en <div style="text-align: justify;"><strong>Aims:</strong> Norway rat (<em>Rattus norvegicus</em>) as a laboratory animal is one of the most popular experimental models for research, which has a similar anatomical structure of the body organs compared to a human. This study aimed at histological and histochemical examination of mucous cells in the esophagus and stomach of Norway rats.<br> <strong>Materials & Methods: </strong>In this experimental study, ten healthy adult male rats (<em>R. norvegicus</em>) were anesthetized using an overdose of chloroform and samples were taken from the esophagus and stomach. The tissues were then excised and fixed with 10% formalin for histological and histochemical studies.<br> <strong>Findings: </strong>Light microscopic observations on sections of the esophagus showed walls consisting of four layers; mucosa, submucosa, muscular and adventitia layer or serosa. The surface layer of the epithelium reacted strongly to PAS staining, but the rest of the epithelium had a moderate reaction to PAS in all regions of the esophagus. The submucosa showed a weak reaction to PAS in all regions of ​​the esophagus. The muscularis layer in the cervical, thoracic, and abdominal esophagus regions reacted moderately to PAS; however, the serosa showed a weakly reaction to PAS in cervical, thoracic and abdominal regions<strong>.</strong><br> <strong>Conclusion:</strong> Recognizing the anatomical and histochemical features of different small mammalians as the models of laboratory animals for testing drug absorbance can help understand the probable results in human patients.</div> Norway Rat,Esophagus,Stomach,Histology, 289 304 http://ijwph.daneshafarand.org/browse.php?a_code=A-10-1867-1&slc_lang=en&sid=3 M.K. Hassani 1003194753284600378310 1003194753284600378310 Yes Department of Biology, College of Science, University of Misan, Amarah, Iraq