Paterna Biosciences says it has determined the set of instructions needed to turn sperm-making stem cells into "normal, mature" sperm. https://www.wired.com/story/startup-says-it-grew-human-sperm-in-a-lab-and-used-it-to-make-embryos/?utm_brand=wired-science&utm_campaign=aud-dev&utm_medium=social&utm_social-type=owned&utm_source=voante-science
