THE (ESOPHAGUS. 



387 



cal papillae of more or less dense connective tissue, containing 

 looped blood-vessels, and lined throughout by stratified pave- 

 ment-epithelium. These papillae attain a marked degree of 

 development in the adult only. In infancy their future pres- 

 ence is indicated by a wavy 

 outline at the internal attached 

 border of the epithelial stratum. 

 This latter portion of the mu- 

 cous membrane con tributes 0.22 

 0.26 mm. toward the entire 

 oesophageal thickness of about 

 4.0 millimetres. 



The muscularis mucoscB con- 

 sists chiefly of longitudinal, un- 

 striped muscle-cells. They are 

 disposed in bundles of differ- 

 ent sizes, separated by varying 

 amounts of connective tissue. 

 Toward the inferior portion of 

 the oesophagus these bundles 

 approach each other, displacing 

 the interposed tissue, and form- 

 ing finally one continuous mus- 

 cular layer. The thickness of this layer varies between 0.2 

 and 0.3 mm. 



The submucous layer is made up of fasciculated connective 

 tissue and elastic fibres. It contains groups of fat-cells, and 

 lodges the mucous glands. The latter closely resemble the 

 glands found in the mouth. They consist of pyramidal or poly- 

 gonal secret ing-cells with conspicuous rounded nuclei, and ducts 

 lined by cylindrical epithelia. The lower portion of the cesoph- 

 agus contains smaller and more superficial acinous glands. 

 In this region they are also found in greater abundance, and 

 around the cardiac orifice they form almost a complete ring. 



The muscular coat has an inner circular and an outer longi- 

 tudinal layer. In man it is formed of both varieties of muscle- 

 cells, the striped and unstriped. The upper portion is composed 

 of striped muscle only, whereas the lower half consists exclu- 

 sively of the unstriped variety. Below the upper one-eighth of 

 the oesophagus smooth muscle-cells first begin to be blended 

 with the other variety ; they rapidly increase as we proceed 



FIG. 164. Transverse section through the 

 lower part of the oesophagus of the newly-born 

 child : a, a, epithelium ; &, mucosa ; c, muscu- 

 laris mucosae ; d, Bubmucotis tissue ; , layer of 

 circular muscular fibres ; /, longitudinal muscu- 

 lar layer ; a, external fibrous layer ; A, A, two of 

 the ganglia of Auerbach. Klein. 



