Microscopes magnify very small objects that are difficult to see with the naked eye using lenses and a source of illumination. Confocal microscopes use a combination of lenses and mirrors illuminated by lasers to view small samples that are labeled with fluorescent molecules (called fluorescence confocal microscopy). Often, thicker samples like organ tissue have to be physically sliced in order to see the cells inside. Organs from an insect, like the brain of a fruit fly, are extremely small (approximately 0.2 millimeters thick) and don’t need to be sliced. A confocal laser scanning microscope images the fruit fly brain as optical rather than physical slices. Optical slices are generated by lasers which are targeted to different layers of the brain, illuminating only what is in that layer.
The lasers sequentially scan sections of the brain (creating a series of optical slices) and excite fluorescent molecules attached to particular structures within the brain. Different structures can be labeled with different colored fluorescent molecules. These molecules emit fluorescence at different wavelengths of light (red, green or blue), which are filtered by a pinhole, collected by a detector, and transmitted to a computer. This series of slices can be assembled into a 3D image of the sample and viewed like a movie where each frame represents an optical slice of tissue.
Data from the lab of Dr. Volker Hartenstein, Department of Molecular, Cell, and Developmental Biology, UCLA
For more information on how a fluorescent confocal microscope works, check out:
Jennifer Lovick (@drjkyl)
Senior Editor, Science in Entertainment, Signal to Noise
PhD, Molecular, Cell, and Developmental Biology
PhD Candidate, Molecular, Cell, and Developmental Biology