Histological development of the long-snouted seahorse Hippocampus guttulatus during ontogeny

RADAELLI G.; DÍAZ AO; OFELIO CLAUDIA; PLANAS M.

JOURNAL OF FISH BIOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2018 vol. 93 p. 72 - 87

0022-1112

Sygnathids are agastric teleosts which no stomach, relying on a the digestive tract using different mechanisms to process and absorb nutrients. This results in a low digestion efficiency, forming a mayor bottleneck in the rearing of these fish. In agastric species, the numerous goblet cells present in the oesophagus could be considered as a morphological adaptation that replaces a functional stomach, although the specialization and number of these cells is species-specific and vary throughout the ontogenetic development and intestinal region. Goblet cells appeared in the digestive tract of Hippocampus guttulatus from birth on, secreting a large amount of acid and neutral glycoconjugates (GCs) released in the buccopharyngeal cavity and oesophagus, while sulphated and neutral GCs are detected throughout the complete digestive tract of the seahorses. The midgut mainly secretes neutral GCs in the early stages (< 15 days after birth, DAB) and acid GCs in more advanced stages, while the hindgut was characterized by the presence of acid GCs throughout the development. A change in the type of GCs observed in the midgut from 15 DAB is in correspondence with an increased intestinal absorptive surface, as quantified using 3D reconstructed µCT data. This change, associated with an increase in the intestinal absorption surface, could explain the better digestive efficiency observed in seahorse juveniles from that age.