The ontogeny of the alimentary tract of larval pandora, Pagellus erythrinus L.
Abstract:The ontogenesis of the alimentary tract and its associated structures (liver, pancreas, gall bladder) was studied in common pandora Pagellus eythrinus L., a promising species for diversification in Mediterranean aquaculture. Mass production of pandora has been limited so far by high larval and juvenile mortalities, which appear to be related to nutritional deficiencies. The development of the larval digestive system was studied histologically from hatching (0 DAH) until day 50 (50 DAH) in reared specimens, obtained by natural spawning from a broodstock adapted to captivity. At first feeding (3–4 DAH) both the mouth and anus had opened and the digestive tract was differentiated in four portions: buccopharynx, oesophagus, incipient stomach and intestine. The pancreas, liver and gall bladder were also differentiated at this stage. Soon after the commencement of exogenous feeding (5–6 DAH), the anterior intestinal epithelium showed large vacuoles indicating the capacity for absorption of lipids, whereas acidophilic supranuclear inclusions indicating protein absorption were observed in the posterior intestinal epithelium. Both the bile and main pancreatic ducts had opened in the anterior intestine, just after the pyloric sphincter, at this stage. Intestinal coiling was apparent since 4 DAH, while mucosal folding began at 10 DAH. Scattered mucous cells occurred in the oral cavity and the intestine, while they were largely diffused in the oesophagus. Gastric glands and pyloric caeca were firstly observed at 28 DAH and appeared well developed by 41 DAH, indicating the transition from larval to juvenile stage and the acquisition of an adult mode of digestion.
Document Type: Research Article
Affiliations: 1: Consiglio Nazionale delle Ricerche, Istituto per l’Ambiente Marino Costiero, sezione di Messina spianata S. Raineri 86, 98122 Messina, Italy; 2: Dipartimento di Sanità Pubblica Veterinaria, Facoltà di Medicina Veterinaria, Università di Messina – Polo Universitario Annunziata, 98168 Messina, Italy; 3: COISPA Tecnologia & Ricerca, Via dei Trulli 18, 70045 Bari -Torre a mare, Italy; 4: Dipartimento di Morfologia, Biochimica, Fisiologia e Produzioni Animali – Facoltà di Medicina Veterinaria, Università di Messina – Polo Universitario Annunziata, 98168 Messina, Italy).
Publication date: December 1, 2004