The peritoneal reflections of ascending and descending colon (white line of Toldt) represent the edge of the fusion fascia formed when the embryonic colon adhered to the posterior parietal peritoneum on either side of the abdomen. Elevating the colon folds the edge of the peritoneum forming an apparent line. If dissection is kept medial to the line, the colon mesentery can be mobilized bloodlessly. The ureter is easily swept posteriorly off the mesentery.