A study of the histology and morphology of the digestive tract of the sea‐bream, Sparus aurata

The anatomy and the histology of the digestive tract of young and adult sea‐bream is described from studies using light and scanning electron microscopy. The dentition in the juvenile (25–30 mm long) comprises all canine‐like teeth, to which plate teeth and transition elements are added in the adult. The oesophagus shows a multi‐layered mucosa in the upper part, and single‐layered regions in the lower part. The multi‐layered regions are formed by epithelial cells, mucus‐secreting cells and by cells rich with eosinophilic granules. The Y‐shaped stomach, clearly distinguishable, has a single‐layered columnar epithelium under which, in the cardiac and fundic portion, gastric glands, comprised of all similar cells, are present. The pyloric region is characterized by four caeca, to the base of which the ductus pancreaticus and the ductus hepaticus discharge. The pancreas is composed of small masses spread along the upper intestine; in the adult, pancreatic infiltrations can be seen in the liver. The intestine is short (relative length 0.5–0.6). The intestine epithelium consists of columnar cells intercalated with mucus‐secreting cells. A funnel‐like valve marks the passage to the intestine terminal region, characterized by a mucosa of cells with an abundance of vacuoles full of eosinophilic granules.