Intercellular junctions

In animal fabrics, the close cells are connected between them by various structures which ensure a coherence of the whole of fabric. These structures which bring into play two cells or more are gathered under the generic term of intercellular junctions. They can be specific (dipositif maculaire), or form a belt around the cell (device zonulaire). All that is not band or circle is complex FASCIA.

In the organization, one finds the types of following junctions:

the communicating junctions: also called junctions has holes or lacunar they are implied in the metabolic and electric coupling of two cells by allowing the passage of small molecules or ions between their cytoplasms. They consist of two connexons (1connexon = assembly of 6 connexines), one by cell which form a channel of very small diameter, thus allowing a selective permeability (ions, amino-acids…)
the Junctions of anchoring: they can be macular (mackled adherens = junction S forms disc) or zonulaires (zonula adherens = girdles adherence). They ensure the mechanical coherence of animal fabrics by linking the cells adjaçantes between them.

There exists a standard aute of junction of anchoring called hémidesmosome (or focal contact), which anchors the epithelial cells to the extracellular matrix.

intercellular cohesion, thanks to the desmogléines, transmembrane Proteins forming between them connections;
intracellular cohesion, thanks to the desmoplakines which establish the link between the filaments of the Cytosquelette and the desmosome.

the tight junctions return seals space intermembranaire between two cells, by amalgamating the external layer of each plasmic membrane. When one has a zonula occludens, the molecules of the extracellular medium as well as membrane proteins cannot circulate from one pole to another of the cell.
the Synapse S transmit the nerve impulse of a Neuron to another.
the driving Plaque transmits the nerve impulse of a Neuron to a muscular cell.

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