This microscope image provided by researchers Gianluca Amadei and Charlotte Handford in August 2022 shows a synthetic mouse embryo with colors added to show brain and heart formation. According to a study published in the journal Nature on Thursday, Aug. 25, scientists have created “synthetic” mouse embryos from stem cells without a dad’s sperm or a mom’s egg or womb. (Gianluca Amadei, Charlotte Handford via AP)