Ontogeny of the digestive tract during larval development of yellowtail flounder: a light microscopic and mucous histochemical study

Abstract

The histological development and mucous histochemistry of the alimentary tract in larval yellowtail flounder were studied using light microscopy. Samples were taken when the larvae were first offered food at 3 days post-hatch, then at 7, 10, 29, 36, and 46 days post-hatch, at which time they were metamorphosing. Regional partitioning of the digestive tract into the buccal cavity, pharynx, oesophagus, post-oesophageal swelling (PES), intestine, and rectum was complete by day 10. Goblet cells were present only in the buccal cavity, pharynx and intestine by day 7, but increased in number and distribution as development continued. By day 29, the posterior zone of the oesophagus had a marked increase in goblet cell density and mucosal folding. At the transition from oesophagus to PES/stomach stratified epithelium with goblet cells changed abruptly to a columnar epithelium with no goblet cells. Multicellular glands in the PES of 36-day larvae allowed it to be defined as a stomach. The distinct brush border of columnar epithelium and the presence of goblet cells characterize the intestine and rectum. All goblet cells throughout the digestive tract were strongly positive for acid mucins as was the luminal layer of the stratified epithelia lining the buccal cavity, pharynx and oesophagus. The PES/stomach epithelium stained weakly for neutral mucins. No mucin staining was associated with the gastric glandular epithelium. The brush borders of the intestine and rectum were strongly positive for combinations of neutral and acid mucins.

Comparative Ontogeny of the Digestive Tract in Sharpsnout Sea Bream Diplodus puntazzo Cetti and Common Pandora Pagellus erythrinus L

“…In D. puntazzo, gastric glands occurred only in the fundic region of the stomach, as was also shown in the yellowtail flounder Pleuronectes ferruginea [39], the summer flounder Paralichthys dentatus [40], the turbot Scophthalmus maximus [41] and the Dover sole Solea solea [42]. On the other hand, gastric glands were only found in the cardiac region in D. sargus [10], shi drum Umbrina cirrosa [28] and red porgy P. pagrus [37], whereas an entirely glandular stomach occurs in common pandora.…”

“…Glycoproteins produced by goblet cells may play an important lubricant role of the buccopharyngeal and oesophageal mucosa, which lack salivary glands. Mucosubstances may also play a role in protecting the digestive mucosa from bacterial and viral attacks [11], as well as in pre-gastric digestion [39]. The mucous content of goblet cells in sharpsnout seabream varied with the digestive region and, in some cases, with the developmental phase.…”

Estudio histologico e histoquimico de la organogenesis del tubo digestivo de Rhamdia quelen en condiciones de larvicultura intensiva

“…Diferenciaciones similares fueron halladas en otras especies (Baglole et al, 1997;Mangetti, 2006;Jaroszewska & Dabrowski, 2008). En el epitelio del esófago de otras especies se observaron células mucosas conteniendo mucinas neutras, ácidas y mixtas (Sarasquete et al, 1995;Ostaszewska, 2005;Yang et Figura 5.…”

Effect of rearing temperature on larval growth and the development in different tilapia species

“…Mucus secreted in the digestive tract is the first protective barrier against mechanical, physical and chemical factors as well as against infections (Morrison and Wright 1999;Yashpal et al 2007). Numerous PAS positive mucous cells appeared along the digestive tract, suggest that, these cells play an important role in pregastric digestion in larvae (Baglole et al, 1997).…”