CH. XXVII.] 



THE (ESOPHAGUS 



447 



phagus this coat is made up principally of striated muscle fibres ; 

 they are continuous with the constrictor muscles of the ~ pharynx ; 

 but lower down the unstriated fibres become more and more numerous, 

 and towards the end of the tube form the entire coat. The muscular 

 coat is connected with the mucous coat by a more or less developed 

 layer of areolar tissue, which forms the submucous coat, in which are 

 contained in the lower half or third of the tube many mucous glands, 

 the ducts of which, passing through the mucous membrane, open on 



~+ 



Fro. 374. Section of the mucous membrane and submucous coat of the oesophagus. 



its surface (fig. 374). In the deepest part of the mucous membrane 

 is a well-developed layer of longitudinally arranged unstriated muscle, 

 called the muscularis mucosce. The corium of the mucous membrane 

 is composed of fine connective tissue, which, towards the surface, is 

 elevated into papillae. It is covered with a stratified epithelium, of 

 which the most superficial layers are composed of squamous cells. 

 The epithelium is arranged upon a basement membrane. 



In newly-born children the corium exhibits, in many parts, the 

 structure of lymphoid tissue (Klein). 



