THE DIGESTIVE TRACT. 



595 



I 



Such an appearance is sometimes produced by tubules which run 

 obliquely or in a winding course, which in vertical sections seem 

 to inosculate with the perpendicular tubules. The gastric glands 

 are lined with cuboidal epithelium, with interspersed formations 

 of large, pale, finely granular epithelia, to the presence of which 

 R. Heidenhain and A. Rollet drew attention. The Greek denom- 

 inations given to them by the last-named observer are super- 

 fluous in the face of the fact that the difference in the appearance 

 of the epithelia is due simply to 

 the process of secretion. The 

 coarsely granular, indistinctly nu- 

 cleated, epithelia are for the time 

 being not engaged in the produc- 

 tion of the mucous secretion 

 termed pepsine; while the large, 

 pale, distinctly nucleated epithe- 

 lia are laden with it. Pepsine 

 consists, in part, at least, of trans- 

 formed living matter of the epi- 

 thelia. By an accumulation of 

 liquid the bioplasson reticulum is 

 at first stretched, afterward torn, 

 and large portions of the bioplas- 

 son perish in the formation of 

 pepsine. By the rupture of the 

 cement investment, the secretion 

 is discharged into the caliber of 

 the tubule. As the glandular epi- 

 thelium forms only one layer, the 

 swelled epithelia bound the caliber 

 in the same manner as the ordi- 

 nary cuboidal ones, and it is only 

 in a surface section of the tubule 

 that the swelled epithelia appear 

 near the basement layer of the connective tissue, as if covered 

 by coarsely granular cuboidal epithelia. These relations are most 

 definitely marked in places where the same tubule is, owing to its 

 winding course, seen in longitudinal and transverse directions. 

 (See Fig. 252.) 



The secretion of the tubular glands the gastric juice owes 

 its acidity to the presence of a small quantity of hydrochloric 

 acid. This reaction is obviously induced through the agency of 



FIG. 252. GASTRIC GLANDS FROM 

 THE STOMACH OF MAN. VERTI- 

 CAL SECTION. 



i, tubule in a longitudinal ; T, tubule 

 in a transverse section, lined by cuboidal 

 epithelia ; P, epithelia laden with pepsine. 

 Magnified 800 diameters. 



