1. Area of adhesion between opposed surfaces of great omentum and transverse mesocolon and colon. 2. Area of adhesion between parietal peritoneum, duodenum, and caudal layer of transverse mesocolon. 3. Adhesion of opposed walls of omental bursa leading to obliteration of distal portion of pouch and producing "gastro-colic" ligament of adult human subject.] The examination of a similar sagittal section representing schematically the adult human arrangement of the parts (Fig. 225) will reveal the following points of difference as compared with the cat: 1. The peritoneum covering the dorsal surface of the pancreas, derived from the primitive dorsal mesogastrium, has become adherent to the parietal peritoneum, as previously described. 2. The cephalic surfaces of the transverse colon and mesocolon fuse with the corresponding area of the dorsal (4th) layer of the great omentum (dorsal mesogastrium). In the human foetus in the 4th month the connection is still so slight that the omentum can readily be separated from the transverse colon and mesocolon. Further dorsad the cephalic layer of the transverse mesocolon adheres to the serous investment of the caudal surface of the pancreas, derived, as we have seen, from the same dorsal layer of the great omentum. 3. The duodenum and mesoduodenum are fixed by adhesion on the one hand to the parietal peritoneum, on the other to the caudal layer of the transverse mesocolon near the root of that membrane. 4. The cavity of the omental bursa is usually obliterated in the adult caudad of the level of the transverse colon, by adhesion of the apposed surfaces of the two intermediate omental layers. We have therefore three general areas of secondary peritoneal adhesion to deal with (Fig. 225), viz.: 1. Dorsal layer of primitive } { Parietal peritoneum, cephalic mesogastrium (great } { layer of transverse omentum) including the } { mesocolon and cephalic surface serous investment of the } to { of transverse colon. dorsal and caudal surfaces } { of the pancreas (Fig. 225, } { 1). } { 2. Transverse duodenum } { Parietal peritoneum and and mesoduodenum (Fig. } to { caudal layer of transverse 225, 2). } { mesocolon. 3. Between the apposed serous surfaces of the intermediate omental layers (Fig. 225, 3). [Illustration: FIG. 226.--Schematic sagittal section of adult human peritoneum]. These areas of adhesion result naturally in the production of secondary lines of peritoneal transition as follows: 1. Figs. 225, 1; 226, 1, from the omentum, dorsal layer, to the caudal surface of transverse colon, caudal layer of transverse mesocolon and caudal surface of the pancreas. 2. Figs. 225, 2; 226, 2, from the caudal layer of the transverse mesocolon across the transverse portion of the duodenum to the parietal peritoneum and mesentery of the jejuno-ileum.