| Abstract: | Ultrastructural studies of Ascidia malaca blood reveal particular cell types, which are characterized by a polymorphism in the organization of the electron dense cytoplasmic material. A new pathway of morula cell differentiation is suggested. X-ray microanalysis shows that vanadium is localized in vacuolated, granular and morular cells. Iron, which is accumulated by this species to a lesser degree than vanadium, is found in vacuolated amebocytes and, together with vanadium, in granular cells. Our results are discussed in the light of the relations between selective metal absorption in blood cells and their specialization and differentiation. |
