Embryology

Question 1

By what week is the oesophagus distinguishable?

Answer 1

week 4

Question 2

by which week do circular muscles of the oesophagus develop?

Answer 2

week 5

Question 3

By which week do the longitudinal muscle of the oesophagus develop?

Answer 3

week 8

Question 4

when does the spleen develop?

Answer 4

week 5

Question 5

when does the spleen develop into an lymphathic organ?

Answer 5

during weeks 15-18

Question 6

what is the spleen a derivative of?

Answer 6

mesoderm

Question 7

what happens in the beginning of week 4 in the midgut?

Answer 7

communicates with yolk sac along its length

Question 8

what happens in the middle of week 4 in the midgut?

Answer 8

connection with yolk sac narrows

Question 9

what happens in the end of week 4 in the midgut?

Answer 9

connected to yolk sac via narrow vitelline duct

Question 10

what happens in week 5 in the the midgut?

Answer 10

midgut has outgrown embryo and bulges ventrally

Question 11

when does the gut re-enter the body cavity?

Answer 11

during week 10

Question 12

what part of the gut returns into the body cavity first?

Answer 12

small intestine

Question 13

what part of the gut returns into the body cavity last?

Answer 13

caecum

Question 14

what is the blood supply to the foregut?

Answer 14

coeliac trunk

Question 15

what is the blood supply to the midgut?

Answer 15

superior mesenteric artery

Question 16

what is the blood supply to the hindgut?

Answer 16

inferior mesenteric artery

Question 17

what structures does the foregut form?

Answer 17

mouth to the proximal hald of duodenum

Question 18

what structures does the midgut form?

Answer 18

distal half of the duodenum to the splenic flexure of the colon

Question 19

what structures does the hindgut form?

Answer 19

descending colon to the rectum

Question 20

what is the endoderm the origin of in the GI tract?

Answer 20

epithelium of mucosa and associated ducts and glands

Question 21

what is the visceral mesoderm the origin of in the GI tract?

Answer 21

lamina propria, muscularis mucosa and muscularis externa, CT of submucosa and external CT

Question 22

what does the ventral mesenteries become?

Answer 22

lesser omentum and falciform ligament

Question 23

what does the dorsal mesenteries become?

Answer 23

dorsal mesogestrium, dorsal mesoduodenum and dorsal mesocolon

Question 24

what does the liver bud grow into?

Answer 24

mesoderm of septum transversum

Question 25

what germ layers are liver cells derived from?

Answer 25

endoderm

Question 26

what germ layers is the lining of biliary tree derived from?

Answer 26

endoderm

Question 27

what does the septum transversum become?

Answer 27

hemotopioetic cells, kupffer cells and connective tissue

Question 28

what is the midgut rotation?

Answer 28

90 degrees around axis of SMA

Question 29

What happens during re-entry?

Answer 29

further 180 degrees rotation, jejunum displaces left and ileum right, descending colon pushed left and transverse colon pushed superiorly

Question 30

when does proliferation of mucosa occur?

Answer 30

weeks 5/6

Question 31

when does recanalisation occur?

Answer 31

week 9

Question 32

what does the umbilical vein in the foetus become in the adult?

Answer 32

ligamentum teres