The End of Males Mouse Made to Reproduce Without Sperm Among mammals, dads are often out of the loop when it comes to producing progeny. After that initial contribution of sperm, they are excluded from pregnancy and are all but superfluous even after birth, when nurturing falls to Mom. Now Japanese scientists have streamlined reproduction even further #151 they have eliminated fathers entirely. Among mammals, dads are often out of the loop when it comes to producing progeny. After that initial contribution of sperm, they are excluded from pregnancy and are all but superfluous even after birth, when nurturing falls to Mom. Now Japanese scientists have streamlined reproduction even further—they have eliminated fathers entirely. endmademalesmousereproducespermthewithout in Bookmarks Toolbar Folder > Sciencewith comesdadsinitialloopmammalsproducingprogenyscience