Effect of cryptorchidism on testicular histology in a naturally cryptorchid animal model.

Purpose: To determine the effect of naturally occurring cryptorchidism on testicular histology in both the cryptorchid and normally descended testis from birth to adulthood using the LE/ORL rat model.
Materials and Methods: Testicular histology was assessed using established morphometric measures in bilaterally descended (BD), unilaterally descended (UD), bilaterally cryptorchid (BC) and unilaterally cryptorchid (UC) testis at days 15, 22, 30, 45 and 60 of age. Testicular mass was also measured at these times.
Results: Changes in testicular histology in the BC and UC testes were not noted on or prior to day 30 of age. Significant changes were noted by day 45 of age and continued into adulthood at day 60 of age. There were no histological abnormalities noted in the UD and BD groups.
Conclusions: Since histological changes seen in this animal model occur after the time of testicular descent (day 28 of age), we hypothesize that these changes are due to an abnormal anatomical position of the testis as opposed to an inherent testicular defect in the LE/ORL rat. This hypothesis is supported by the fact that no histological differences were noted between the scrotal testes of unilaterally cryptorchid animals and bilaterally descended control animals.