Abstract
An anomalous peritoneal sac enclosing almost completely the windings of the small intestine was encountered in a human cadaver dissected in the gross-anatomy laboratory. Judging from the general features, it seems apparent that this peritoneal sac is not formed by pathological changes of the peritoneum such as inflammatory adhesions. Different from the cases reported hitherto, the present specimen shows a peculiarity that the ascending colon is involved in the anterior wall of the sac.
Topographical relations o f the sac to the mesentery proper as well as the mode of arterial supply to the ascending colon suggests that the left half or lobe of the sac is derived from the original ascending mesocolon, while the right half may be formed by the omentum-like extension of the same mesocolon.
