Nuclei of 3T3 cells grown in culture were stained with with the fluorophore DAPI and imaged utilizing a combination of fluorescence and phase contrast illumination.

Incident light fluorescence microscopy is growing rapidly in importance as an investigational tool in the fields of medical and biological research. All photomicrographs in this gallery were taken with Olympus microscopes employing UIS optics and a PM-30 automatic camera system.

The specimen is a semi-confluent layer of 3T3 cells in tissue culture that were fixed and stained using DAPI. Photomicrographs were recorded utilizing a UPL 40x fluorite objective coupled to a WU dichroic filter combination. The fixed and stained culture was also photographed simultaneously with phase contrast illumination to visualize non-fluorescent cell structures. A 3.3x projection photo eyepiece was used to transfer light from the intermediate image plane to the photographic emulsion.

The Swiss mouse has provided a cell line, commonly known to researchers as the 3T3 strain, which is widely utilized in and most valuable to in-vitro cancer research. A major advantage of this cell line is found in its high sensitivity to contact inhibition. Such sensitivity allows 3T3 cells to successfully serve as host in oncogenic viral studies. Current emphasis has been placed on those oncogenic or cancer-causing viruses that pose a threat to humans. Of special significance to scientists investigating malignancy in cell culture are the changes that normal cells undergo as they approach the limits of the division cycle and become malignant.