First morpho-functional characterization of Anemonia viridis amoebocytes: a light microscopy study

For the first time, we studied the morpho-functional characteristics of amoebocytes of the sea anemone Anemonia viridis. A histochemical approach was adopted and two subpopulations of amoebocytes from mesoglea were observed: granulocytes and hyalinocytes. Granulocytes showed a high number of cytoplasmatic granules, while hyalinocytes had no or few granules. Amoebocytes showed both round and spreading shapes and were divided in basophil, neutrophil or acidophil cells. Amoebocytes actively phagocytized yeast cells and produced superoxide anion. The presence of hydrolytic enzymes in amoebocytes was also investigated. Positive cells to acid phosphatase, acid esterase and non-specific esterase were found, with granulocytes and hyalinocytes that did not show different responses in term of positivity. Although preliminary, the results of this study can help to understand the features and immune role of A. viridis amoebocytes and the development of defense strategies in multicellular organisms. Moreover, this study lay the foundations for future more in-depth studies, including those at the ultrastructural level.