E coli bacteria in the oesophagus. Coloured scanning electron micrograph (SEM) of the lining (epithelium) of the human oesophagus (gullet, blue) and e. coli bacteria (pink). The lining of the oesophagus is composed of non-keratinised, striated, squamous epithelial cells. They have a surface covered in these ridges (microplicae) that protect against the abrasion of rough food. Many types of bacteria are found in the alimentary canal, of which the oesophagus is the upper part. Rod-shaped varieties of bacteria are known as bacilli. The oesophagus is a muscular tube, about 25 centimetres long, that runs from the back of the throat down to the alimentary canal; Magnification: x2000 when printed at 10 centimetres wide.