git

1. DEVELOPMENT
OF GIT

3. • With the formation of head and tail folds,
parts of yolk sac become enclosed within
the embryo.
• A tube is lined by endoderm is formed in
the embryo

4. This is the primitive Gut.
• The gut is in wide
communication with the yolk
sac
• The part of the gut cranial to
this communication is called
foregut
• The part caudal to this
communication is called
hindgut
• The intervening part is called
midgut

5. The communication with the yolk sac become
narrow.
Now it is called definitive yolk sac (umbilical vesicle)
The narrow channel connecting to the gut is called
the Vitellointestinal duct
Cranially the FG separated from the stomodeum by
the Buccopharyngeal memb.

6. • The Superior mesenteric artery now run in the
mesentery of this loop.
• Loop is divided in to per and post arterial segment
• Caecal bud arise from the post arterial segment

7. • The allantoic diverticulum opens in to the ventral aspect of hindgut
• The part of hindgut caudal to the diverticulum is called the cloaca
• Cloaca subdivides in to ventral and dorsal part separated from urorectal septum
• Ventral: Primitive urogenital Sinus
• Dorsal: Primitive rectum
• Caudally the hindgut is separated from the proctodaeum by the cloacal
membrane

14. DIVISION ARTERY VEIN LYMPHATICS SYMPATHETIC
PARASYM
PATHETIC
FOREGUT:
Oesophagus
Stomach
Proximal half of
duodenum (up to common
bile duct (CBD))
Liver
Pancreas
CELIAC
ARETERY
PORTAL VEIN
Spleenic vein
Gastric vein
CELIAC
NODES
CELIAC
GANGLIA
VAGUS
MIDGUT:
Distal half of duodenum
(from CBD)
Jejunum
Ileum
Appendix
Caecum
Ascending colon
Right 2/3 of transverse
colon
SUPERIOR
MESENTERIC
ARTERY
SUPERIOR
MESENTERIC
VEIN
SUPERIOR
MESENTERIC
NODES
SUPERIOR
MESENTERIC
GANGLIA
VAGUS
HINDGUT:
Left 1/3 of transverse
colon
Descending colon
All of rectum down to
ano-rectal line
INFERIOR
MESENTERIC
ARTERY
INFERIOR
MESENTERIC
VEIN
INFERIOR
MESENTERIC
NODES
GANGLIA
HYPOGASTRIC
PLEXUS
PELVIC
SPLANCH
NIC
NERVES
Functional divisions of primitive GI system

16. ROTATION OF GUT

17. • During the 3rd week of IUL the midgut loop elongates rapidly.
• Liver is developing in the same time
• Abdominal cavity become too small temporarily to accommodate
all loop
• During the 6th week the loop of midgut herniated through
umbilical opening
• This is called physiological hernia

18. • After the formation of midgut loop it lies outside the abdominal
cavity of embryo in a part of extra embryonic caelom that persist
near umbilicus
• The loop has pre and post arterial segment
• Initially the loop is in sagittal plane

19. • The midgut Loop now undergoes rotation
• Viewed from the ventral side the loop undergoes 90
degree anticlock wise rotation, now lies in horizontal
plane.

20. • The pre arterial segment come to lie on the right side
• The post arterial segment come to lie on the right side

21. The pre arterial segment undergoes great increase
in length to forms the coils of jejunum and ilium

22. • The pre arterial segment now return to the abdominal
cavity.
• Now midgut loop undergoes a further anticlockwise
rotation
• Now coils of jejunum and ilium pass behind the SMA in to
the left half of abdominal cavity

23. • The post arterial segment of midgut loop now return to
the abdominal cavity.
• Now undergoes a further anticlockwise rotation with the
result that the TC lies ant. To the SMA and caecum comes
to lie right side.

24. FIXATION OF THE GUT
• At first all parts of the small and large intestines have a
mesentery by which they are suspended from the posterior
abdominal wall.
• After the completion of rotation of the gut, the duodenum,
the ascending colon, the descending colon and the rectum
become retroperitoneal (by fusion of their mesenteries with the
posterior abdominal wall).
• The original mesentery persists as;
• The mesentery of small intestine,
• The transverse mesocolon,
• The pelvic mesocolon.

26. Pyloric Stenosis- abnormally
narrowing of lumen

27. Hirschprung Disease
(congenital megacolon)
• Occurs in ~1:5000 births
• Caused by failure of vagal
neural crest cells to migrate
into a portion of the colon
• Upstream regions become
distended (hence
“megacolon”)
• Surgically repaired by
removing affected region

28. Tracheo-oesophageal Fistula

29. Development of Liver,
Gallbladder, Pancreas & Spleen

30. 2/4/2024

31. 2/4/2024

32. 2/4/2024

33. Functions in the fetus
• Hematopoiesis
Begins during 6th week
subsides during the last 2 months only
• Bile production
Starts at 12th week
gives dark green colour to the meconium
• Liver 10 percent of total wt 10th week
• Meconium is the intestinal content

34. 2/4/2024

36. Anomalies of Liver and Gall bladder
• Duplication of Gall
bladder
(Complete or partial)
• Absence of Gall
bladder
• Accessory hepatic
duct

37. • Phrygian cap
• Septum of gall
bladder
• Diverticulum of
gallbladder
Hartmann’s pouch
(infundibulum)
Phrygian cap Hartmann’s pouch
sessile gall bladder

39. 2/4/2024

44. INTRAEMBRYONIC COELOM
• Appears as isolated spaces in the lateral
mesoderm
• In the 4th week, the spaces fuse to form a single
horseshoe-shaped (U-shaped) cavity
• The coelom divides the lateral mesoderm into:
1. Somatic (parietal) layer: under ectoderm
2. Splanchnic (visceral) layer: over endoderm
• Somatopleure = somatic mesoderm + overlying
ectoderm
• Splanchnopleure = splanchnic mesoderm +
underlying endoderm

45. INTRAEMBRYONIC COELOM
• DERIVATIVES: It gives rise to three body cavities:
1. A pericardial cavity: the curve of U
2. Two pericardioperitoneal canals (future pleural
cavities): the proximal parts of the limbs of U
3. Two peritoneal cavities: the distal parts of the
limbs of U
• Each cavity has a parietal layer (derived from
somatic mesoderm) & a visceral layer (derived
from visceral mesoderm)
• FUNCTION: It provides space for the organs to
develop & move

51. DEVELOPMENT OF DIAPHRAGM
• The diaphragm develops from:
1. Septum transversum: forms the central
tendon
2. Dorsal mesentery of esophagus: forms the
right & left crus
3. Muscular ingrowth from lateral body wall:
posterolateral part (costal part)
4. Pleuroperitoneal membranes: small portion
of diaphragm

54. CONGENITAL DIAPHRAGMATIC HERNIA

56. CONGENITAL DIAPHRAGMATIC HERNIA
• A posterolateral defect of diaphragm
• Cause: defective formation and/or fusion of
pleuroperitoneal membrane with other parts of
diaphragm
• Effects:
1. Herniation of abdominal contents into thoracic
cavity
2. Peritoneal & pleural cavities are connected with
one another
• The defect usually occurs in the left side

57. CONGENITAL HIATAL HERNIA
• Herniation of part of the stomach
through a large esophageal hiatus
(opening)

58. The end of the journey!
9 months of
journey is really
hard!