A large, nucleated, embryonic type of cell that is a precursor of erythrocytes in an abnormal erythropoietic process observed in pernicious anemia; a megaloblasts four stages of development are as follows: 1) promegaloblast, 2) basophilic m., 3) polychromatic m., 4) orthochromatic m.. SEE ALSO: erythroblast. [megalo- + G. blastos, + germ, sprout]
* * *
meg·a·lo·blast 'meg-ə-lō-.blast n a large erythroblast that appears in the blood esp. in pernicious anemia
meg·a·lo·blas·tic .meg-ə-lō-'blas-tik adj
* * *
n.
an abnormal form of any of the cells that are precursors of red blood cells (see erythroblast). Megaloblasts are unusually large and their nuclei fail to mature in the normal way; they are seen in the bone marrow in certain anaemias (megaloblastic anaemias) due to deficiency of vitamin B12 or folic acid.
• megaloblastic adj.
* * *
meg·a·lo·blast (megґə-lo-blast″) [megalo- + -blast] a large, nucleated, immature progenitor of an abnormal red blood cell series seen in some types of anemia; it follows the promegaloblast in development and retains some of its features. Megaloblasts correspond to normoblasts (see erythroblast) of the normal red cell maturation series and are correspondingly classified as basophilic, polychromatophilic, and orthochromatic. See also megaloblastic anemia, under anemia.Medical dictionary. 2011.