A COMPARATIVE HISTOLOGICAL AND HISTOCHEMICAL-STUDY OF THE POST-GASTRIC ALIMENTARY CANAL FROM 3 SPECIES OF PLEURONECTID, THE ATLANTIC HALIBUT, THE YELLOWTAIL FLOUNDER AND THE WINTER FLOUNDER

The histology and mucus histochemistry of the pleuronectid post-gastri c alimentary canal was examined using light and electron microscopy. D istinct differences in goblet cell mucus histochemistry were observed between species, with the two closest taxonomic species, the winter fl ounder and the yellowtail flounder showing the most diversity and the halibut showing regional variation. Numbers of goblet cells within pos t-gastric regions did not differ significantly between species, but we re significantly different between regions within species increasing t oward the rectum. The post-gastric region was divisible into two areas based upon the ultrastructural features of lipid digestion and absorp tion in the intestine and pyloric caeca, and of exogenous protein in t he rectum. The combination of species-specific histochemical differenc es in mucus and general histological and ultrastructural differences w ithin the post-gastric regions between these species suggest a correla tion between lumenal environmental conditions/histology and natural pr ey preference. (C) 1996 The Fisheries Society of the British Isles