Scientists have developed a new microscope that produces high-resolution images of entire organisms in all three dimensions, giving a clearer, more comprehensive view of biological processes as they unfold in living animals.
It works at speeds fast enough to watch cells move as a developing embryo takes shape and to monitor brain activity as it flashes through neuronal circuits.
Researchers at the Howard Hughes Medical Institute's Janelia Research Campus in US built the first light microscope capable of imaging large, non-transparent specimens at sub-second temporal resolution and sub-cellular spatial resolution in all dimensions.
Researchers wanted to understand how a functioning nervous system emerges in an embryo.
The microscope, called the IsoView light sheet microscope improves spatial resolution without sacrificing the performance features of the team's previous microscopes.
"We had decent microscopes for the type of imaging that we do - rapid imaging of cellular dynamics in large, living specimens," Janelia group leader Philipp Keller said.
"The temporal resolution matched the timescales of the processes we're looking at, and we had microscopes that could give us good coverage and allow us to image for a long time without perturbing the system," Keller said.
"But we hadn't really tried to push spatial resolution much in our microscopes to date," he said.
Scientists have found ways around this problem, and several new imaging technologies produce astonishingly detailed three-dimensional images.
But none of those technologies combines high spatial resolution with the other features that Keller needed for his experiments.
Rather than collecting a single image of a sample with a single objective, the new microscope simultaneously collects light and creates images from multiple angles.
Each image still suffers from poor resolution along one axis, but the most useful data from each image can be combined to generate a final image with good resolution in all dimensions.
Keller and a postdoctoral researcher in his lab, Raghav Chhetri, designed a microscope with four objective lenses positioned around the sample at right angles to one another, like traffic lights at an intersection.
Each objective sends light into the sample to illuminate it, and also collects fluorescent light emitted by the sample.
The beams from each of the four objectives are staggered so that they do not interfere or intersect with one another, and a rolling shutter in each camera keeps pace with the beam, so that the camera's detector remains focused on the narrow slit along which it can pick up high-resolution information.
The study was published in the journal Nature Methods.
