GIT Development

1. 6.53
DEVELOPMENT
OF GIT
Nabil

2. DEVELOPMENT OF GIT
Sagittal Plane
Transverse Plane
Before After
Longitudinal & lateral folding of
embryo
Primitive gut formation which
then differentiates to FG, MG
and HG
Before After
End of 4th Week
• Rupture of
oropharyngeal
membrane at FG
Mouth
End of 5th Week
• Connection btw Yolk
Sac & MG narrows
as embryo folds
Vitelline duct
7th Week
• Rupture of cloacal
membrane at HG
Urogenital tract & Anal
openings

3. 7/1/20XX 3
DEVELOPMENT OF GIT
Derivatives
Dorsal mesentery Dorsal mesogastrium 
greater omentum
Dorsal mesoduodenum
Mesentry proper
Dorsal mesocolon
Ventral mesentery Lesser omentum
Falciform ligament
Derivatives of FG in Digestive System
Mnemonics :
DOn’t (Duodenum) MES Personal Live with your BP
• Duodenum
• Mouth
• Esophagus
• Stomach
• Pancreas
• Liver
• Biliary apparatus
• Pharynx (Primordial)

4. 4
FOREGUT DERIVATIVES
Before After
Part of Stomodeum
(Ectoderm) & FG
(endoderm) when
Buccopharyngeal
membrane ruptures
Mouth
• Epithelium of lips,
cheeks & palate
(Ecto)
• Epithelium of tongue
(Endo)
Cranial most part of FG
(Pharyngeal gut)
Pharynx
Before After
Dorsal portion of FG Esophagus
• Reaches its final
relative length by 7th
week
• Epithelium & glands
(endoderm)
• Muscular coat
(splanchnic
mesoderm)

5. 7/1/20XX 5
Before After
Space behind the stomach due to the
pull of dorsal mesogastrium to the left
Omental busa
Developed btw 2 layers of dorsal
mesogastrium
Spleen
Dorsal Mesogastrium Liorenal ligament
• Btw posterior body wall (kidney) &
spleen
Gastrolienal ligament
• Btw spleen & stomach
Developed btw ventral mesogastrium Liver
• As liver cords grow into it, it thins to
form peritoneum of liver, falciform
ligament and lesser omentum
1st Rotation
(90’ clockwise around longitudinal
axis)
Before After
Bulging down of
dorsal mesogastrium
Greater omentum
2nd Rotation
(clockwise around anteroposterior
axis)
 Original dorsal border grows faster than
ventral border  greater curvature and
lesser curvature respectively
DEVELOPMENT OF STOMACH

6. 6
DEVELOPMENT OF LIVER, BILIARY APPARATUS & GALLBLADDER
Liver & Biliary Apparatus
Before After
Enlargement of liver buds or
hepatic diverticulum
• Pars hepatica  liver cords
continue to penetrate septum
transversum
• Pars cystica
Vitelline & Umbilical Vein Liver sinusoids
Mesoderm of septum
transversum
Hematopoietic cells, Kupffer
cells & connective tissue cells
Septum transversum • Peritoneum of liver except
bare area
• Falciform ligament
• Lesser omentum
Cranial surface of liver
uncovered by peritoneum
Bare area of liver
Obliteration of umbilical vein in a
free margin of falciform ligament
Ligamentum teres hepatis
Pars cystica Gallbladder & cystic duct
Stalk connecting hepatic &
cystic duct to FG
Bile duct
Growth & rotation of duodenum Opening of bile duct carried to
posteromedial position from
ventral position
Gallbladder

7. 7
DEVELOPMENT OF PANCREAS & DUODENUM
Duodenum Before After
Terminal part of FG & Proximal
part of MG
Duodenum
• Receive blood from celiac trunk (FG
artery) & superior mesenteric artery
(MG artery)
Rotation of stomach & rapid
growth of pancreatic head
Duodenum swinged from mid to right
• Mesoduodenum disappears
• Small portion near pylorus
• Duodenum become fixed at
retroperitoneal position
• Remains intraperitoneally
2 endodermal buds (dorsal &
ventral pancreatic buds ) arise
from caudal part of FG
Pancreas
Rotation of duodenum VPB moves dorsally and lie below & behind
DPB before fusing forming a single mass
Ventral Pancreatic Bud Uncinate process and inferior part of
pancreas head
Remaining part is from DPB
Distal part of Dorsal pancreatic
duct and entire ventral pancreatic
duct
Main pancreatic duct
Proximal part of dorsal pancreatic
duct
Accessory pancreatic duct
Pancreas

8. 8
DEVELOPMENTAL ERRORS
Congenital anomalies
• Accessory spleens
(Polysplenia) –may exists in
one of the peritoneal folds.
• Congenital hypertrophic
pyloric stenosis
• Duodenal stenosis
• Duodenal atresia
Spleen
Accessory spleen
Duodenal stenosis
• Oesophageal atresia and/or
tracheoesophageal fistula.
• Polyhydramnios
• Oesophageal stenosis.
• Congenital hiatal hernia -
Short oesophagus
VACTERL association

9. 9
MIDGUT DERIVATIVES
Before After
Elongation of
MG
Primary Intestinal Loop (cephalic limb &
caudal limb)
Superior
mesenteric
artery
Axis of Primary Intestinal Loop
Cephalic limb
(pre-arterial)
Distal part of Duodenum, Jejunum & Ileum
Caudal limb
(post-arterial)
Lower part of ileum, appendix, cecum,
ascending colon & right proximal 2/3 of
transverse colon
Before After
At 6th week
• Rapid elongation of Primary IL
especially cephalic limb
• Rapid growth & expansion of liver
• Lack of room in abdominal cavity to
accommodate all the intestinal loops
Physiological umbilical herniation

10. 7/1/20XX Pitch deck title 10
ROTATION OF MG Process Description
1
(8th W)
Brings the :
• Cephalic limb to the right
• Caudal limb to the left
The loop lies outside the body cavity
2
(10th–11th W)
Elongation of Cephalic limb > Caudal limb
3
(10th W)
Return of the herniated intestinal loop back into abdominal cavity due
to
• Expansion of abdominal cavity with the embryo growth
• Reduced liver growth
• Regression of mesonephric kidney
Proximal portion of jejunum (cephalic limb) returns first and lie on left
side on abdominal cavity
Remaining coils of cephalic limb (distal part of jejunum & ileum) returns
gradually and occupies more towards right side
Cecal bud (caudal limb) return to abdominal cavity and temporarily
occupies the right upper quadrant below right lobe of liver  descent
to its adult position of R iliac fossa  elongation of caudal limb
downwards  formation of ascending colon and hepatic flexure of
colon
Remaining part of caudal limb  2/3 transverse colon

11. 7/1/20XX 11
Before After
Cecal bud Cecum and Appendix
Distal end (apex) Appendix
After birth, growth of
lateral wall > medial wall
of cecum
Appendix comes to open on its
medial side
Posterior to cecum (retrocecal0 or
colon (retrocolic)
1. Large intestine enlarges &
lengthen  their mesenteries &
duodenal mesentery (duodenum &
pancreas) are pressed against the
peritoneum of posterior abdominal
wall and get fused except the first
part of duodenum
2. Ascending & descending colon are
permanently anchored
retroperitoneally
3. Transverse colon fuses with post.
Wall of greater omenta  mobile
4. Jejunoileal loop, appendix, lower
end of cecum and sigmoid colon
retain their mesenteries
MIDGUT
DERIVATIVES
FIXATION OF INTESTINE

12. 12
HINDGUT DERIVATIVES
Before After
Dorsal part of cloaca Rectum and upper part of anal canal
Ventral part of cloaca Urogenital sinus
At 7th week
• Growth of urorectal septum
towards cloacal membrane and
fuses
Dorsal anal membrane and ventral
urogenital membrane
Perineal body between two
membranes
proctodeum

13. 13
DEVELOPMENTAL ERRORS
Pathological Disorder Characteristic Diagram
Congenital Omphalocele • Abdominal viscera herniates via an
enlarged umbilical ring
• May included Liver, Intestines, Stomach,
Spleen & Gallbladder
• Covered by amnion
Umbilical Hernia • Herniation via an imperfectly closed
umbilicus
• Greater omentum & part of small intestine
• Covered by SC tissue & Skin
Gastroschisis • Abdnominal contents herniate via body
wall directly into amniotic cavity
• Lateral to umbilicus & on right side
• Viscera not covered by peritoneum or
amnion

14. 14
VITELLINE DUCT ABNORMALITY
Pathological
Disorder
Characteristic
Meckel’s
diverticulum
• 2ft from ileo-cecal valve
• Gastric or pancreatic type
of ectopic mucosa
• 2 inch long
Vitelline cyst
Vitelline fistula
GUT ROTATION DEFECTS
Pathologica
l Disorder
Characteristic
Malrotation • Incomplete 270’ counterclockwise
rotation or may rotate only 90’
• Colon & cecum firstly return to abdomen
& lie on left side
Reverse Rotation • Primary intestinal loop rotates 90’
clockwise
• Transverse colon lies behind the
duodenum & superior mesenteric artery
• Result in volvulus and gangrene
Subhepatic
cecum &
appendix
• Anomalies of midgut rotation
Mobile cecum • Persistence of mesocolon portion 
Incomplete fixation of ascending colon
Internal hernia • Portion of small intestine passes into
mesentery & entrapped in it
Stenosis and
atresia of intestine
• Failure of formation of enough number of
vacuoles during recanalization

15. 15
HINDGUT ABNORMALITIES
Pathological Disorder Characteristic Diagram
Congenital megacolon /
Hirschsprung’s disease
• Absent parasympathetic ganglia in the
bowel wall
Imperforate anus • Failure of rupture of anal membrane at end
of 8th week  Thin layer of anal membrane
separates the anal canal from exterior 
no anal opening
Rectovaginal fistula • Incomplete separation of cloaca by
urorectal septum
Anorectal atresia
Rectourethral/Urorectal
fistula