464 



DISSECTION OF THE ABDOMEN. 



Fig. 156. formly diffused than the apertures of the 



tubules in the small gut. A vertical section of 

 the membrane ( 2 ) will show the tubes to ex- 

 tend vertically from the surface into the sub- 

 mucous coat, and to be longer than the crypts 

 of Lieberkiihn in the jejunum and ileum ; they 

 measure from ^ ff th to ^th of an inch in length. 

 The so-called solitary glands (fig. 156, A ) 

 are scattered here and there through the large 

 intestine ; but they are in greatest number in 

 the csecum and vermiform appendix. They 

 are whitish rounded bodies from ^th to T \ytli 

 of an inch in diameter, and are situate in the 

 submucous layer amongst the tubules. They 

 are lymph follicles with a structure like that 

 in the small intestine. 



The epithelium is of the columnar kind, 

 and enters the tubules. 

 Vessels. The distribution of the vessels in the wall of the large intes- 

 tine is the same as in the smaller bowel. 



Nerves. In the coats of the large intestine the nerves have the plexi- 

 form arrangement like that in the small gut. 



The absorbent vessels form two sets as in the small intestine; after leav- 

 ing the gut they join the lymphatic glands along the side of the colon. 



ENLARGED VIEW OF "A SOLITARY 

 GLAND," and of the tubules of 

 the mucous coat. (Boehm.) 



A. Gland of the large intestine. 



B. Tubules of the mucous mem- 



brane. 



1. Surface opening. 



2. Side view of the tubes. 



3. Pits for the closed ends of the 



tubes in the submucous 

 tissue. 



THE PANCREAS. 



The pancreas (fig. 1 45, e) is a narrow flattened gland, from six to eight 

 inches in length, which has some resemblance to a dog's tongue. It is 

 larger at the right than the left end ; and it is divided into head, tail, and 

 body. 



The head, or the right extremity, occupies the concavity of the duo- 

 denum; and the left extremity, or the tail, is rounded, and touches the 

 spleen. 



The body of the gland is narrowest a little to the right of the vertebral 

 column, and is thickest at the upper border ; it measures about one inch 

 and a half in breadth, and from half an inch to an inch in thickness. 

 The connections of the pancreas with surrounding parts are described at 

 p. 446. 



Dissection. Let the pancreas be placed on the anterior surface, and 

 let the excretory duct be traced from the head to the tail by cutting away 

 the substance of the gland. The small duct will be recognized by its 

 whiteness. 



STRUCTURE. The pancreas is a gland consisting of separate lobules, 

 and is provided with a special duct. It is destitute of a distinct capsule ; 

 but it is surrounded by areolar tissue, which projects into the interior, 

 and connects together its smaller pieces. The fluid secreted by it assists 

 in the digestion of the aliment. 



The lobules are soft and loose, and of a grayish-white color, and are 

 united into larger masses by areolar tissue, vessels, and ducts. Each con- 

 sists ultimately, as in the parotid, of the branchings of the excretory duct, 

 which end in closed vesicular extremities, and are surrounded by a plexus 

 of vessels. In the vesicles the epithelium is spheroidal. 



