Block 2 Anatomy Embryo GI system - Cell Bio Transduction part 1 Flashcards
Describe the morphology of the developing gut tube including the cloacal membrane, allantois and vitelline duct
Cloaca
- Latin word for sewer is cloaca
- This primitive portion of posterior hindgut receives outflow of GI tract and urogenital system
- Urorectal septum divides cloaca into rectum and precursor of urinary bladder
- Covered more extensively with urogenital development
Allantois
Allantois: duct connecting the developing bladder to the placenta so wastes can be removed
Vitelline duct
Vitelline duct: connection between the yolk sac and gut tube
Origins of Different Components of Gut Tube
Origins of Different Components of Gut Tube
- Luminal Lining Epithelium from Endoderm
- Resident Cells in lamina propria, submucosal CT, muscularis externa, and adventital CT from splanchnic mesoderm
- Myenteric (Auerbach’s) plexus and Submucosal (Meissner’s) plexus from neural crest
- Lymphoid tissue from bone marrow (mesoderm)
Origins of Components of Liver, Pancreas, and Gall Bladder
Origins of Components of Liver, Pancreas, and Gall Bladder
- Hepatic parenchymal cells, pancreatic acinar cells, islet tissue, luminal lining of gall bladder from endoderm
- CT in capsules and rest of organ, blood vessels, smooth muscle in wall of gall bladder from mesoderm.
- In liver, CT and blood vessels from septum transversum, rest from splanchnic mesoderm
Bottom Line
- If it is derivied from the gut tube itself, it is endoderm
- If it is associated tissue, it is mesoderm
- If it is neural, it is neural crest
Divisions of Primitive Gut Tube
Divisions of Primitive Gut Tube
- Foregut-from buccopharyngeal membrane to anterior intestinal portal
- Midgut-from anterior to posterior intestinal portal
- Hindgut-from posterior intestinal portal to cloacal membrane
Blood Supply to Embryonic Divisions of Gut Tube
Blood Supply to Embryonic Divisions of Gut Tube
- Lower foregut-celiac trunk
- Midgut-superior mesenteric artery
- Hindgut-inferior mesenteric artery
Cranial Foregut Derivatives
Cranial Foregut Derivatives
- Epithelium lining posterior oral cavity
- Thyroid epithelium
- Respiratory diverticulum
- Epithelium of auditory tube
- Epithelium of palatine tonsils
- Epithelium of parathyroids
- Epithelium of thymus
Caudal Foregut Derivatives
Caudal Foregut Derivatives
- Oropharynx and Esophagus
- Stomach
- First part of duodenum
- Liver, pancreas, and gall bladder
Midgut Derivatives
Midgut Derivatives
- Second part of duodenum
- Ileum and jejunum
- Cecum and vermiform appendix
- Ascending colon
- Transverse colon to middle
Hindgut Derivatives
Hindgut Derivatives
- Second half of transverse colon
- Descending colon
- Sigmoid colon
- Rectum
- Anus to anal valves (pectinate line)
Gastric Rotation
Gastric Rotation
- Stomach forms from dilation of caudal foregut
- Has both dorsal and ventral mesogastrium
- First rotation carries dorsal mesogastrium from dorsal to ventral, elongating it extensively to form greater omentum
- Second rotation brings cardiac stomach down and to left, pyloric up and to right