Key Points. 1  Megaloblasts are large nucleated RBC precursors with noncondensed chromatin. 2  The most common causes of megaloblastic, macrocytic anemia are deficiency or defective utilization of vitamin B12 or folate. 3  Do CBC, RBC indices, reticulocyte count, and peripheral smear.
vein. 1. Any of the blood vessels that carry blood toward the heart. Veins are thin-walled and contain valves that prevent the backflow of blood. All veins except the pulmonary vein (which returns to the heart from the lungs) carry blood having low levels of oxygen. 2.
Vein: A blood vessel that carries blood that is low in oxygen content from the body back to the heart. The deoxygenated form of hemoglobin (deoxy-hemoglobin) in venous blood makes it appear dark. Veins are part of the afferent wing of the circulatory system, which returns blood to the heart. In contrast, an artery is a vessel that carries blood that is high in oxygen away from the heart to the body.