Codocyte

Codocytes, also known as target cells or Mexican hat cells, are red blood cells that have the appearance of a shooting target with a bullseye. In optical microscopy these cells appear to have a dark center (a central, hemoglobinized area) surrounded by a white ring (an area of relative pallor), followed by dark outer (peripheral) second ring containing a band of hemoglobin. However in electron microscopy they appear very thin and bell shaped. Because of their thinness they are referred to as leptocytes and because of the wavy bowl shape they are referred to as Mexican hat cells. On routine smear morphology, some people like to make a distinction between leptocyes and codocytes- suggesting that in leptocytes the central spot is not completely detached from the peripheral ring, i.e. the pallor is in a C shape rather than a full ring.