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Gastroschisis
Exomphalos
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- Gut forms as midline tube of endoderm
- visceral peritoneum, muscle and connective tissue from
splanchnopleuric mesoderm
- parietal peritoneum, muscle and connective tissue of gut wall
somatopleuric mesoderm
- tube remains suspended from dorsal mesentery
- foregut develops into terminal oesophagus, stomach, duodenum to papilla of
Vater.
- Supplied by coeliac artery
- foregut also has ventral mesentery
- midgut develops into caudal duodenum, jejunum, ileum, caecum ascending
colon and most of transverse colon.
- Supplied by superior mesenteric artery
- massive elongation of midgut causes it to herniate into umbilical cord
- undergoes anticlockwise rotation
- ascending colon becomes attached to posterior abdominal wall on right-
- hind gut develops into splenic flexure, descending colon, rectum, 2/3 anal
canal.
- Supplied by inferior mesenteric artery
- hindgut pushed to left by rotation
- attaches to posterior abdominal wall
9.2.2.1 Development of liver and pancreas
| Development of hepato-pancreatic diverticulum, dorsal and
ventral pancreatic buds; growth into dorsal and ventral mesenteries |
| Umbilical vein, ductus venosus; changes in circulation at
birth; ligamentum teres, ligamentum venosum |
| Relative movement of parts to adult positions |
Liver
- hepatopancreatic diverticulum forms at junction of foregut and midgut
- grows into septum transversum
- divides into hepatic and cystic parts
- contribution by mesoderm of septum tranversum
- hepatic sinusoids connect to right and left umbilical and viteliine veins
- right umbilical vein regresses, left umbilical
vein forms ductus venosus
- after birth closes to leave ligamentum teres (umbilical vein),
ligamentum venosum (ductus venosus)
- vitelline veins become hepatic portal vein
- cystic diverticulum becomes gall bladder on ventral edge of undivided part
of hepatic diverticulum
Pancreas
- forms dorsal and ventral parts
- ventral forms lower part of head and uncinate process
- dorsal bud forms upper part of head, body, neck and tail
- superior mesenteric artery and vein trapped between two parts
- bile duct runs behind first part of duodenum
- duct of ventral part takes over from duct of dorsal part
Spleen
- develops in dorsal mesogastrium
- connected to pancreas by lienorenal ligament
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