Bone marrow is a vascularized substance situated in the bone cavities. It exists in two types: the red and the yellow bone marrow. Despite their strong associations, there is a myriad of differences between the two.
Summary Table
| Red Bone Marrow | Yellow Bone Marrow |
| Also called medulla osium rubra | Also called medulla osium flava |
| Mainly located in the shoulder blades, skull, and long bones and flat bones | Mainly located in the hollow cavity of long bones |
| Present from fetal maturity to adulthood | Slowly acts as a replacement of the red bone marrow from the fifth post-natal year onward |
| Level slowly decreases with age | Level slowly increases with age |
| Rich in hematopoietic cells | Rich in adipocytes |
| Color: red | Color: Yellowish |
| Responsible in the production of platelets, red blood cells, and white blood cells | Responsible for the storage of fats and the release of blood cells during emergency situations |
| Comprised of active cells that continuously divide and multiply to develop and release blood cells | Comprised of inactive cells that release blood cells in emergency situations |
Definitions
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Red bone marrow is a red-colored tissue that contains reticular networks critical in the development and production of platelets, red blood cells, and white blood cells. It is situated in long and flat bones, including the skull, vertebrae, ribs, and hip bones.
Getty Images/Science Photo Library/JUAN GAERTNER/SCIENCE PHOTO LIBRARY
Meanwhile, yellow bone marrow, which is found in the hollow parts of compact bones, is a yellow-colored tissue responsible for storing fats and producing blood cells during life-threatening situations.
Red vs Yellow Bone Marrow
While both are integral parts of the body, there is a huge difference between red and yellow bone marrow.
Terminology
In the medical field, red bone marrow is popularly known as medulla osium rubra, while yellow bone marrow is called medulla osium flava.
Location
Red bone marrow is mainly situated in the shoulder blades, skull, and long bones. Once the body matures, red bone marrow becomes predominant in flat bones, including the sternum and pelvic girdle. Meanwhile, yellow bone marrow is mainly located in the hollow cavity of long bones, which make up the axial skeleton.
Development
The yellow and red bone marrow have an inversely proportional relationship as the number of red bone marrow present in the body decreases as the level of yellow bone marrow increases. From fetal development to childbirth, only red bone marrow is present in the bone cavities. After the fifth post-natal year, red bone marrow found in the long bones of the body is slowly replaced by yellow bone marrow.
Components
Unlike yellow bone marrow, red bone marrow is abundant in hematopoietic cells, which release white blood cells, platelets, and erythrocytes. However, red bone marrow does not store as many adipocytes as the yellow bone marrow. Adipocytes are cells that mainly function as fat storage and are mostly found in the connective tissue.
Color
Red bone marrow is rich in hemoglobin, which is responsible for its red color. Meanwhile, yellow bone marrow is distinct for its yellowish color, which is caused by the carotenoid present in the tissue’s fat droplets.
Function
Red bone marrow plays a significant role in the production of platelets, white blood cells, and red blood cells. The main function of yellow bone marrow, on the other hand, is the storage of fats and the release of blood cells in emergency situations. In case of life-threatening situations that lead to rapid blood loss, yellow bone marrow converts into red bone marrow to produce blood cells and sustain life. Similarly, the fats stored in the yellow bone marrow acts as the body’s last source of energy in case of extreme hunger. The yellow bone marrow also converts into bones and cartilage when needed.
Cell Types
Red bone marrow is made up of active cells that continuously divide and multiply to produce blood cells, while yellow bone marrow is comprised of inactive cells that only produce blood cells during emergency situations.