Colonic Diverticulosis of the Sigmoid Colon

A 72-year-old man from a Western low-fibre background presents with left lower quadrant pain and low-grade fever. CT imaging shows sigmoid diverticula with pericolic fat stranding. The resected sigmoid specimen is opened along the antimesenteric border, revealing the classic gross pathology. Numerous small saccular outpouchings (5–10 mm diameter) are seen in orderly rows. The structure marked **A** in the diagram represents these saccular diverticula positioned between the mesenteric and antimesenteric taeniae. Which of the following best explains why these structures at site **A** are classified as PSEUDODIVERTICULA rather than true diverticula?