!62 NORMAL HISTOLOGY. 



non-striped or involuntary in character ; in the middle third 

 both kinds exist, the striated fibres gradually disappearing as the 

 non-striped fibres increase. The latter extend highest in the circular 

 coat and somewhat farther in the anterior than on the posterior wall. 

 The last traces of voluntary muscle appear as short, isolated striped 

 fibres among the surrounding fasciculi of non-striated tissue. 



The fibrous coat envelops the muscular tunic externally, strength- 

 ening the tube and affording attachment to the surrounding areolar 

 tissue connecting the oesophagus with neighboring organs. Con- 

 siderable elastic tissue is found in this coat, the elastic fibres forming 

 net-works intimately connected with the bundles of involuntary 

 muscle. 



The larger blood-vessels penetrate the outer coats and ramify- 

 within the submucous tissue, from which branches pass to supply the 

 muscular and mucous tunics, the capillaries within the latter ending 

 as net-works within the inner part of the tunica' propria. The 

 lymphatics of the deeper layers of the mucosa terminate in the 

 larger vessels of the submucosa. Numerous nerve -fibrillae pass 

 from the submucous tunic into the mucosa to end beneath the 

 epithelium. 



THE STOMACH. 



The stomach must be regarded as a dilated and specialized portion 

 of the general digestive tube, its walls consisting of the four coats 

 common to the other parts of the tract namely, the mucous, the 

 submucous, the muscular, and the serous or fibrous tunic. 



The mucous membrane is covered by a simple columnar 

 epithelium, the squamous cells of the oesophagus abruptly ter- 

 minating at the cardiac orifice to be replaced by the columnar ele- 

 ments of the gastric epithelium, many of which are goblet-cells. 

 The free inner surface of the stomach presents, in addition to the 

 conspicuous folds or rugae, minute inequalities and pits, which 

 mark the openings of the gastric glands ; the mouths of the latter 

 show as minute depressions, between which the intervening por- 

 tions of the mucosa extend as apparent elevations. 



The gastric glands are of two kinds the peptic glands, situ- 

 ated in the middle and cardiac thirds, and the pyloric glands, 

 found in the pyloric third of the stomach. Both varieties are limited 

 to the mucosa, extending in length the entire thickness of this coat. 



The peptic glands are slightly wavy, simple tubular depressions, 

 in which a duct, a neck, and a fundus are recognized. In excep- 

 tional cases the fundus is divided, while in nearly all it is tortuous or 

 spiral, its extremity being often sharply bent at right angles to the 

 general axis of the tube. The columnar epithelial cells of the ad- 



