Fluorescence a useful phenomenon

Fluorescence microscopy is a variant of light microscopy, which is based on the principle of fluorescence. The property of certain fluorescent substances (fluorochromes) is exploited to absorb light - in this case an FITC-filter was used - and release it again with a different longer wavelength, in this case green. However, there is also the limitation of this type of microscopy, since only samples in which these substances have been introduced or which they naturally contain (auto-fluorescence) can be observed. The fluorescence microscope finds great application above all in biology, biochemistry and biophysics, where it is used for the observation of cell components. because it can also represent structures that are far below the resolution limit. 

In the fluorescence photographs shown here, taken of a cross section of a Convallaria rhizome, we see certain structures such as the xylem and the endodermis fluorescently light up. The sample has been stained with acridine orange, thus nuclei visible on the enlarged image are most probably specifically reacting with the dye. 

The enlarged image (objective 20X) also clearly shows the depth effect of fluorescence microscopy as fluorescent structures light up at all levels in the specimen, such as the dividing walls with pits between the cells of the bark parenchyma.

With thanks to Dr. Cristina Silva

Prepared slide by Lieder www.lieder.com