Real-time in vivo confocal fluorescence microscopy – possibilities and limitations

The confocal scanning microscope is well-known for its ability to perform optical sectioning: a thin plane or section within a thick turbid medium is non-invasively imaged with high resolution and contrast [1]. Since its invention and development, confocal scanning microscopes have been extensively used in biomedicine for imaging human and animal tissues in vivo. Nuclear, cellular and morphologic detail is imaged in living intact tissue without having to physically excise and prepare thin sections or cultures. By comparison, the conventional microscope images nuclear and cellular detail either within prepared thin sections or in culture (in vitro). Histology is a well-known example: it involves the removal of tissue (biopsy), followed by fixing or freezing, cutting into thin sections with a microtome, staining with hematoxylin-and-eosin or other dyes to enhance contrast, and finally, viewing with the microscope.