Even when the stomach is empty, the organ is not entirely inactive. A cycle of electromechanical activity, known as the migrating motor complex, occurs in humans about once every one and a half to two hours throughout the gastrointestinal tract. There are four phases of the cycle, which is thought to help clear out any residual material in the digestive system. In the first phase, gastrointestinal smooth muscle is largely quiescent, very few contractions taking place for nearly an hour. The initiation of peristalsis in the stomach marks the second phase of the migrating motor complex. The contractions gradually become more frequent and regular so that after about a half hour they are very rapid and recur at precise intervals, which is characteristic of the third phase. After approximately five to fifteen minutes, peristalsis begins to subside and the final transition phase ensues as the muscle returns to a quiescent state.

The section of rat stomach tissue featured in the digital image above was labeled with Oregon Green 488 conjugated to wheat germ agglutinin, a lectin that selectively binds to sialic acid residues found in both mucoproteins and glycoproteins. The cells were also stained with Alexa Fluor 568 conjugated to phalloidin and the dye Hoechst 33342, which target the cytoskeletal filamentous actin network and nuclear DNA, respectively. 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.