Development of stomach, duodenum and pancreas

Stomach

Origin: Endodermal

  • Lower part of foregut, swelling appears
  • Anterior border connected to anterior abdominal wall by ventral mesogastrium
  • Posterior border connected to posterior abdominal wall by dorsal mesogastrium
  • Posterior border grows more – forms greater curvature of stomach
  • Anterior border forms lesser curvature
  • Stomach then rotates 90 degrees clockwise (due to growth of liver)
  • So dorsal mesogastrium forms lesser sac
  • Liver develops in ventral mesentery – mesentery becomes lesser omentum
  • Spleen develops in dorsal mesentery – mesentery becomes gastrosplenic ligament

 

Clinicals: Congenital hypertrophy of pyloric sphincter – narrows pyloric canal. More common in males.

NB: Development of stomach and rotation causes right vagus nerve to become posterior vagus trunk. Left vagus nerve becomes anterior vagus trunk

Image result for development of stomach


 

Duodenum

Origin: Endodermal

  • Distal foregut and proximal midgut
  • Form a “C” shaped loop projecting ventrally
  • Due to stomachs rotation 90 degrees clockwise
  • Duodenal loop carried dorsally and to the right, becomes adherent to posterior abdominal wall
  • Mesentery of duodenum disappears except in the 1st and 4th part (ligament of trietz)
  • The lumen is temporarily obstructed and canalized again

 

Congenital anomalies:

  1. Incomplete canalization/ atresia – green vomit, no bowel movement
  2. Incomplete fixation to posterior abdominal wall – sites of internal hernia

Image result for development of duodenum


Pancreas

Origin: 2 endodermal buds form:

  1. Endoderm of dorsal wall of duodenum – dorsal pancreatic bud
  2. Endoderm of ventral wall of duodenum from hepatic bud stem – ventral pancreatic bud
  • Dorsal pancreatic bud arises slightly above liver bud, extends dorsally and upwards into mesoduodenum
  • Ventral pancreatic bud migrates dorsally to lie below and behind dorsal bud
  • The 2 buds fuse together (ventral bud – head and uncinate process)
  • Ducts of the 2 buds join – main pancreatic duct
  • Islets of Langerhans appear – insulin secretion begins in 5th month

 

Congenital anomalies:

  1. Annular pancreas – develops as a ring around 2nd part duodenum
  2. Ectopic pancreatic tissue – eg. wall of duodenum, jejunum, ileum or stomach

 

Image result for development of pancreas

 

Image result for development of pancreas

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