Rat Rectum Tissue
The digital image in the above section is a reconstruction of rat rectum tissue stained with Alexa Fluor 488 (wheat germ agglutinin; highlighting lectins), Alexa Fluor 568 (phalloidin; labeling actin filaments), and SYTOX Green (nuclei). The rectum has small shelves in it called transverse folds which keeps stool in place until stretch receptors from the nervous system located in the rectal walls encourage the need to defecate. The stool then enters the lower rectum, moves into the anal canal, and then passes through the anus.