autocrine versus juxtacrine signaling modes" - illustration at sysbio.org Cell signaling