S.E.M. and cytofluorimetric characterization of Dinocras cephalotes haemocytes (Plecoptera, Perlidae)

Haemocytes of the stonefly Dinocras cephalotes have been characterized by light and scanning electron microscopy (SEM), adherence to a plastic surface, and phagocytosis of latex particles. Haemocytes appear to consist of at least two cell populations: granulocytes and plasmatocytes, which can be distinguished by morphological and functional criteria. Morphologically, granulocytes are rounded and vesiculated, while plasmatocytes have an irregular shape, with many filopodia, and a slightly vesiculated content. Culturing haemocytes "in vitro" resulted in the spreading onto the surface of an adherent population (plasmatocytes), and in a loosely attached population (granulocytes). Phagocytosis assay showed the capacity of D. cephalotes plas- matocytes to engulf exogenous particles. Haemocytes of adults and nymphs of D. cephalotes were also analysed by flow cytometry and compared with those of Perla grandis, another species of Perlidae. We observed a slight difference in haemocyte morphology among nymphs and adults, and a shift of cell popula- tions was also detected.