Ontogeny of the digestive tract in sharpsnout sea bream Diplodus puntazzo (Cetti, 1777)
V. Micale1, A. Di Giancamillo2, C. Domeneghini2, C.C. Mylonas3, N. Nomikos3, I.E. Papadakis3 and U. Muglia4
1National Research Council, Institute for Marine Coastal Environment (CNR-IAMC), Messina, Italy, 2Department of Veterinary Sciences and Technologies for Food Safety, Faculty of Veterinary Medicine, University of Milan, Italy, 3Hellenic Center for Marine Research, Institute of Aquaculture, Iraklion, Crete, Greece and 4Department of Morphology, Biochemistry, Physiology and Animal Production, Faculty of Veterinary Medicine, University of Messina, Italy.
Offprint requests to: Dr. Valeria Micale, Consiglio Nazionale delle Ricerche, Istituto per l’Ambiente Marino Costiero, spianata S. Raineri 86, 98122 Messina, Italy. e-mail: valeria.micale@iamc.cnr.it
Summary. The ontogeny of the digestive tract was studied histologically and histochemically in sharpsnout sea bream Diplodus puntazzo from hatching (0 DAH, Days After Hatching) until day 57 (57 DAH). At hatching, the digestive tract appeared as a histologically undifferentiated straight tube lying dorsally to the yolk sac. When the mouth opened at 3 DAH, the digestive tract was differentiated into buccopharynx, oesophagus, incipient stomach and intestine. The pancreas, liver and gall bladder were also differentiated at this stage and both the bile and pancreatic duct had opened into the anterior intestine. Active feeding began in 50% of larvae at 4 DAH, although permanence of yolk reserves until 7 DAH suggests a period of both endogenous and exogenous feeding. Nutrient absorption was first visible from 5 DAH, as colourless supra- and infranuclear vacuoles in the anterior intestinal mucosa, suggesting a lipid content, as well as supranuclear, eosinophilic vacuoles, containing protein, in the posterior intestinal mucosa. Early caecal development could be detected from 10 DAH, whereas gastric glands appeared at 30 DAH, indicating the transition from larval to juvenile stage and the acquisition of an adult mode of digestion. Goblet cells appeared in the digestive tract of sharpsnout sea bream larvae shortly after first feeding. The mucus content of goblet cells varied with the digestive region and, in the buccal cavity and oesophagus, also with the developmental phase. This study provides knowledge for better husbandry practices in the aquaculture industry, as well as for the implementation of future nutritional studies. Histol Histopathol 23, 1077-1091 (2008)
Key words: Digestive system, Diplodus puntazzo, Larval development, Histology, Histochemistry
DOI: 10.14670/HH-23.1077