LAUSR

Hemocyte populations from the ascidian Ciona robusta, separated through a Percoll discontinuous density gradient, are further characterized by May-Grünwald-Giemsa staining and a cytochemical reaction for phenoloxidase. Variability in cell density, acidophilic property and phenoloxidase activity suggest multiple hemocyte type populations, cell lineages and morphotypes that may be involved in distinct cellular responses. Therefore, unilocular refractile granulocytes, typical of this ascidian species, enriched in a fraction separated from the hemolymph show in vitro phenoloxidase-dependent cytotoxic activity against mammalian erythrocytes and a tumor cell lineage, in addition the properties listed above indicate relationships with vacuolated signet ring cells. Finally, bromo-deoxyuridine with, diamino-phenylindole fluorescent reaction and May-Grünwald-Giemsa staining show that in the hemolymph there are hyaline amoebocytes and granulocytes with potential proliferating activity. Present findings and reviewed images of previously reported inflammatory hemocytes in the tunic and pharynx allow us to speculate on theoretical outlines of hemocyte differentiation pathways.