Embryo/Teratogenesis Flashcards
The coeliac artery supplies the (fore/mid/hindgut).
Foregut
The Superior mesenteric artery supplies the (fore/mid/hindgut).
Midgut
The Inferior mesenteric artery supplies the (fore/mid/hindgut).
Hindgut
Which parts of the GIT arise from the foregut?
1) Esophagus
2) Stomach
3) 1st 2 parts of duodenum
4) Liver
5) Gallbladder
Where do the bones, muscles and cartilage in the head and neck region arising from?
Pharyngeal arches
In embryonic development what supplies the pharynx?
Thoracic aorta
Where do the esophageal epithelium and glands arise from?
Foregut endoderm
Where do the esophageal muscles arise from?
Mesoderm surrounding foregut
Initially, the embryonic esophageal lumen is filled, in development it undergoes ________ to become hollow.
Recanalisation
What are 3 examples of components of the GIT system is derived from the endoderm?
1) Mucosal epithelium
2) Mucosal glands
3) Submucosal glands
What are 6 examples of components of the GIT system is derived from the mesoderm?
1) Lamina propria
2) Muscularis mucosa
3) Submucosal connective tissue
4) Blood vessels
5) Muscularis externa
6) Adventitia/serosa
What component of the GIT system is derived from the neural crest cells?
Nerves of the submucosal and myenteric plexus
The dorsal border of the mesogastrium has (greater/lesser) curvature than the ventral border. During clockwise rotation, the dorsal mesogastrium would have (greater/lesser) momentum than the ventral mesogastrium.
Dorsal → greater curvature and momentum
Ventral → lesser curvature and momentum
Describe the rotation(s) of the embryonic stomach.
1) 90 degree clockwise → creates omental foramen (allows for communication btwn greater and lesser sacs of peritoneal cavity)
2) frontal plane → repositions superior and inferior regions of stomach
Rotation of the stomach brings the duodenum into position turning it into a __________ loop on the (right/left) side of the abdominal cavity.
C-shaped loop on the right side of the abdominal cavity
Initially, the embryonic duodenum lumen is filled, in development it undergoes ________ to become hollow.
recanalisation
The proximal 1/3 of the duodenum arises from the ________ while the distal 2/3 arises from the ______.
proximal 1/3 from foregut
distal 2/3 from midgut
What do the liver, gall bladder and biliary duct system arise from?
Liver bud/hepatic diverticulum
Which germ layer do hepatocytes arise from?
Endoderm
Which germ layer do Kupffer cells arise from?
Mesoderm
Which germ layer do hepatic hematopoietic tissues arise from?
Mesoderm
How does the pancreas form?
Dorsal and ventral pancreatic buds unit to give rise to 1 pancreas as duodenum rotates
Which germ layer do pancreatic parenchyma arise from?
Endoderm
Which germ layer do pancreatic islets arise from?
Mesoderm
How does the spleen form?
Developed from mesenchymal cells in the fold of dorsal mesogastrium
The gastrosplenic and splenorenal ligaments are remnants of what embyronic structure?
Remnants of the dorsal mesogastrium
What are 5 congenital anomalies associated with the foregut?
1) Esophageal atresia
2) Esophageal stenosis
3) Congenital hiatal hernia
4) Pyloric stenosis
5) Annular pancreas
What is an esophageal atresia?
Abnormal tracheoesophageal septum (usually occurs w a tracheoesophageal fistula)
- lead to complications (eg. inflammation, infection)
What is an esophageal stenosis?
Narrowing of the esophageal lumen due to failure to recanalise
What is a congenital hiatal hernia?
Enlarged esophageal hiatus due to defect/weakness in diaphragmatic muscles
What is a pyloric stenosis?
Hypertrophy of smooth muscle of the pyloric sphincter
- associated with forceful vomiting shortly after feeding
What is an annular pancreas?
Abnormalities in rotation of ventral bud of the pancreas
- ventral bud surrounds/constricts duodenum → blockage
Which parts of the GIT arise from the midgut (7)?
1) Distal 2/3 of duodenum
2) Jejunum
3) Ileum
4) Coecum
5) Appendix
6) Ascending Colon
7) Proximal 2/3 of transverse colon
How does physiological herniation occur in GIT development?
Formation of small intestine
- Primary intestinal loop (from midgut) herniates through vitelline duct
- cranial loop → jejunal and ileal portions of small intestine
- caudal loop → coecum, appendix, ascending colon, proximal 2/3 of transverse colon
How does the large intestine form?
Develop as dilation of caudal limb of herniated primary intestinal loop
What are 3 congenital anomalies associated with the midgut?
1) Meckel’s diverticulum
2) Congenital umbilical hernia
3) Abnormal rotation of midgut
What is meckel’s diverticulum?
Remnant of vitelline duct persists as ileal diverticulum
- asymptomatic but susceptible to infections
What is a congenital umbilical hernia?
Incomplete closure/weakness of umbilical ring
- weak point in abdominal wall → prone to herniation
- incomplete closure of umbilical ring → protrusion of abdominal contents
What are 2 abnormal rotations of the midgut?
1) Non-rotation
2) Mixed rotation of midgut
- cephalic and cranial loops rotate incorrectly
Which parts of the GIT arise from the hindgut (4)?
1) Distal 1/3 of transverse colon
2) Descending colon
3) Sigmoid colon
4) Upper part of anal canal
The hindgut ends with the _____.
Cloaca
The ______ divides the cloaca into the _____ and ______.
Urorectal septum
1) urogenital sinus (anterior)
2) anorectal (posterior)
The superior 2/3 of the anorectal canal forms the _____.
distal portion of hindgut
The inferior 1/3 of the anorectal canal is formed from which germ layer?
Ectoderm
What is a congenital abnormality associated with the hindgut?
Imperforate anus
What is an imperforate anus?
A congenital anorectal malformation
- normal anal opening absent at birth
What is the mesentery?
Mesenchymal (connective tissue) covering passing over developing gut tube from posterior body wall.
- suspends the gut and organs within abdomen
What does the dorsal mesentery form (5)?
1/2) Mesenteries of Large and Small intestine
3) Mesentery of mesocolon
4) Mesentery of mesoappendix
5) Greater omentum
What does the ventral mesentery form (2)?
1) Lesser omentum
2) Falciform ligament
What are 3 primary retroperitoneal organs?
1) Thoracic esophagus
2) Rectum
3) Anus
What are 4 secondarily retroperitoneal organs?
1) Proximal 2/3 duodenum
2) Pancreas
3) Ascending colon
4) Descending colon
