Colon cross-section - image description

This illustration has two parts. The first  shows a cross-section of the bowel. It shows the different layers that make up the bowel wall.  The second shows an enlarged part of the cross-section which is labelled with the names of the different layers. The thin, innermost layer of the bowel wall is called the mucosa. The next layer is called the submucosa. These together make up the inner layer of the bowel. After the inner layer is a thicker layer of muscle. After that is a layer called the serosa, also called the outer layer.

The first cross-section illustration shows various tumours that represent the ‘T’ stages of cancer. The Tis tumour is shown only affecting the mucosa (the innermost layer). The T1 tumour is affecting the mucosa and the submucosa. The T2 tumour is affecting the mucosa, submucosa and the muscle layer. The T3 tumour is affecting the mucosa, submucosa, muscle layer and the serosa (outer layer). The T4 tumour is shown to affect all layers of the bowel and has gone beyond the outer layer of the bowel.