TeratomaTesticular NeoplasmsSacrococcygeal RegionDermoid CystMediastinal NeoplasmsNeoplasms, Germ Cell and EmbryonalDysgerminomaOvarian NeoplasmsRetroperitoneal NeoplasmsEmbryonic Stem CellsGerminomaAbnormalities, Severe TeratoidIsochromosomesMesonephromaStruma OvariiCoccyxPluripotent Stem CellsOvarian CystsInduced Pluripotent Stem CellsRetroperitoneal SpaceCell Differentiationalpha-FetoproteinsEndodermal Sinus TumorNeoplasms, Multiple PrimaryOctamer Transcription Factor-3SOXB1 Transcription FactorsChoriocarcinomaParaneoplastic Syndromes, Nervous SystemSpinal NeoplasmsTomography, X-Ray ComputedTwins, ConjoinedSeminomaCarcinoma, Embryonal