Image: transition in the alimentary tract, from the esophagus to the stomach (cardiac region) of a rat. Staining: hematoxylin-eosin.
Esophagus: posterior part of the esophagus.
Stomach: cardiac region of the stomach.
Esophagus epithelium: it is keratinized stratified squamous epithelium. Rats eat harsh food, that is why there is an upper cornified layer for protection.
Mucosa: it is the outer layer of the alimentary tract, composed of epithelium, connective tissue and a thin layer of smooth muscle cells.
Submucosa: it is a layer of connective tissue found below the mucosa. The submucosa is a highly vascularized layer.
Muscularis: it is a layer of smooth muscle cells found below the submucosa. The muscularis is made up of and inner layer with circularly arranged muscle cells and an outer with longitudinal arranged muscle cells.
Adventitia: it is the outermost layer of the alimentary canal. The adventitia is a thin layer of connective tissue.