The ontogenesis of hemoglobins in Macaca nemestrina.

Macaca nemestrina have two fetal hemoglobins which differ in the structures of their .y chains. Thus animals of this species, like man, appear to possess duplicate y-chain loci. In this study, the ontogenesis of hemoglobins in M. nemestrina was followed in animals ranging in age from the 60th day of gestation to adulthood. Fetuses in the 60th day of gestation had the two fetal hemoglobins and a small amount of presumed embryonic hemoglobin. Fetuses between 60 and 132 days’ gestation had only the two fetal hemoglobins. Adult hemoglobin appeared in the last month of gestation. The subsequent transition from ‘yto /3-chain formation was nearly completed by the end of the second postnatal month. The two fetal hemoglobins were present in 2:1 proportions throughout fetal development and the period spanning the shift from .Yto /3-chain formation. The pattern of hemoglobin development in these macaques differs from that in man in the following ways: (1) The relative activities of the two y-chain loci do not change. (2) a-Chain synthesis is adequate throughout gestation (no y-chain tetramers were found). (3) The transition from yto /3chain synthesis is more abrupt.