A startup out of Utah, Paterna Biosciences, says it has successfully grown functional human sperm in a lab and used the sperm to make visibly healthy-looking embryos. The technique could eventually help men with certain types of infertility have biological children.

The findings have not yet been published in a peer-reviewed journal or independently verified. WIRED is the first to report the advance.

The process involves isolating sperm-making stem cells from testicular tissue and coaxing the cells into becoming fully-fledged sperm in a dish. Scientists have been attempting to produce sperm outside the body, known as in vitro spermatogenesis, for almost a century.…