Blood volume and red cell concentration in the normal chick embryo

¹ Department of Medicine, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania

A method for the determination of red cell mass, which employs the use of radioisotopically-labeled erythrocytes, in the embryonated hen egg is described and results of total blood volume, plasma volume, red cell mass and red cell concentration determinations during the period from 9 to 18 days of incubation presented. Considerations of the values obtained in terms of absolute quantities and relative to embryonic mass are discussed. It is suggested that expansion of the red cell mass and somatic growth are portions of a common process and may be subject to a complex of similar regulatory factors in the normal chick embryo.