[Ultrastructure of endodermal sinus tumor of the ovary (author's transl)]

The ovarian endodermal sinus tumor is a relatively rare type of malignant neoplasm. Ultrastructurally, the tumor cells proved to have numbers of ribosomes, glycogen granules and well-developed rough endoplasmic reticulum surrounding the mitochondria. The photomicroscopically visible hyaline globules were observed as round homogeneous non-structural substances both in and outside the cytoplasm. It was surmised that it is synthesized in the rough endoplasmic reticulum. The tumor cells could be classified into three types on the basis of the forms of cytoplasmic organella and intracellular homogeneous spheres. The first type of cell proved to be well-developed cytoplasmic organella, with a few small spheres and a large aggregate of glycogen granules and ribosomes. The second type of cell proved to have extensive non-structural cytoplasm and a number of largesized spheres. The third type was deemed to be of the intermediate type. In other words, it was assumed that morphological changes were responsible for the tumor cells changing from the first type to the second type. A similarity was noted between these ultrastructures and the yolk sac endodermal cells of the very initial stage, therefore the name endodermal sinus tumor was assumed to be adequate.