Morphologic and cytochemical features of fetal liver–derived cells in culture with IL-5 (5 ng/mL).

Cytospin preparations of fetal liver–derived cells from wild-type (A,C) and Syk^−/− (B,D) mice, maintained for 2 (A,B) and 12 (C,D) days after EPO staining and counterstaining. EPO is present in both mature and immature forms of eosinophils even when eosinophilic granules are not prominent. EPO⁺ cells at day 2 display the morphologic characteristics of precursors (large cell size and large unsegmented nucleus with loose chromatin), whereas EPO⁺cells at day 12 display characteristics of mature eosinophils (smaller cell size, donut-shaped nucleus with compact chromatin). Original magnification × 100.