The tissues of an organism are formed by clusters of cells that are similar in morphology and physiology, requiring in some organic situations of extreme connection between adjacent (neighboring) cells, ensuring, for example: protection against penetration of pathogenic microorganisms (that cause disease), and in other cases, structures that provide the exchange of substances.
Such functions occur due to specializations present in regions mediated by the plasma membrane and cell envelopes, called intercellular junctions, namely: desmosomes, tight zonules (tight junctions), adhesion zonules and nexuses (gad junctions).
Desmosome → bridge established between two neighboring cells, through which intermediate filaments connect, forming a structure of great tensile strength, composed of several intracellular (placoglobin and desmoplaquin) and extracellular (desmoglein and desmocholin) proteins, existing mainly in the lining epithelial tissue (the skin) and muscle cardiac.
Occlusive zonules → union between cells (of the intestine), preventing the passage and storage of substances and macromolecules in the intercellular spaces, blocking the communication between two media (cavities).
Nexos → are communicating points between the membrane of one cell and another, through transmembrane proteins of both cells, forming pores (channels) through which ions and small molecules pass. This type is found in embryonic tissues, cardiac and liver cells.
Adhesion zonule → regions that unite neighboring cells by means of intercellular adhesive substances, causing adhesion without contact between plasma membranes.
By Krukmenberghe Fonseca
Graduated in Biology
Source: Brazil School - https://brasilescola.uol.com.br/biologia/adesao-comunicacao-entre-as-celulas.htm