Histochemical and ultrastructural observations on goblet cells of the digestive tract of turbot (Scophthalmus maximus).

VIGLIANO, F.A.; QUINTÁNS, L.; BERMÚDEZ, R.; QUIROGA, M.I.; NIETO, J.M.

Foz do Iguaçu, Brasil/Puerto Iguazú, Argentina

Congreso; XV Pan American Congress of Anatomy; 2004

Pan American Association of Anatomy

Literature about the histology of the digestive tract of fish is scarce, and some of them are exclusively focused on ultrastructural studies of particular portions. Goblet cells are a plentiful component in the gastrointestinal tract of turbot. These cells produce mucusubstances of different chemical nature which are related with several digestive functions as digestion and emulsification of food, absorptive and secretory functions. Therefore, the aim of the present paper is the performance of a histological, histochemical and ultrastructural study of the goblet cells of turbot, which allow a better understanding of its chemical nature and function in the gastrointestinal tract of this fish. To carry out this work, 9 healthy turbot, of both sexes, coming from a fish farm (Galicia, Spain) were employed. Necropsy was carried out and digestive tract were extracted and prepared for studies of light and scanning and transmission electron microscopy. The histochemical techniques employed for detection of mucins were periodic acid-Schiff (PAS), Alcian blue (AB), PAS-AB, Aldehyde fuchsin-AB. The existence of significant differences (p lesser than 0.05) in the number of cells in different portions of the digestive tract were assessed by Kruskal-Wallis test. Goblet cells were located in the more superficial strata of the lining epithelium of the digestive tract excepting the stomach. Histochemically, these cells presented neutral and acid mucins in oesophagus, and neutral mucins in the different portions of the digestive tract. Ultrastructurally, they showed a moderate amount of mitochondria, abundant ribosomes, a well-developed rough endoplasmic reticulum with expanded cisternae whit an electron-lucent content, and apical vesicles with different electron-density. Cellular junctions with the enterocytes were frequently seen, as well as the secretion product associated to the outlet of these cells in the lumen of the organ. The number of goblet cells was higher in the oesophagus, with differences statistically significant between this portion and the different areas of intestine (p lesser than 0.01), with the exception of the medium intestine. There were not differences statistically significant between the remaining portions of the digestive tract. The presence of acid mucins in the oesophagus should indicate that digestion process begins in that organ. The existence of neutral carbohydrates throughout all digestive tract should be related with the absorption of easily digestible substances.