Nucleated red blood cell

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(Redirected from
Normoblast
)
peripheral blood smear
; NRBCs are visible as larger cells with dark centers.

A nucleated red blood cell (NRBC), also known by several other names, is a red blood cell that contains a cell nucleus. Almost all vertebrate organisms have hemoglobin-containing cells in their blood, and with the exception of mammals, all of these red blood cells are nucleated.[1] In mammals, NRBCs occur in normal development as precursors to mature red blood cells in erythropoiesis, the process by which the body produces red blood cells.

NRBCs are normally found in the

myelomas, leukemias, lymphomas), and in chronic hypoxemia.[5]

Nomenclature

Normocyte, Giemsa stain

Several names are used for nucleated RBCs—erythroblast, normoblast, and megaloblast—with one minor variation in word sense.[6][7][8][9] The name normoblast always refers to normal, healthy cells that are the immediate precursors of normal, healthy, mature (anucleate) RBCs. The name megaloblast always refers to abnormally developed precursors. Often the name erythroblast is used

hypernym. In the latter sense
, there are two types of erythroblasts: normoblasts as cells that develop as expected, and megaloblasts as unusually large erythroblasts that are associated with illness.

Healthy development

There are four stages in the normal development of a normoblast.:

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

Pathogenesis

A megaloblast is an unusually large erythroblast that can be associated with

folic acid deficiency, or both (such anemias are collectively called megaloblastic anemias). This kind of anemia leads to macrocytes (abnormally large red cells) and the condition called macrocytosis. The cause of this cellular gigantism is an impairment in DNA replication that 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.

Additional images

  • Blood cell lineage
    Blood cell lineage
  • Hematopoiesis
    Hematopoiesis

See also

References

  1. PMID 16824014
    . Retrieved October 28, 2016.
  2. ISBN 978-1-4963-6713-6
    .
  3. ISBN 978-1-4443-9857-1
    .
  4. ^ Shehata, Amira M.F. (2020-09-30). "Clinical significance of nucleated red blood cell count in pediatric patients with transfusion-dependent beta thalassemia". Menoufia Medical Journal. 33 (3): 949–955.
  5. ^ Blood Smear: Details on RBCs, WBCs
  6. ^ "Erythroblast" at Dorland's Medical Dictionary
  7. ^ "Normoblast" at Dorland's Medical Dictionary
  8. ^ "Megaloblast" at Dorland's Medical Dictionary
  9. ^ Normoblasts at the U.S. National Library of Medicine Medical Subject Headings (MeSH)

External links

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