Embryology Flashcards
By what week is the oesophagus distinguishable?
week 4
by which week do circular muscles of the oesophagus develop?
week 5
By which week do the longitudinal muscle of the oesophagus develop?
week 8
when does the spleen develop?
week 5
when does the spleen develop into an lymphathic organ?
during weeks 15-18
what is the spleen a derivative of?
mesoderm
what happens in the beginning of week 4 in the midgut?
communicates with yolk sac along its length
what happens in the middle of week 4 in the midgut?
connection with yolk sac narrows
what happens in the end of week 4 in the midgut?
connected to yolk sac via narrow vitelline duct
what happens in week 5 in the the midgut?
midgut has outgrown embryo and bulges ventrally
when does the gut re-enter the body cavity?
during week 10
what part of the gut returns into the body cavity first?
small intestine
what part of the gut returns into the body cavity last?
caecum
what is the blood supply to the foregut?
coeliac trunk
what is the blood supply to the midgut?
superior mesenteric artery
what is the blood supply to the hindgut?
inferior mesenteric artery
what structures does the foregut form?
mouth to the proximal hald of duodenum
what structures does the midgut form?
distal half of the duodenum to the splenic flexure of the colon
what structures does the hindgut form?
descending colon to the rectum
what is the endoderm the origin of in the GI tract?
epithelium of mucosa and associated ducts and glands
what is the visceral mesoderm the origin of in the GI tract?
lamina propria, muscularis mucosa and muscularis externa, CT of submucosa and external CT
what does the ventral mesenteries become?
lesser omentum and falciform ligament
what does the dorsal mesenteries become?
dorsal mesogestrium, dorsal mesoduodenum and dorsal mesocolon
what does the liver bud grow into?
mesoderm of septum transversum
what germ layers are liver cells derived from?
endoderm
what germ layers is the lining of biliary tree derived from?
endoderm
what does the septum transversum become?
hemotopioetic cells, kupffer cells and connective tissue
what is the midgut rotation?
90 degrees around axis of SMA
What happens during re-entry?
further 180 degrees rotation, jejunum displaces left and ileum right, descending colon pushed left and transverse colon pushed superiorly
when does proliferation of mucosa occur?
weeks 5/6
when does recanalisation occur?
week 9
what does the umbilical vein in the foetus become in the adult?
ligamentum teres
