Cytometric investigations on hemocytes of the American oyster, Crassostrea virginica

Pericardial hemolymph was obtained from American Oysters (Crassostrea virginica) and the hemocytes characterized by flow cytometry. The cells were found to have a broad unimodal size distribution with a median diameter of 7 micrometers. Total protein measured by flow cytometric fluorescence of dansylated cells also revealed a broad unimodal distribution similar to that obtained for size. The proportion of hemocytes in each stage of the cell cycle was measured using DNA-specific DAPI fluorescence. Histograms showed a single peak representing the G(0)/G(1) population. There was no evidence of S or G(2)+M phases of the cell cycle, nor was polyploidy seen. The forward and orthogonal light scatter of fixed hemocytes showed no evidence of sub-populations on the basis of cytoplasmic granularity. Thus, in terms of these parameters, oyster hemocytes appear to represent a single population exhibiting graded cellular differences.