Synthetic Embryos Developed

Scientists have created human embryo-like structures grown solely from stem cells capable of developing outside of the womb for more than a week, according to research published yesterday. The breakthrough is expected to enable the study of the earliest stages of embryonic growth.

Known as embryogenesis, the first eight weeks of gestation involve a number of complex interacting processes (see 101)—issues during this early period may lead to critical conditions or diseases later in development. Despite its importance, studying the earliest stages has been challenging due to technical limitations and ethical concerns.

Researchers reported the new structures displayed functions and cell types very similar to naturally fertilized embryos—commercial pregnancy tests used on the samples returned positive results. The study was capped at the gestational equivalent of 14 days, the point at which naturally fertilized embryos begin to develop the precursor to organs.