GILLS OF THE FRESH-WATER FISH HYPOSTOMUS-COMMERSONII VAL., 1840 (LORICARIIDAE) ANALYZED THROUGH ELECTRON-MICROSCOPY TECHNIQUES

The superficial morphology of the gill filaments and branchial pharyng eal region of the freshwater fish Hypostomus commersonii was studied t hrough scanning and transmission electron microscopy techniques. Two r ows of long and elaborate rakers cover great part of the branchial fil aments. Spines and taste buds were not found. The food selection proba bly happens passively through the rakers projections and with the help of abundant mucous secretion. The rakers morphology and positioning, as well as the mucous secretion present on all branchial arch (except on the respiratory lamellae), protect and favor the secondary lamellae respiratory function.