The cell surface is a selective interface between the cell and the outside environment. It receives and transmits incoming messages, controls which substances enter and leave the cell, and mediates attachments to and interactions with other cells and extracellular material. The features of a cell's surface identify it as belonging to a particular species, to a particular individual, and to a particular tissue within that individual. The surface consists of molecules embedded in and extending from the cell membrane.
Cell surfaces guide embryonic cells to form tissues and organs.
The human leukocyte antigen cell surface markers establish self and are associated with increased risk of developing certain disorders. A biological membrane consists of a phospholipid bilayer embedded with movable proteins, glycoproteins, and glycolipids, like a fluid mosaic. The percentage and distribution of membrane proteins varies in different cell types. Membrane proteins include receptors, carriers, adhesion molecules, and cell surface proteins establishing self. Substances cross cell membranes in several ways.