Kidney Kidneys are retroperitoneal organs from the very beginning and do not develop within the mesentery of the stomach. Pancreas is a secondarily retroperitoneal organ. It originally develops within the mesentery and is covered by mesentery, but later. fuses with the posterior body wall to become a retroperitoneal organ.Liver and Spleen develop within the mesentery of the stomach and remain intraperitoneal organs.Let's have a look on development of above organs in brief.Liver (& gall bladder):Develops from endodermal bud at the distal end of the foregut.Liver bud grows into the ventral mesogastrium & penetrates the septum transversum.Umbilical & vitelline veins in the septum transversum are broken to form the sinusoids of the liver.Endomermal cells of the hepatic bud give rise to the parenchyma of the liver and to bile capillaries.The mesoderm of the septum transversum gives rise to hematopoietic cells, Kupffer cells and connective tissue cells.The small caudal pa of the hepatic diveiculum (bud) becomes the gall bladder and the stalk of the diveiculum forms the cystic duct.Pancreas:It is formed by two endodermal buds, dorsal and ventral arising from caudal pa of the foregut.The larger dorsal pancreatic bud grows between the layers of the dorsal mesentery and the ventral bud develops in ventral mesentery.With the rotation of the duodenum, ventral bud is carried dorsally with the bile duct. It soon lies posterior to dorsal bud and later fuses with it.The ventral bud forms the uncinate process and inferior pa of the head of the pancreas:The remaining pa of the gland is derived from the dorsal bud.Pancreas is said to be secondarily retroperitoneal as it is originally covered by peritoneum, but later fuses with the posterior body wall to become retroperitoneal.Spleen:It is derived from mesenchymal cells located between the layers of the dorsal mesogastrium.Dorsal mesogastrium gets divided into -Gastrosplenic ligament from stomach to spleenLienorenal ligament .froth spleen to the left kidneyKidneys:Kidneys develop from two sourcesMetanephros - give rise to excretory tubules. Ureteric bud - diveiculum arising .from lower pa of mesonephric duet gives rise to the collecting pa of the kidney & ureter.Kidneys do not develop in mesentery of the stomach. They are retroperioneal from the beginningNote: Some students were of the view that the question was asked - 'which organ develops from the mesentery of the stomach.' In that case 'spleen' is the only option in whose development mesenchymal cells from the dorsal mesogastrium contribute. Rest of the given options- Liver, Pancreas and Kidneys do not take origin from the mesentery of the stomach.