Surgical correction of cryptorchism at 2 years: electron microscopic and morphometric investigations.

Electron microscopic and morphometric investigations on undescended testicles show a decreased volume density of the spermatogonia up to the age of 5 (approximately 60%, p smaller than 0.005), corresponding to investigations by light microscopy. There are no ultrastructural differences in the seminiferous tubules between normal and undescended testicles up to the age of 1 yr. There are ultrastructural changes of Leydig cells within the first year of life. Based on these investigations, we conclude that the optimal time for surgical intervention in case of undescended testes is in the second year.