Handling individual mammalian embryos using microfluidics

We have designed, built, and tested microfluidic systems capable of transporting individual, preimplantation mouse embryos (100-/spl mu/m m to 150-/spl mu/m diameter) through a network of channels. Typical channels are 160 to 200 /spl mu/m deep, 250 to 400 /spl mu/m wide at the top, and narrower at the bottom (0 to 250 /spl mu/m wide) due to the fabrication process. In these channels, a pressure gradient of 1 Pa/mm causes the medium to flow on the order of 10/sup -10/ m/sup 3//s (100 nl/s), with an average speed of 1 to 2 mm/s. Under these flow conditions the embryos roll along the bottoms of the channels, traveling at 1/2 the speed of the fluid. By manipulating the pressure at the wells connected to the ends of the channels, the embryos can be transported to (and retained at) specific locations including culture compartments and retrieval wells.