Video report by ITV News Science Editor Tom Clarke
A medical breakthrough has given hope to boys treated for cancer before they hit puberty.
Until now, chemotherapy and radiotherapy patients have had to run the risk of not being able to have children after their treatment has ended. Many will have their sperm frozen before they start, but for those yet to begin producing it, little can be done.
Now scientists say a baby monkey, Grady, could be the first sign of progress in the field. Testing has meant he has been born from a father previously thought to be infertile.
Dr Rod Mitchell from the University of Edinburgh's Centre for Reproductive Health told ITV News: "We can store testicular tissue from these boys, but until now we haven't really known how we can use that to restore their fertility.
"This study really allows us to look at how we can now start to think about doing that."