Part of “CHAPTER 113 – MORPHOLOGY AND PHYSIOLOGY OF THE TESTIS“

In most mammalian species, the testis is located within the scrotum, having descended from an intraabdominal position during fetal development1 (see Chap. 93). The intrascrotal posi-tion allows the testis to function at a lower temperature than is found within the abdomen. This is a requirement for normal spermatogenesis in many mammals including humans, although in some, such as the elephant, the testes do not descend and spermatogenesis is unaffected by the higher temperature within the abdomen. Because of testicular descent, the vascular supply originates relatively proximally, from the aorta near the origin of the renal arteries. The venous drainage, commencing as an anastomotic plexus of veins (the pampiniform plexus that surrounds the testicular artery), terminates in the renal vein on the left and in the inferior vena cava on the right. This arrangement of vessels acts as a countercurrent mechanism to maintain lower testicular temperature; the cooler venous blood surrounds the testicular artery, decreasing its temperature as it approaches the testis.