Microtubules (green) and actin microfilaments (red) were fluoresently stained and imaged with a confocal microscope. Guidance cues control growth cone motility and axon guidance by regulating these two key cytoskeletal elements. Image courtesy of Paul Letourneau, University of MN.
Phase contrast microscopy allows filopodia of less than 500 nm in diameter to be observed in a non-destructive manner. Using this technique, filopodia of greater then 100 microns in length have been observed to stimulate complex changes in growth cone behavior (see Gomez and Letourneau, J Neurosci 14, 5959-5972). Scale bar,10 µm