Feb16 M1-Embryology #3- Foregut_Midgut_Stomach_duodenum_rotation

Question 1

asymmetrical genetic expression in embryo determined how

Answer 1

nodal region in the trilaminal embryo. monicilia beat in one direction (nodal flow of ECF)

Question 2

important gene expressed very early in embryo + does what

Answer 2

nodal gene. creates cascade of TFs

Question 3

important TF causing many cascades of genes

Answer 3

Pitx2

Question 4

where kidneys form in mesenchyme (name)

Answer 4

intermediate mass

Question 5

important structure that forms in mesogastrium

Answer 5

omental bursa: fluid filled sac lined by mesogastrium: role in rotation and formation of greater omentum

Question 6

where omental bursa grows

Answer 6

endodermal outgrowth to septum transversum where liver will form. coelomic epith lining it (just as it lines whole peritoneal cavity)

Question 7

where pitx2 expressed in gut

Answer 7

left side of dorsal mesogastrium

Question 8

what forms gut wall

Answer 8

splanchnopleure (IS MESENCHYME): gives mesothelium

Question 9

primitive gut is what

Answer 9

endoderm overgrowth of simple columnar layer (endodermal sterm cells)

Question 10

what coelomic epithelium (lining perit cavity) forms

Answer 10

becomes mesothelium (like splanchnopleure did) and secretes fluid

Question 11

how arteries veins and lymphatics get to primitive gut

Answer 11

through dorsal mesentery (arteries from aorta)

Question 12

what also migrates in dorsal mesentery

Answer 12

neural crest cells

Question 13

NCC goal

Answer 13

form SS innervation in gut

Question 14

PSS innervation in gut origin

Answer 14

vagus long neurons long axons supply esophagus right (post vagal trunk) and left vagus (ant vagal trunk) + muscles and secretory structures

Question 15

where vagus stops in gut

Answer 15

2 thirds of TC (end of midgut)

Question 16

NCC form what 2 important structures

Answer 16

*pass with veins and with the vagus and will form Auerbach’s plexus (SM) and Meissner’s plexus (PSS) for glands

Question 17

consequence of pitx2 expression in dorsal mesentery

Answer 17

left dorsal mesentery will form dorsal curvature in dorsal mesogastrium: ROTATION 90 degrees clockwise of BURSA and stomach

Question 18

ventral mesentery is where

Answer 18

duodenum where endoderm outgrows into septum transversum (LIVER FORMS IN VENTRAL MESENTERY)

Question 19

important effect of bursa rotation

Answer 19

facilitates stomach rotation + allows GROWTH OF GREATER OMENTUM

Question 20

(IMPORTANT) 3 components of the ventral mesentery

Answer 20

1. lesser omentum
2. capsule
3. falciform ligament

Question 21

what forms the diaphragm

Answer 21

septum transversum

Question 22

what forms CT in the liver

Answer 22

septum transversum

Question 23

what forms vessels in the liver

Answer 23

vitelline vessels

Question 24

bare area: what happens there

Answer 24

portal-systemic anastomoses (varicosity)

Question 25

ligamentum teres is what originally

Answer 25

left umbilical vein (that was going to the liver)

Question 26

umbilical porto-caval anastomoses are what

Answer 26

small potential vessels connecting to anterior abd wall vessels that are NEAR free edge of falciform ligament

Question 27

bursa connected to what and key event that it helps

Answer 27

right peritoneal cavity. helps growth of greater omentum

Question 28

where lesser peritoneal sac forms

Answer 28

behind the stomach

Question 29

stomach orientation after rotation 90

Answer 29

lesser curv on right

greater curv on left

Question 30

bursa location

Answer 30

in right peritoneal cavity, within the mesogastrium

Question 31

bursa 2 fcts

Answer 31

expands to form greater omentum + contributes to greater omentum

Question 32

outer layer of greater omentum

Answer 32

mesothelium

Question 33

greater omentum fuses with what

Answer 33

transverse colon

Question 34

mesoduodenum connection and mvmt

Answer 34

connected to liver + moves to right as liver goes to right

Question 35

important events in omental bursa formation

Answer 35

**lig of treitz allows duodenum fixation on back wall (retroperit) (facilitated by liver growth in right perit space + rotation of stomach)

Question 36

how pancreas fixed

Answer 36

fixed to transverse colon on ALL its inferior length

Question 37

inferior fixation of pancreas forms what

Answer 37

inferior border of lesser sac

Question 38

when greater omentum finishes its growht and goes over TC

Answer 38

after hindgut rotation

Question 39

consequence of duodenum bad fixation and cause

Answer 39

lig of Treitz too long: loose duodenum. intraperitoneal (affects later events)

Question 40

bad duod fixation consequence on TC

Answer 40

TC rotation may go under duodenum. complete rotation of vessels to duodenum. malrotation of midgut

Question 41

other conseq of long lig of treitz

Answer 41

short lig of treitz = no paraduod fossa

long lig of treitz = paraduod fossa where may have herniation

Question 42

fixation of mesoduodenum allows what

Answer 42

formation of ligaments** (gastrosplenic, greater omentum, falciform, lig teres, duodenohepatic lig is the triad + gastrohepatic lig = lesser omentum)

Question 43

most lateral aspect of lesser sac

Answer 43

gastrosplenic and lienorenal ligs

Question 44

limits of lesser sac superiorly and inferiorly

Answer 44

sup = diaphragm
inf = mesocolon that became fixed (inferior fixation of pancreas to mesocolon)