Sperm made from human bone marrow

From Science:

Normally these stem cells from the bone marrow would develop into the different cell types in muscle tissue. But the researchers induced a small number of them to develop into what appeared to be spermatagonial cells - cells found in the testes which would normally develop into mature sperm cells. This is the first time human spermatagonial cells have been made artificially in this way. And lead researcher Professor Karim Nayernia, now at the North-east England Stem Cell Institute based at the Centre for Life in Newcastle upon Tyne, said he hopes his investigations will mean he might one day be able to treat young men rendered infertile by chemotherapy.

He said: "We're very excited about this discovery. "Our next goal is to see if we can get the spermatagonial cells to progress to mature sperm in the laboratory and this should take around three to five years of experiments." He acknowledged that the law may be a stumbling block.

More here.