Light and Electron Microscopic Observations on the Peripheral Blood Cells of Yellow Catfish,Pelteobagrus fulvidraco(Bagridae: Teleostei)

Earth-pond-reared adult yellow catfishwere fully recovered in the indoor laboratory recycle system and usedto examine the normal haematological features of yellow catfish(Pelteobagrus fulvidraco) by both light and transmission electron microscope(TEM).Erythrocytes,thrombocytes,lymphocytes,neutrophilsand monocytes were identified in blood smears and confirmed by TEM.Immature erythrocytes and occasionally dividing erythrocytes were also present in smears.The thrombocyteswere the most abundant cell type after erythrocytes,representing 78% in differential leucocyte counts(DLC).The lymphocytes constituted 17.5% in DLC and had the highest nuclear:cytoplasmic ratio of all the leucocytes observed.A unique lymphocyte that was morphologically similar to the channel catfish non-specific cytotoxic cells(NCCs)was observed.Neutrophils,the only type of granulocytesidentifiedin yellow catfish,had the largest mean cell diameter of all leucocytes and constituted 3.7% in DLC.The only type of the specific granules in the neutrophils contained fibrillous material and were ovoid or rod-like in shape.Monocytes represented less than 1% in DLC.