Development of the Foregut
Dr Rania Gabr
OBJECTIVES
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1- Identify the results of folding.
2- Identify the derivatives of the gut.
3- Describe the development of the
esophagus.
4- Describe the development of the
stomach.
5- Identify the congenital anomalies of
the esophagus and stomach.
Folding of the embryo leads to :
Development of the primitive gut tube:
 It extends from the oral membrane to the
cloacal membrane.
It is divided into:
 1-foregut: from pharynx to the 2nd part of
duodenum.
 2-midgut : from 2nd part of duodenum to the
junction between medial 2/3 & lateral 1/3 of
transverse colon.
 3-hindgut: the remaining part of large intestine.
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The derivatives of The Foregut are
1- Pharynx
2- The lower respiratory system
3- The esophagus and stomach
4- The duodenum, distal to the opening of
the bile duct
5- The liver, biliary apparatus (hepatic
ducts, gallbladder, and bile duct), and
6- Pancreas
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The derivatives of The Midgut are:
1-Rest of the duodenum
2- Jejunum
3- Ileum
4- Appendix
5- Cecum
6- Ascending colon
7- Right colic flexure
8- Right 2/3 of transverse colon.
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The derivatives of The Hindgut are:
1- Left 1/3 of transverse colon.
2- Left colic flexure.
3- Descending colon.
4- Segmoid colon.
5- Rectum.
6- Upper ½ of anal canal.
7- Primitive urogenital sinus derivatives.
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Mesenteries
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Initially, the gut is in contact with the posterior body
wall.
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By 5th week, the connecting tissue (mesenchyme)
between the gut and body wall narrows.
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Thus, caudal part of the foregut, midgut and major
part of the hindgut are suspended by the dorsal
mesentery.
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Dorsal mesentery forms: greater omentum,
mesoduodenum, mesocolon and mesentery proper.
Mesenteries
Dorsal Mesentery
Ventral Mesentery
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Ventral mesentery exists only at the lower end of esophagus,
stomach and upper part of the duodenum.
Ventral mesentery is derived from the septum transversum.
The growth of the liver into the septum transversum results in
division of the ventral mesentery.
The part of the ventral mesentery between the liver and stomach
forms the lesser omentum.
The part between the liver and anterior abdominal wall forms the
Falciform ligament.
Mesenteries
Fixation of various parts of
intestines
The enlarged colon
presses the duodenum &
pancreas against the
posterior abdominal wall.
C&F
Intestines prior to fixation
Intestines after fixation
Most of duodenal
mesentery is absorbed,
so most of duodenum
( except for about the first
2.5 cm derived from
foregut) & pancreas
become retroperitoneal.
C&F
Development of the Esophagus
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It develops from the foregut caudal to
laryngo-tracheal groove till stomach.
Origin:
Endoderm of foregut  mucosa & its glands.
Splanchnic secondary mesoderm 
submucosa & musculosa.
Mesenchyme of branchial arches striated
muscles of upper 1/3 of oesophagus.
Development of the Esophagus
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The part of the foregut
extending from the
buccopharyngeal
membrane to the
respiratory diverticulum is
called the pharyngeal gut
(considered with
pharyngeal arches).
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The Remaining part
extends from the
respiratory diverticulum to
the liver bud.
Development of Esophagus
The Esophagus: Develops
from the foregut between
the respiratory diverticulum
and the stomach.
The muscle wall of the
(esophagus) develops from
the splanchnic mesoderm
(upper 1/3-skeletal, middle
1/3-mixed and lower 1/3smooth).
Esophagus elongates due to
the descent of heart and
lungs.
Development of the
Esophagus:
 The oesophagus is first
short then elongates.
 The trachea develops
from its ventral border.
 They are comunicating
then a
tracheaoesophageal
septum develops
between them.
 Epithelium of
oesophagus
proliferates, obliterating
the lumen then
recanalization occurs.
Development of Esophagus
Development of Esophagus
Congenital anomalies:
1. Short oesophagus:
Due to failure of elongation . It is associated
with thoracic stomach.
2.Tracheo-oesophageal fistula:
Due to non separation between trachea and
oesophagus  milk in lungs pneumonia.
 air in stomach  respiratory distress.
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3- Esophageal
Atresia:
Due to failure of
recanalization.
4. Oesophageal
stenosis:
Due to incomplete
recanalization
Esophageal atresia with tracheoesophageal
fistula
Developmet of the Stomach
Origin:
 Endoderm of foregut
mucosa & its glands.
 Splanchnic secondary mesoderm
submucosa, musculosa and serosa.
Development:
Fusiform part of foregut:
1- Its dorsal border grows more
greater
curvature.
2- Its dorsal border grows less
lesser
curvature.
3- Most cranial part of dorsal border grows
rapidly
fundus.
Final Shape of Stomach
Steps of stomach development
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It starts at the 5th week by a fusiform dilatation
which has:
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Upper and lower narrow ends.
Anterior and posterior borders which are connected
to anterior and posterior abdominal walls by ventral
and dorsal mesogastrium.
Right and left surfaces which are covered with
peritoneum.
-This is followed by rapid growth of the
posterior border to form greater curvature
while the anterior border forms lesser
curvature.
Liver is formed in the ventral
mesentery, the spleen is formed in
dorsal mesentery.
-Rotation of the stomach to the
right (clockwise) for 90 degrees.
- Results of rotation:
1- Lesser curvature is directed to
the right, while greater curvature
is directed to left.
2- Left surface is directed
anteriorly, right surface is
directed posteriorly.
3- Formation of a peritoneal sac
behind the stomach, called
lesser sac.
4- Left & right vagi will be anterior and posterior gastric
nerves.
5- Ventral mesogastrium forms the lesser omentum,
capsule around liver, falciform ligament and coronary
ligaments.
6- Dorsal mesogastrium forms gastrophrenic,
gastrosplenic, lienorenal ligaments and greater omentum.
N.B. The Stomach is supplied by the artery of foregut
which is the Celiac trunk
Congenital Anomalies
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1- Pyloric stenosis: Congenital
narrowing of pyloric
orifice.(SPHINCTER)
2- Hour glass stomach:
constriction of stomach dividing it
into 2 dilated parts with a
narrowing inbetween.
3- Thoracic stomach:
Protrusion of upper part of
stomach through diaphragm due
to short esophagus.(partial or
complete)
4- Transposition of stomach:
Right sided stomach.( situs
inversus)