Sources of autofluorescence in cells and tissues:

The diagram at left outlines the biological molecules that we have found to be autofluorescent in vivo using MPE and shows their approximate emissions. Although these components could be readily excited using single photon excitation, MPE has several advantages over conventional confocal microscopy: (1) only one color of light is needed to access a wide spectrum of different components, which can then be separated by their emission spectra (i.e. RBL-2H3 cells); (2) deep UV optics are not needed for excitation of species such as the indoleamines and certain UV absorbing structural proteins; and (3) in thick specimens, MPE penetration and MPE emission collection is more efficient and less sensitive to optical aberrations.

Extracellular structural proteins:

The next three images are pseudocolor merges of two emission channels (see filter diagram at above) taken with 710 nm excitation in fresh tissue biopsies. Shown here are: A, an alveoli in lung (dog); B, an arteriole in a lymph node; and C, a sinus inside a lymph node. In general, elastins emit at redder wavelengths then the collagens (green pseudocolor).

   

Next