Ultrastructure of the testis in Klinefelter's syndrome.

The ultrastructure of the testis in 5 cases of Klinefelter's syndrome was studied. In 3 cases there was complete hyalinization of the seminiferous tubules. In one case Sertoli cells were present, and in another case focal areas of spermatogenesis were seen in the tubules. Hyperplasia of the Leydig cells was found in every case. The Leydig cells had usually abundant smooth endoplasmic reticulum and lipofuscin pigment in the cytoplasm. This suggested that the function of the Leydig cells was normal. The Sertoli cells contained lipid droplets and glycogen-filled vacuoles in the cytoplasm.