Technically it is now possible for boys whose testicles are damaged before puberty to become a father.

Sperms were developed from undeveloped testicles tissues of a mouse. With the help of these sperms 12 healthy mice were born.

http://www.independent.co.uk/news/scien ... 51008.html#

Original article here:

http://www.nature.com/nature/journal/v4 ... 09850.html