This was discovered in 1969 by Nishizuka and Sakakura who showed that in mice, thymectomy 3 days after birth led to the depletion of Foxp3+ Tregs and development of autoimmune oophoritis.10 In contrast, mice who had thymectomy at day 7 remained healthy as the tTregs had already migrated to the periphery by this point.11 Over a decade later, Sakaguchi et al demonstrated that day-3 thymectomy autoimmune oophoritis could be prevented with CD4+ T-cell inoculation from healthy syngeneic donors. Here, CD4 is linked to autoimmune oophoritis.