Jerusalem Post/Health & Wellness/Health and Wellness Around the WorldFor the first time, testicular tissue frozen before puberty was replanted and led to sperm production.Follow us on GoogleTesticular tissue successfully produced sperm after 20 years(photo credit: SHUTTERSTOCK)ByWALLA! HEALTHMAY 28, 2026 17:00An exciting scientific breakthrough comes from the field of fertility: For the first time, researchers have successfully replanted testicular tissue in an adult man that had been frozen when he was a child, discovering that it resumed producing sperm cells. This is a breakthrough that could change the future of children undergoing harsh medical treatments that might impair their fertility.The study was conducted at the Vrije Universiteit Brussel, where researchers have been working for years on developing methods for preserving and restoring fertility in men. In this current case, the tissue was removed from the patient when he was 10 years old and frozen before he underwent prolonged treatments, including chemotherapy and a bone marrow transplant, due to a chronic illness.Now, at age 27, the tissue was thawed and replanted in his body. Following medical monitoring, it was found that the tissue was accepted, maintained a normal structure, and even began the process of sperm generation, a process known as spermatogenesis.This is an especially significant achievement because until today there was no proven option for fertility preservation in boys before puberty. While it is possible to freeze sperm in adult men or eggs and ovarian tissue in women, young children do not yet produce reproductive cells, and therefore the options for them were highly limited.The researchers emphasize that this is a first proof of concept in humans: It is still unclear whether the sperm cells produced will be able to fertilize an egg and lead to pregnancy, but they appear biologically normal.The replanted tissue was not connected directly to the sperm delivery system, and therefore the cells were not found in the semen itself, but were rather extracted in a separate examination one year after the transplantation.Despite this being an experimental stage only, the findings arouse great hope: More and more children who underwent harsh treatments, like chemotherapy or radiation, may face impaired fertility in the future. Preserving testicular tissue before treatment may become a routine solution in the future.Experts estimate that in the coming years, many patients whose tissues were preserved in their childhood will arrive, hoping to realize the possibility of having biological children.However, the researchers emphasize that further studies are required to establish the method, test its efficacy, and make it safe and accessible to the general public.Follow us on Google