Oesophagus epithelium. Coloured scanning electron micrograph (SEM) of the lining of the human oesophagus or gullet (yellow) and two unknown bacteria (pink & purple). The lining is composed of non-keratinised striated squamous epithelial cells, which have a surface covered in characteristic ridge-like folds (microplicae). Many types of bacteria are found throughout the alimentary canal. Rod-shaped varieties are known as bacilli, and ball-shaped varieties are known as cocci. The oesophagus is a muscular tube about 25 centimetres long that runs from the back of the throat to the stomach. Magnification: x 1700.