In vivo cell kinetics studies of the duodenum during and after healing of cysteamine‐induced duodenal ulcer in rats using bromodeoxyuridine incorporation

The present study investigated the defect of duodenal defence responsible for the tendency of recurrence of duodenal ulcer. Male Wistar rats were treated with cysteamine‐HCl subcutaneously to induce duodenal ulcer, and bromodeoxyuridine (BrdU) was given intraperitoneally 1 h before laparotomy. Serial tissue sections and immunocytochemical staining of BrdU were done to study the cell kinetics during and after healing. Deep ulcers developed in the proximal part of the duodenum 24 h after cysteamine injection, and the ulcer was replaced by scar tissue 1 week later. BrdU‐labelling index of normal duodenal mucosa in control rats was 30–34%. On the peripheral part of the regenerative mucosa, BrdU‐labelling index increased from 1.5% to 26–27%, 1–4 weeks after injection and remained at this level thereafter. On the central part, except the most central area, the labelling index remained at 0% until 3 weeks, and was 15% 6 weeks after cysteamine treatment. It never achieved the level seen in control normal mucosa. The labelling rate of fibrous cells in scar tissue decreased from 28% to nearly 0% 1–4 weeks after the injection. It is concluded that both the ulcer scar and the regenerative mucosa do not achieve a mature state in the initial scarred stage; they need more time to reach a relatively mature condition. Moreover, the regenerative mucosa will be the weak, easily damaged part of the duodenum.