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.
A vein is an elastic blood vessel that transports blood from various regions of the body to the heart. Veins can be categorized into four main types: pulmonary, systemic, superficial, and deep veins. Pulmonary veins carry oxygenated blood from the lungs to the left atrium of the heart.