Embryology

Question 1

What is gastrulation?

Answer 1

formation of trilaminar germ disc from a bilaminar disc

Question 2

when does ovulation start in regards to menstrual cycle?

Answer 2

ovulation starts roughly 14 days before your period starts

Question 3

when does the bilaminar disc form?

Answer 3

week 2

Question 4

which gene is a transcription factor for establishing left sidedness?

Answer 4

PTX2

Question 5

What happens during week 3?

Answer 5

gastrulation
CNS induction
Neurulation

Question 6

What is week 3-8 called?

Answer 6

organogenesis

Question 7

where do the visceral and parietal mesoderm arise from?

Answer 7

lateral plate mesoderm

Question 8

when does the gut tube form?

Answer 8

3rd and 4th week

Question 9

what does the gut tube form from

Answer 9

the endoderm lining of the yolk sac

Question 10

which membrane closes the gut tube at it’s cranial end? (closer to head)

Answer 10

oropharyngeal membrane

Question 11

which membrane closes the gut tube at it’s caudal end?

Answer 11

cloacal membrane

Question 12

how does the molecular regulation of craniocaudal organisation of the gut come about? which transcription factors are involved?

Answer 12

SHH transcription factor is secreted from the gut endoderm and induces the HOX gene in the mesoderm

Question 13

where does the foregut form from?

Answer 13

the cranial part of the primitive gut tube

Question 14

which structures/organs are included in the term foregut?

Answer 14

pharynx
oesophagus
stomach
upper duodenum

Question 15

the laryngeal -tracheal diverticulum (lung bud) form from

Answer 15

ventral wall of the foregut

Question 16

function of Tracheo- oesophageal septum

Answer 16

divided the foregut tube into trachea and oesophagus

Question 17

what happens to the foregut in the 4th week?

Answer 17

it dilates to form the stomach

also: -
- it creates both the greater and lesser curvatures
- 2 rotations to create final adult position

Question 18

how is the stomach attached to the dorsal and ventral wall?

Answer 18

a mesentery called mesogastrium

Question 19

where does the lesser sac lie?

Answer 19

behind the stomach

Question 20

what is the duodenum formed from

Answer 20

the caudal part of the foregut and cranial part of the midgut

Question 21

name the blood supply of the duodenum

Answer 21

coeliac trunk

superior mesenteric artery

Question 22

when is the liver bud created?

Answer 22

week 3

Question 23

what does the liver bud grow into

Answer 23

the septum transversum

Question 24

what forms the gall bladder and cystic duct?

Answer 24

ventral outgrowth from the bile duct

Question 25

Key points of spleen formation

Answer 25

week 5 - spleen is a mesodermal derivative

15-17 - colonised by T- cells
23 - B cell precursors arrive and the spleen can then start its lymphoid function

Question 26

Describe the formation of the pancreas

Answer 26

forms from 2 buds
these grow from the endodermal lining of the duodenum in week 5

dorsal and ventral buds fuse to form the pancreas

Question 27

what makes up the main pancreatic duct?

Answer 27

ventral duct

distal part of dorsal duct

Question 28

what are Esophageal atresia and trachea-esophageal fistula?

Answer 28

If the tracheo - esophageal septum deviates incorrectly => incomplete separation of laryngo -tracheal tube (lung bud) which results in these 2 things

Question 29

annular pancreas

Answer 29

ventral bud fails to migrate around the duodenum

may cause duodenal stenosis
or pancreatic tissue may form in other areas of foregut - accessory pancreatic tissue

Question 30

what is the midgut?

Answer 30

the distal part of duodenum, jejunum, ileum, caecum, appendix, asc and transverse colon

Question 31

what does the cephalic part of the midgut become?

Answer 31

distal duodenum, jejunum and proximal ileum

Question 32

what does the caudal part of the midgut become

Answer 32

distal ileum, caecum, appendix, ascending colon and the proximal 2/3rds of the transverse colon

Question 33

what must the midgut undergo to reach adult pattern?

Answer 33

rotation and physiological herniation

Question 34

when does rotation of the midgut begin

Answer 34

week 6

Question 35

physiological herniation: what does the gut tube herniate through

Answer 35

the extraembryonic cavity in the umbilical cord

Question 36

abnormalities in midgut development (4)

Answer 36

abnormal rotation of primary intestinal loop

reversed rotation

omphalocele - herniation of intestinal loop through enlarged umbilical ring + failure of retraction of viscera

anomaly - remnants of vitelline duct

Question 37

what forms meckel’s diverticulum

Answer 37

remnants of vitelline duct

Question 38

what does the endoderm of the hindgut form? (2)

Answer 38

lining of the bladder and urethra

Question 39

which part of the hindgut joins with the posterior part of the cloaca?

Answer 39

the terminal portion

Question 40

what does the allantois enter into?

Answer 40

the anterior part of the cloaca

Question 41

define cloaca

Answer 41

endoderm lined cavity with surface ectoderm at its ventral boundary

Question 42

blood supply to the foregut

Answer 42

coeliac artery

Question 43

blood supply to the midgut

Answer 43

superior mesenteric artery

Question 44

blood supply to the hindgut

Answer 44

inferior mesenteric artery

Question 45

abnormal development of the hindgut

Answer 45

Urorectal fistula
Rectovaginal fistula
Rectoanal atresia
Imperforate anus