Bone Marrow and Blood Formation

     Bones are not solid but instead are made up of two distinct regions. The outter weight bearing area is hard compact and calcium based. It surrounds a lattice work of fibrous bone known as cancellous tissue. The inner region, or marrow,which is one of the largest organs in the body, is located inside the bones.It fills the shafts of the long bones and continues down to the boney canals that hold the blood vessels.