GI/Liver Embryology Flashcards
What leads to primitive gut formation?
Lateral folding
What is the embryological start and end of foregut?
Oropharyngeal membrane to liver bud
What is the embryological start and end of midgut?
Liver bud to 2/3 along transverse colon
What is the embryological start and end of hindgut?
Distal 1/3 of transverse colon to cloacal membrane
What are the stages of midgut development?
- Elongation
- Herniation
- Retraction
- Fixation
What happens during elongation?
Loop of the midgut elongates rapidly
What happens during herniation?
The midgut is pushed into the extraembryonic cavity through the umbilical cord
What happens during rotation?
The loop of midgut rotates 270 degrees anticlockwise
What happens during retraction?
The herniated midgut begins to return to the abdominal cavity, jejunum first and cloacal membrane last. The appendix also develops during this time.
What happens during fixation?
Some gut mesenteries fuse with posterior abdominal wall
Which organs are fixed, and which ones are mobile?
- Fixed:
Duodenum
Ascending and descending colon
Rectum
- Mobile: Stomach Jejunum and ileum appendix transverse and sigmoid colon
What are the oropharyngeal and cloacal membranes?
Future mouth and anus. Where the ectoderm and endoderm come into contact.
How many meseteries do the foregut, midgut and hindgut have?
Foregut - 2
Midgut and hindgut - 1
What is the gut derived from?
- Endoderm and visceral mesoderm
What is derived from the endoderm?
- Epithelium of bowel.
- Hepatocytes.
- Endo/exocrine cells of pancreas.
What is derived from the visceral mesoderm?
- Muscle wall.
- Connective tissue for the muscle wall and pancreas/liver.
- Visceral peritoneum
Where is the liver derived from?
Ventral mesentery
Where is the spleen derived from?
Dorsal mesentery
Where is the pancreas derived from?
Parts of the ventral and dorsal mesentery which then fuse together
What happens to the stomach during development?
- Rotation.
- Dorsal edge elongates to become greater curve.
