282 



THE DIGESTIVE SYSTEM 



more or less removed from the lumen they possess an extensive 

 system of pericellular secretory canals which invest the cell in a 



basket-like manner and convey its secre- 

 tion to the glandular lumen, where it 

 mixes with the secretion of the chief 

 cells. The parietal cells also possess a 

 system of intracellular canaliculi. 



Pyloric Glands. These are branched 

 convoluted tubular glands with relatively 

 long crypt-like ducts, into the bottom of 

 which several secreting tubules open. 



The typical convolution is found only 

 in the fundus of the gland, the course of 

 the ducts being nearly straight. The 

 branching, on the other hand, is chiefly 

 confined to the ducts, which occupy the 

 superficial two-thirds to three-fourths of 

 the entire depth of the mucous mem- 

 brane. In the pyloric mucosa, there- 

 fore > thre zones m *J ^ Q distinguished- 



GLANDS OF 

 STOMACH. 



THE DOG'S 



Golgi stain. (After Miiller, 

 from Oppel.) 



. 233.-SECKETOKY 



LABIES OF THE FUNDUS a superficial, middle, and deep. 



The superficial zone is narrow and 

 contains the wide-mouthed crypts or 

 foveolae which are lined by tall columnar 

 cells similar to those of the fundus crypts. 



The middle zone contains the narrowed portion of the ducts 

 and is the broadest of the three zones. Several of the narrow 

 ducts open into each foveola and further branching of the secret- 

 ing tubules occurs to a limited extent. The epithelium of the 

 ducts is of the low columnar variety, whose deeply stained basal 

 nuclei are spheroidal or ovoid, and are progressively flattened as 

 the secreting portion is approached. The superficial cytoplasm 

 of these cells stains readily with muchematein and often has a 

 coarsely granular or reticular appearance. 



The deepest zone contains the convoluted secreting portions 

 and is sharply demarked from the adjacent ducts, since in a transec- 

 tion of the stomach wall its tubules, owing to their convolution, 

 are nearly all cut across, while the ducts are in longitudinal sec- 

 tion ; the clear tall columnar epithelium and broad lumen of the 

 fundus, also, contrast strongly with the low finely granular epithe- 

 lium and narrow lumen of the duct. It is this narrow zone of 



