csontveln

Csontveln, commonly referred to in English as bone marrow, is soft, vascular tissue located inside the medullary cavities of bones. It is the primary site of hematopoiesis, the production of blood cells, and also acts as a reservoir of fat and as part of the bone’s immune-supporting microenvironment.

There are two main types: red marrow, which is hematopoietic, and yellow marrow, which contains more fat cells. In children, most bones harbor red marrow; in adults, red marrow remains mainly in the pelvis, skull, ribs, sternum, vertebrae, and the proximal ends of the femur and humerus, while the interiors of long bones increasingly contain yellow marrow.

Hematopoiesis begins with hematopoietic stem cells that differentiate into erythroid, myeloid, and lymphoid lineages, producing red blood cells, white blood cells, and platelets. The marrow’s stromal and endothelial cells form a niche that supports the growth, maturation, and release of blood cells into the bloodstream.

Developmentally, hematopoiesis shifts from the fetal liver and spleen to bone marrow after birth. Over time, red marrow is progressively replaced by yellow marrow in many bones, though red marrow persists in sites crucial for ongoing blood cell production.

Clinical relevance is significant: bone marrow can be sampled by aspiration or biopsy to diagnose hematologic disorders. Bone marrow transplantation treats conditions such as leukemia and certain lymphomas or metabolic diseases. Diseases affecting the marrow include aplastic anemia, myelodysplastic syndromes, and leukemias, among others.

Research areas include marrow adiposity, the hematopoietic niche, and aging-related changes in marrow function.