Feb 26 M1-Embryology Liver, Pancreas and Portal system Flashcards
important thing in gut through development
apoptosis cranial t ocaudal (recanalization)
3 main events of gut dev
- stomach rotation
- midgut umb herniation: cecum and appendix counterclockwise rotation
- abdominal counterclockwise rotation
2 mechanisms important for recanalization
- genetic
- vascular
fatal failure of apoptosis
in biliary tree
main duodenal congenital anomalies
- duodenal atresia (distal to major duod papilla)
- duodenal stenosis (distal to major duod papilla)
- intussusception
2 causes for duodenum congenital problems
apoptosis failure and bad vascularization (causes failure of apoptosis)
consequence of duod atresia or stenosis
polyhyramnios
bilous vomiting in newborn
duod atresia or stenosis on radiograph
double bubble sign (air in stomach and in D1 or D2)
main cause for duodenal atresia
genetics (associated with trisomy 21) (bad vascularization too leading to failure of apoptosis)
cause for duodenal intussusception
poor vascularization.
(IMPORTANT) cause for most anomalies in duodenum vs jejunum and ileum
duod: genetics
jejunum + ileum: vascular
ventral and dorsal pancr buds formed where + origin
ventral: septum transversum
dorsal: dorsal duodenum
ENDODERMAL in origin
origin of exocrine and endocrine cells of the duodenum
endoderm
what distinguishes segments of intestine when it’s forming
Hox genes (homeobox genes)
critical hox gene defining whole duodenum AND pancreas later
pdx1
where and how pancr buds fuse
in clockwise rotation of stomach (foregut rotation). pancreas becomes retroperit
structure that rotates with ventral bud
common bile duct (and is placed posterior to D2)
in what bud islets of langerhans form
in both
last step of pancreas formation
union of the ducts
what dorsal pancreatic bud forms
upper head, neck, body tail
what ventral pancreatic bud forms
lower head + uncinate process
dx sign for duodenum atresia
double bubble sign
annular pancreas cause
ventral bud is a bifid structure and not the whole bifid structure goes around at rotation. some stays with bile system = annular pancreas (ring around duod)
annular pancreas dx sign
double bubble (+ narrowing on baryum contrast)
how portal vein can cause duod obstruction
if goes anteriorly instead of posteriorly, pressure on duod bc carries lot of blood
(EXAM) what forms the portal system
vitelline veins
(EXAM) what supplies (vascularization) the gut in embryo
vitelline vessels (arteries and veins)
(EXAM) what forms drainage of the whole gut
vitelline veins
structures crossing uncinate process
SMA and SMV
drainage to the liver before the portal vein was defined (before rotation of ventral bud)
2 vitelline veins passing near the 2 pancreatic buds. anastomotic channels between them
what determined what formed portal vein
vein and anastomotic way that took was the most direct to the liver = portal vein (remained after foregut rotation)
problem of anterior portal vein other than duod obstruction
get 2 portal veins (quadrate instead of triad) bc splenic vein doesn’t fuse with portal vein
midgut position as is in umbilicus
proximal midgut to embryo and distal coming back. SMA in between with branches to the 2 parts
consequence of umbilical opening too big for midgut
anomalies of rotation + anomalies related to lig of treitz and inferior band
rotation of midgut
in umbilicus. 6-10 wks. 90 counterclockwise
2 primitive charact of embryo x section at 8 wks
- endoderm lining (colonic epith and lumen) with cells apoptosing
- walls of colon vs rest of GIT diff in size
colon charact at 8 wks + what will form SM
has differentiated mesenchyme: will form SM
what forms Auerbach’s plexus and Meissner’s plexus
NCCs migrating
consequence of NCC migration defect
megacolon (no Auerbach’s = no peristalsis)
cause of umbilica-body wall transitional area
lateral folding defects
2 types of umbilica-body wall transitional area
umb herniation and omphalocele
omphalocele def
hole too small for grown intestine to reduce back in abdomen. large prominence there at birth
umb herniation def
intestine reduced but hole too big so went back there
lining of umb cord in omphalocele vs umbilical herniation
omphalocele = amnion
umb herniation = peritoneum lining
omphalocele assoc with what
chromosomal abnormalities
gastroschisis def
intestines go in amniotic cavity (NOT in umb cord) through the body wall on side of umb cord. go through abd wall. split abd wall
left and right umb veins in embryo which will be more important
left becomes prominent: goes to liver, ductus venosus.
right will regress
surface of umbilicus charact
surface ectoderm. skin absent (not developed yet). structure is firm
region near umb junction to abd wall charact
single layer of ectoderm on periphery of that
where right umb vein regresses
right side of umb junction with abd wall (where single ectoderm layer)
gastroschisis cause
unknown
