144 



NORMA L HISTOLOG Y. 



variety, so-called because more abundant at the pyloric end of the 

 stomach, and the " cardiac" variety, which preponderate near the 

 eardiac end. 



The pyloric glands (Fig. 121) have the simpler structure. They 

 possess a comparatively deep and open mouth, lined with columnar 

 epithelial cells similar to and continuous with those lining the de- 

 pressions already mentioned, and, like them, mucigenons. Into 

 these mouths one or more straight tubular glands, lined with low, 

 granular columnar cells, discharge their secretion. 



The cardiac glands (Fig. 122) have shallower mouths than the 

 pyloric glands, and the tubes that open into them contain two sorts 

 of epithelial cells : 1, the "chief" or central cells, which line and 

 nearly fill the whole tubule, leaving only a very small and some- 

 what tortuous lumen in the centre ; and, 2, the parietal cells, lying 

 at intervals between the central cells and the surrounding connective 

 tissue, but sometimes projecting between two central cells nearly 

 or quite to the lumen of the gland. Very fine channels run from 

 that lumen to and around these parietal cells, which are believed to 

 produce the free acid of the gastric juice (Figs. 123-125). 



Fig. 123. 



Fig. 124. 



Fig. 125. 



Cross-sections of gastric glands ; dog. (Hamburger.) 

 Figs. 123 and 124.— From the cardiac end of the stomach, showing the chief or central cells 

 and the parietal cells. 123, from a dog killed during the second hour of digestion. The 

 central cells are relatively large, and the lumen is reduced to a mere line, appearing as 

 a dot in the centre of the cross-section. 124, from a dog killed during the seventh hour of 

 digestion. The parietal cells are relatively large, and the lumen more distinct than in 

 123, owing to loss of material on the part of the central cells and a gain on the part of the 

 parietal cells. One of the latter is in communication with the lumen through a small 

 channel between the central cells. 

 Fig. 125— From the pyloric end of the stomach during the fifth hour of digestion. The cells 

 b have parted with their secretion and are compressed by the cells a, which still retain 

 the materials stored for secretion. The lumen of the gland is much larger than that of 

 the glands at the cardiac end of the stomach. 



Besides the secreting glands, the mucous membrane of the stom- 

 ach sometimes contains small lymph-follicles. Its blood- and 

 lymph-supplies arc abundant, and nerves are distributed to its 

 various tissue-elements. 



