BGDB Gastrointestinal - Activity 2

From Embryology
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Practical 1: Activity 1 | Activity 2 | Activity 3 | Activity 4


Learning Activity 2

  1. Describe how elongation and rotation of the simple primitive tube establish the gut anatomy.
  2. Explain the developmental processes of elongation, herniation and rotation of the mid-gut.
  3. Describe the structure of the attachment of the gut to the body wall.
  4. Identify the developmental origins of abnormalities of the gut lumen, innervation, herniation and malrotation.


The early developing gastrointestinal tract The later developing gastrointestinal tract
Early Embryo Later Embryo

1. Mechanical Changes

Transverse section of the developing stomach mid-embryonic period (Week 5 Carnegie stage 13)

Stage 13 image 075.jpg Stage14 stomach.jpg
Stage14 bf28.jpg
Stomach rotation 01 icon.jpg
 ‎‎Stomach Rotation
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Lesser sac 01 icon.jpg
 ‎‎Lesser sac
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2. Mesentery

Greater-omentum.jpg

In the second trimester, the ventral and dorsal mesenteries associated with the stomach are still anatomically different from the newborn. The figure shows a lateral view of this process comparing the early second trimester arrangement with the newborn structure.

Pancreas rotation.jpg After the stomach the initial portion of the gastrointestinal tract tube is the duodenum which initially lies in the midline within the peritoneal cavity.

This region, along with the attached pancreas, undergoes rotation to become a retroperitoneal structure.

This diagram shows the rotation with spinal cord at the top, vertebral body then dorsal aorta then pertioneal wall and cavity.

3. Mid-Gut

Human Embryo MRI at the end of embryonic development (GA week 10).
Observe:

  • midgut herniated at the umbilicus, lying outside the ventral body wall, connected by mesentry
  • large liver lying directly under the diaphragm and occupying the entire ventral body cavity with other organs "embedded"
  • developing pancreas lying in the loop between stomach and duodenum


Late Embryo


Early Fetal
Human week 10 fetus 26.jpg Human week 10 fetus 01.jpg


Mid-Gut Rotation/Sliding

Very simplified demonstration of midgut reorganisation to establish adult anatomical positions.

Green ring = ventral body wall    Red vessels = superior mesenteric artery


Normal intestinal rotation cartoon.jpg


4. Abnormality Origins

Omphalocele

Omphalocele ruptured during birth exposing liver and small intestine.[1]

Abdominal wall herniation abnormality occurs in both omphalocele and gastroschisis with different developmental origins. Omphalocele involves "covered by membranes" and a lack of normal return of the bowel to the abdominal cavity and has a different position relative to the umbilical cord.


Gastroschisis

Gastroschisis 01.jpg

Gastroschisis is a developmental abnormality occurs due to an abdominal wall defect, that allows the evisceration of the intestine.



Volvulus of small intestine

Midgut volvulus
Midgut volvulus

 ICD-11 DA91.1 Volvulus of small intestine - A volvulus is an abnormal twisting of the intestine around the axis of its own mesentery, resulting in obstruction of the more proximal bowel. Twisting of the mesentery may involve the mesenteric vessels and so make the involved loop particularly susceptible to strangulation and gangrene, with resulting perforation, peritonitis, and sepsis.

Diagnosis is generally by upper gastrointestinal radiologic examination or less frequently by barium enema or CT scan. Corrective surgery is generally by the Ladd's procedure, even with surgical treatment there is still significant associated complications and long-term morbidity.

Hirschsprung disease

 ICD-11 LB16.1 Hirschsprung disease - This is a developmental anomaly affecting the intestinal tract characterized by congenital absence of myenteric ganglion cells (aganglionosis) in a segment of the large bowel. Due to the absence of intrinsic innervation of the muscle layers of the affected segment, there is a loss of motor function. This results in an abnormally large or dilated colon (congenital megacolon) with intestinal occlusion or constipation. This condition becomes evident shortly after birth.


(intestinal aganglionosis, Hirschsprung's disease, aganglionic colon, megacolon, congenital aganglionic megacolon, congenital megacolon) A condition caused by the lack of enteric nervous system (neural ganglia) in the intestinal tract responsible for gastric motility (peristalsis). In general, its severity is dependent upon the amount of the GIT that lacks intrinsic ganglia, due to developmental lack of neural crest migration into those segments. (More? neural crest abnormalities)

Megacolon stoma1.jpg Megacolon stoma2.jpg  
Ostomy - Aganglionic portion removed Stoma - intestine attached to the abdomen wall
Megacolon surgery 01.jpg Megacolon surgery 02.jpg Megacolon surgery 03.jpg
Short section of the colon without smooth muscle neural ganglia Aganglionic segment removed Reattachment

Interactive Component

Attempt the Quiz



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Practical 1: Activity 1 | Activity 2 | Activity 3 | Activity 4


Additional Information

Additional Information - Content shown under this heading is not part of the material covered in this class. It is provided for those students who would like to know about some concepts or current research in topics related to the current class page.
Gastrointestinal Tract Terms  
  • allantois - An extraembryonic membrane, endoderm in origin extension from the early hindgut, then cloaca into the connecting stalk of placental animals, connected to the superior end of developing bladder. In reptiles and birds, acts as a reservoir for wastes and mediates gas exchange. In mammals is associated/incorporated with connecting stalk/placental cord fetal-maternal interface.
  • amnion - An extra-embryonic membrane, ectoderm and extraembryonic mesoderm in origin, also forms the innermost fetal membrane, that produces amniotic fluid. This fluid-filled sac initially lies above the trilaminar embryonic disc and with embryoic disc folding this sac is drawn ventrally to enclose (cover) the entire embryo, then fetus. The presence of this membrane led to the description of reptiles, bird, and mammals as amniotes.
  • amniotic fluid - The fluid that fills amniotic cavity totally encloses and cushions the embryo. Amniotic fluid enters both the gastrointestinal and respiratory tract following rupture of the buccopharyngeal membrane. The late fetus swallows amniotic fluid.
  • atresia - is an abnormal interruption of the tube lumen, the abnormality naming is based upon the anatomical location.
  • buccal - (Latin, bucca = cheek) A term used to relate to the mouth (oral cavity).
  • bile salts - Liver synthesized compounds derived from cholesterol that function postnatally in the small intestine to solubilize and absorb lipids, vitamins, and proteins. These compounds act as water-soluble amphipathic detergents. liver
  • buccopharyngeal membrane - (oral membrane) (Latin, bucca = cheek) A membrane which forms the external upper membrane limit (cranial end) of the early gastrointestinal tract. This membrane develops during gastrulation by ectoderm and endoderm without a middle (intervening) layer of mesoderm. The membrane lies at the floor of the ventral depression (stomodeum) where the oral cavity will open and will breakdown to form the initial "oral opening" of the gastrointestinal tract. The equivilent membrane at the lower end of the gastrointestinal tract is the cloacal membrane.
  • celiac artery - (celiac trunk) main blood supply to the foregut, excluding the pharynx, lower respiratory tract, and most of the oesophagus.
  • cholangiocytes - epithelial cells that line the intra- and extrahepatic ducts of the biliary tree. These cells modify the hepatocyte-derived bile, and are regulated by hormones, peptides, nucleotides, neurotransmitters, and other molecules. liver
  • cloaca" - (cloacal cavity) The term describing the common cavity into which the intestinal, genital, and urinary tracts open in vertebrates. Located at the caudal end of the embryo it is located on the surface by the cloacal membrane. In many species this common cavity is later divided into a ventral urogenital region (urogenital sinus) and a dorsal gastrointestinal (rectal) region.
  • cloacal membrane - Forms the external lower membrane limit (caudal end) of the early gastrointestinal tract (GIT). This membrane is formed during gastrulation by ectoderm and endoderm without a middle (intervening) layer of mesoderm. The membrane breaks down to form the initial "anal opening" of the gastrointestinal tract.
  • coelomic cavity - (coelom) Term used to describe a space. There are extra-embryonic and intra-embryonic coeloms that form during vertebrate development. The single intra-embryonic coelom forms the 3 major body cavities: pleural cavity, pericardial cavity and peritoneal cavity.
  • crypt of Lieberkühn - (intestinal gland, intestinal crypt) intestinal villi epithelia extend down into the lamina propria where they form crypts that are the source of epithelial stem cells and immune function.
  • duplication - is an abnormal incomplete tube recanalization resulting in parallel lumens, this is really a specialized form of stenosis. (More? Image - small intestine duplication)
  • esophageal - (oesophageal)
  • foregut - first embryonic division of gastrointestinal tract extending from the oral (buccopharyngeal) membrane and contributing oesophagus, stomach, duodenum (to bile duct opening), liver, biliary apparatus (hepatic ducts, gallbladder, and bile duct), and pancreas. The forgut blood supply is the celiac artery (trunk) excluding the pharynx, lower respiratory tract, and most of the oesophagus.
  • galactosemia - Metabolic abnormality where the simple sugar galactose (half of lactose, the sugar in milk) cannot be metabolised. People with galactosemia cannot tolerate any form of milk (human or animal). Detected by the Guthrie test.
  • gastric transposition - clinical term for postnatal surgery treatment for esophageal atresia involving esophageal replacement. Typically performed on neonates between day 1 to 4. (More? gastrointestinal abnormalities | PMID 28658159
  • gastrointestinal divisions - refers to the 3 embryonic divisions contributing the gastrointestinal tract: foregut, Midgut and hindgut.
  • gastrula - (Greek, gastrula = little stomach) A stage of an animal embryo in which the three germ layers (endoderm/mesoderm/ectoderm) have just formed. All of these germ layers have contributions to the gastrointestinal tract.
  • gastrulation - The process of differentiation forming a gastrula. Term means literally means "to form a gut" but is more in development, as this process converts the bilaminar embryo (epiblast/hypoblast) into the trilaminar embryo (endoderm/mesoderm/ectoderm) establishing the 3 germ layers that will form all the future tissues of the entire embryo. This process also establishes the the initial body axes. (More? gastrulation)
  • Guthrie test - (heel prick) A neonatal blood screening test developed by Dr Robert Guthrie (1916-95) for determining a range of metabolic disorders and infections in the neonate. (More? Guthrie test)
  • hindgut - final embryonic division of gastrointestinal tract extending to the cloacal membrane and contributing part of the transverse colon (left half to one third), descending colon, sigmoid colon, rectum, part of anal canal (superior), urinary epithelium (bladder and most urethra). The hindgut blood supply is the inferior mesenteric artery.
  • inferior mesenteric artery - main blood supply to the hindgut
  • intestinal perforation - gastrointestinal abnormality identified in neonates can be due to necrotizing enterocolitis, Hirschsprung’s disease or meconium ileus.
  • intraembryonic coelom - The "horseshoe-shaped" space (cavity) that forms initially in the third week of development in the lateral plate mesoderm that will eventually form the 3 main body cavities: pericardial, pleural, peritoneal. The intraembryonic coelom communicates transiently with the extraembryonic coelom.
  • meconium ileus intestine obstruction within the ileum due to abnormal meconium properties.
  • mesentery - connects gastrointestinal tract to the posterior body wall and is a double layer of visceral peritoneum.
  • mesothelium - The mesoderm derived epithelial covering of coelomic organs and also line their cavities.
  • Midgut - middle embryonic division of gastrointestinal tract contributing the small intestine (including duodenum distal bile duct opening), cecum, appendix, ascending colon, and part of the transverse colon (right half to two thirds). The midgut blood supply is the superior mesenteric artery.
  • neuralation - The general term used to describe the early formation of the nervous system. It is often used to describe the early events of differentiation of the central ectoderm region to form the neural plate, then neural groove, then neural tube. The nervous system includes the central nervous system (brain and spinal cord) from the neural tube and the peripheral nervous system (peripheral sensory and sympathetic ganglia) from neural crest. In humans, early neuralation begins in week 3 and continues through week 4.
  • neural crest - region of cells at the edge of the neural plate that migrates throughout the embryo and contributes to many different tissues. In the gastrointestinal tract it contributes mainly the enteric nervous system within the wall of the gut responsible for peristalsis and secretion.
  • peritoneal stomata - the main openings forming the pathways for drainage of intra-peritoneal fluid from the peritoneal cavity into the lymphatic system.
  • pharynx - uppermost end of gastrointestinal and respiratory tract, in the embryo beginning at the buccopharyngeal membrane and forms a major arched cavity within the phrayngeal arches.
  • recanalization - describes the process of a hollow structure becoming solid, then becoming hollow again. For example, this process occurs during GIT, auditory and renal system development.
  • retroperitoneal - (retroperitoneum) is the anatomical space (sometimes a potential space) in the abdominal cavity behind (retro) the peritoneum. Developmentally parts of the GIT become secondarily retroperitoneal (part of duodenum, ascending and descending colon, pancreas)
  • somitogenesis The process of segmentation of the paraxial mesoderm within the trilaminar embryo body to form pairs of somites, or balls of mesoderm. A somite is added either side of the notochord (axial mesoderm) to form a somite pair. The segmentation does not occur in the head region, and begins cranially (head end) and extends caudally (tailward) adding a somite pair at regular time intervals. The process is sequential and therefore used to stage the age of many different species embryos based upon the number visible somite pairs. In humans, the first somite pair appears at day 20 and adds caudally at 1 somite pair/4 hours (mouse 1 pair/90 min) until on average 44 pairs eventually form.
  • splanchnic mesoderm - Gastrointestinal tract (endoderm) associated mesoderm formed by the separation of the lateral plate mesoderm into two separate components by a cavity, the intraembryonic coelom. Splanchnic mesoderm is the embryonic origin of the gastrointestinal tract connective tissue, smooth muscle, blood vessels and contribute to organ development (pancreas, spleen, liver). The intraembryonic coelom will form the three major body cavities including the space surrounding the gut, the peritoneal cavity. The other half of the lateral plate mesoderm (somatic mesoderm) is associated with the ectoderm of the body wall.
  • stomodeum - (stomadeum, stomatodeum) A ventral surface depression on the early embryo head surrounding the buccopharyngeal membrane, which lies at the floor of this depression. This surface depression lies between the maxillary and mandibular components of the first pharyngeal arch.
  • stenosis - abnormal a narrowing of the tube lumen, the abnormality naming is based upon the anatomical location.
  • superior mesenteric artery - main blood supply to the Midgut.
  • viscera - the internal organs in the main cavities of the body, especially those in the abdomen, for example the Template:Intestines.
  • visceral peritoneum - covers the external surfaces of the intestinal tract and organs within the peritoneum. The other component (parietal peritoneum) lines the abdominal and pelvic cavity walls.
  • yolk sac - An extraembryonic membrane which is endoderm origin and covered with extraembryonic mesoderm. Yolk sac lies outside the embryo connected initially by a yolk stalk to the midgut with which it is continuous with. The endodermal lining is continuous with the endoderm of the gastrointestinal tract. The extra-embryonic mesoderm differentiates to form both blood and blood vessels of the vitelline system. In reptiles and birds, the yolk sac has a function associated with nutrition. In mammals the yolk sac acts as a source of primordial germ cells and blood cells. Note that in early development (week 2) a structure called the "primitive yolk sac" forms from hypoblast, this is an entirely different structure.
  • yolk stalk - (vitelline duct, omphalomesenteric duct, Latin, vitellus = yolk of an egg) The endodermal connection between the midgut and the yolk sac. See vitelline duct.
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Cite this page: Hill, M.A. (2019, July 17) Embryology BGDB Gastrointestinal - Activity 2. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/BGDB_Gastrointestinal_-_Activity_2

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© Dr Mark Hill 2019, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G
  1. Akakpo-Numado GK, Gnassingbe K, Boume MA, Sakiye KA, Mihluedo-Agbolan K, Attipou K & Tekou H. (2012). Emergency treatment of a ruptured huge omphalocele by simple suture of its membrane. Ann Surg Innov Res , 6, 2. PMID: 22325297 DOI.
  2. Feldkamp ML, Carey JC & Sadler TW. (2007). Development of gastroschisis: review of hypotheses, a novel hypothesis, and implications for research. Am. J. Med. Genet. A , 143A, 639-52. PMID: 17230493 DOI.