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

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