Abdominal Cavity Embryology

Question 1

ectoderm

Answer 1

forms integument and nervous system, lining of anus and mouth

pectinate line

Question 2

mesoderm

Answer 2

muscles, mesentaries, bone, connective tissue, blood

somatic (body wall) or splanchnic (lines organ)

Question 3

endoderm

Answer 3

internal lining of gut and gut derived abdominal organs

Question 4

umbilical vesicle

cranial-caudal folding

Answer 4

yolk sac forms week 2
-provides nutrients for 2 weeks
-primordial gut and forms gut tube and respiratory tract
-give rise to gonads
-blood develops here until liver functional

Question 5

allantois

Answer 5

waste sac

Question 6

vitelline duct + yolk sac

Answer 6

form gut tube

Question 7

recanalization

Answer 7

process of vacules/holes developing in the lumen of gut tube after epithelial cells take over

failure often at duodenum

Question 8

narrow lumen/stenosis

Answer 8

poor vacuole formation so only small hole

Question 9

atresia/ no lumen

Answer 9

no vacuole form at all so complete blockage in lumen

Question 10

esophageal development

Answer 10

tracheoesophageal fold divides future trachea and esophagus

fold fuses and splits tubes

Question 11

polyhydramnios

Answer 11

excess liquid in amniotic sac

if have atresia then fluid can’t pass thru fetus like normal so have too much

normally drink sac fluid then pee out

Question 12

stomach development

Answer 12

dorsal border grows faster than ventral = curvatures

rotates 90 degress clockwise and takes L. vagus with it so ventral (R vagus is dorsal)

L vagus does parasympathetics to gut cavity

Question 13

pancreatic development

Answer 13

start as ventral and dorsal buds

rotation brings buds together so fuse into head/body/tail of pancreas

problem if bilobed & twists opposite into annular pancreas = blocks duo

Question 14

splenic development

Answer 14

from mesoderm not endoderm

forms and grows in mesentary (primary)

Question 15

umbilical folds

Answer 15

1. median: urachus and paraumbilical veins
   -urachus main drain tube of nitrogenous waste
2. medial: umbilical artery TO placenta, paired
3. lateral: inferior epigastrics

Question 16

midgut development

intestines

Answer 16

all intestines elongate and herniate thru umbilicus bc no room in cavity

wind around SMA 90 degress counter clockwise as grow

small intestines return first
large intestines rotate 180 more

cecum and appendix move to RLQ in end

Question 17

secondary retroperitoneal organs

Answer 17

after rotating mesentaries fuse in new positions = ascending, descending colon, pancreas, duodenum become retro

Question 18

development errors

midgut

Answer 18

mixed rotation & volvulus = small twists around large so blockages

reversed rotation = small wraps around transverse so blocks, like atresia

subhepatic cecum/appendix = not move down to RLQ, stuck in RUQ so pain can be confused for gallbladder

internal hernia sac= small in mesentary

midgut volvulus & duodenal obstruction = large wraps around small so blocks transverse or duodenum

Question 19

necessary steps of hindgut development

Answer 19

1. proctodeum meets endoderm
2. urorectal septum separates cloaca into urogenital and anal membranes