Differences in burst morphology among baboon species

Baboon species differ markedly in the proportions of fetal hemoglobin (HbF) they produce in response to hemopoietic stress. Bone marrow erythroid progenitor cells from untreated and stressed baboons of three species were cultured to determine if differences in number, size, or other characteristics of the colonies and bursts could be correlated with the HbF response. BFU-E from adult Papio cynocephalus produced high proportions of macroscopic, well-hemo-globinized bursts, whereas those from P. anubis and P. papio produced only small, moderately hemoglobinized bursts. The species-specific differences in burst characteristics did not correlate with the in vivo HbF response to stress and they were not altered by variations in culture conditions. However, bone marrow BFU-E from P. anubis and P. cynocephalus fetuses produced similar bursts, suggesting developmental regulation of progenitor cell growth patterns. The proportions of macroscopic bursts were reduced in P. cynocephalus animals undergoing hemopoietic stress, suggesting that culture is a more severe erythropoietic stress for P. anubis and P. papio BFU-E than for P. cynocephalus BFU-E.