Stomatocytes

3D Model

The biconcave shape of an erythrocyte can be pushed in two directions. At the extreme end of convexity are the completely round spherocytes. The opposite case, of the cell becoming increasingly concave, results in stomatocytes which come in a range of cupped shapes. Stomatocytes are caused by changes in the permeability of the plasma membrane and how much water flows in or out of the cell changing its volume.