ABSTRACT
An exception to the exclusive localization of an adult bird’s erythropoiesis to the bone marrow has been identified in the migratory Sturnus roseus the rosy or rose-colored starling. During the months of October to April, histologic sections of the liver reveal nodules composed primarily of lymphocytes and monocytes. At the peak of the development of a nodule the generation of erythrocytes is also noted. Mitotic figures are identifiable. Approximately 50 erythroblasts are identifiable in nodules whose plane of section traverses the entire nodule. Other cellular components of the nodule are reticuloendothelial cells and phagocytes that have accumulated lipid droplets. In regard to the quantitative representation of the hemopoietic nodules in the rosy starling’s liver, they have diameters of 120µm in width and depth, are always located near or attached to a small blood vessel, and are present in each 10 square millimeters of sectioned tissue.
