“…We have been investigating defense cellular reactions, including phagocytosis, in a solitary ascidian, H. roretzi, which occupies a phylogenetical position between vertebrates and invertebrates (Azumi and Yokosawa, 1996). H. roretzi hemocytes undergo various defense reactions, such as phagocytosis (Ohtake et al, 1994), hemocyte aggregation (Takahashi et al, 1994), and a self and non-self recognition reaction (Fuke, 1980).…”