Ultraestructura citohematológica de la trucha arco iris <i>Oncorhynchus mykiss</i> (Salmoniformes: Salmonidae)

Abstract

Peripheral blood samples from five adult specimens of rainbow trout (Oncorhynchus mykiis) from an introduced population cultured in the Neusa's Experimental Fish Hatchery (73°38'28" W; 5°8'30" N) were studied with the electron microscope. The blood was fixed in 3% buffered glutaraldehyde, followed by 1 % buffered osmium tetraoxíde, dehydrated In ascending alcohols, and embedded in resines. Cells observed were erythrocytes, Iymphocytes, monocytes, polímorphonuclear leucocytes (PMN) and plateletes. Erythrocytes had picnoúc nucleus, políribosomes and mitocondria; Iymphocytes were of two types acording to nuclear morphology, one with roundéd nucleus and other with indented, notched nucleus. Both had dense cytoplasm without membranes, ribosomes, and mitocondria gathered in clumps of 5 or 6 located in a paranuclear posiúon. Monocytes presented an iregular nucleus and a cytoplasm with ribosomes and granules of variable density, grouped with mitocondria along the concave face of the nucleus. PMN have lobated nucleous, numerous dense granules rounded and elípsoid granules of diferent sizes concentrated towards the notched nuc1eous, were abundant mitocondria are also present. Plate1ets were occasionally seen as vacuolated non nucleated cells with small, oval dense granules. The results are similar to those of temperate populations.