In which part of a long bone is red bone marrow found and new erythrocytes produced?

Red bone marrow is primarily located in the medullary cavity of long bones. This area is crucial for hematopoiesis, the process through which new blood cells, including erythrocytes (red blood cells), are produced. In adults, red bone marrow can also be found in certain regions of flat bones and in the trabecular (spongy) parts of long bones, but its presence in the medullary cavity is significant due to its role in producing blood cells to maintain proper blood counts and overall health.

The diaphysis is mainly composed of compact bone and contains the medullary cavity but does not produce erythrocytes itself. The epiphysis, which is the end part of a long bone, is more involved in joint articulation and contains some red marrow, but it is not the primary site for erythrocyte production. Meanwhile, articular cartilage, which covers the ends of bones at joints, is not involved in blood cell production at all. Thus, the medullary cavity is recognized as the key area for red bone marrow and erythrocyte generation.