Teratoma formation assays. (A) Teratoma formation control from an iPSC line. (B) Teratoma formation assays in WA01 cells under NCM conditions (passage number 13, designated as mcp13). Cells were injected into the kidney capsule and testis sites of three mice. Tumor samples at day 40 after injection were fixed and stained with hematoxylin and eosin (H&E), and photographed for histological analyses. Variously differentiated tissues that represent the three germ layers are shown and indicated by arrowheads. Abbreviations: BV, blood vessels; CT, connective tissues; EC, ectoderm; EN, endoderm; ME, mesoderm.