The stem cells formed a sac that then folded in half
a couple days later (see image above, courtesy of Nature),
forming the optic cup.

What’s the News: Give a blob of cells the right environment—lots of nutrients, special chemical signals, and a comfy gel cushion—and they just might grow you a body part. In a feat of bioengineering, scientists at the RIKEN Center for Developmental Biology in Japan have grown a retina from mouse embryonic stem cells. Remarkably, much of the development happened spontaneously, indicating that even undifferentiated cells have a blueprint in mind. Researchers hope the work will someday yield transplantable retinas for people with diseases like retinitis pigmentosa.

“When I received the manuscript, I was stunned, I really was,” commented human molecular geneticist Robin Ali (via Nature News). “I never though I’d see the day where you have recapitulation of development in a dish.”

How the Heck: Supported by a gel that mimics cells’ natural environment, the stem cells were immersed in a bath of chemicals that directed their growth into retinal cells. Just as in normal embryonic development, over the course of about a week the cells organized themselves into ...