RESUMO
The thrombocytes and leukocytes of 'dourado' fish Salminus maxilosus peripheral blood were studied by means of light microscopy and transmission electron microscopy techniques. In respect to the morphological and ultrastructural aspects of thrombocytes and granulocytes, the cellular elements that appear with high frequency in the light microscopy preparations stained by the Rosenfeld method, three different types of granulocytes could be differentiated at the electron microscope, based on the ultrastructural aspect of the cytoplasmic elements: type I granulocyte that possibly corresponds to the type I neutrophil described under light microscopy; type II granulocyte is possibly the cell identified as type II neutrophil by the morphological analysis; type III granulocyte is equivalent to the eosinophils described in the samples stained by Rosenfeld methods.