340 



THE ANATOMY OF THE HORSE. 



4. The Mucous Coat. — It is desirable to study this on the stomach 

 of an animal recently killed. If possible, take such a stomach with 

 about a foot of the duodenum and a few inches of the oesophagus 

 attached, and fasten the duodenum to a tap. Let water flow into 

 the organ, and it will be noticed that, even when the stomach is 

 much distended, none of the water escapes by the orifice of the 

 gullet, although that is unligatured. This is an instructive experi- 

 ment, as showing the difficulty of vomition in the horse. Now allow 



the contents of the stomach to escape 

 by the duodenum ; and either evert the 

 organ and inflate it, or incise it along 

 its convex curvature. It will at once 

 be noticed that the mucous lining is 

 not the same throughout. The left or 

 cardiac half of the cavity is lined by 

 a mucous membrane termed cuticular ; 

 the right or pyloric half has a totally 

 different lining, termed villous. The 

 cuticular portion is pale, harsh, without 

 glands, and covered on its free surface 

 by a thick stratified squamous epi- 

 thelium. It is, in fact, an extension 

 of the oesophageal mucous membrane, 

 which it resembles in all respects. 

 Towards the middle of the stomach it 

 is separated from the villous half by 

 an abrupt, raised, and slightly sinuous 

 line of demarcation — the cuticular ridge. 

 is rosy, soft, and 

 velvety (but without villi), thickly 

 beset with gastric glands, and possessed 

 of a single layer of columnar epithelium. The gastric glands are of 

 the tubular variety, and by the aid of a lens numbers of them may 

 be seen opening together into pits, or alveoli, of the mucous membrane. 

 The cuticular portion is but slightly vascular, but the villous portion 

 is richly supplied with blood-vessels. In the collapsed organ the 

 mucous membrane is thrown into folds, or rugce. 



The (Esophageal Orifice, it will now be seen, is very narrow, 

 and obstructed by the mucous membrane gathered into folds. 



The Pyloric Orifice is much larger, and in the horse it appears 

 to be never quite closed, notwithstanding the presence of the pyloric 

 ring of circular fibres around it. 



In the interior of the duodenum, about six inches from the pylorus, 

 the openings of the bile and pancreatic ducts will be found. The 



Fig. 44. 

 Vertical Transverse Section of the 

 Coats of a Pig's Stomach. 30 

 Diameters (from Kolliker). 

 a. Gastric glands ; b. Muscular layer 

 of the mucous membrane ; c. Submucous The villous half 

 or areolar coat ; d. Circular muscular 

 layer; e. Longitudinal muscular layer; 

 /. Serous coat. 



