Mechanisms of columnar metaplasia and squamous regeneration in experimental Barrett's esophagus.

BACKGROUND: This study examined the effect of the lower esophageal milieu on the healing of a mucosal defect. METHODS: With a canine model a mucosal defect was created in the lower esophagus, and acid reflux was promoted by a cardioplasty and pentagastrin injection in 10 animals. At 3 months the regenerated mucosa was excised and underwent histologic examination. Six of these animals underwent an antireflux procedure, had their acid secretion suppressed, and were followed up for a further 3 months, at which time they were killed and the entire esophagus underwent histologic examination. RESULTS: When reflux was stimulated, healing of the mucosal defect was by columnar epithelium alone in seven of 10 animals. After reflux control in six animals healing was again by columnar epithelium, but in all six cases islands of squamous epithelium occurred. Histologic examination showed both types of regenerating epithelium to be in continuity with the ducts of the esophageal glands, lined in their proximal two thirds by columnar and in their distal one third by squamous cells. CONCLUSIONS: It is suggested that the type of regenerating epithelium is determined by the depth of injury to mucosa or gland ducts. If both cell types survive, a mixed pattern of regeneration may occur, but columnar repair will usually predominate because of its more rapid turnover. If the squamous cells of the mucosa and ducts are destroyed, however, repair will be by columnar epithelium alone.