Immunolocation of phenoloxidase in vacuoles of the compound ascidian Botryllus schlosseri morula cells

Using a polyclonal antibody raised against purified phenoloxidase from the colonial ascidian Botryllus schlossen, we studied its distribution among haemocytes and its intracellular location. The enzyme is present inside granular amoebocytes and morula cells, thus confirming the close relationship between the two cell types, as suggested by previous histochemical and histoenzymatic analysis. Immunocytochemistry in both light and electron microscopy shows that phenoloxidase is located inside the vacuoles of morula cells, known to be the effectors of the rejection reaction.