Fluorescence stereomicroscopic comparison of donor cell distribution at 48 hours postinjection of PKH-67–labeled BM cells. (A) Fetal abdomen after IP injection. (B) Fetal thorax after IP injection. (C) Fetal abdomen after IC injection. (D) Fetal thorax after IC injection. Note the persistence of donor cells in the peritoneal cavity and paucity of engrafted donor cells in the FL after IP injection. In contrast, the FL and intercostal vascular bundles have large numbers of engrafted and circulating PKH⁺ cells following IC injection. H, heart; I-CV, intercostal vessels.