SR-bFGF-cultured hESCs maintain potential to generate derivatives of 3 germ layers. (A-B) In vitro, in addition to generation of hematopoietic cells (part of mesoderm development; Figures 3 and 4), SR-bFGF-cultured hESCs also contained capacity to differentiate into endoderm (HNF3α) and ectoderm (Pax-6) derivatives according to gene expression determined by a quantitative real-time PCR. (C-H) In vivo, 5 of 5 NOD/SCID mice produced teratomas 6 weeks after injection of SR-bFGF-maintained hESCs (passage 26) into the testis capsule. Microscopic examination from a representative teratoma revealed that the tumor was composed of tissues representing all 3 embryonic germ layers, including ectoderm ([C] cystic epithelium, [D] neural rosettes, [E] squamous epithelium), mesoderm ([F] muscle, [G] osteoid island showing bony differentiation), and endoderm ([H] glandular epithelium). Hematoxylin and eosin staining. Bars = 50 μm.