The term stomatocyte is derived from the Greek term stoma, meaning mouth. Stomatocytes have elongated or slit-like central pallors, which may be curved, giving the central pallor an appearance of a smiling mouth. The occasional stomatocyte seen in normal smears is the result of a slight pH change in the environment, similar to the in vitro changes that cause cells to assume the echinocyte shape. Two stomatocytes are indicated by arrows on this slide.
