Undergraduate MBBS lecture on GI development and concepts of Peritoneum. The entire session is to be covered in successive nine (9) lectures. This is the whole PPT covering the topic.

1. GI Development &
concept of Peritoneum
Hironmoy Roy
Associate Professor
Anatomy, IPGME&R

2. Peritoneum_ a sac
• A closed sac inside abdominal cavity
• Lined by simple squamous epithelium
• Every viscera is pushing it either from above,
or, below, or back. None to push from front.
• Everyone is extra-peritoneal

4. Where from the sac comes?
• Cavity has two linings- inner & outer
• The somato-pleuric layer (upper layer, attached with
ectoderm) of the lateral plate mesoderm makes the
lining of body cavity &
• The splancno-pleuric layer (lower layer, attached
with endoderm) makes the lining of gut (developed
from endoderm).

5. Gut=
Stomodeum to Proctodeum
Made by folded endoderm

6. Foregut-Midgut- Hindgut
• Depends with the feeder artery
Feeder artery Portion
Coeliac trunk Foregut
Superior mesenteric
artery
Midgut
Inferior mesenteric
artery
Hindgut

7. ‘Intestinal portals’ demarcates the fore, mid & hind gut
‘Retention bands’ (present slightly below the intestinal
portals) embarks the mid-gut loop

11. Stomodeum
Proctodeum
Ant Ints Portal
Post Intes. Portal
Superior Retention Band
Inferior
Retention
Band

12. Stomodeum
Anterior Intestinal Portal
Respiratory
passage
Mouth/ Oral
cavity/ Tongue/
Pharynx
Septum
Transversum
Oesophagus
Stomach
Duodenum

13. Anterior Intestinal Portal
PosteriorIntestinal Portal
Caecum- appendix
Ascending Colon
Transverse colon
2/3
Duodenum
Small Intestine

14. Posterior Intestinal Portal
Proctodeum
Descending Colon
Transverse colon 1/3
Sigmoid Colon
Urinary bladder,
Urethra
Rectum
Anal-canal

15. So,
Duodenum has two sources- Foregut & Midgut
Transverse colon has two sources- Midgut & Hindgut

16. The story of fore gut

17. Parts of Foregut
• Laryngeal
• Pre-laryngeal
• Post-laryngeal • Esophageal
• Gastric
• Duodenal

18. Development of esophagus
• Develops from the post-laryngeal part of foregut
above the septum transversum
• Initially short in length, elongates gradually, the
lumen gets narrow due to proliferating
epithelium.
• Mucosa is initially ciliated columnar, then
becomes simple squamous, then finally becomes
stratified squamous.

19. Anomalies

20. Tracheo-esophageal fistula

22. Anomalies

23. Development of stomach
• Develops from “gastric” part of the foregut as the
fusiform dilatation, by the 4th week of IUL.

24. Primitive Mesentry

25. Buds/Offshoots from foregut
From the primitive duodenum three buds
appears
Two ventrally-
1. Ventral pancreatic bud &
2. Hepatic
they appear at the level of anterior intestinal portal
One dorsally- Dorsal pancreatic bud
it appears above the level of anterior intestinal portal

26. Development of Liver
• 4th week
• Develops as “hepatic bud” from the ventral border
of primitive duodenum (endoderm).
• It grows up, touches the septum transversum (ST)
within the ventral mesogastrium, divides in right
and left branch
• Within the ST each branch gives rise to cluster of
liver cells, the “hepatic cylinders”. The cells gets
arranges in plate to make the hepatic parenchyma

27. Development of Liver (contd...)
• The ST makes the fibro-areolar stroma within the
liver (mesoderm)
• The Kuppffer’s cells are contributed by the
migration of neural crest cells (ectoderm).

28. Septum transversum
• Divides the ventral mesogastrium in two parts
• Growing hepatic bud divides it is (a) cranial part,
the pars diaphragmatica & (b) the caudal part, the
pars mesenterica
• The pars diaphragmatica differentiates in upper
part to make the fibrous pericardium & the lower
part, to make the antero-median part of the
diaphragm

29. Development of Gall bladder
• Cystic bud develops from the bile duct
• Distal part gets swollen, de-canalises to make the
lumen
• Distal part makes the gall bladder & proximal part
makes the cystic duct

30. Derivatives of ventral mesogastrium
• Falciform ligament
• Hepato-gastric ligament
(Lesser omentum)

31. Development of spleen
• Spleen develops from
mesoderm within the dorsal
mesogastrium
• Starts to develop by 5th week
• Initially developed as multiple
lobules, which later on fuses
together to make the
lobulated mass of spleen.

32. Derivatives of dorsal mesogastrium
• Gastro-phrenic ligament
• Gastro-splenic liagment
• Lieno-renal ligament
• Gastro-colic ligament

33. Omentum (pl. Omenta)
• A bilayered fold of peritoneum that connects the
surfaces of stomach with any other intra-
abdominal viscera
• Three (3)-
a) Gastro-Colic ligament= Greater Omentum
b) Gastro-Hepatic ligament= Lesser Omentum
c) Gastro-splenic ligament= 3rd Omentum

34. Making of the lesser sac
• Right lobe of the liver becomes more heavy that left
side
• It pushes the entire system to right side at 90 degree
rotation in horizontal plane
• Part of the peritoneal cavity trapped behind the
stomach- Lesser sac
• Part of the peritoneal cavity infront of the stomach-
Greater sac
• They are connected by – ‘Epiploic foramen of Winslow’

35. Epiploic foramen of Winslow
• Window by which the greater sac communicates
with lesser sac
• Boundary:
Above - caudate process of liver
Below – 1st part of duodenum
Infront - right free margin of lesser omentum with
porta hepatis
Behind – Inferior Vena Cava
• Applied- Internal Hernia

38. Lesser sac (Omental bursa)
• A diverticulum of greater sac
• Situated behind the stomach
• “Bursa”- cushion to stomach

41. The story of mid gut

42. The story of Midgut
• Midgut = Supplied by Sup. Mesenteric artery (AXIS)
• Midgut = Anterior intestinal portal TO posterior
intestinal portal
• Midgut = Freely hanging outside the umbilicus by
“physiological hernia”
• Vitelline duct (alias. Vitellointestinal duct) gradually
becomes regressed
• Preaxial part= Cephalic limb
• Postaxial part= Caudal limb

43. Midgut......
Pre-axial part =
Cephalic limb
Post-axial part =
Caudal limb
Lower part of duodenum
distal to the attachment
of hepato-pancreatic bud
Ileum- remaining part
Jejunum Caecum-
appendix
Ileum- Major part Ascending colon
Proximal 2/3rd of
transverse colon

44. The midgut returns in abdomen
5th-10th wk
• Stage- 1 (Rotation): Saggitally oriented midgut loop
rotates 90 degree (anticlockwise, when seen from
front) & becomes horizontal

47. The midgut returns.....
5th-10th wk
Stage- 2 (Regression):
• Caecum develops in postaxial limb & makes it
prominent & heavy.
• Huge intestinal coils appears in the preaxial limb
• Progressive decrease of the dimension of liver &
growth of the abdominal cavity, allows the herniated
loop to return
• Lighter loop (preaxial) enters first in the right side of
the cavity

48. The midgut returns.....
5th-10th wk
Stage- 2:
• All the loops can’t be housed in the right part/half of
the cavity; then, the left half also gets used up.
• Still it is less. Then finding no way, the proximal part
(i.e the duodenal portion) get space dorsal to the
origin of SMA.
• Ultimately, the right side, left side all gets occupied
by the intestinal coils (Pre-axial part)
• Till now, caecum just observes the happenings
(Neutral Observer)

49. The midgut returns.....
5th-10th wk
Stage- 2:
• Now, the post-axial part attempts to return.
• They gets no space in the left half. (pre-occupied)
• Caecum finds space at right subhepatic region

50. The midgut returns.....
5th-10th wk
Stage- 3 (Fixation):
• Gradually due to the increase of colon length, it
finally gets housed in right illiac region- definitive
position
• The dorsal mesentry only persists for (1) jejunum-
ilieum (2) transverse colon (3) sigmoid colon

53. Vitello-intestinal duct regression anomalies

54. Exomphalos (Omphalocoele)

55. Gastrochisis

56. Midgut rotation anomalies
Non Rotation In case of over dilated umbilical ring, the gut is reduced en-
masse. Then the small gut occupies the right side & large gut
occupies the left side
Mal Rotation When caecum enters first alongwith the post axial limb.
Obviously in that case the colon and caecum goes behind the
SMA & the small intestine remains ventral to it.
Undescended caecum Caecum remains in sub-hepatic region

58. The offshoots of
Foregut & Midgut

59. Stomodeum
Proctodeum
Ant Ints Portal
Post Intes. Portal
Superior Retention Band
Inferior
Retention
Band

60. Stomodeum
Anterior Intestinal Portal
Respiratory
passage
Mouth/ Oral
cavity/ Tongue/
Pharynx
Septum
Transversum
Oesophagus
Stomach
Duodenum

61. Anterior Intestinal Portal
PosteriorIntestinal Portal
Caecum- appendix
Ascending Colon
Transverse colon
2/3
Duodenum
Small Intestine

62. Development of Duodenum
• Two(2) sources- (a) duodenal part of foregut above
the hepatopancreatic bud & (b) proximal part of
midgut
• It presents initially as a loop with ventral convexity
• Rotates 90 degree- due to push of developing right
lobe of liver
• Gets pushed to dorsal body wall- due to push by
returning mass of large intestine
• As a result the ventral border becomes right lateral
border

63. Development of Duodenum.....
• Zygosis obliterates the visceral layer of peritoneum
and fixes the duodenum with dorsal body wall- it
becomes secondarily retroperitoneal
• Uneven axial rotation brings the lateral margin to
the medial side.
• Lumen decanalised by 8th week & subsequently
recanalised by 12th week. [Applied- Atresia]

64. Development of Pancreas
2 buds-
Ventral pancreatic bud (bilobed) from the
location of anterior intestinal portal (AIP)
&
Dorsal pancreatic bud proximal to AIP

65. Development of Pancreas
When the second part of duodenum undergoes the Axial rotation, the
VPB comes “just to dorsal/POSTERO-MEDIAL” to the DPB
Both starts to get fused
Head, neck, body, tail is formed by the contribution of DPB
& Uncinate process is formed by the VPB
Main pancreatic duct is formed by
1. Distal part of the duct of DPB
2. Oblique cross connection of DPB & VPB
3. Proximal part of bile duct

68. Annular pancreas
The two lobes of the VPB instead of getting fused, migrates around the
duodenum in opposite direction to meet the DPB. This makes the annular
pancreas

69. The story of Hind gut

70. The story of Hind gut
Posterior intestinal portal to the cloacal
opening
Artery= Inferior Mesenteric artery
Allantois divides it in pre-allantoic
& post-allantoic part

71. Pre-allantoic part
• Makes-
1. Distal third of transverse colon
2. Descending colon
3. Sigmoid colon

72. Post-allantoic part
Endodermal cloaca.
Makes-
1. Rectum
2. Anal canal (upper part)
3. Urinary bladder
4. Urethra

73. Division of Endodermal cloaca
• Uro-Rectal septum
• Having three components-
1. One vertical fold of Tournex
2. Two lateral fold of Rathke (containing the Msn &
Para msn ducts)
They meets at bottom. Prior to meet they retain the
cloacal duct (common passage). Once they meet
(point= Perineal body), they makes urogenital
membrane in front & anal membrane behind.

74. Division of Endodermal cloaca......
• On anal membrane from surface a depression is
formed- Proctodeum/anal pit
• Finally the membrane ruptures
• Endoderm gets confluenced with ectoderm. Line-
Pectinate Line
• Anal canal has two sources-
1. Above the PL- endodermal cloaca
2. Below the PL- ectodermal proctodeum

83. Development of Rectum
Mucosa Muscle

84. Anomalies of
development of Hind gut

85. When to suspect?
If the baby not passes meconium after 6 hours
of birth [meconium- the first stool]

86. 1. Hirschprung’s disease

87. Hirschprung’s disease...
• Hirschsprung disease (HSCR) is a birth defect.
• This disorder is characterized by the absence of
autonomic particular nerve cells (ganglions) in a
segment of the bowel in an infant.
• The absence of ganglion cells causes the muscles in
the bowels to lose their ability to move stool through
the intestine (peristalsis).
• When in colon- Congenital Megacolon

88. Hirschprung’s disease....
• The genes associated with HSCR are in two major
groups called RET genes and EDNRB genes.
• When the disorder involves a short segment of the
colon, the major gene involved is the RET gene
located on chromosome 10q11.2

89. 2. Undivided cloaca

91. • A persistant cloaca is a congenital disorder, where
the rectum, vagina and urethra meet and fuse to
make common exit channel.
• Failure of the Uro-rectal septum to touch the
bottom.

92. 3. Imperforate anus

93. Imperforate anus....
• Congenital blocked/missing anal opening.
• Anal canal ends as a pouch and doesnot connect the
rectum; instead of joining the anal canal, the rectum
joins to the other nearby viscera
• ‘Invertogram’ reveals the high or low variety
depending upon the extent of gas shadow

94. Imperforate anus....
Primary-
1. Failure of rupture of anal membrane
2. Non development of ectodermal cloaca
3. Atresia of lower part of rectum
Secondary-
Due to persistant Rectal fistulae

95. 4. Rectal fistula
• Recto-vescical
• Recto-vaginal
• Recto-urethral

98. Ano-rectal malformations
(as a whole)

103. Peritoneal folds in adult

104. Longitudinal tracing
1. Median
2. Left paramedian
3. Extreme left paramedian
4. Extreme right paramedian

105. Horizontal tracing
1. Above epiploic foramen
2. At the level of epiploic foramen
3. Infracolic
4. pelvic

106. Greater omentum
• Bilayered peritoneal fold connecting the greater
curvature of stomach to the transverse colon.
• Initially have four layers. Layer 1& 4 by greater sac
whereas the layer 2 & 3 by lesser sac
• & reflects from stomach to the pancreas.
• Afterwards layer 2&3 get fused by zygosis and
disappears.
• & gets finalised to pasted on transverse colon
• Layer 1& 4 exists only

109. Greater omentum

110. Abdominal policeman
• In infection focus in abdomen, the greater
omentum first moves to localise it.
• So called “policeman”

111. Lesser Omentum
• Bilayered peritoneal fold connecting the lesser
curvature of stomach with the liver & duodenum
• J shaped
• Vertical limb attached to the floor of fissure for
ligamentum venosum of liver
• Horizontal limb is attached to the two lips of
porta hepatis
• Anterior layer is from greater sac & posterior
layer is from the lesser sac

113. Contents....
• Gastric vessels & nerves (close to lesser
curvature)- at border close to lesser
curvature
• Porta hepatis at right free margin

114. Epiploic foramen of Winslow
• Window by which the greater sac communicates
with lesser sac
• Boundary:
Above - caudate process of liver
Below - D1
Infront - right free margin of lesser omentum with
porta hepatis
Behind - IVC
• Applied- Internal Hernia

117. Lesser sac (Omental bursa)
• A diverticulum of greater sac
• Situated behind the stomach
• “Bursa”- cushion to stomach

121. Pouch of Douglas

122. Pouch of Douglas.....
• Most depended peritoneal space in female in
standing posture
• Boundary-
In front- Supravaginal part of cervix & posterior fornix of
vagina
Behind- middle 3rd of rectum
Two sides- recto-uterine folds of peritoneum
Bottom- recto-vaginal fold
The bottom lies 5.5 cm above the anus & 7.5 cm above
the external vaginal orifice
• Applied-Collection of pus/blood may be drained by
posterior colpotomy

123. Hepato-renal Pouch of Morison

124. Hepato-renal Pouch of Morison.......
Most dependent abdominal peritoneal space in
supine position

125. Thank you