[Light and electron microscopic observations on endodermal sinus tumor of the ovary]

The results of light and electron microscopic studies of the endodermal sinus tumor of ovary are presented. Although histologic features of the tumors appeared to be much varied, ultrastructurally all tumor cell seemed to show changes essentially of the same nature. The histogenesis of endodermal sinus tumor production of AFP by the hyaline globule and the basement membrane-like substance present only in this type of tumor, are discussed. The results of the present study support the view that the tumor originate from the embryonal yolk sac cells.