a, Experimental schema. fESC, ntESC, F-iPSC, and B-iPSC were derived from B6/CBA F1 mice by reprogramming and/or cell culture, characterized for pluripotency by criteria applied to human cells, followed by differentiation analysis for osteogenic or hematopoietic lineages. b, Expression of pluripotency markers NANOG and OCT4 by immunohistochemistry. 4,6-Diamidino-2-phenylindole (DAPI) staining for total cell content. Feeder fibroblasts serve as internal negative controls. c, Teratoma analysis: tumor histology from indicated cell lines shows highly cystic structures consisting of differentiated elements of all three embryonic germ layers. Scale bar, 200μm.