Erythropoiesis during Amphibian Metamorphosis. I. Site of Maturation of Erythrocytes in Rana catesbeiana

The site of maturation of the erythroid cells in premetamorphic, metamorphic, and adult stages of R. catesbeiana has been investigated by comparing the percentages of immature, hemoglobin-containing erythroid cells in circulating blood, liver, spleen, kidney, and bone marrow. In both premetamorphic and thyroxine-treated tadpoles, the liver was found to be the main site of maturation of the red cells. The corresponding site in the frog is the bone marrow.