Embryology: Development of the Major Organ Systems

Question 1

What are the main events at week 4 of foetal development?

Answer 1

Closure of the neural tube, folding of the embryo, the pharyngeal arches and the beginnings of the limbs

Question 2

What are the main events at week 5 of foetal development?

Answer 2

The growth of the head and heart and kidneys

Question 3

What are the main events at week 6 of foetal development?

Answer 3

Progress of the development of the limbs and heart and start of spontaneous movements

Question 4

What are the main events at week 7 of foetal development?

Answer 4

Cell death to shape the limbs and face and the growth and development of the gut

Question 5

What are the main events at week 8 of foetal development?

Answer 5

Bone formation and more of the development of the gut

Question 6

What do neural crest cells become?

Answer 6

The peripheral nervous system

Undergo conversion from epithelia to mesenchymal cells –> migrate to form PNS

Question 7

What is the notochord?

Answer 7

A cartilaginous skeletal rod supporting the body embryonic development that is involved in signalling to cause differentiation in the development of the foetus

Question 8

How is the neural tube formed?

Answer 8

From merging of the ends of the neural plate, and this structure will go on to form the brain and spinal cord, with a layer of neural crest cells above

Question 9

What happens if the inferior portion of the neural tube doesn’t close properly at week 4?

Answer 9

Spina bifida develops

Question 10

What happens if the superior portion of the neural tube doesn’t close properly at week 4?

Answer 10

Anencephaly

Question 11

Which pharyngeal arch will form most of the face?

Answer 11

Arch 1 (maxillary arch)

Question 12

What is the philtrum?

Answer 12

Joining of the two medial nasal prominences, which also forms part of the upper lip

Question 13

What is the primary palate?

Answer 13

Philtrum and 4 central incisor teeth, and stems from the mergin of the medial nasal prominences

Question 14

What is the secondary palate?

Answer 14

Formed from the maxillary palatal shelves which grow inferiorly to begin with (either side of tongue) and then rotate horizontally when the tongue moves into the throat

Question 15

How is cleft lip caused in the 5th week of foetal development?

Answer 15

Failure of the maxilla to fuse with the medial nasal prominence, leading to a cleft between the Philtrum and the rest of the upper lip, and between the central and lateral incisors

Question 16

How is cleft palate caused in the 5th week of foetal development

Answer 16

Failure of palatal shelves to fuse (from maxillary prominences).

Question 17

Why may cleft palate develop?

Answer 17

Because the tongue is too large, the shelves rotate upwards late, shelves are too small to touch or due to failure of ectoderm to break down to allow fusion

Question 18

What is the metanephric system?

Answer 18

The definitive kidney

Question 19

What is a pelvic kidney?

Answer 19

When the kidney has not ascended into the thoracic cavity

Question 20

What is a horseshoe kidney?

Answer 20

When the two kidneys combine to form a horseshoe shape

Question 21

What is the function of cranial folding in the 6th week of foetal development?

Answer 21

Forces primitive heart tubes into the thoracic cavity

Question 22

What is the function of lateral folding in the 6th week of foetal development?

Answer 22

Tubes come to lie closer to each other and begin to fuse into a single, primitive tube

Question 23

What four regions are present in the primitive heart tube in the 6th week of foetal development?

Answer 23

Cranial portion is known as the truncus arteriosus (vessels will arise here), the bulbous cordis, primitive ventricle and primitive atrium most caudally.

Question 24

Describe the derivatives of the embryological foregut

Answer 24

Supplied by aortic arch arteries and coeliac artery and contains the pharynx, oesophagus, stomach and superior portion of duodenum

Question 25

Describe the derivatives of the embryological midgut

Answer 25

Supplied by the superior mesenteric artery and contains the inferior half of the duodenum, the jejunum, ileum, caecum, appendix and ascending colon

Question 26

Describe the derivatives of the embryological hindgut

Answer 26

Supplied by the inferior mesenteric artery and contains the left 1/3 of the transverse colon, the descending colon, sigmoid colon and rectum

Question 27

Where do the greater and lesser curvatures of the stomach lie on a sagittal section

Answer 27

Greater curvature is anterior, (towards abdomen) and the lesser curvature is posterior

Question 28

Which nerves innervate the anterior and posterior wall of the stomach?

Answer 28

Anterior wall = left vagus

Posterior wall = right vagus

Question 29

What is omphalocoele?

Answer 29

When there is a failure of the umbilicus to close completely combined with failure of the mid gut to herniate back into the abdominal cavity fully

Question 30

What is gastroschisis?

Answer 30

The baby’s intestines stick outside of the baby’s body, through a hole beside the belly button