Phenotypic analysis of hematopoiesis in Ts1Cje postnatal mice detects peripheral blood abnormalities. (A) Ts1Cje mice at 1, 3, 6, and 10 months display abnormalities in the red cell lineage. (For each genotype at each age, n > 7, except 10 months, when n = 4). Platelet counts, however, are normal at all 4 ages and P < .001 for red blood cell count at 3 and 6 months, and for mean corpuscular volume at all 4 ages. (B) Sternum and spleen sections from 2-month-old Ts1Cje and disomic control mice. Slightly increased numbers of nucleated erythrocytes (arrow) were observed in the Ts1Cje spleen, and reduced numbers were present in the BM. BM images: original magnification ×200; spleen, original magnification ×100 and ×200. Sections are representative of 3 mice per genotype.