Mucous gland metaplasia in the esophagus and gastric mucosa in baboons

Background: Chewing of regurgitated food elicits in baboons life-long gastro-esophageal reflux (GER). The acid reflux transforms the multilayered squamous cell epithelium of the esophagus into columnar-lined mucosa with mucus-producing accessory glands. The function of this mucous gland metaplasia (MGM), which mimics Barrett's mucosa with MGM in humans, is to buffer the gastric acid entering the esophagus during regurgitation. In a previous study of entire esophagi, the majority of baboons showed MGM. The gastric mucosa was not investigated. Materials and methods: Hematoxylin-eosin-stained sections from the esophagus, from the lesser gastric curvature and from the greater gastric curvature were collected separately from 50 adult baboons. The presence of MGM was assessed in each one of these locations. Results: MGM was demonstrated in 92% (46/50) of blocks from the esophagus, in 98% (49/50) of blocks from the lesser curvature and in 90% (45/50) of those of the greater curvature (fundus). Conclusion: The majority of the animals had MGM, not only in the esophagus but also in the proximal gastric mucosa. Rationally, MGM in baboons starts in the distal esophagus and proceeds downwards, towards the proximal stomach. The histogenesis of the MGM in Barrett's mucosa in humans (that is Barrett's mucosa type 2) remains elusive. Therefore the baboon might be an important animal model for studying the histogenesis of Barrett's mucosa with MGM in humans, a recognized pre-cancerous lesion.