Megaloblast

A megaloblast is an unusually large erythroblast that can be associated with Vitamin B₁₂ deficiency (as caused by pernicious anemia or dietary insufficiency) and/or folic acid deficiency (collectively called megaloblastic anemia). It is differentiated from a normoblast, which is a normally-sized erythroblast. This kind of anemia leads to macrocytes (abnormally large red cells). The cause of this cellular gigantism is an impairment in DNA synthesis which delays nuclear maturation and cell division. Because RNA and cytoplasmic elements are synthesized at a constant rate despite the cells' impaired DNA synthesis, the cells show nuclear-cytoplasmic asynchrony.