Embryology Flashcards

1
Q

What is gastrulation?

A

formation of trilaminar germ disc from a bilaminar disc

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2
Q

when does ovulation start in regards to menstrual cycle?

A

ovulation starts roughly 14 days before your period starts

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3
Q

when does the bilaminar disc form?

A

week 2

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4
Q

which gene is a transcription factor for establishing left sidedness?

A

PTX2

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5
Q

What happens during week 3?

A

gastrulation
CNS induction
Neurulation

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6
Q

What is week 3-8 called?

A

organogenesis

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7
Q

where do the visceral and parietal mesoderm arise from?

A

lateral plate mesoderm

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8
Q

when does the gut tube form?

A

3rd and 4th week

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9
Q

what does the gut tube form from

A

the endoderm lining of the yolk sac

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10
Q

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

A

oropharyngeal membrane

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11
Q

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

A

cloacal membrane

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12
Q

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

A

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

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13
Q

where does the foregut form from?

A

the cranial part of the primitive gut tube

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14
Q

which structures/organs are included in the term foregut?

A

pharynx
oesophagus
stomach
upper duodenum

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15
Q

the laryngeal -tracheal diverticulum (lung bud) form from

A

ventral wall of the foregut

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16
Q

function of Tracheo- oesophageal septum

A

divided the foregut tube into trachea and oesophagus

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17
Q

what happens to the foregut in the 4th week?

A

it dilates to form the stomach

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

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18
Q

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

A

a mesentery called mesogastrium

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19
Q

where does the lesser sac lie?

A

behind the stomach

20
Q

what is the duodenum formed from

A

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

21
Q

name the blood supply of the duodenum

A

coeliac trunk

superior mesenteric artery

22
Q

when is the liver bud created?

23
Q

what does the liver bud grow into

A

the septum transversum

24
Q

what forms the gall bladder and cystic duct?

A

ventral outgrowth from the bile duct

25
Key points of spleen formation
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
26
Describe the formation of the pancreas
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
27
what makes up the main pancreatic duct?
ventral duct | distal part of dorsal duct
28
what are Esophageal atresia and trachea-esophageal fistula?
If the tracheo - esophageal septum deviates incorrectly => incomplete separation of laryngo -tracheal tube (lung bud) which results in these 2 things
29
annular pancreas
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
30
what is the midgut?
the distal part of duodenum, jejunum, ileum, caecum, appendix, asc and transverse colon
31
what does the cephalic part of the midgut become?
distal duodenum, jejunum and proximal ileum
32
what does the caudal part of the midgut become
distal ileum, caecum, appendix, ascending colon and the proximal 2/3rds of the transverse colon
33
what must the midgut undergo to reach adult pattern?
rotation and physiological herniation
34
when does rotation of the midgut begin
week 6
35
physiological herniation: what does the gut tube herniate through
the extraembryonic cavity in the umbilical cord
36
abnormalities in midgut development (4)
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
37
what forms meckel's diverticulum
remnants of vitelline duct
38
what does the endoderm of the hindgut form? (2)
lining of the bladder and urethra
39
which part of the hindgut joins with the posterior part of the cloaca?
the terminal portion
40
what does the allantois enter into?
the anterior part of the cloaca
41
define cloaca
endoderm lined cavity with surface ectoderm at its ventral boundary
42
blood supply to the foregut
coeliac artery
43
blood supply to the midgut
superior mesenteric artery
44
blood supply to the hindgut
inferior mesenteric artery
45
abnormal development of the hindgut
Urorectal fistula Rectovaginal fistula Rectoanal atresia Imperforate anus