Evaluation of Blood and Bone Marrow, Rat

Abstract

The examination of blood and bone marrow is a relatively universal feature of dose-response studies which utilize the laboratory rat. Changes in the hemopoietic system may arise as primary effects on the blood cells themselves or secondarily due to irritation in the tissues exposed by the route of administration of the test substance. Thus, myeloid hyperplasia may result without an apparent target in response to lithium or with a direct target in response to injury in the gut, lung, or skin. Similarly, erythropoiesis may be directly depressed by toxic exposure or increased due to hypoxia, hemolysis, or blood loss. While the changes in the blood may be readily apparent, the mechanisms by which these alterations occurred may be less clear. In general, the marrow and blood need to be considered together in a precursor-product relationship and changes interpreted with knowledge of the type and extent of lesions occurring elsewhere in the body.