Structure that does not cross the midline is:

A i.e. Left gonadal vein- Left gonadal vein, left suprarenal vein & right renal vein do not cross mid line.Hemiazygous vein cross midline at T8 veebral level to join azygous vein.Left renal vein is longer than right renal vein and cross midline anterior to aoa to drain into IVC. However, left gonadal & supra renal veins drain into left renal vein (almost veically) without crossing midline