The barrier between the rat stomach and esophagus is very strong. This fact, along with the inability of the rodent’s diaphragm muscles to contract independently and the lack of certain nervous system connections, renders the rat nonemetic. Animals that are nonemetic are never able to involuntarily expel the contents of the stomach, an act commonly known as vomiting. One of the main purposes of vomiting is to protect the body by quickly eliminating any ingested toxins. Since they cannot vomit, rats must protect themselves from toxic substances via other means. One of the methods they employ is to taste new items they encounter in very small quantities so that if they are toxic they are likely to only become sick rather than to be more seriously harmed. If illness does develop, they learn to avoid that food in the future. Another way rats handle toxins is to consume clay or other nonfood substances if they become nauseous. Such materials can combine with toxins in the stomach in order to mitigate their effects.

The cytoskeletal F-actin network was targeted in a sample of the pylorus region of a rat stomach (presented above) with phalloidin conjugated to Alexa Fluor 488. Phalloidin is a member of the phallotoxin group of bicyclic peptides isolated from the deadly Amanita phalloides mushroom. The tissue section was also labeled for nuclear DNA with Hoechst 33342 and the Golgi complex with Texas Red conjugated to wheat germ agglutinin (WGA). 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.