512 PAPILLARY LAYER FIBROUS LAYER. 



The Proper mucous, or Papillary layer is analogous to the papillary 

 layer of the skin, and, like it, is the formative structure by which the epi- 

 thelium is produced. Its surface presents several varieties of appearance, 

 when examined in different parts of its extent. In the stomach it forms 

 polyhedral cells, into the floor of winch the gastric follicles open. In the 

 small intestine it presents numerous minute, projecting papillae, called 

 villi. The villi are of two kinds, cylindrical and laminated, and so abun- 

 dant, as to give to the entire surface a beautiful velvety appearance. In 

 the large intestine the surface is composed of a fine network of minute 

 polyhedral cells, more numerous than those of the stomach, but resem- 

 bling them in receiving the secretion from numerous perpendicular fol- 

 licles into their floors. 



The Fibrous layer (sub-mucous, nervous) is the membrane of support 

 to the nrucous membrane, as is the corium to the papillary layer of the 

 skin. It gives to the mucous membrane its strength and resistance, is but 

 loosely connected with the mucous layer, but is firmly adherent to the 

 muscular stratum, and is called, in the older works on anatomy, the 

 "nervous coat." 



Glands. In the loose areolar tissue connecting the mucous with the 

 fibrous layer, are situated the glands and follicles belonging to the mucous 

 membrane : these are the 



Pharyngeal glands, 

 (Esophageal glands, 

 Gastric follicles, 

 Duodenal glands (Brunner's), 

 GlandulaB solitaries, 

 Glandulae aggregate (Peyer's), 

 Simple follicles (Lieberkiihn's). 



The Pharyngeal glands are situated in considerable numbers beneath 

 the mucous membrane of the pharynx, particularly around the posterior 

 nares. Two of these glands, of larger size than the rest, and lobulated 

 in structure, occupy the margin of the opening of the Eustachian tube. 



The (Esophageal glands are small lobulated bodies, situated in the sub- 

 mucous tissue, and opening upon the surface of the oesophagus by a long 

 excretory duct, which passes obliquely through the mucous membrane. 



The Gastric follicles are long tubular follicular glands, situated perpen- 

 dicularly side by side in every part of the mucous membrane of the sto* 

 mach. At their terminations they are dilated into small lateral pouches, 

 which give them a clustered appearance. This character is more clearly 

 exhibited at the pyloric than at the cardiac end of the stomach. They are 

 intended, very probably, for the secretion of the gastric fluid. 



The Duodenal, or Brunner's* glands, are small flattened granular 

 bodies, compared collectively by Von Brunn to a second pancreas. They 

 resemble in structure the small salivary glands, so abundant beneath the 

 mucous membrane of the mouth and lips ; and, like them, they open 

 upon the surface by minute excretory ducts. They are limited to the 

 duodenum. 



The Solitary glands are of two kinds, those of the small and those of 

 the large intestine. The former are small circular patches, surrounded 



John Conrad von Brunn: "Glandulse Duodeni seu Pancreas Secundarium ? " 1715. 



