STRUCTURE OF THE STOMACH. 



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162. Structure of the Stomach. 



Structure. [The walls of the stomach consist of four coats, which 

 are from without inwards 



(1) The serous layer, from the peritoneum. 



(2) The muscular layer, composed of three layers of non-striped 



muscular fibres (), longitudinal; (6), circular; (c), 

 oblique (see p. 309). 



(3) The sub-mucous layer, of loose connective-tissue, with the 



larger blood-vessels, lymphatics, and nerves. 



(4) The mucous layerJ] 



The well-developed mucous membrane of the stomach is thrown 

 into a series of folds or rugae, in the contracted condition of the 

 organ. With the aid of a hand-lens, it is seen to be beset with small 

 irregular depressions or pits (Vidius, 1567 Fig. 133). Throughout 

 its entire extent it is covered by a single layer of moderately tall, 

 narrow cylindrical epithelium, which seems to consist of mucus-secret- 

 ing goblet cells (Fig. 135, d). The epithelium is sharply defined at 

 the cardia from the stratified epithelium of the oesophagus, and also at 

 the pylorus, from the true cylindrical epithelium with the striated disc in 

 the duodenum. [The cells in the passive condition seem to consist of 

 two zones, an outer clear part, next the lumen of the organ, consisting 

 of a substance (mucigen) which 

 yields mucus, the attached end 

 of the cell being granular.] 

 The oval nucleus lies about the 

 centre of the cells. Spindle- 

 shaped, nucleated cells, probably 

 for replacing the others, are said 

 by Ebstein to occur at their 

 bases. All the cells are open at 

 their free-ends, so that the mucus 

 is readily discharged, leaving the 

 cells empty (F. E. Schultze). 

 Numerous tubular glands of two 

 distinct kinds are placed ver- 

 tically, like rows of test-tubes, in 

 the mucous membrane. 



Fundus-glands. On making a 

 vertical section of the cardiac 

 portion of the gastric mucous 

 membrane, and submitting it to 

 microscopic examination, it is seen to consist of a number of tubular glands 



Fig. 133. 



Surface section of the dog's gastric muc- 

 ous membrane, showing the crater-like 

 depressions or pits, I i ; a, the elevations 

 round it. 



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