Histologic and hematologic abnormalities in secondary recipients of cultured Fancc^-/-cells. (A) Cellular and histologic evaluation of the hematopoietic organs. The test cell genotype and individual animal numbers are indicated. The top panel shows the bone marrow (BM) histology (original magnification × 200) subsequent to staining with hematoxylin and eosin. Specimens reconstituted with WT cells (b^-2) or freshly isolated Fancc^-/- cells (2^-2) have normal histology, whereas the bone marrow from 2 recipients of Fancc^-/- cells that had been cultured ex vivo prior to transplantation had significant hypoplasia (no. 12^-2) or had a hyperplastic marrow with a homogeneous population of immature blasts (no. 10^-2). The bottom panel shows the splenic histology (original magnification × 100) with insets of the red pulp of spleen (original magnification × 400). The b^-2 and 2^-2 recipients have normal splenic architecture, whereas there is a disruption of the normal red and white pulp with myeloid cell invasion in no. 12^-2 and no. 10^-2, respectively. (B) Representative blast cells from the peripheral blood of mouse no. 10^-2 (original magnification × 1000). (C) The clonogenic growth of a representative small, dysplastic myeloid colony from mouse no. 10^-2 on day 7 of culture is shown in the photomicrograph on the left (original magnification × 200). A photograph of the same colony is shown on day 35 of culture (middle; original magnification × 50). (Right) Cells isolated from that colony revealed a homogeneous population of immature phenotypic cells shown using fluorescence cytometry.