Vascular anatomy of experimentally induced left varicocele in the rat.

A variety of techniques have been used by various investigators to study the effects of experimentally induced left varicocele in the rat model. It has become apparent that information about the vascular anatomy of this condition in the rat is deficient, though such information could be important to understanding the model. We have examined the left and right venous architecture serving the testes in rats with and without experimentally induced left varicocele. The left spermatic vein has four consistent collaterals that are tributary to the left iliac vein. The right spermatic vein does not have these consistent collaterals, but many times a collateral develops from the right spermatic vein to either the right iliac vein or the distal part of the caudal vena cava. When this occurs, the remaining length of the right spermatic vein becomes a minor effluent vessel. Eleven irregularly observed vessels were identified, none of which existed on the left and only two of which were observed on the right. Experimentally induced left varicocele is associated with dilatation of the left spermatic vein and all collaterals to the left iliac vein. The condition does not cause dilatation of the right venous system, but one collateral was identified that communicated between the left and right sides via the vesicular plexus. It is speculated that the differences between left and right sides in the number of consistent collaterals might be due to the patterns of embryologic development, which differ somewhat between the left and right spermatic veins.