HANDBOOK OF PHYSIOLOGY. 



structure and secretion of these glands, and to the secretion (succus 

 entericus) which is poured out into the intestines from the glands lining 



them. 

 o 

 \l j THE PANCREAS, AND ITS SECRETION. 



The Pancreas is situated within the curve formed by the duode- 

 num; and its main duct opens into that part of the small intestine, 

 through a small opening, or through a duct common to it and to the 

 liver, about two and a half inches from- the pylorus. 



Structure. In structure the pancreas bears some resemblance to the 

 salivary glands. Its capsule and septa, as well as the blood-vessels and 

 lymphatics, are similarly distributed. It is, however, looser and softer, 

 the lobes and lobules being less compactly arranged. The main duct 



FIG. 203. Section of the pancreas of a dog during digestion, a, alveoli lined with cells, the 

 outer zone of which is well stained with haematoxylin; d, intermediary duct lined with squamous 

 epithelium, x 350. (Klein and Noble Smith.) 



divides into branches (lobar ducts), one for each lobe, and the-e branches 

 subdivide into intralobular ducts, and these again by their division and 

 branching form the gland tissue proper. The intralobular ducts corre- 

 spond to a lobule, while between them and the secreting tubes or alveoli 

 are longer or shorter intermediary ducts. The larger ducts possess a 

 very distinct lumen and a membrana propria lined with columnar epi- 

 thelium, the cells 'of which are longitudinally striated, but are shorter 

 than those found in the ducts of the salivary glands. In the intralobu- 

 lar ducts the epithelium is short and the lumen is smaller. The inter- 

 mediary ducts opening into the alveoli possess, a distinct lumen, with a 

 membrana propia lined with a single layer of flattened elongated cells. 

 The alveoli are branched and convoluted tubes, with a membrana pro- 

 pria lined with a single layer of columnar cells. They have no distinct 

 lumen, the centre portion of the tube being occupied by fusiform or 

 branched cells. Heidenhain has observed that the alveolar cells in 



