Lead Paterna Biosciences has successfully grown functional human sperm in a laboratory setting, a breakthrough that could provide new treatment options for men with severe infertility. Context The effort follows almost a century of attempts to produce sperm outside the body. The first viable mouse sperm was produced in 2011, and a French company, Kallistem , claimed success in 2015, though its results were questioned. Key Data The lab process takes a little over two months and involves coaxing sperm‑forming stem cells through meiosis to produce cells with 23 chromosomes. Roughly half of all infertility cases are linked to male factors, and 10‑15% of infertile men have a complete absence of sperm in the ejaculate. Quotes Alexander Pastuszak, CEO and cofounder of Paterna, said the company has identified the strict control mechanisms and instructions needed to guide the stem cells to mature, normal sperm. Larry Lipshultz, a professor of urology at Baylor College of Medicine, described the breakthrough as huge, noting that the growth factors required had previously been unclear but are now identified by Paterna. Outlook If the findings can be replicated and validated, Paterna could offer a new therapeutic pathway for men who currently have no biological options, potentially reshaping the fertility treatment landscape.