A new experimental inbred Wistar rat varicocele model: anatomy of the left spermatic vein and the effect on histology.

Because of venous anatomical differences between rats and humans and the personal interpretation of these differences, there is neither consistent animal prototype nor consistent results in the study of varicocele. We established a new substrain of Wistar inbred rats, of which the left testis vein has no significant branches to the common iliac vein up pampiniform plexus, but instead enters the left renal vein directly (similar to humans) and used them to create experimental varicocele model by partial ligation of the left renal vein. One month later, the predominant lesion of the left testis in induced group was spermatogenic arrest at the spermatid and preliminary spermatocyte phases, and considerable interstitial and Sertoli cell vacuolation. The right testis also showed spermatogenic arrest. Most important, the characteristics of the lesions differed in both testes, with the left testis having more severe lesions. Allowing for the unique anatomy of the left spermatic vein, the standard of the surgical procedure, the high rate of varicocele induction, and identical histological alteration as occurs in humans, we believe that this inbred Wistar rat substrain is suitable for the creation of an experimental varicocele model, which has promise for practical application in humans.