The ontogeny of erythropoiesis in the mouse detected by the erythroid colony-forming technique. II. Transition in erythropoietin sensitivity during development.

The erythroid colon-forming technique has been used to study the erythropoietin (Ep) sensitivity of CFU-E during ontogenesis. Evidence is provided which indicates that an age-related decreasing Ep sensitivity of CFU-E occurs as the animal develops. In addition, an intermediate Ep-sensitive CFU-E population represented by the 2-day-old neonate is present during the transition from foetus to adult. The Ep sensitivity of the foetal, neonatal and adult CFU-E populations is shown to be an intrinsic property of these populations.