Parameters of hemocyte populations have been considered as relevant
indicators of bivalve health and are currently used in immunotoxicological
studies. Hemocytes in hemolymph can be collected by puncturing either the
pericardial cavity or the adductor muscle sinus with a syringe. Flow
cytometry is a methodological approach that is increasingly being used in
laboratories for the study of hemocyte parameters in aquatic invertebrates.
However, various protocols for hemocyte processing in laboratories equipped
with different types of cytometers have been published. In this context, two
flow cytometers (EPICS XL4®, Beckman Coulter and
FacsCalibur®, Becton Dickinson) and two sites of hemocyte
collection (pericardial cavity and adductor muscle sinus) were compared for
the analysis of hemocyte parameters in the Pacific oyster, Crassostrea gigas. Hemolymph cells
were analyzed in terms of their number and organelle contents. Cell
mortality, phagocytosis, non specific esterase, extension of the lysosomal
compartment and production of reactive oxygen species were quantified. The
results showed that the phagocytic index was higher for hemocytes obtained
in the muscle sinus hemolymph. The results are discussed with respect to the
potential use of flow cytometry as a tool for hemocyte studies in bivalves.