Juveniles of Odontesthes argentinensis were collected from Mar Chiquita coastal lagoon, Argentina. The morphology of the gills was analyzed by scanning electron microscopy. The surface of the filaments and the pharyngeal region of the gill arch were covered by a mosaic of polygonal epithelial cells with apical concentric microridges. The apical crypts of mitochondria-rich cells were mainly found in the trailing edge of the filament epithelium and in the interlamellar surfaces. Glycoconjugates (GCs) elaborated by the secretory cells in the epithelium covering the gill filaments and the pharyngeal region of O. argentinensis were studied by means of a series of carbohydrate histochemical methods. Mucous cells among the lining epithelium of the pharynx showed a histochemical profile similar to that of mucous cells of filaments and secondary lamellae. Mucous cells showed the presence of neutral, sulphated, carboxylated and sialylated GCs. Glycoconjugates secreted on the surface of the gills could be associated with different functions such as lubrication, ionic regulation and inhibition of pathogen proliferation.

Fil: Tano de la Hoz, María Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina

Fil: González Castro, Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina

Fil: Díaz, Alcira Ofelia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina

Fil: García, Alicia Mabel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina