NEGATIVE SURFACE CHARGE OF ABNORMAL HUMAN TROPHOBLAST

In order to characterize the negative surface charge of the abnormal human trophoblast and to cast light on its biological role, the negative charges on the trophoblastic surface of spontaneous abortion, partial mole and complete mole were investigated by electron microscopy using cationized ferritin as an ultrastructural marker. The degree and distribution of negative charge were also studied in comparison with surface ultrastructure and surface glycoprotein identified by ruthenium red staining. In a case of spontaneous abortion, the surface structure of the human trophoblast differed from site to site, correlating best with the degree of degeneration of the syncytiotrophoblast itself. For villi from a spontaneous abortion, which were otherwise normal in routine electron microscopy, the surface glycoprotein was observed to make prominent aggregates on the trophoblastic surface in concomitance with the reduced negative surface charge. In a severely degenerated system, the basic structure of the surface glycoprotein was lost in accordance with significant decrease of the negative surface charge. This finding seems to show the possible role of the negative surface charge of the trophoblast, that with the electrostatic repulsive forces, the membrane-bound glycoproteins can maintain their normal regular positions and, as a result, membrane specificity of the trophoblast can be expressed. When both complete hydatidiform mole and partial mole were observed by electron microscopy using ruthenium red staining and cationized ferritin, the complete mole differed essentially from the partial mole in that the former resembled normal villi while the latter resembled spontaneous abortion.