Confocal microscopy showing the colocalisation of VASA and GFP in recipient testes transplanted with germ cells RA-derived from iPS cells (a–d). VASA expression in normal mouse testes served as a positive control (e–h). DAPI, 4′,6′-diamidino-2-phenylindole; GFP, green fluorescent protein; RA, retinoic acid; VASA, DEAD box protein 4.