| Abstract: | In a microspectrophotometric study, photographic emulsions and a computer are used for measuring the hemoglobin content of a large number (about 50,000) of erythroid cells in fetal mice. Histograms of the hemoglobin content in erythroid cells illustrate the kinetics of erythropoiesis in yolk sac derived nucleated cells in the fetal peripheral blood, in fetal liver, and in fetal spleen. After the occasional extrusion of their nucleus, yolk sac derived erythrocytes remain as “macrocytes” in fetal circulation two or three days longer than the nucleated yolk sac derived erythrocytes do. Erythrocytes in fetal liver have a constant hemoglobin content of 28 pg 2 until day 17 of gestation. During further erythropoiesis in liver and then in the spleen, this amount is gradually adapted to the normal hemoglobin content in red blood cells of 16 pg. |
