ANÁLISE HISTOLÓGICA, HISTOQUÍMICA E ULTRAESTRUTURAL DA MUSCULATURA DORSAL E VENTRAL DO GUARU (Poecilia vivipara BLOCHI & SCHNEIDER, 1801)

Poecilia vivipara (guaru), a neotropical, small, euryhaline fish, has been being used as a biomonitor. Dorsal and ventral muscles of Poecilia vivipara were analyzed to standardize methodologies for evaluating the normal tissue structure, in order to use them in toxicity studies. Thus, chemical and physical fixations were carried out, aiming at the histological and histochemical procedures of staining and reaction. The methods HE and MT revealed the organization of SSMF with epiaxial and hypaxial muscle bundles and associated conjunctive. MA marked the SSMF and facilitated the observation of sarcomeres in the presence of a thin metacromatically stained band. Part of the SSMF was positive PAS and reactive amylase, indicating the distribution of glycogen within the fibers. In the presence of SBB the fibers were reactive mainly in the dorsal region, indicating the presence of lipids. Cells with mitochondrial enzyme-rich cytoplasm were found in SDH pH 10.5. The SSMF stained with AT were arranged in alternating transverse bands, which correspond to the pattern seen under the MET. The use of these methodologies allowed the indication of Poecilia vivipara muscles as a tool for environmental variations studies, because its normal structure is standard in teleosts. KEYWORDS: Morphology, muscle fiber, neotropical fish.