VIII GASTRIC GLANDS 131 



{s.m), corresponding to the derm and called the siibmucosa. 

 The epithelium consists of a single layer of cells only (b, ep), 

 all columnar, and with their long axes at right angles to the 

 elevations into which, as we have seen (p. 71), the mucous 

 membrane is thrown. Amongst the ordinary epithelial cells, 

 numerous mucus-secreting goblet-cells will be recognised. 

 The submucosa, like the derm, contains blood-vessels, lym- 

 phatics, and nerves. 



The muscular layer (A, 111) is also divisible into two ; an 

 outer layer of longitudinal fibres (b, l.ni), running parallel 

 with the long axis of the tube, and an inner, much thicker 

 layer of circular fibres (c.m) which encircle it, and conse- 

 quently lie at right angles to the longitudinal fibres. Thus 

 in a transverse section, such as Fig. 39, the fibres of the 

 circular layer are cut longitudinally, those of the longitudinal 

 layer transversely, while the opposite would be the case in a 

 longitudinal section. 



The peritoneum (/r) which, as we have seen (p. 27) 

 forms an outer covering to the intestine, is formed of an 

 inner layer of connective tissue and an outer of squamous 

 epithelium. 



The Stomach. — Transverse sections of the stomach (Fig. 

 40) show it to differ from the intestine not only in the much 

 greater thickness of all its layers, but in the fact that the 

 epithelium, instead of simply forming an even layer over the 

 ridges of mucous membrane, is sunk into the submucosa in 

 the form of simple or branched tubes, the gastric glands 

 (g. gl). These differ from the cutaneous glands in being 

 not flask-shaped but test-tube shaped, each being a long, 

 narrow tube, with an extremely small cavity (b and c, c). 

 They are lined by a single layer of gland-cells, and open 

 by minute apertures (w) on the surface of the mucous 

 membrane. 



K 2 



