Testicular biopsy and hormonal study in a male with Noonan's syndrome.

The testicular biopsy study of a 17-year-old male with Noonan's syndrome revealed seminiferous tubules of reduced diameter with hypospermatogenesis. Many spermatocytes underwent degeneration and many spermatids developed abnormal. The Sertoli cells were similar to immature Sertoli cells. Fully differentiated Leydig cells were rare while precursor Leydig cells were numerous. Both gonadotropin and testosterone levels were low, and a lack of response to LH-RH as well as to clomiphene was found. The testicular biopsy performed at 20 years of age revealed a certain maturation of the seminiferous tubules which increased the germ cell number. The abnormalities in the spermatogenesis as well as the immature appearance of Sertoli cells continued. Leydig cells were more numerous and showed a certain development without reaching the normal pattern. Gonadotropin levels were normal while testosterone levels low. The response to LH-RH was increased and the absence of response to clomiphene persisted. These features suggest a delayed puberty.