Appendix artery. Coloured scanning electron micrograph (SEM) of an artery containing red blood cells (erythrocytes, red) from the human appendix. The appendix is a finger-shaped pouch that projects from the colon on the lower right side of the abdomen. The intestinal vasculature is crucial for nutrient absorption, as a barrier against microbes, and for the recruitment and conditioning of immune cells. Arteries carry oxygenated blood to the body's tissues. They typically have a thick wall to cope with the high pressure of the blood being pumped around the body by the beating heart. Magnification: x1600 when printed at 10 centimetres wide.