GI Embryology Flashcards
peritoneum is formed from
mesoderm
when is primitive gut tube formed
week 4
where is primitive gut tube formed from
top of yolk sac
how does the embryo fold to form gut tube
cranially-caudally and laterally
gut tube is formed from
yolk sac endoderm
what happens along with gut tube formation
body cavity and anterolateral body wall are formed, amnion encases embryo
epithelial lining of gut tube is formed from
endoderm
all layers of gut tube wall except epithelial lining are formed from
mesoderm
path of unpaired aortic branches in embryo
travel from posterior body wall to to gut tube through dorsal mesentery
where is gut tube suspended from
posterior body wall
what suspends gut tube from posterior body wall
dorsal mesentery
where does the liver bud off into
ventral mesentery
spleen develops from
mesoderm in dorsal mesentery of stomach
rotation of the stomach
90 degrees clockwise so that the left side faces anteriorly
the dorsal mesogastrium becomes
the greater omentum
the lesser omentum arises from
stomach rotation
dorsal mesentery of the stomach aka
dorsal mesogastrium
how does stomach rotation affect the liver
it moves the liver to the right side of the abdomen
how does the retroperitoneal duodenum and pancreas occur
the rotation of the stomach pushes the duodenum, pancreas, and part of dorsal mesentery against the posterior body wall
parts of dorsal mesentery of the stomach that don’t fuse with parietal peritoneum covering the posterior body wall
splenorenal ligament, gastrosplenic ligament, greater omentum
ventral mesentery comes from
septum transversum
ventral mesentery becomes
lesser omentum and falciform ligament
what structures come off of liver bud
liver bud, biliary duct system, gallbladder
what causes pancreatic buds to fuse
foregut rotation
physiological herniation
herniation of intestines into umbilical cord
jejunum and upper ileum formed by
cranial limb of midgut loop
lower ileum through proximal 2/3 of transverse colon formed by
caudal limb of midgut loop
when does physiologic herniation occur
6 weeks
when does the intestine return to abdomen
10 weeks
pyloric stenosis results from
hypertrophy of muscularis externa of pyloris
signs of pyloric stenosis
projectile, nonbilious vomiting
symptoms of pyloric stenosis begin when
3-5 weeks of age
cause of pyloric stenosis
multifactorial (genetic and enviornmental)
annular pancreas results from
the ventral pancreatic bud having two lobes that move in opposite directions during foregut rotation
annular pancreas causes
an obstructive ring around the 2nd part of the duodenum at the foregut-midgut junction
symptoms of annular pancreas present during
neonatal period
symptoms of annular pancreas
feeding intolerance, nonbilious vomiting, abdominal distention
omphalocele is caused by
midgut loop fails to return to the abdominal cavity
what is midgut loop covered by in omphalocele
amnion covered parietal peritoneum
what is gastroschisis
abdominal viscera herniate through body wall directly into amniotic cavity
usual location of gastroschisis
to the right of the umbilicus
cause of gastroschisis
defect in lateral folding of embryo that leaves a gap or weakness in anterior abdominal wall
what is Meckel’s diverticulum
persistence of the proximal portion of the yolk sac
Meckel’s diverticulum is most common in
men
what can be present in Meckel’s diverticulum
ectopic gastric mucosa
usual location of Meckel’s diverticulum
2 feet from the ileocecal junction
if no rotation of the midgut occurs
small intestine ends up on the right and large intestine ends up on the left
clockwise rotation of the midgut results in
large intestine is posterior to the duodenum
what is malrotation of midgut
mesentery doesn’t fuse properly resulting in small intestine twisting around SMA and volvulus
symptoms of volvulus
vomiting, absence of stool, abdominal distention
duodenal atresia results from
failed recanalization of lumen of midgut
symptoms of duodenal atresia
bilious vomiting, distended abdomen, stenosis distal to ampulla of vater
failure of neural crest cell migration leads to
aganglionic megacolon
lateral fold defects include
omphalocele, gastroschisis
Meckel diverticulum aka
persistent vitelline duct
in what way is the spleen unique among abdominal organs
it is derived from mesoderm
