Feb16 M1-Embryology #3- Foregut_Midgut_Stomach_duodenum_rotation Flashcards
asymmetrical genetic expression in embryo determined how
nodal region in the trilaminal embryo. monicilia beat in one direction (nodal flow of ECF)
important gene expressed very early in embryo + does what
nodal gene. creates cascade of TFs
important TF causing many cascades of genes
Pitx2
where kidneys form in mesenchyme (name)
intermediate mass
important structure that forms in mesogastrium
omental bursa: fluid filled sac lined by mesogastrium: role in rotation and formation of greater omentum
where omental bursa grows
endodermal outgrowth to septum transversum where liver will form. coelomic epith lining it (just as it lines whole peritoneal cavity)
where pitx2 expressed in gut
left side of dorsal mesogastrium
what forms gut wall
splanchnopleure (IS MESENCHYME): gives mesothelium
primitive gut is what
endoderm overgrowth of simple columnar layer (endodermal sterm cells)
what coelomic epithelium (lining perit cavity) forms
becomes mesothelium (like splanchnopleure did) and secretes fluid
how arteries veins and lymphatics get to primitive gut
through dorsal mesentery (arteries from aorta)
what also migrates in dorsal mesentery
neural crest cells
NCC goal
form SS innervation in gut
PSS innervation in gut origin
vagus long neurons long axons supply esophagus right (post vagal trunk) and left vagus (ant vagal trunk) + muscles and secretory structures
where vagus stops in gut
2 thirds of TC (end of midgut)
NCC form what 2 important structures
*pass with veins and with the vagus and will form Auerbach’s plexus (SM) and Meissner’s plexus (PSS) for glands
consequence of pitx2 expression in dorsal mesentery
left dorsal mesentery will form dorsal curvature in dorsal mesogastrium: ROTATION 90 degrees clockwise of BURSA and stomach
ventral mesentery is where
duodenum where endoderm outgrows into septum transversum (LIVER FORMS IN VENTRAL MESENTERY)
important effect of bursa rotation
facilitates stomach rotation + allows GROWTH OF GREATER OMENTUM
(IMPORTANT) 3 components of the ventral mesentery
- lesser omentum
- capsule
- falciform ligament
what forms the diaphragm
septum transversum
what forms CT in the liver
septum transversum
what forms vessels in the liver
vitelline vessels
bare area: what happens there
portal-systemic anastomoses (varicosity)
ligamentum teres is what originally
left umbilical vein (that was going to the liver)
umbilical porto-caval anastomoses are what
small potential vessels connecting to anterior abd wall vessels that are NEAR free edge of falciform ligament
bursa connected to what and key event that it helps
right peritoneal cavity. helps growth of greater omentum
where lesser peritoneal sac forms
behind the stomach
stomach orientation after rotation 90
lesser curv on right
greater curv on left
bursa location
in right peritoneal cavity, within the mesogastrium
bursa 2 fcts
expands to form greater omentum + contributes to greater omentum
outer layer of greater omentum
mesothelium
greater omentum fuses with what
transverse colon
mesoduodenum connection and mvmt
connected to liver + moves to right as liver goes to right
important events in omental bursa formation
**lig of treitz allows duodenum fixation on back wall (retroperit) (facilitated by liver growth in right perit space + rotation of stomach)
how pancreas fixed
fixed to transverse colon on ALL its inferior length
inferior fixation of pancreas forms what
inferior border of lesser sac
when greater omentum finishes its growht and goes over TC
after hindgut rotation
consequence of duodenum bad fixation and cause
lig of Treitz too long: loose duodenum. intraperitoneal (affects later events)
bad duod fixation consequence on TC
TC rotation may go under duodenum. complete rotation of vessels to duodenum. malrotation of midgut
other conseq of long lig of treitz
short lig of treitz = no paraduod fossa
long lig of treitz = paraduod fossa where may have herniation
fixation of mesoduodenum allows what
formation of ligaments** (gastrosplenic, greater omentum, falciform, lig teres, duodenohepatic lig is the triad + gastrohepatic lig = lesser omentum)
most lateral aspect of lesser sac
gastrosplenic and lienorenal ligs
limits of lesser sac superiorly and inferiorly
sup = diaphragm inf = mesocolon that became fixed (inferior fixation of pancreas to mesocolon)
