Bone marrow histogenesis: a comparison of fatty and red marrow.

Histogenesis of fatty marrow in extramedullary sites was compared to histogenesis of the red marrow. Both tissues undergo a similar sequence of events leading to reconstruction of hemopoietic marrow nodules. Histogenesis of yellow marrow then continues; such implants become nodules of fatty marrow, whereas implants of red marrow remain hemopoietically active. This observation supports the concept that histogenesis of the bone marrow recapitulates the ontogeny of this organ and indicates an intrinsic difference between the stroma of red and yellow marrow.