Differential expression of aquaporin gene transcripts in primitive and adult definitive erythroid cells. Aqp1, Aqp3, Aqp8, and Aqp9 expression in primitive and BM definitive erythroblasts quantitated by Affymetrix intensity (A) and qPCR (B) relative to 18S RN(A) (C). Primitive erythroblasts (E10.5) have higher baseline levels of ROS compared with adult definitive erythroblasts and circulating RBCs. Exogenous H₂O₂ causes ROS to accumulate in primitive but not definitive erythroblasts.