270 



DIGESTION. 



In the greater number of the glands which are branched 

 at their deeper extremities, the spheroidal epithelium exists 

 Fig. 71.* in the divisions, while the main duct 



and the upper part of the branches are 

 lined by the cylindrical variety (fig. 

 70, c). In the human stomach, ac- 

 cording to Dr. Brinton, the simple un- 

 divided tubes are the rule, and the 

 branched the exception. 



The varieties in the epithelial cells 

 lining the different parts of the tubes, 

 correspond probably with differences 

 in the fluid secreted by their agency 

 the cylinder-epithelium, like that on 

 the free surface of the stomach being 

 probably engaged in separating the 

 thin alkaline mucus which is always 

 present in greater or less quantity, 

 while the larger glandular cells probably secrete the proper 

 gastric juice. 



Near the pylorus there exist glands branched at their 

 deep extremities, which are lined throughout by cylinder- 

 epithelium (fig. 70, a\ and probably serve only for the 

 secretion of mucus. 



All the tubular glands, while they open by one end into 

 the cavity of the stomach, rest by their blind extremities 

 on a bed or matrix of areolar tissue (fig. 69), which is 

 prolonged upwards between them, so as to invest and 

 support them. 



Lenticular glands. Besides the cylindrical glands, there 



* Fig. 71. Part of one of the gastric glands, highly magnified, to 

 show the arrangement of the epithelium in its interior ; a, columnar 

 cells lining the upper part of the tube ; I, small angular cells, into 

 which these merge below to form a central or axial layer within ; c, the 

 proper gastric or glandular cells (after Brinton). 



