s2. development of the gut 1 and 2 Flashcards
what are the 3 sections of the mesoderm
lateral plate
intermediate
paraxial (next to notochord)
what’s the two divisions of the lateral plate of mesoderm?
SOMATIC (body walls)
SPLANCHNIC (viscera)
ectoderm gives rise to
epidermis
nerve tissue
endoderm gives rise to
epithelial lining of GI tract
intermediate plate of mesoderm gives rise to
kidneys and gonads
paraxial plate of mesoderm gives rise to
somites> skeletal muscle, vertebra, cartilage
two types of folding that occur in early embryo
saggital
cranio-caudal
transverse
what embryonic structures are present after saggital folding
amniotic cavity
trilaminar disc
yolk sac
head and tail end
what is the vitelline duct? pathology?
connection between midgut and yolk sac
usually obliterates by birth.
if not: Merckel’s Diverticulum= out pouch of small intestine > faecal material leaking from umbilicus
cranio caudal folding results in
foregut (oesophagus>duodenum-midpoint of 2nd part)
midgut (duodenum> distal 2/3 transverse colon)
hindgut (distal 1/3 transverse colon> upper anal canal)
mouth
heart
anus
FORMS HEAD AND TAIL END
splanchnopleuric mesoderm forms
viscera
somatopleuric mesoderm forms
body walls and dermis
intraembryonic coelom gives rise to
thoracic and abdominal cavities
what forms the gut tube
yolk sac
when does the bucopharyngeal membrane rupture?
4th week to give mouth open to amniotic cavity
when does cloacal membrane rupture?
7th week (anus)
describe embryonic blood supply to the gut
foregut- coeliac artery
midgut- superior mesenteric artery
hindgut- inferior mesenteric artery
what happens to the foregut in the 5th week and pathology?
endoderm proliferates
occludes lumen temporarily
rencanalise (9th week)
- failed proliferation of endoderm > end up with closed sections of gut
- failed recanalisation 1/3000 births
differences in pain in relation to somatic and splanchnic mesoderm
parietal peritoneum>somatic- can localise pain (good sensory supply)
visceral peritoneum>splanchnic- vague pain
what is Epiploic foramen (also called the foramen of Winslow) ?
passage between the greater sac and the lesser sac. >allowing communication between these two spaces.
how are the peritoneal sacs formed?
from foregut rotation
greater sac= bulk of peritoneal cavity
lesser sac= behind stomach
list the peritoneal ligaments from anterior to posterior
falciform ligament (liver) lesser momentum (stomach) gastrosplenic ligament (spleen) spleno-renal ligament (L kidney)
these are all double folds of peritoneum
how does the pancreas form embryonically
develops in 2 buds within ventral (front) and dorsal (back) mesentery
ductal systems fuse from both (if not have an accessory pancreatic duct)
