Evaluation of testicular hCG binding in unilaterally cryptorchid rats following administration of ethane dimethane sulphonate (EDS).

Administration of ethane dimethane sulphonate (EDS) (75 mg/kg) to unilaterally cryptorchid rats, results in a rapid decline in serum testosterone levels and a marked reduction in hCG binding to homogenates of scrotal and cryptorchid testes, consistent with the destruction of Leydig cells within the testes as shown by morphological and morphometric analysis. Between 3 and 7 days after EDS, serum LH and FSH levels rise, LH to levels found in castrate rats. hCG binding begins to recover in scrotal testes, reaching 32% of control values 28 days after EDS. However, the recovery of hCG binding to cryptorchid testes is more rapid, reaching 51% of control levels by 21 days which coincides with the re-establishment of serum testosterone to normal levels. Since a different rate of recovery is observed for hCG binding to scrotal and cryptorchid testes, and both testes are exposed to the same circulating levels of LH and FSH, the likely stimulus for recovery of hCG binding and regeneration of Leydig cells is intratesticular in origin. This supports the concept that local factors, released following damage to the seminiferous epithelium by cryptorchidism, play a role in the differentiation and growth of Leydig cells within the testis.