THE DIGESTIVE TRACT. jgt 



situated within the interlobular connective tissue, the larger trunks 

 accompanying the main blood-vessels. 



The nerves distributed to the salivary glands constitute a rich 

 supply, composed of both medullated and pale fibres. From the 

 larger trunks of the interlobular net- works, along the course of which 

 minute ganglia occur, smaller branches enter the lobules and extend 

 between the acini. Regarding the ultimate distribution of the many 

 fibres passing to the glandular tissue little is definitely known, not- 

 withstanding the laborious investigations undertaken with a view 

 to solve this difficult problem. The nerve-fibres may be traced to 

 the basement-membrane of the acini, around which net-works are 

 formed ; as to the further fate of the fibrillae, however, little can be 

 regarded as proved. While an intimate relation between the nerves 

 and the secreting cells may be assumed as undoubtedly existing, no 

 direct continuity between these structures has been established, not- 

 withstanding the already-published assertions and elaborate descrip- 

 tions of such connections. 



THE PANCREAS. 



The pancreas is, as aptly described by its German name, ' ' Bauch- 

 speicheldriise, " the abdominal salivary gland, belonging to the 

 serous type, and closely corresponding 

 in structure and in the nature of its secre- FIG. 230. 



tion to the parotid gland. 



The connective-tissue framework of 

 the organ divides the glandular tissue into 

 lobes, which are subdivided by septa into 

 the lobules, these, in turn, being com- 

 posed of groups of acini. The laminated 

 fibrous connective tissue constituting the 

 walls of the pancreatic duct is clothed by 

 a single layer of columnar epithelium. 

 The branches of the main duct divide at Section of human pancreas, fa- 

 once into the long intermediate tubules, ^ din * several acini and 7 duc ' s : 



the cells present a central granular 

 the intralobular duCtS, Or Salivary tubes, and a peripheral clear zone. 



being wanting ; it follows that the vertical 



striation of the epithelium lining these tubes, so conspicuous in sections 



of the parotid gland, is absent in the pancreas. 



The cylindrical cells of the larger ducts gradually pass into the 

 lower cuboidal and flattened plates lining the intermediate tubules. 

 The acini of the pancreas are more tubular than those of the parotid 

 gland, while the secreting cells suggest more strongly the cylin- 

 drical or pyramidal type than those of the salivary gland ; these 

 cells are further characterized by the presence of a zone, next the 



