THE STOMACH 



1157 



from which branches are distributed to the muscularis and the mucosa as for the intestine in 

 general. 



Development. — The stomach at first lies in the mid-sagittal plane in the cervical region. 

 It participates in the general descent of the viscera (the oesophagus becoming correspondingly 

 lengthened) and reaches its permanent vertebral level in the 17 mm. embryo (Jackson). In 

 the meantime, beginning in the 7.5 mm. embryo (F. T. Lewis), a rotation of the stomach has 

 occurred. The rotation is around the long axis, so that the anterior border (lesser curvature) 

 is turned to the right, and the posterior border (greater curvature) to the left. The right 

 surface therefore becomes posterior and the left anterior. During the process of descent, the 

 pyloric end is the first to become fixed (at about 12 mm.). As the cardiac end continues to 

 descend, it is displaced to the left, so the oblique position of the stomach is estabUshed early. 

 The stomach is at first spindle-shaped, but the upper end begins to enlarge at about 10 mm. 

 The fundus develops somewhat later as a localized outgrowth (Keith and Jones). 



The foetal stomach is somewhat crowded to the left by the relatively large liver (fig. 953). 



Fig. 914. — Outline Showing the Average Position of the Abdominal'IiViscera in 

 40 Bodies, on a Centimetre Scale (Reduced to .36 Natural Size). ML, anterior mid-line 

 EF, horizontal line half-way between pubes and suprasternal margin ("transpyloric" line), 

 CD, line half way between pubes and line EF. (Addison.) 



and its relations to surrounding organs undergo considerable change. Even in the fcetus it is 

 quite variable, but its general form and position do not differ essentially from the adult condition. 

 Glands. — According to Johnson, in an embryo of 16 mm., the fining epithehum shows the 

 primitive foveolse as pit-like depressions which become elongated, forming irregular anasto- 

 mosing grooves, separated by villus-fike projections. The pits multiply and deepen, and from 

 their bottoms the gastric glands bud off (at 120 mm.). The parietal cells appear very early 

 in the gland fundus, but the differentiation of gland cells is still incomplete at birth. 



