Tunichrome content in the blood cells of the tunicate, Ascidia callosa Stimpson, as an indicator of vanadium distribution.

Morula, compartment, signet ring, orange, lymphocyte and amoebocyte (granular and agranular) cells have been identified in the blood of A. callosa; in addition, nephrocytes have been described. Blood cell lysates contain a yellow chromogen with spectrophotometric and fluorimetric properties similar to tunichrome. The fluorescent characteristics of each of the seven blood cell types were determined using microspectrofluorimetry. Vanadium in A. callosa blood cells is primarily associated with tunichrome extracts, although lesser amounts are measurable in blood plasma and blood cell residues; both vanadium and tunichrome concentrations are in the order morula greater than compartment greater than signet ring cells.