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TEXT-BOOK OF PHYSIOLOGY. 



cell appears to be surrounded and penetrated by a system of passages which 

 open into the lumen of the gland by means of a delicate cleft or canaliculus 

 (Fig. 73). Glands with these histologic features are most abundant in the 

 middle zone of the stomach. 



The pyloric glands are also formed by an involution of the mucous mem- 

 brane and lined by epithelial cells (Fig. 74). The ducts are much longer 

 than the ducts of the fundic glands. At its extremity each duct becomes 

 branched, giving rise to a number, from 2 to 10, of short tubes, each of which 

 has a large lumen and communicates with the duct by a narrow short neck. 

 The ducts are lined throughout by columnar epi- 

 thelium. According to Mall, the total number of 

 openings on the surface of the mucous membrane of 

 the dog's stomach is somewhat over 1,000,000, and 

 the total number of blind tubes opposite the muscu- 

 laris mucosae exceeds 16,500,000. According to 

 Sappey, the surface of the mucous membrane of the 

 human stomach presents over 5,000,000 orifices of 

 gastric glands. 



Blood-vessels, Nerves, and Lymphatics. The 

 blood-vessels of the stomach after entering the mucosa 

 break up into a number of branches which are dis- 

 tributed to the muscle and mucous coats. The 

 branches to the latter soon form a capillary network 

 with oblong meshes which not only surround the 

 tubules but form a network just beneath the surface 

 of the mucosa. Veins gradually arise from the 

 capillaries which empty into the larger veins of the 

 mucosa. The glands are also supported by proc- 

 esses of smooth muscle-fibers passing up from the 

 muscularis mucosae. 



The nerve-fibers distributed to the stomach are 

 derived from the vagus and the sympathetic branches 

 of the solar plexus. After piercing the serous coat 

 the fibers form or unite with a plexus of fibers situa- 

 STOMACH! te( ^ between the circular and longitudinal layers of 

 m, Mouth of duct; n, neck, the muscle-coat. At the nodal points of this plexus 

 (Landois) large nerve-ganglion cells are to be found, the whole 



forming the mechanism known as Auerbach's plexus. A similar plexus 

 of cells and fibers in more or less intimate anatomic connection with the 

 foregoing is found between the muscle and submucous coats, and is known 

 as Meissner's plexus. From this plexus fine nerve filaments are distrib- 

 uted to muscle-fibers, blood-vessels, and glands. In the latter structure ter- 

 minal arborizations have been detected in close contact with the secreting 

 cells themselves. 



The lymphatics, which are quite numerous, originate in the meshes of the 

 mucosa. The larger trunks enter lymph-glands lying along the greater and 

 lesser curvatures of the stomach. 



Gastric Fistulas. The general process of digestion, as it takes place in 

 the stomach, has been studied in human beings and animals with a fistula in 



