Rodlet cells in the digestive tract of turbot (Scophthalmus maximus): histological and ultrastructural analysis.

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

Rodlet cells have been described in teleost fishes, related with unspecific immune response function. In the present study, we described the morphology of these cells and their distribution in the digestive tract of turbot in order to contribute to their function knowledge and to establish normal parameters to be used as basis for the study of several digestive diseases in this specie. Ten healthy turbot were used. Different portions of digestive tract were dissected out, fixed and processed using conventional techniques for their study by light and electron microscopy. Hematoxilin-eosin, PAS-Alcian blue and Jones? Metenamine (JM) stains were carried out on paraffin sections. 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. The morphology of rodlets cells was similar in different portions of the digestive tract, even though their number increased from cranial to caudal portions. There were differences statistically significant only between stomach and posterior gut (p lesser than 0.001) and pyloric caeca and posterior gut (p lesser than 0.001). These cells showed oval to round-shape, with a bright cytoplasm which presented elongated PAS and JM positive granules. A clear cytoplasmic polarity was observed with the rough endoplasmic reticulum, the Golgi complex and the nucleus in a basal location, and their granules and abundant mitochondria in the apical zone. Below plasma membrane a weak PAS-positive capsule were observed, which had filaments similar, by their size and structure, to those of actin and myosin of the smooth muscle cells. Sometimes, rodlet cells were seen in contact with the lumen of the organ by means of a citoplasmic projection with their fibrous capsule disintegrated and a reduction in the number of cytoplasmic granules. The presence of a capsule with a putative contractile property and the cellular polarization observed suggest that rodlet cells could develop their immune function through the secretion of their granules.