Normoblast

An normoblast is a type of red blood cell which still retains a cell nucleus. It is the immediate precursor of a normal erythrocyte (by opposition to the megaloblasts being an abnormal precursor).

Nomenclature

The term normoblast is sometimes used as a synonym for erythroblast, but at other times it is considered a subcategory. In the latter context, there are two types of erythroblasts:

• "normoblasts" - develop as expected
• "megaloblasts" - unusually large erythroblasts that can be associated with vitamin B12 deficiency (as in pernicious anemia) or folic acid deficiency (collectively called megaloblastic anemia)

Development

There are four stages in the development of a normoblast.

A comprehensive diagram of human hematopoiesis

Illustration	Description	Image
	Pronormoblast
	Basophilic normoblast
	Polychromatic normoblast (also polychromatophilic)
	Orthochromatic normoblast (also orthochromatophilic)

Additional images

• 
  Hematopoiesis

See also

• Erythropoiesis
• Hemopoiesis
• Pluripotential hemopoietic stem cell

External links

• Normoblasts at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
• Histology image: 01804loa – Histology Learning System at Boston University - "Bone Marrow and Hemopoiesis bone marrow smear, erythroblast series with proerythroblast "
• Histology at uiowa.edu