Allogeneic organ transplantation is a powerful tool for clinical and basic research studies.However, the graft is often rejected by the host organism.Here, we describe a protocol that uses immunodeficient rag1 mutant zebrafish.These Back Cinch zebrafish escaped rejection, which made it possible to successfully transplant fragments of an allogeneic testis and testicular hyperplasia.This protocol can be used to amplify and maintain testicular hyperplasia grafts for several years (Kawasaki et Bronzers al.
, 2016).The amplified hyperplasias are likely to be a good source of somatic and germ cells such as Sertoli cells and spermatogonial stem cells.