Identification features of oesophagus are all except

Oesophagus is lined by Stratified squamous non-keratinized epithelium.The oesophagus is covered by an adventitia until it pierces the diaphragm, after which it is covered by a serosa.Oesophagus and duodenum have submucosal glandsThe muscularis externa of the upper third of the oesophagus has mostly skeletal muscle, the middle third has both skeletal and smooth muscle, and the lowest third has only smooth muscle fibers.Reference: Krishna Garg Histology; 5th edition; Page no: 130