C.J. Baglole, H.M. Murray, G.P. Goff, G.M. Wright-1997
Journal of Fish Biology, 51 (1) : 120-134 (from Current Contents)
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.
(Univ Prince Edward Isl, Atlantic Vet Coll, Dept Anat & Physiol, Charlottetown PE C1A 4P3, Canada)
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