abnormal mucosa in esophaguserythematous mucosa in esophagusgastric mucosa in esophagusnormal mucosa in the whole esophagusectopic gastric mucosa in esophagusoesophagus mucosamucosal lining of esophagusbarrett's mucosaoesophagus barretts mucosanormal esophageal mucosaesophageal squamous mucosadistal esophageal mucosa