Macrocytes

3D Model

Macrocytes are erythrocytes with a diameter greater than 9 microns, compared to the average size of 7 microns (two of the three cells here). They arise due to problems with the development of erythroblasts into mature red blood cells. Common causes are deficiency in vitamin B12 or folate, both of which are required for DNA synthesis. The resulting defects in cell division and differentiation mean the erythrocyte ends up having too large a volume and not enough haemoglobin, this impairs oxygen transport and passage through capillaries.