While infertility is a pivotal side effect of oncological treatment, cryopreservation of sperm prior to gonadotoxic treatments is well-established to preserve male fertility. This is not suitable for pre-pubertal boys, however. Cryopreserving immature testicular tissue containing spermatogonia is a promising alternative, yet this treatment remains experimental, so far only established in animal models. Besides, too little is known about the impact of gonadotoxic treatments on spermatogenesis. This research area aims to overcome these issues by utilising primates as powerful model to develop protocols and generate sperm from spermatogonia. Moreover, it will uncover the cellular and molecular impact of radiation-based treatment regimens on testicular tissues.