A series of nucleated cells in the bone marrow that go through various stages of development until they form ERYTHROCYTES. They may appear in the blood in certain diseases.
The biconcave red blood cells that carry oxygen from the lungs to the tissues, and return carbon dioxide (see also RESPIRATION). They have an excess of membrane, some of which may be lost in various disorders, as a result of which they become progressively more spherical and rigid. Erythrocytes, which have no nuclei, are formed during ERYTHROPOEISIS from ERYTHROBLASTS in the BONE MARROW, and each mm3 of blood contains 5 million of them. They are by far the largest constituent among the blood cells and they contain large amounts of the oxygen-carrier HAEMOGLOBIN. They have a life of about 120 days after which they are absorbed by macrophages (see MACROPHAGE), the blood’s scavenging cells. Most components of the erythrocytes, including the red pigment haemoglobin, are re-used, though some of the pigment is broken down to the waste product BILIRUBIN.... erythrocytes
n. any of a series of nucleated cells (see normoblast; proerythroblast) that pass through a succession of stages of maturation to form red blood cells (*erythrocytes). Erythroblasts are normally present in the blood-forming tissue of the bone marrow, but they may appear in the circulation in a variety of diseases (see erythroblastosis). See also erythropoiesis.... erythroblast
n. the presence in the blood of the nucleated precursors of the red blood cells (*erythroblasts). This may occur when there is an increase in the rate of red cell production, as in haemorrhagic or haemolytic *anaemia, or in infiltrations of the bone marrow by tumours, etc.... erythroblastosis
Health Encyclopedia