Powerful microscopes capable of three-dimensional imaging and tracking of the cells in a developing fly embryo are described by two independent studies published online this week in Nature Methods.

Philipp Keller and colleagues and Lars Hufnagel and colleagues independently designed and built similar microscope systems that allow fast three-dimensional imaging of fluorescently labelled cells throughout an embryo-up to several millimeters in size-every 30 seconds or less. By illuminating the specimen with two independent and perpendicular sheets of light and imaging from two sides, they achieved sufficient speed and resolution to track fast-moving individual cells, as well as changes in their shape at a subcellular scale; the technique was able to image an entire fly embryo for up to 20 hours until the embryo hatched and the larvae crawled away.

These microscope systems acquire hundreds of megabytes of image data every second and should allow for the observation of small living organisms in their entirety at a previously inaccessible level of detail.