Blood volume, platelet counts, and platelet mass during neonatal development. (A) Body weights were obtained in healthy mice during the first 2 weeks of life at the time points indicated. Each symbol represents an individual mouse. (B) After transfusion with a known number of biotinylated RBCs, the blood volume was calculated in mice of different ages and was correlated to each animal’s body weight. Each symbol represents an individual mouse. (C) Platelet counts were measured in the first 2 weeks of life and in adult mice at the ages indicated. Each symbol represents an individual animal; horizontal lines indicate the mean for each group. (D) Total platelet number was calculated for each animal by multiplying the platelet count × blood volume (in µL). The bars represent the mean ± SD of at least 11 individual mice at each postnatal age indicated. (E) MPVs were measured in mice at the postnatal ages indicated. Each data point represents the mean ± SD of 7 to 8 individual mice. (F) Total platelet mass was calculated in mice at the ages indicated by multiplying the platelet count × the blood volume × the MPV. Bars represent the mean ± SD of at least 11 individual mice at each time point.