A glycocalyx is a network of polysaccharides that project from cellular surfaces, e.g. those of bacteria. It serves to protect the bacterium or allows the bacterium to attach itself to inert surfaces (like teeth or rocks), eukaryotes (e.g. streptococcus pneumoniae attaches itself to lung cells), or other bacteria (their glycocalyxes can fuse to envelop the colony).

Its presence on inert materials (such as metal hardware implanted for fracture fixation or total joint replacement) make it difficult to eradicate deep infections as the bacteria will 'cling' on to the material via the glycocalyx. It is therefore often necessary to completely remove the hardware device in order to fully eradicate a wound infection.

The glycocalyx can be found just outside the cell wall of a bacterium. A distinct, gelatinous glycocalyx is called a capsule, while an irregular, diffuse layer is called a slime layer. Glycocalyx can help protect bacteria from phagocytes. It also helps in the formation of biofilms such as a coating on inert surfaces such as teeth or rocks.

The glycocalyx is also the name given to a specific structure of a mature platelet. The glycocalyx is unique among the cellular components of the blood. It is similar to the bacterial glycocalyx above in that it is made up of glycoproteins and allows the platelet to adhere to surfaces such as collagen of damaged vessels. The glycocalyx appears as a fluffy coat to the outer membrane of platelets and contains many of the receptor proteins that allow adhesion.

The glycocalyx is chemically unique in everyone but identical twins, and acts like an identification tag that enables the body to distinguish its own healthy cells from transplanted tissues, invading organisms and diseased cells. Human blood types and transfusion compatibility are determined by glycoproteins.

Functions

Glykokalyx | Glycocalyx | Glikokaliks | Glicocálix