Flashcards in Development of the Digestive System Deck (67)
What does the foregut give rise to in the thorax?
pharynx, larynx, trachea, lungs, and esophagus
What does the foregut give rise to in the abdominal cavity? What artery supplies it?
stomach, proximal half of duodenum (up to entrance of bile duct), liver, gallbladder, bile & hepatic duct system, pancreas, and spleen
Blood supply: Celiac artery only
What does the midgut give rise to and what artery supplies it?
Distal half of duodenum (past pile duct), jejunum ileum, cecum & appendix, ascending colon, and proximal 2/3 of transverse colon
All supplied by superior mesenteric artery
What does the hindgut give rise to and what artery supplies it?
Distal 1/3 of transverse colon, descending colon, sigmoid colon, and rectum up to the pectinate line. It also gives rise to urinary bladder and urethra.
Blood: Inferior mesenteric artery
What is the primary control over which division of the primordial gut develops where?
Retinoic acid gradient released by visceral mesoderm, increasing in concentration from oropharyngeal membrane to cloacal membrane.
This riggers regional expression of specific transcription factors within the endoderm.
What is the reciprocal control of gut differentiation?
Endoderm which has been induced to make transcription factors also produces sonic hedgehog, which induces expression of nested HOX genes within neighboring mesoderm
HOX gene expression within mesoderm is the final determinant of development
What does the endoderm become in the GI tract?
epithelium and glands
What does splanchnic mesoderm give rise to in the GI tract?
Lamina propria, muscularis mucosae, submucosa, blood vessels, lymphatics, and adventitia (visceral peritoneum)
What does the somatic mesoderm give rise to?
Musculature and skeletal components of body wall, has nothing to do with gut tube. Lines abdominal and pelvic cavities with parietal peritoneum
What do neural crest cells give rise to in the GI tract?
submucosal and myenteric nervous plexus
What is the dorsal mesentery / where does it form? What is at its base? What is special about early on?
It is the structure which suspends the primordial gut off the body wall inferior to the thoracic diaphragm, and is derived by splanchnic mesoderm. Within it, there are blood vessels, lymphatics, connective tissues, and autonomic input.
The descending aorta is positioned at its base.
Early on in development, EVERYTHING is peritoneal.
What are the four divisions of the dorsal mesentery? What do they contain?
1. Dorsal mesogastrium - celiac artery
2. Dorsal mesoduodenum - suspends duodenum
3. Mesentery proper - all SMA derivatives
4. Dorsal mesocolon - all IMA derivatives
What structures other than the stomach does the dorsal mesogastrium give rise to?
Dorsal pancreas and spleen, gastrosplenic and splenorenal ligaments. Also greater omentum
What is the ventral mesentery? Where is it attached to the anterior body wall?
Double-layered mesothelium that is derived from septum transversum of developing thoracic diaphragm. It is shorter than the dorsal mesentery and suspends esophagus, stomach, and 1/2 duodenum as they develop.
Attachment: Diaphragm to umbilicus
What ligaments does the ventral mesentery give rise to?
1. Lesser omentum - between liver and stomach
2. Falciform ligament - Between ventral surface of liver and anterior abdominal wall
3. Coronary and triangular ligaments - suspend liver off inferior surface of thoracic diaphragm
What gives rise to the posterior mediastinum?
The esophagus as it elongates behind pleural and pericardial cavities, and it is invested by connective tissues from splanchnic mesoderm. Will contain trachea, right + left vagal nerves, roots of lungs, esophagus, and phrenic nerves
What creates the esophageal opening of the adult thoracic diaphragm?
When the esophagus is approached by the pleuroperitoneal folds and the septum transversum
What is the first developmental shift of the stomach?
Since it is attached by dorsal and ventral mesogastrium, it is flanked by right and left vagal trunks.
First shift: Rotates 90 degrees clockwise about its longitudinal axis (From cranial view). This includes distal half of esophagus + proximal duodenum.
What happens from the first rotation of the stomach?
Left side of stomach becomes ventral surface, with left vagal trunk.
Right side becomes dorsal surface, with right vagal trunk.
What forms the greater and lesser curvature of the stomach?
Prior to the 90 degree rotation, the dorsal surface of the developing stomach grows faster than the ventral surface. Thus, with 90 degrees rotation, the right surface becomes the lesser curvature, and the left surface becomes the greater curvature.
What is the second rotation of the stomach?
55-60 degree rotation along its anterior/posterior axis, causing distal end of stomach to move upward and right, and cardiac portion of stomach to be displaced slightly downward and to the left.
What are the regional transcription factors for GI development?
Respiratory - TBX4
Esophagus + stomach - SOX
Duodenum - PDX1
Jejunum and ileum - CDXC
Large intestine + rectum - CDXA
What is the space between the dorsal mesogastrium and the dorsal surface of the stomach?
The omental bursa, i.e. the lesser sac of the peritoneal cavity. Forms greater omentum
What happens to dorsal mesogastrium that comes in contact with the parietal peritoneum of the body wall?
They fuse together. The posterior sheet will degenerate, leaving only the anterior sheet of dorsal mesogastrium covering the posterior abdominal wall
What causes the duodenum to become related to the posterior abdominal wall? What structure does the ventral mesoduodenum give rise to?
Rotation of stomach via rotation of primary intestinal loop. Duodenum gives rise to hepatic diverticulum
Stomach + intestinal turning gives rise to C-shape of duodenum
What is the hepatic diverticulum and what induces it? What side does it originally start?
Bud which gives rise to liver, hepatic / bile system, gall bladder + cystic duct, and ventral pancreatic bud. It forms off of mid-duodenum, induced by release of local fibroblast growth factors (FGF) from cardiac mesoderm early on
Starts on ventral side of duodenum before clockwise stomach rotation allows bile duct on the inferior right side of the duodenum
What forms the liver parenchyma(Germ layer + where)?
Endoderm in the foregut region of future mid-duodenum branching from hepatic diverticulum.
Liver hepatocytes proliferate within the right septum transversum.
What forms liver sinusoids?
Intermingling of vitelline and umbilical veins
What part of the liver is actually formed by the mesoderm of the septum transversum?
Hematopoietic cells, Kupffer cells, and connective tissues in the liver.