Feb14 M3-Embryology of the Foregut Flashcards
(IMPORTANT) 2 key events for setting of restricted space for gut formation in order
- normal umbilical cord size (normal lateral folding of the trilaminar embryo to form cylindrical embryo)
- normal diaphragm formation
liver fct early (6-12 wks)
hemopoietic organ
where gut goes 6=12 wks
goes in umb cord, grows there, rotates, comes out
where intra embryonic coelum forms
in lateral plate mesoderm
what intra embryonic coelum forms (will lead to)
pericardium, pleura, peritoneum
origin of the gut wall and origin of body wall
gut wall: splanchnopleure (mesenchyme of the lateral plate ectoderm)
body wall: somatopleure
what intra embryonic coelum and midgut connect to
- intra emb coelum to extra emb coelum around yolk sac
- midgut connected to yolk sac
(IMPORTANT) yolk sac fct in embryo early embryo + related anomaly
hemopoietic organ + attached to yolk sac. if doesn’t regress = Meckel’s diverticulum
2 anomalies in gut tube formation (this being 3rd critical event)
- atresia (bc of problem in the cranial-caudal apoptosis of endodermal cells)
- duplication of the gut
rotations that happen in the gut
stomach: clockwise
midgut and hindgut: counterclockwise
+ have to become fixed
common gut development problems
malrotation, malfixation apoptosis problem
(EXAM) 4 things in order for normal gut embryogenesis
- embryo folding and umb cord formation
- diaphragm formation
- normal gut rotation and fixation
- normal gut apoptosis
(EXAM) consequence of defective embryo folding and umb cord formation
umbilical herniations
(EXAM) consequence of defective diaphragm formation
diaphragmatic herniation
(EXAM) consequence of defective gut rotation and fixation
malrotation of the gut
(IMPORTANT) function of dorsal mesentery for gut dev + other name for it
carries veins, arteries, lymphatics and nerves. (is the visceral peritoneum)
what’s inside the visceral peritoneum
visceral epithelium (came from splanchnopleure)
kidneys and gonads intra or retroperitoneal
retroperitoneal
kidneys = primarily retroperitoneal
(IMPORTANT) space that can form behind ascending and descending colon if incomplete fixation + consequence
paracolic gutters. can be sites of herniation
secondarily retroperitoneal structures
D2,D3,D4. ascending and descending colon and mesocolon
vessels in primitive mesentery and their origin
celiac trunk, SMA, IMA (come from aorta feeding vessels in dorsal mesentery)
name of lymph nodes draining the foregut
celiac nodes
midgut is from where to where
from duodenum (at common bile duct, so foregut goes til there) to two thirds of transverse colon
region where spleen forms
mesogastrium
other structures forming in mesogastrium
gastrosplenic ligament and lienorenal ligament
dorsal pancreatic bud origin and what duct is in there
duodenum endoderm. has the dorsal pancreatic duct
2 supporting structures for gut rotation and holding it in umbilical cord
superior and inferior retention bands
(IMPORTANT) superior retention band becomes what
ligament of Treitz
(IMPORTANT) inferior retention band becomes what
phrenicocolic ligament
spleen fct in embryo (2)
- hemopoietic organ
2. separates the 2 lig near it from the omental bursa (a fluid filled sac lined by mesothelium)
hemopoietic organs transition in order
- yolk sac
- liver
- spleen
(IMPORTANT) why dorsal pancreatic duct continuous from duodenum to spleen
mesogastrium and mesoduodenum are continuous
spleen formation anomaly
can get a 2nd accessory spleen in the pancreatic tail (bc spleen formed in mesogastrium)
cells that are precursors of hemopoietic organs like the spleen
hemangioblasts (hemopoietic stem: forms all blood cell lineages. angioblasts: form endothelium)
ventral mesentery only associated (found) where
with foregut structures (where hepatic duct forms and around liver)
liver forms where
in mesenchyme called septum transversum
anomaly possible in mesenteric arteries
celiac trunk and SMA can be joined (bc initially all vessels go to yolk sac but then separate in 3 groups)
2 very important structures for midgut rotation and duodenum fixation
ligament of Treitz (and other important structure is phrenicocolic ligament)
consequence of lig of Treitz too long
U shaped duodenum
other importance of lig of Treitz
needed to make duodenum retroperitoneal (push it on the wall)
phrenicocolic ligament attaches where
diaphragm to splenic flexure of the colon
