Red Blood Corpuscles – Erythrocytes (Commonly referred to as red blood cells or RBC’s)
The most numerous type in the blood –
Average 7 micrometer in diameter
Women average about 4.8 million of these cells per cubic millimeter (mm cubed, which is the same as a microliter of blood.
Men average about 5.4 x 10 to the 6th per microliter
These values can vary over quite a range depending on such factors as altitude and health.
(Peruvians, for example, living at 18,000 feet may have as many as 8.3 x 10 to the 6th RBC’s per microliter.
RBC precursors mature in the bone marrow and are closely attached to a macrophage.
They manufacture hemoglobin until it accounts for some 90% of the dry weight of the cell.
In mammals, the nucleus is squeezed out of the cell and is ingested by the macrophage.
All of the mitochondria, endoplasmic reticulum and Golgi apparatus are destroyed.
No longer needed proteins are expelled from the cell in vesicles called exosomes.
RBC’s have a characteristic biconcave shape. The interior will show up on electron microscope as darkened in the center to show this characteristic. They sort of resemble a donut.
RBC’s are terminally differentiated meaning they can never divide. They live about 120 days and are ingested by phagocytic cells in the liver and spleen. Most of the iron in their hemoglobin is reclaimed and recycled. The other heme portion of the molecule is degraded into bile pigments and excreted by the liver. Some 3 million RBC’s die and are scavenged by the liver every second.
RBC’s are responsible for the transport of oxygen and carbon dioxide.