Development of foregut,midgut and hindgut by Dr imtiyaz. Contains information about embryology of GIT

1. Dr. Mohammed Imtiyaz Shaikh MD.
MIMS.

2.  Divisions of gut tube.
 Derivatives of different parts mesogastrium.
 Development of Oesophagus.
 Development of Stomach.
 Development of Duodenum.
 Development of Liver and Gallbladder.
 Development of Pancreas.

3.  Langman’s Medical Embryology by T.W.Sadler
 Ninth edition
 Chapter 13
 Page No.: 285 to 304.
 Figures: 13.1 to 13.23
 Other reference text book:
 Keith Moore’s Developing Human

7.  Epithelium of gut tube and parenchyma of glands like
liver, pancreas derived from endoderm while muscles,
connective tissue and peritoneal component derived
from splanchnic mesoderm.
 Divided in to four sections:
 Pharyngeal gut: from buccopharyngeal membrane to
tracheobronchial diverticulum.
 Foregut: From caudal to pharyngeal tube to liver
outgrowth.
 Midgut: From caudal to liver to junction of right two-
thirds and left one-third of transverse colon.
 Hindgut: From left one third of transverse colon to
cloacal membrane.

10.  Ventral mesogastrium: forms falciform
ligament of liver and lesser omentum
 Dorsal mesogastrium: forms greater
omentum, lienorenal ligament and
gastrolienal ligament.
 Lesser sac(Omental bursa) develops
behind stomach due to rotation of
stomach.

14.  Oesophagus develops from foregut due to
separation of lung bud by tracheoesophageal
septum. Ventral part form trachea and dorsal
part form esophagus.
 Initially oesophagus is short but later on
elongates.
 Oesophageal atresia: absence of formation of part
of oesophagus.
 Atresia of oesophagus leads to polyhydramnios.

17.  Stomach develops as fusiform dilatation of
foregut.
 Rotation of 90 degrees clockwise leads to
anterior border becomes lesser curvature and
posterior border becomes greater curvature.
 Formation of mesogastrium and its derivatives:
 Peritonael ligaments and folds, lesser sac
 Pyloric stenosis: narrowing of pylorus causing
obstruction to food passage.

19.  Duodenum up to opening of bile duct derived from
foregut.
 Duodenum from opening bile duct till end is derived
from midgut.
 Forms C-shaped loop and rotates to the right.
 Liver develops as outgrowth from duodenum known
as hepatic diverticulum(liver bud).
 Elongation of diverticulum form bile duct and gall
bladder.
 Hepatic cords-endodermal in origin form parenchyma
of liver.
 Connective tissue, Kupffer cells and haemopoietic cells
are derived from mesoderm of septum transversum.

20. Development of
pancreas
•Develops from two buds:
•Ventral pancreatic bud:
form uncinate process and
inferior part of head of
pancreas.
•Dorsal pancreatic bud:
form superior part of head,
neck, body and tail of
pancreas.
•Both bud fuse due to
rotation and differntial
growth.
•Main pancreatic duct:
whole ventral duct and
distal part of dorsal duct.
•Accessory pancreatic duct:
proximal part of dorsal
duct.

21. During rotation or migration of ventral pancreatic bud some
pancreatic tissue surround the duodenum. Such condition is
known as Annular Pancreas.
It leads to duodenal obstruction.

22. Dr. MOHAMMED IMTIYAZ
SHAIKH. MD.
MIMS

23.  Midgut derivatives.
 Rotation of midgut.
 Embryological basis of organ positions in
abdomen.
 Anomalies of rotation.
 Omphalocele.
 Meckel’s diverticulum

24.  Langman’s Medical Embryology by T.W.Sadler
 Ninth edition
 Chapter 13
 Page No.: 304 to 313.
 Figures: 13.24 to 13.33
 Other reference text book:
 Keith Moore’s Developing Human

28.  Midgut: From caudal to liver to junction of right two-thirds and
left one-third of transverse colon.
 Due to small abdominal cavity, initial development of midgut
takes place in umbilicus. It is physiological hernia.
 Midgut Rotation: The midgut loop is divided into prearterial
segment and post arterial segment by superior mesenteric artery.
 Due to growth of the prearterial segment fater then postarterial
segment, there is gradual rotation of the midgut loop. First
rotation is 90 degrees anticlockwise. Later on as the abdominal
cavity expands and intestinal loops returning to abdomen there is
another rotation of 180 degrees anticlockwise(counterclockwise).
So midgut loop rotates total 270 degrees anticlockwise before
returning to abdomen.
 Due to rotation duodenum is placed behind transverse colon and
small intestine below transverse colon. Cecum initially below the
liver later on descends to right iliac fossa. Appendix formed at
cecum due to differential growth of cecum.

32.  Duodenum after opening of bile duct
 Jejunum and Ileum
 Cecum and appendix
 Ascending colon
 Right two third of transverse colon.
 Artery Supplying Midgut is Superior
Mesenteric Artery.

33.  Reverse rotation: It leads to transverse colon
behind the duodenum. It leads to intestinal
obstruction. Volvulus-twisting of the intestinal
loops.
 Non-rotation: It leads to small inteatine on one
side and large intestine on another side in
abdomen.
 Omphalocele: Persistence of intestinal loops in
the umbilicus covered by amnion.
 Meckel’s diverticulum: persistence of
vitelointestinal duct

37.  Divisions of Hindgut.
 Derivatives of Hindgut.
 Cloaca and its derivatives.
 Hindgut Abnormalities:
 Rectoanal atresia and fistula.
 Imperforate anus.
 Congenital megacolon.

38.  Langman’s Medical Embryology by
T.W.Sadler
 Ninth edition
 Chapter 13
 Page No.: 313 to 318.
 Figures: 13.36 to 13.37
 Other reference text book:
 Keith Moore’s Developing Human

39.  Hindgut is the part of gut from junction of right 2/3rd and
left 1/3rd of transverse colon to cloacal membrane.
 Developing hindgut is supplied by inferior mesenteric artery.
 It is divided into:
 Part cranial to allantois: forms left 1/3 of transverse colon,
descending colon, pelvic colon.
 Part caudal to allantois: Dilates to form the cloaca. It forms
rectum, upper part of anal canal, urinary bladder, female
urethra and most of male urethra.
 Proximal part of Anal canal(Endodermal) is supplied by
Superior rectal artery –branch of inferior mesenteric artery.
 Distal part of Anal canal(Ectodermal) is supplied by Inferior
rectal artery –branch of Internal Pudendal artery.

43.  It is caudal part of hindgut, just below attachment of
allantois.
 Uro-rectal septum is a down growing mesoderm that
lies between allantois and hindgut proper.
 This septum divides cloaca into ventral primitive
uro-genital sinus and dorsal ano-rectal canal.
 Primitive uro-genital sinus is divided by opening of
mesonephric duct into: vesico-uretheral canal and
defenitive uro-genital sinus.
 This septum divides also cloacal membrane into
ventral urogenital membrane and dorsal anal
membrane.

44.  Dorsal part of cloaca (ano-rectal canal) forms the
mucosa of rectum and upper ½ of anal canal. While
their muscles are developed from surrounding
mesoderm.
 Lower ½ of anal canal is developed from
proctodeum (ectodermal depression below anal
membrane).
 Anal membrane ruptures at 9th week to allow
continuity between 2 parts of anal canal.
 Upper ½ of anal mucosa is endodermal while lower
½ is ectodermal. Pectinate line separates between 2
parts in adult.

45.  Imperforate Anus: Failure of rupture of anal
membrane.
 Rectoanal atresia: Abnormal formation of cloaca.
 Recto-vesical fistula: Abnormal communication
between rectum and urinary bladder.
 Recto-vaginal fistula: Abnormal communication
between rectum and vagina.
 Congenital megacolon (Aganglionic megacolon-
Hirschsprung disease): Absence of parasympathetic
ganglia in bowel wall due to failure of neural crest cells
to migrate in bowel wall. It leads to dilatation of the
colon due to collection of fecal matter.