Normoblast

(histology) The smallest of the nucleated precursors of the erythrocyte; slightly larger than a mature adult erythrocyte. Also known as acidophilic erythroblast; arthochromatic erythroblast; eosinophilic erythroblast; karyocyte; metakaryocyte; metanitricyte; metarubricyte.

A nucleated red blood cell found in the peripheral bloodstream in severe pernicious anemia and in some leukemias.

A nucleated red blood cell, the immediate precursor of a normal red blood cell in humans.

A nucleated precursor cell in the erythrocytic series; metarubricyte.
Four developmental stages are recognized: the pronormoblast (prorubricyte); the basophilic normoblast (basophilic rubricyte, erythroblast), in which the cytoplasm is basophilic, the nucleus is large with clumped chromatin, and the nucleoli have disappeared; the polychromatic normoblast (polychromatic erythroblast, rubricyte), in which the nuclear chromatin shows increased clumping and the cytoplasm begins to acquire hemoglobin and takes on an acidophilic tint; and the orthochromatic normoblast (acidophilic normoblast, metarubricyte, orthochromatic erythroblast), the final stage before nuclear loss, in which the nucleus is small and ultimately becomes a blue-black homogeneous structureless mass.

An erythroblast is a type of red blood cell which still retains a cell nucleus. It is the immediate precursor of a normal erythrocyte.

Contents 1 Nomenclature 2 Development 3 Additional images 4 See also 5 External links

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 pernicious anemia and folic acid deficiency (collectively called megaloblastic anemia)

Development

There are four stages in the development of a normoblast.

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

Additional images

Blood cell lineage

Hematopoiesis

See also

• Erythropoiesis
• Hemopoiesis
• Pluripotential hemopoietic stem cell

External links

• Pronormoblasts Presented by the University of Virginia
• Basophilic Normoblasts Presented by the University of Virginia
• Polychromatophilic Normoblasts Presented by the University of Virginia
• Orthochromatic Normoblasts Presented by the University of Virginia
• Normoblast at Dorland's Medical Dictionary
• Erythroblast at Dorland's Medical Dictionary
• normoblast at eMedicine Dictionary
• MeSH Normoblasts
• Histology at BU 01804loa - "Bone Marrow and Hemopoiesis bone marrow smear, erythroblast series with proerythroblast "
• Histology at uiowa.edu

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