Evaluation of Mammalian Bone Marrow

The production of cells found in peripheral blood, or hematopoiesis, occurs primarily in the bone marrow, which is referred to as medullary hematopoiesis. Blood cell production occurring outside the bone marrow, most notably in the spleen, and lymph nodes, is called extramedullary hematopoiesis. Erythropoiesis, the production of erythrocytes, in small exotic mammals appears to be the same process as that in domestic mammals. Subpopulations of the granulocytic stem cells will then differentiate into the neutrophils, eosinophils, and basophils found in the peripheral blood. Granulocyte production in the normal bone marrow is predominated by the neutrophil lineage. Cytoplasmic fragments from megakaryocytes become the platelets seen in peripheral blood. Cells of the monocyte series comprise the monoblast, promonocyte, and mature monocyte. Hypoplasia of the bone marrow can result from infectious disease, estrogen toxicity, myelofibrosis, or immune-mediated disorders. The bone marrow evaluation of rodents is the same as that of domestic mammals, such as the dog and cat.