Embryology

Question 1

4 stages in the formation of the intestines

Answer 1

1. Growth and rotation
2. Herniation and coiling
3. Re-entry and placement
4. Completion

Question 2

The hindgut becomes the

Answer 2

Descending colon

Question 3

The dorsal border of the stomach grows ___ than the ventral border, producing the ___ curvature of the stomach

Answer 3

Faster; greater

Question 4

Which component of the endoderm forms a wide connection with the yolk sac

Answer 4

Midgut

Question 5

3 primordial germ layers

Answer 5

-ectoderm
-mesoderm
-endoderm

Question 6

The mesoderm separates into 2 layers:

Answer 6

-Splanchnic
-Somatic

Question 7

The Coelom (2)

Answer 7

-space between the splanchnic and somatic mesoderm layers
-main body cavity that contains the organs

Question 8

The endoderm forms

Answer 8

The primitive gut

Question 9

3 parts to the primitive gut

Answer 9

-foregut (blind ending)
-midgut (connected to yolk sac)
-hindgut (blind ending)

Question 10

Which 2 parts of the endoderm are blind ending

Answer 10

Foregut and hindgut

Question 11

The foregut is supplied by the

Answer 11

Coeliac artery

Question 12

The midgut is supplied by the

Answer 12

Cranial mesenteric artery

Question 13

The hindgut is supplied by the

Answer 13

Caudal mesenteric artery

Question 14

Which part of the endoderm is connected to the yolk sac

Answer 14

Midgut

Question 15

The foregut becomes (7)

Answer 15

-pharynx
-oesophagus
-stomach
-liver
-pancreas
-proximal duodenum
-gall bladder

Question 16

The midgut becomes (7)

Answer 16

-duodenum distal to bile duct
-jejunum
-yolk stalk in umbilical cord (vitelline duct)
-ileum
-caecum
-ascending colon
-part of transverse colon

Question 17

The hindgut becomes (4)

Answer 17

-distal transverse colon
-descending colon
-rectum
-proximal anal canal

Question 18

The ectoderm becomes (5)

Answer 18

-epithelium of oral cavity
-outer portion of anal canal
-teeth
-nerves
-skin

Question 19

The mesoderm becomes (5)

Answer 19

-lamina propria
-submucosa
-muscle layers
-serosa/adventitia
-blood and lymph vessels

Question 20

The endoderm becomes (3)

Answer 20

-mucosal epithelium
-mucosal glands
-glandular parts of the liver and pancreas

Question 21

Formation of the digestive tract includes (3)

Answer 21

-thickening of the wall
-elongation of the tube (coiling and twisting)
-stomach and caecum dilations

Question 22

What region of the digestive tract differentiates first during organogenesis

Answer 22

Cranial regions

Question 23

What part of the digestive tract develops first during organogenesis

Answer 23

Circular layer of muscle (tunica muscularis)

Question 24

The oesophagus during gestation (4)

Answer 24

-initially a short narrow tube
-links pharynx to stomach
-elongates with the neck and thorax
-NEVER has a typical Mesentery (serosa)

Question 25

Halfway through gestation, the oesophagus goes from

Answer 25

Ciliated to stratified squamous epithelium

Question 26

During development, the stomach (4)

Answer 26

-starts as a slight swelling in the foregut
-is flattened laterally
-initially in the neck
-moves caudally with elongation

Question 27

Stomach development in 5 steps

Answer 27

1. Dorsal border (greater curvature) grows faster than the ventral border (lesser curvature)
2. Elongates and curves
3. Rotates on long axis so the greater curvature lies on the left hand side
4. Displaced by the liver, greater curvature turned caudal
5. Fundic region arises as a bulge cranially

Question 28

Mucosal glands on the stomach form

Answer 28

Halfway through gestation

Question 29

The somtach’s full secretory activity (especially parietal cells) begins

Answer 29

After birth

Question 30

The early intestine is divided into

Answer 30

-cranial
-caudal

Question 31

The intestines grow ___ in a __ space, causing them to ___

Answer 31

Fast; limited; loop and coil

Question 32

Early cranial intestine becomes the

Answer 32

Small intestine

Question 33

The early caudal intestine will become the

Answer 33

Ileum and large intestine

Question 34

During intestinal growth and rotation

Answer 34

intestines move ventrally and rotate clockwise

Question 35

Since there is insufficient space for the intestines in the abdominal cavity,

Answer 35

The intestines herniated through umbilicus into the umbilical cord

Question 36

Herniation of the intestine through the umbilicus and into the umbilical cord occurs

Answer 36

1/6 of way through gestation

Question 37

The caudal loop (outpouching) of developing intestines becomes the

Answer 37

Caecum

Question 38

The cranial loop of the developing intestine becomes the

Answer 38

Jejunum

Question 39

Re-entry and placement of the developing intestine (5)

Answer 39

-growth of abdominal cavity provides extra space, intestine returns
-jejunum returns first and fills the left side of the abdomen
-descending colon is pushed to the left
-caecum and ascending colon enter last on the right hand side
-continuation of rotation of loop

Question 40

During completion of the developing intestine (3)

Answer 40

-intestines assume adult conformation
-final growth of caecum and ascending colon (especially in the horse)
-rotation of 270 degrees around root of Mesentery

Question 41

4 types of developing intestine malformations

Answer 41

-umbilical hernia, fistula, diverticula
-stenosis (localized narrowing of the intestine)
-atresia (closure of the intestine)
-omphalocoeal (failure of intestine to re-enter abdominal cavity)

Question 42

Meckel’s Diverticulum (3)

Answer 42

-horses
-remnant of omphalomesenteric duct (vitelline duct/yolk sac)
-associate with the distal ileum)

Question 43

3 defects associated with the vitelline duct

Answer 43

-meckel’s diverticulum
-cyst
-fistula

Question 44

3 defects associated with the vitelline duct

Answer 44

-meckel’s diverticulum
-cyst
-fistula