This bone marrow is referred to as red marrow because it contains few adipocytes, or fat cells, among an abundance of hemopoietic cells.

It is difficult to identify the individual precursors of red and white blood cells because they are closely packed and condensed during the fixation of the tissue (*).

The following elements are identified:

• a megakaryocyte (M), which is a very large polyploid cell responsible for the production of blood platelets
• one adipocyte (Ad)
• two blood sinuses (S)

The walls of these vessels are the sites where newly formed erythrocytes and leukocytes pass from the connective tissue into the blood circulation.

Stain: H–­­E
Magnification: ×600