Three-dimensional autofluorescence spectroscopy of rat skeletal muscle tissue under two-photon excitation.

We report on three-dimensional autofluorescence spectroscopy obtained from rat skeletal muscle tissue under two-photon excitation by an ultrashort pulsed-laser beam. It is demonstrated that two types of fluorophores within the skeletal muscle tissue can be simultaneously excited with the laser beam at a wavelength of 800 nm. The two fluorophores exhibited unique fluorescence spectral peaks at wavelengths of 450 and 550 nm. These spectroscopic signals can be used to form a three-dimensional image, giving the information about the biochemical makeup of the skeletal muscle tissue.