FIGURE 5.

Teratoma formation reflects intrinsic metabolic capacity. A, cells were sorted based on mitochondrial activity, and equal numbers (3 × 10⁶) of high, low, or unsorted mES cells were injected into SCID mice. Twenty-five days later, tumors were excised, and the sizes of tumors were measured. B–E, hematoxylin and eosin stains of teratomas formed from ΔΨ_mH cells demonstrating the presence of tissue components originating from all three germ layers including epidermal tissue of ectodermal origin. C and D, skeletal muscle tissue (C) and cartilage (D) of mesodermal origin. E, gastrointestinal tract-like epithelium of endodermal origin. F, stained and sectioned mouse embryo following blastocyst injection of β-galactosidase containing ROSA26 ΔΨ_mH. The ΔΨ_mH-derived cells (blue) appear to contribute widely to all three germ layers.