This image depicts fibers made from electrospinning, which is coextrusion of two polymer solutions under an electric field.  This would be equivalent to squeezing two-colored toothpaste out of a tube, only that the squeezing or coextrusion results in ‘fiber that is ten times thinner than human hair, and has the same physical features as hair. The polymer solutions are prelabeled with fluorescent dyes that result in bright red and green colors.  The long fiber is then ‘sectioned’ or ‘sliced’ into smaller cylinders, each about 100 micrometers in length, and visualized via confocal laser scanning microscopy. These polymers are biodegradable and could be used in bioengineering applications.