Bone marrow is a semi-solid tissue found within the spongy or cancellous portions of bones. In birds and mammals, bone marrow is the primary site of new blood cell production.
https://en.wikipedia.org/wiki/Bone_marrow
Bone marrow is a semi-solid tissue found within the spongy or cancellous portions of bones. In birds and mammals, bone marrow is the primary site of new blood cell production.
https://en.wikipedia.org/wiki/Bone_marrow