Digestive tract

Cypriniformes

Ecology

Biology

Fish <Actinopterygii>

Chromatography

Fishery

Endocrinology

Hatching

Actinopterygii

Digestion (alchemy)

Larva

Midgut

Cyprinidae

Anatomy

Internal medicine

Medicine

Chemistry

Ontogeny

Zoology

Hindgut

Italian Journal of Zoology

The development of digestive tract and accessory glands in Hamun mahi (Schizothorax zarudnyi, Family: Cyprinidae) from hatching to 21 days after hatching (DAH) is described in this study. This information is critical for evaluating the digestive tract functional capacity and physiology of digestion in larvae, and designing optimal rearing techniques and artificial diets for this commercially valuable species. Based upon its feeding mode and structural changes in the digestive tract, larval ontogeny in S. zarudnyi was divided into three stages, Stage 1: 0–2 DAH, Stage 2: 3–8 DAH and Stage 3: from 9 DAH onwards. As in most teleosts, Hamun mahi at hatching had an undifferentiated digestive tract. The most critical ontogenetic events occurred at Stage 2. At the beginning of Stage 2, mouth opened in conjunction with the differentiation of the digestive tract. During Stages 2 and 3 the gut differentiated, and buccopharyngeal cavity, oesophgus and incipient intestine became distinguishable. At this stage digestive tract processes continued to develop (e.g. entrocyte’s brushborders, appearance of digestive mucous cells at 4 DAH, and gut mucosal folds). The first taste buds and pharyngeal teeth appeared at the beginning of Stage 2. Histological observations suggest that digestive tract development of the Hamun mahi larvae, involving the presence of functional liver (vacuolated hepatocyes), exocrine and endocrine pancreas, and gallbladder enabled early larvae (from 3 DAH) to ingest, digest and assimilate the first exogenous food, even before endogenous reserves were completely resorbed. From Stage 3 onwards, most organs essentially exhibited an increase in tissue structure, size and number.

Early ontogenetic development of digestive system in<i>Schizothorax zarudnyi</i>Nikolskii, 1897 (Actinopterygii: Cyprinidae) larvae

Early ontogenetic development of digestive system inSchizothorax zarudnyiNikolskii, 1897 (Actinopterygii: Cyprinidae) larvae