This section shows the simple squamous epithelium (mesothelium)
that forms the outer covering of the ileum, part of the small intestine. Note
the flattened, darkly stained nuclei (arrow)
that bulge outward into the peritoneal cavity. The cytoplasm
of the cells is not visible because it is very thin. Beneath the serosa is
the muscularis externa of the ileum, composed of smooth muscle.
