SOME recent newborns conceived through IVF may owe their existence to the fact that they spent their first few days resting on a bed of nails. In vitro fertilisation occurs in a dish. After a few days of culturing, the fertilised egg is implanted into the uterus. But, clearly, a dish is an unnatural environment for a fertilised egg to spend its first days, says Gary Smith at the University of Michigan, Ann Arbor. “The idea is to ask how embryos develop in the body and copy that in the laboratory,” he says. His team has focused on mimicking the pulses of nutrient-rich fluid sent washing over the embryo by muscle contractions within the fallopian tubes. To do this, they created a plastic chip containing a small well to house the embryo. The bottom of the well sits in a network of 30-micrometre-deep channels filled with a nutrient and hormone-rich medium. Underneath these channels is a flexible polymer, and beneath this an array of moveable pins taken from an electronic Braille display (see diagram).
