Some long bones have red bone marrow. Why?
Marrow is a red, soft, semi-solid (gelatinous) substance that is found in the axial skeleton. Marrow is very vascular and surrounded with blood vessels and capillaries. There are two kinds of marrow - red (or hematopoietic) marrow and yellow marrow.
The functions of red bone marrow are:
- It produces red blood cells, white blood cells, and platelets.
- It gets its red color from the hemoglobin that resides in its erythroid cells. Hemoglobin is important in the transport of oxygen.
- Hematopoietic cells mature and migrate to sinusoids (channels through which venous blood passes through organs) and enter the circulation when they are formed.
- Red bone marrow is very vascular. This means that it contains vessels that help to transport fluids such as blood or lymph.