Figure 3: Final position of the abdominal organs - normally and in cases of left and right isomerism (drawings). A) Normally: Left-sided stomach (Sto), tail of pancreas (Pa) and spleen (Sp). Note the positions of the portal vein (pV) above the superior part of duodenum (D) and of the superior mesenteric artery and vein (smAV) in front of the inferior part of duodenum. Note the regular position and fixation of the large intestine – ascending, transverse and descending colon (a/t/dC) - around the small bowel (in graph severed). B) Left isomerism (e.g. A 612): Right-sided stomach, tail of pancreas and multiple spleens (m-Sp). Note the abnormal route of the duodenum (D) in combination with an abnormal position of the portal vein (pV) below its superior part and the superior mesenteric vessels (smAV) behind. In consequence, the midgut-derivatives were malrotated with subsequent dextroposition and malfixation of the large intestine – ascending, transverse and descending colon (a/t/dC) - following the leftsided small bowel (in graph severed). C) Right isomerism (e.g. A 722): Right-sided stomach, tail of pancreas and spleen. Note abnormal route of the duodenum (D) in combination with an abnormal position of the portal vein (pV) left to the superior part of duodenum and of the superior mesenteric vessels (smAV) right to the duodenum. In consequence, the midgut-derivatives were malrotated with subsequent malposition and malfixation of the large intestine – ascending, transverse and descending colon (a/t/ dC) - behind the small bowel (in graph severed).