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Description: Image of the pampiniform plexus, the arteriovenous network formed by the testicular artery and the testicular vein near the testis. Image was taken during a dissection of a bull after the left rear leg and the scrotum had been removed to reveal the testes and left spermatic cord. Part of the visceral layer of the tunica vaginalis distal to the testis has been removed to expose a portion of the pampiniform plexus. In most mammals the testicular vein and testicular artery form the pampiniform plexus, an extensive network of intimate contact between the artery and vein. This plexus resembles the arteriovenous plexus at the base of the ovary in many mammals such as ewes (NAL #4754) and cows (NAL #4759). As one consequence of the pampiniform plexus, testosterone in the venous effluent is transferred across the pressure gradient into the arterial supply to the testis. Thereby, testosterone concentrations in the arterial blood arriving at the testis are greater than in the aorta supplying blood to the testicular artery. Additionally, the pampiniform plexus is important in thermoregulation of the testis. Venous blood from the testis cools the arterial blood from the body flowing through the pampiniform plexus. This heat exchange in addition to heat radiation from the plexus and testis maintains the temperature of the testes a few degrees cooler than core body temperature. This is essential for spermatogenesis. For more details of images 2 and 3, see O. J. Ginther, Comparative Anatomy of Uteroovarian Vasculature, in Veterinary Scope, The Upjohn Company, 1976. http://hdl.handle.net/10113/33280

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