Kinetics of recovery after acute hemolysis by phenylhydrazine administration. A single dose of phenylhydrazine (60 mg/kg body weight) was administered intraperitoneally on days 0 and 1 (arrows). Wild-type and mutant mice were killed at 1, 2, 4, or 7 days after the final administration (arrowheads). Recovery was monitored by measurement of hematocrit (A) and reticulocytes (B). CFU-Es (mean ± SD) of 25 000 BM nucleated cells (C) and 100 000 spleen nucleated cells (D) from wild-type and mutant mice on days 2, 3, and 5 (n = 3 to 5 for each genotype) were assessed by semisolid methylcellulose cultures.