THE STOMACH. 



131 



beneath the longitudinal fibres. At the pylorus they are most abundant, and 

 are aggregated into a circular ring, which projects into the cavity, and forms, 

 with the fold of mucous membrane covering its surface, the pyloric valve. 



The oblique fibres are limited chiefly to the cardiac end of the stomach, where 

 they are disposed as a thick uniform layer covering both surfaces, some passing 

 obliquely from left to right, others from right to left, round the cardiac orifice. 



Fig. 399. The Muscular Coat of the Stomach. 



The cellular coat consists of a loose, filamentous, areolar tissue, connecting 

 the mucous and muscular layers. It is sometimes called thesubmucous coat. It 

 supports the bloodvessels previous to their distribution to the mucous mem- 

 brane ; hence it is sometimes called the vascular coat. 



The mucous membrane of the stomach is thick ; its surface smooth, soft, and 

 velvety. During infancy, and immediately after death, it is of a pinkish tinge ; 

 but in adult life, and in old age, it becomes of a pale straw or ash-gray color. 

 It is thin at the cardiac extremity, but thicker towards the pylorus. During 

 the contracted state of the organ, it is thrown into numerous plaits or rugae, 

 which, for the most part, have a longitudinal direction, and are most marked 

 towards the lesser end of the stomach, and along the greater curvature (Fig. 

 398). These folds are entirely obliterated when the organ becomes distended. 



Structure of the mucous membrane (Fig. 400). When examined with a lens, 

 the inner surface of the mucous membrane presents a peculiar honeycomb ap- 

 pearance from being covered with small shallow depressions or alveoli, of a 

 polygonal or hexagonal form, which vary from T ^ 7 to 3^ of an inch in dia- 

 meter, and are separated by slightly elevated ridges. In the bottom of the 

 alveoli are seen the orifices of minute tubes, the gastric follicles, which are situ- 

 ated perpendicularly side by side, in the entire substance of the mucous mem- 

 brane. They are short, and simply tubular in character towards the cardia ; 

 but at the pyloric end, they are longer, more thickly set, convoluted, and ter- 

 minate in dilated saccular extremities, or are subdivided into from two to six 

 tubular branches. The gastric follicles are composed of a homogeneous base- 

 ment membrane, lined upon its free surface by a layer of cells, which differ in 

 their character in different parts of the stomach. Towards the pylorus, these 

 tubes are lined throughout with columnar epithelium ; they are termed the 



