Acipenser naccarii: fine structure of the alimentary canal with references to its ontogenesis.

Summary This study was aimed at investigating the anatomy and luminal surfaces of the entire gut of Acipenser naccarii , through optic and transmission and scanning electron microscopy (TEM and SEM). Two-year-old individuals as well as larval and post-larval developmental stages were studied. The results confirm the gross morphology found in the entire genus Acipenser . The presence of numerous ciliated cells in the gastric and intestinal parts of the alimentary canal and a spiral valve show ancient features in these fish. From an aquaculture perspective, observations on the ontogenesis of the digestive system suggest that feeding should start as soon as the connection between oesophagus and stomach is established. Our observations indicate that A. naccarii reach this functional threshold not before the eighth day post-hatching (larval rearing temperature: 21°C). [ABSTRACT FROM AUTHOR]