Two-photon fluorescence microscopy of in-vivo human skin

We present images of human skin obtained by a two-photon fluorescence microscope, which has been optimised for in-vivo imaging. Using autofluorescence as a contrast mechanism various layers of the skin, e.g., stratum corneum, viable epidermis, basal layer and upper dermis could be clearly distinguished. A comparison between two-photon fluorescence images and reflectance images (taken by a confocal video microscope) shows that there is a clear difference in the information content provided by both techniques. In particular, the fluorescence images of the dermis show detail that is absent in the reflectance images.