glicocalíc

The glycocalyx is a carbohydrate-rich layer that coats the exterior of many cells, especially animal cells. It consists of membrane-anchored glycoproteins and proteoglycans, linked glycolipids, and, in some tissues, secreted mucins that form a hydrated, gel-like matrix. Bacteria also possess a glycocalyx in the form of a capsule or slime layer that surrounds the cell surface and contributes to adhesion and protection.

Composition and structure: The main constituents are glycoproteins, proteoglycans with glycosaminoglycan chains (such as heparan sulfate, chondroitin sulfate, and hyaluronic acid), and glycolipids. The layer is dynamic and varies with cell type, developmental stage, and environmental conditions. In many epithelia and endothelial cells, the glycocalyx is relatively thick and highly hydrated, while other cell types have a thinner coating.

Functions: The glycocalyx provides mechanical protection and lubrication, helps form a barrier against physical damage and pathogens, and participates in cell–cell and cell–matrix adhesion. It mediates receptor recognition and signaling, contributing to development, immunity, and tissue organization. The endothelial glycocalyx, lining blood vessels, influences vascular permeability, shear-stress sensing, and anti-thrombotic properties.

Clinical relevance: Alterations in glycocalyx composition or thickness have been linked to inflammation, diabetes, sepsis, and vascular disease, and can affect leukocyte recruitment and tumor cell adhesion. The glycocalyx is a focus of ongoing physiological and biomedical research due to its roles in mechanotransduction and barrier function.