Definition

Noun: - An abnormally large, immature, and dysfunctional red blood cell (erythroblast) found in the bone marrow and sometimes in the bloodstream. It is characterized by a large, oval shape and delayed nuclear maturation, and is a hallmark of certain anemias caused by deficiencies in vitamin B12 or folic acid.

Usage

The term is used specifically in medical hematology to describe a pathological cell type. It is a countable noun. - The presence of megaloblasts in a bone marrow aspirate is a key diagnostic feature. - A megaloblast has a nucleus that appears less mature than its cytoplasm.

Examples

• The hematologist identified megaloblasts on the blood smear, indicating a probable vitamin B12 deficiency.
• Megaloblast formation occurs when DNA synthesis in red blood cell precursors is impaired.
• Pernicious anemia leads to the production of megaloblasts.

Advanced Usage

• Megaloblastic anemia: The type of anemia characterized by the presence of megaloblasts in the bone marrow. This is a related compound term listed separately here as it is the primary clinical condition associated with the cell.
• Megaloblastic change: Refers to the abnormal cellular morphology affecting not only red blood cell precursors but sometimes other rapidly dividing cells like those in the gastrointestinal tract.

Variants and Related Words

• Megaloblastic (adjective): Describing the morphology or pertaining to megaloblasts.
  • The patient had megaloblastic erythropoiesis.
• Normoblast (noun): A normal, mature red blood cell precursor, often contrasted with a megaloblast.

Synonyms

• Macrocyte precursor (though this is less specific, as a macrocyte is the large mature red cell, and a megaloblast is its immature precursor).
• Giant erythroblast (a descriptive synonym).

Antonyms

• Normoblast: A normally sized and matured red blood cell precursor.

Noun

1. abnormally large red blood cell present in pernicious anemia and folic acid deficiency