Morphological and Surgical Overview of Adolescent Testis Affected by Varicocele
Figure 1
(a) Symmetric stage of the human vascular system development (4-week embryo). Three symmetric paired veins form the basis of the early venous system, draining into the heart: vitelline veins, umbilical veins, and cardinal veins. Both cardinal veins empty into the common duct of Cuvier. (b) Asymmetric stage of the human vascular system development (5-week embryo). Note the persistence of only the right vitelline vein, which, together with the hepatic segment, forms the upper portion of the inferior vena cava (*). The posterior cardinal veins appear as paired, symmetrical vessels extending from the duct of Cuvier to the tail region. In the subhepatic region, paired vessels (right and left subcardinal veins) and intersubcardinal anastomosis are formed. (c) At the 6th week posterior cardinal veins are completely obliterated on the left side, whilst, on the right side, only the inferior part remains (arrow). A similar process involves the left subcardinal vein. On the right side, the subcardinal vein is maintained, thus forming the intermediate part of the inferior vena cava. (d) At the end of the developmental processes the right testicular vein drains into the definitive inferior vena cava, formed by four parts (1, 2, 3, and 4) of different origins. The left testicular vein drains in the left renal vein, derived from the intersubcardinal anastomosis.
