Bone Marrow: Structure, Composition, and Functions


Bone marrow is a soft, spongy tissue found within the cavities of bones. It plays a crucial role in producing blood cells, including red blood cells that transport oxygen, white blood cells that fight infections, and platelets that aid in blood clotting. The marrow also contains stem cells that produce various blood cell types. It’s essential for maintaining overall health and proper circulatory and immune system functioning.

    • Bone Marrow plays a pivotal role in keeping the bones healthy and strong. The soft tissues inside the bone consist of red blood cells, white blood cells, and platelets. These components are important for the living of an individual. The absence of cells and platelets causes fatal situations. In such scenarios, bone marrow donation is a helpful option to avoid worsening conditions.

Structure of Bone Marrow

Vascular Section– The vascular section of bone marrow consists of blood vessels. These blood vessels supply nutrients and stem blood cells to the bones for their proper functioning. The network of thin walls is supported by hematopoietic cells. The section also provides essential nutrients, oxygen, and endocrine factors for healthy living. Improper functioning of the vascular area of the bone can cause issues such as various bone diseases, skeletal ageing, and haematological disorders.

 Non-Vascular Section– The blood cell formation happens in the non-vascular section of the bones. The area consists of fat blood cells, immature blood cells, and white blood cells. Thin branches of reticular connective tissue are also available in this section. Hematopoiesis, or blood cell formation, happens in this section. The procedure involves the production of vital components of blood and plasma. The cells are packed in the middle of other essential elements such as fibroblasts of bone, collagen fibres, and dendritic cells.

Composition of Bone Marrow

Bone marrow consists of a combination of various cell types and components, including –

    • Hematopoietic Cells – These include stem cells that give rise to different blood cell types, such as red blood cells, white blood cells, and platelets.
    • Stromal Cells – These support cells provide a framework for the bone marrow and facilitate the growth and development of blood cells.
    • Adipocytes (Fat Cells) – Adipocytes store energy in the form of fat and contribute to the overall structure of bone marrow.
    • Blood Vessels – Blood vessels are essential for supplying nutrients, oxygen, and hormones to the bone marrow and transporting newly formed blood cells.
    • Extracellular Matrix – This complex network of proteins and fibres provides structural support to the bone marrow and facilitates cell interactions.
    • Immune Cells – Various immune cells, including macrophages and lymphocytes, are present in the bone marrow to support immune functions.

Light micrograph of red bone marrow, showing active hematopoietic tissue (purple, pink) and adipocytes (white spaces). Hematoxylin and eosin stain.

The composition of bone marrow is dynamic and it plays a vital role in hematopoiesis and overall immune system function.

Function of Bone Marrow

    • Bone marrow is responsible for the composition of red blood cells, white blood cells, and platelets. These components, when combined, form blood in the body. These cells are made in millions and are replaced after adequate time. Bone marrow also stores fat. The fat is used as energy when needed by the body. It also produces cartilage and bone. The production of blood cells can be hampered by health conditions such as low oxygen in body tissues, anaemia, or a low count of red blood cells. In such situations, the kidneys release erythropoietin to balance the human body’s internal system, indicating the marrow produces more red blood cells. T and B cells vital for immunity are also transported through the bone marrow. The bone marrow also stimulates white blood cells and platelets to control infection and heavy bleeding.

The largest cell in the red bone marrow is the megakaryocyte(located in the centre). It is responsible for the production of blood platelets 

When to Consult a Doctor

You can also get in touch with the expert Oncology doctors at Narayana Healthcare based in your city to get immediate attention and medical support during injuries, health disorders or any other health concern.


The soft and spongy tissue inside the bone is known as Bone Marrow. These tissues consist of different types of cells responsible for the production of blood. It comprises red blood cells, white blood cells, and platelets for healthy bones. In case of any problem with this spongy tissue, it can be resolved with the help of transplantation.


Q. What is Bone Marrow?
It is a spongy tissue inside the bones that is helpful for the production of important elements of blood, cartilage, and fat.

Q. What are the types of Bone Marrow?
Red and yellow bone marrow are the different types of Bone Marrow that are helpful in various stages of an individual’s life.

Q. What is a bone marrow problem?
Less than required production of red blood cells, white blood cells, and platelets can cause bone marrow problems.

Q. What is a Megakaryocyte?
The largest cell in the red bone marrow is the megakaryocyte. It is responsible for the production of blood platelets

Q. What is the function of bone marrow?
Bone marrow functions primarily in the production of blood cells (hematopoiesis), including red and white blood cells and platelets. It also stores hematopoietic stem cells and can transition between red and yellow marrow, with red marrow being essential for ongoing blood cell production.

Reference Links

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