Microscopic gonadoblastoma in dysgenetic gonad of an infant: an ultrastructural study.

A microscopic gonadoblastoma found in the dysgenetic gonad of a six-month-old phenotypic female with a 46,XY genotype was studied with the electron microscope and compared with the cells from the testicular portion of the contralateral gonad. The germ cells within the tumor resembled the testicular germ cells and were not different from previously described germ cells in other gonadoblastomas of postpubertal patients. The sex cord cells of the present tumor were inactive and immature, but differed from the Sertoli cells of the patient's testis. The presence of hyalin globules and Call-Exner bodies in the epithelial tumor nests, coupled with the ultrastructural appearance of the sex cord cells is more consistent with them being immature granulosa rather than Sertoli cells. The immaturity of the sex cord cells in gonadoblastoma of this infant suggest that they are responsive to normal regulatory hormonal influences.