Early detection of colorectal cancers is very important because those discovered at an early stage have a much better chance of being cured. Detection is often delayed, however, because many cases do not produce palpable symptoms. If symptoms do develop, they often include blood in the stool, rectal bleeding, diarrhea, constipation, gas pains, bloating, stomach cramps, unexplained weight loss, fatigue, and vomiting. Since these symptoms can be indicative of a wide variety of other problems or disorders, medical testing is necessary to provide a definitive diagnosis.

A rat rectum tissue section (shown above) was stained with Texas Red conjugated to wheat germ agglutinin, a plant-derived lectin that targets the Golgi apparatus, as well as Alexa Fluor 488 conjugated to phalloidin for cytoskeletal actin. Cell nuclei were labeled with Hoechst 33342. Images were recorded in grayscale with a 12-bit digital camera coupled to a Nikon Eclipse 80i microscope equipped with bandpass emission fluorescence filter optical blocks. During the processing stage, individual image channels were pseudocolored with RGB values corresponding to each of the fluorophore emission spectral profiles.