The fine structure of a virilizing human granulosa–theca cell tumor. Observations on the nature of the hormone producing cell

Abstract
The ultrastructure of a virilizing granulosa–theca cell tumor is reported. Although the histologic appearance is characteristic of a granulosa–theca tumor, several tumor cells contain crystalloids of Reinke which have not been associated with sex-cord-stromal tumors, but which are often present in ovarian hilus cells and Leydig cells. The steroidogenic cell in this case displays many fine structural features common to mammalian steroidogenic cells, namely abundant smooth endoplasmic reticulum, a dispersed Golgi, mitochondria with tubular cristae, and lipid droplets. Other features of this cell, which contains crystalloids of Reinke, more closely resemble those of a theca–lutein cell than a granulose–lutein or hilus cell and support a stromal origin. However, this tumor illustrates the striking overlap in morphologic features and function among granulosa, theca, hilus, and Leydig cells.