Light micrograph of cross-section through the lining of the appendix. The appendix is a hollow blind-ending narrow tube attached to the caecum (beginning of the large intestine). In structure it resembles the large intestine but has numerous lymphoid follicles (round) and associated lymphocytes (white blood cells, red) just beneath the inner surface epithelium. Mucous cells (blue) are present in the lining. The function of the appendix is not well understood, although it is thought to have a role in regulating bacteria within the bowel. Magnification: x200 when printed at 15cm wide.