EXPERIMENTAL PRODUCTION OF GASTRIC ULCER. 131 



Microscopically a section through a well-formed ulcer shows a sharply cut 

 crater resembling a peptic erosion. The walls of the mucosa dip in on either 

 side, disclosing the muscularis or submucosa as the floor of the ulcer. In the 

 ulcer proper we find granular debris consisting of digested mucosa, food par- 

 ticles, and occasional hemorrhages. Frequently, however, the walls, instead of 

 being sharply cut, sloped gradually, giving the ulcer the appearance of an exca- 

 vation. Another form is seen where three-fourths of the mucosa takes a more 

 or less basic stain and sloughs off, leaving a few rows of intact cells below. Fre- 

 quently a number of polynuclear leucocytes are seen in the base of the ulcer, 

 together with a little fibrin; but connective-tissue proliferation does not take 

 place, which is in accordance with the acute character of the lesion. Usually 

 hemorrhagic areas are seen between the sloughed-off part of the mucosa and the 

 intact mucosa below. This might suggest hemorrhage as the primary cause of 

 the ulcer, but far more frequently areas of mucosa are seen which take a more 

 or less basic stain. Under the high power various stages of nuclear degenera- 

 tion are seen in these areas. The large majority of the nuclei are shrunken and 

 do not take the stain. The protoplasm of the gland cells is granular and fre- 

 quently has entirely disappeared in the upper layers, leaving nothing but poorly 

 stained, shrunken nuclei and connective-tissue fibrils. This area contrasts 

 strongly with the gastric tubules below, in which the cells are intact. 



Interesting is the fact that in these superficial areas, when all other ele- 

 ments are necrotic, the acid cells stain well and seem able to resist digestion 

 much better than the parietal cells. This was observed in a number of in- 

 stances, and is in accord with Bolton's observations on the effect of the gastro- 

 toxic sera on the gastric cells in vitro. 



Every intermediate stage has been observed from slight change with no 

 sloughing of the mucosa to actual ulcer, and frequently without hemorrhage. In 

 this very early stage not even capillary hemorrhages can be seen. On the other 

 hand, small submucous hemorrhages have been observed without any change 

 in the overlying mucosa. In a study of a great number of sections, many of 

 them serial, only one marked instance of submucous hemorrhage was found, 

 and in this case no change was visible in the overlying mucosa. In several 

 instances where gastric ulceration and hemorrhage were present, parenchy- 

 matous hemorrhages into the spleen were also observed. 



The possibility of hemorrhage occurring in parts of the small or large intes- 

 tines was thoroughly studied. The entire gastro-intestinal tracts of about 25 

 animals were carefully examined. No case of extra-gastric hemorrhage was 

 observed, except in one case in which a little blood-stained fluid was found in 

 the small intestine. 



The vessels in the vicinity of the ulcer are often thrombosed; and fre- 

 quently a peripheral rim of leucocytes, due to a gradual slowing of the circula- 

 tion, Avas seen in these thrombi. That these thrombi are not the cause of the 

 ulcer, but are secondary, will be shown later. They seal the vessels and thus 

 prevent hemorrhage. Frequently the capillaries immediately surrounding the 

 ulcer are congested. 



