• Examine the marrow cavity of the long bones decalcified and sectioned in these two slides: sample 1 and sample 2.
• Identify adipocytes and estimate whether this is “red marrow” or “yellow marrow.”
• Note the overall organization of marrow and identity sinusoids bounded by endothelial cells and containing circulating blood.
• Identify hemopoietic cords in the stroma.
• Cells in mitosis should be visible here.
• Identify the stromal fibroblasts and large macrophages.

Next, examine this bone marrow needle biopsy of normal bone marrow. The specimen retains much of the normal organization of the marrow in bone. Identify the cellular constituents

• Adipocytes,
• Blood sinusoids,
• Hemopoietic cords,
• Megakaryocytes and
• Stromal cells

Clinical note: Because hematopoietic populations undergo continuous rapid cell renewal, they are easily damaged by chemo-therapeutic drugs and ionizing radiation. Want to see how a bone marrow sample is obtained?

Bone marrow smear.