DND1 and testicular teratoma: In the current study, we newly generated Dnd1-Δ, a conventional knockout allele of Dnd1 (S1E Fig), and found that the Dnd1-Δ mutant mice showed defects similar to those of Ter mutant mice in spermatogenesis, oogenesis, and incidence of testicular teratomas, with a slight difference in spermiogenesis.