Disease relevance of Megaloblasts

• Detection of methionine in pernicious anemia megaloblasts and other types of erythroid precursors [1].

High impact information on Megaloblasts

• Early megaloblasts, especially in severe megaloblastosis, showed a marked decrease in C3b receptor activity, again in proportion to the level of maturation arrest [2].
• In conclusion, the expression of HLA class I and II Ag is not detected on primitive megaloblasts, but is gradually induced on definitive FL progenitors and precursors, possibly via production of specific cytokines in the FL microenvironment, i.e., IFN-gamma and TNF-alpha for class I Ag and IL-1 beta for class II Ag [3].
• Prior to therapy ineffective erythropoiesis was grossly increased but this was reversed within 24 h of giving vitamin B12, suggesting that most of the existing megaloblasts are enabled to mature into circulating red cells [4].
• The biopsies were embedded in wax and in epoxy resin, and after staining for light and electron microscopy, they were semiquantitatively examined for several parameters: cellularity, myeloid:erythroid (M:E) ratio, megakaryocytes, fatty tissue, megaloblasts, and marrow iron [5].
• Biosynthesis of predominantly arginine-rich histones in megaloblastic bone marrows was markedly reduced as compared to normoblastic bone marrows, which was consistently associated with elongation and despiralization of chromosomes and finely stippled nuclear chromatin in megaloblasts [6].

Anatomical context of Megaloblasts

• Bone marrow aspiration revealed abnormalities in erythropoiesis (megaloblasts, 4%; sideroblasts, 84%; ring-formed, 39%, and PAS-positive, 5%) [7].
• In children with malaria, normal or increased levels of red cell folate were found in 75 patients at presentation and in 15 patients 1-2 weeks after treatment with anti-malarials alone, despite the presence of giant metamyelocytes and megaloblasts in the bone marrow in some cases [8].

Associations of Megaloblasts with chemical compounds

• Despite the evidence for impaired thymidylate synthesis, the duration of the S phase of megaloblasts appears to be normal or only modestly increased [9].

References