CHAP, i.] TISSUES AND MECHANISMS OF DIGESTION. 383 



been regarded as young reserve cells which will upon the destruc- 

 tion of any of the mucous cells grow up to take their place. 



212. The body of the gland is not only in itself distinctly 

 less in diameter than the mouth (so that a larger amount of 

 vascular connective tissue lies between the bodies than between 

 the mouths), but has a much narrower, indeed very narrow and 

 tortuous lumen, and is lined by cells of a wholly different character. 

 These are of two kinds. 



Throughout its whole length below the mouth the gland is 

 Jined continuously with a single layer of polyhedral or cubical or 

 at times conical cells, the outlines of which are remarkably 

 indistinct. The cell-body of each of these, which contains a 

 spherical nucleus placed near the centre of the cell but more 

 outside towards the basement membrane, varies, as we shall see 

 later on, very much in appearance according to what has been 

 taking place in the stomach, and to the mode of preparation. In 

 sections of a stomach hardened and prepared in an ordinary way 

 the cell-bodies frequently present a "faintly granular" appearance. 

 Cells of this kind are spoken of from their position as central cells, 

 or sometimes, for reasons which we shall see presently, as chief 

 cells. 



The cells of the other kind do not form a continuous layer but 

 are scattered along the length of the body of the gland, being most 

 numerous (but smaller) in the region of the neck, and less frequent 

 (but larger) at the bottom or fundus of the gland. They are more- 

 over in the lower part of the gland and indeed over the greater 

 part placed outside the central cells, being wedged in between 

 these and the basement membrane and frequently causing the 

 latter to bulge out ; they therefore in most cases do not abut on 

 the lumen of the gland and their only direct connection with 

 the lumen is through spaces between the central cells. In the 

 neck of the gland they may however bound the lumen. Each 

 cell is ovoid in form with an outline which, in contrast to that of 

 the central cells, is sharp and well defined, and possesses an ovoid 

 nucleus placed in the middle of a cell-body which like that of the 

 central cell varies in appearance according to circumstances, but 

 which in a section of stomach hardened and prepared in an ordinary 

 way is frequently 'coarsely' granular. Cells of this kind are called 

 from their position parietal cells or, from their shape, ovoid cells. 

 Even the smaller of them are larger than the central cells. 



A characteristic ' gastric gland ' then of the cardiac region of 

 the stomach is a tubular depression often straight and simple, but 

 at times bifurcating towards the lower part or otherwise dividing, 

 the ends frequently curling. Each depression consists of a mouth, 

 with a broad lumen lined by slender mucous cells, a neck in 

 which the mucous cells suddenly change to central cells with 

 numerous ovoid cells lying among them, and in which the lumen 

 becomes narrowed and tortuous, and a body ending in a blind 



