Fertility and unilateral undescended testis in the rat model III: ultrastructural changes in the contralateral descended testis.

Fertility is decreased in rats with experimentally-created unilateral undescended testis (UUDT). Although light microscopy has shown changes in the UDT, it has consistently failed to demonstrate any significant damage in the contralateral descended testis (CDT) of these animals in previous experimental studies utilizing the same model. To study the ultrastructural details of the CDT and the ipsilateral UDT using transmission electron microscopy (TEM) in rats with experimentally-created UUDT, in Wistar albino rat pups UUDT was experimentally created in accordance with the model described previously. Ten rats with UUDT were compared with 10 control rats. The UDT and CDT were harvested at 135 days of age and sections from specimens studied by TEM for changes in the seminiferous tubules, Leydig cells, and extracellular matrix. All observations were graded and analyzed for statistical significance. TEM of the testes of control rats was normal, while both the ipsilateral UDT and the CDT showed significant changes. Significant changes in the CDT included thickening of the basement membrane ( P=0.001), a decrease in spermatogenic cell lines ( P=0.02), vacuolation ( P=0.0001) and other features of degeneration ( P=0.02), single cell apoptotic figures ( P=0.02), and an increase in Sertoli-cell numbers ( P=0.01), size ( P=0.01), and endoplasmic reticulum ( P=0.01). Another significant feature was the occurrence of morphologic sperm abnormalities in the form of tail denudation ( P=0.02). The surgically-created UDT showed changes of gross degeneration and atrophy. TEM studies thus revealed gross ultrastructural damage to the UDT and similar subtle but significant changes in the CDT. These may explain the decrease in fertility in rats with UUDT.