When material first reaches the stomach, it has already been through the initial stages of digestion involving mastication and exposure to saliva. The digestive process continues in the stomach, where secreted chemicals and enzymes, as well as the strong contractions of gastric muscles, help to further breakdown foodstuffs. Solids are liquefied in the stomach before they are gradually moved into the small intestine for the next stage of digestion. The stomach is highly expandable and because the transfer of material out of the organ is slow, individuals are able to consume relatively large amounts of food at one time without overwhelming the digestive system. The stomach serves as a storage site until the ingesta is properly broken down and able to be transferred along the gastrointestinal tract.

In order to localize a red fluorescent tag to F-actin in the sample of rat stomach tissue presented in the digital image above, the specimen was labeled with Alexa Fluor 568 conjugated to a phallotoxin (phalloidin). Oregon Green 488 conjugated to the lectin wheat germ agglutinin, which selectively binds to N-acetylglucosamine and N-acetylneuraminic residues, was also applied to the tissue sample, as was the nuclear counterstain 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.