The ultrastructural response of human Leydig cells to exogenous estrogens.

The effect of long term treatment with estrogens alone or along with medroxyprogesterone acetate on the Leydig cell ultrastructure was studied in testes from males undergoing surgery for sexual reassignment. The testes were fixed for electron microscopy by a perfusion method to insure uniform preservation. The morphological features were not the same in all the treated testes. Therefore, the cells found in the intertubular region were classified into three groups: (A) Leydig cells very similar to controls; (B) Absence of typical Leydig cells, but with cells having increased microfilaments, abundant smooth endoplasmic reticulum and some lipid droplets; (C) Absence of any cell type possessing abundant smooth endoplasmic reticulum, but having varying amounts of microfilaments and pigmentation. It is suggested that some of the cell types found in the intertubular region are dedifferentiated Leydig cells. This study indicates that the human testis from transsexuals of reproductive age is an appropriate model to study the indirect and direct effects of estrogens on the ultrastructure of cell types found in the human testes.