BONE MARROW PATHOLOGY Latest Edition by BARBARA J. BAIN Ebook PDF
BONE MARROW PATHOLOGY Latest Edition by BARBARA J. BAIN Ebook PDF During extra – uterine life haemopoiesis is normally confi ned to the bone marrow, which occupies interstices within bone. An understanding of normal bone structure is necessary for interpreting bone marrow specimens. Bones are composed of cortex and medulla. The cortex is a strong layer of compact bone; the medulla is a honeycomb of cancellous bone, the interstices of which form the medullary cavity and contain the bone marrow.
Bone marrow is either red marrow, containing haemopoietic cells, or yellow marrow, which is largely adipose tissue. The distribution of haemopoietic marrow is dependent on age. In the neonate virtually the entire bone marrow cavity is fully occupied by proliferating haemopoietic cells; haemopoiesis occurs even in the phalanges.
As the child ages, haemopoietic marrow contracts centripetally, being replaced by fatty marrow. By early adult life haemopoietic marrow is largely confi ned to the skull, vertebrae, ribs, clavicles, sternum, pelvis and the proximal half of the humeri and femora; however, there is considerable variation between individuals as to the distribution of haemopoietic marrow  . In response to demand, the volume of the marrow cavity occupied by haemo-
poietic tissue expands.