“We have the bone marrow, which produces the blood cells, and when you need them, you need them urgently. But how do they get out?” said Svetlana Komarova, who studies bone biology at McGill University in Montreal.
[…]
[osteoporosis] drugs might increase bone density, but might lessen blood flow between the marrow and the exterior of the bone.
Anatomy of surprise: Scientists discover hidden blood networks that cross through bone