Cytochemical localization of vanadium(III) in blood cells of ascidian Phallusia mammillata Cuvier, and its relevance to hematic cell lineage determination.

When the blood cells of ascidians Phallusia mammillata are stained with the ligand 2,2'-bipyridine, those cells which contain vanadium(III), in an easily sequestered form, take up the stain producing in situ, a purple complex. This material extracted displays spectral characteristics consistent with the formation of an oxo-bridge vanadium(III) bipyridine dimer. The staining is localized in the signet ring cell, a bivacuolated cell, a cell type with numerous darkly staining compartments, and also by the vacuolated amoebocyte. The possible ramifications of these observation are discussed in relation to the delineation of the signet ring cell lineage.