Researchers Grow Sperm Stem Cells In Laboratory Cultures

A team of researchers working with cells from mice has overcome a technical barrier and succeeded in growing sperm progenitor cells in laboratory culture. The researchers transplanted the cells into infertile mice, which were then able to produce sperm and father offspring that were genetically related to the donor mice.
http://www.sciencedaily.com/releases/2004/11/041103230553.htm