Systemic embryology and congenital malformations

Question 1

Three layers in trilaminar embryonic disc

Answer 1

Ectoderm, mesoderm, endoderm

Question 2

Parts of body from ectodermal germ layer

Answer 2

Skin/ear/nose/eye

Contact with outside world

Question 3

How does neural tube form?

Answer 3

Ectoderm - neuroectoderm

Question 4

3 parts of mesodermal germ layer

Answer 4

Paraxial, intermediate, lateral plate

Question 5

What are neuromeres?

Answer 5

Somitomeres in association with neural plate

Question 6

What do neuromeres do?

Answer 6

Contribute to connective tissue in head

Question 7

What are somites?

Answer 7

Somitomeres on either side of neural tube

Question 8

What are somites made from?

Answer 8

Paraxial mesoderm

Question 9

At what rate do new somites appear?

Answer 9

3 pairs per day

Question 10

How many somites formed at end of 5th week?

Answer 10

42-44

Question 11

What does intermediate mesoderm form?

Answer 11

Urogenital system - primordial germ cells, gametes and gonads

Question 12

What does lateral plate mesoderm split into?

Answer 12

Somatic (parietal) and visceral (splanchnic)

Question 13

What does parietal layer do?

Answer 13

Lines body walls

Question 14

What does lateral plate mesoderm form?

Answer 14

Skin, ribs, limbs, blood cells, blood vessels

Question 15

What does endodermal germ layer form?

Answer 15

GI tract, bladder, urethra, auditory tube,

Question 16

What is morphogenesis?

Answer 16

Form shaping process in embryo - differential tissue growth

Question 17

What is dysmorphogenesis?

Answer 17

developing abnormally, outside arbitrary range

Question 18

What is deformation?

Answer 18

Secondary morphologic defects that are imposed upon an organ or body part due to mechanical forces over a prolonged period - an indirect effect e.g. club feet

Question 19

Symtoms of Down’s syndrome

Answer 19

• Trisomy 21
• Flat facial feature with small nose
• Reduced muscle tone (hypotonia)
• Upwards/downward slant to eye
• Large tongue that sticks out
• Single deep dcrease across palm
• Hyper-flexibility of joints

Question 20

Symptoms of foetal alcohol syndrome

Answer 20

• Short palpebral fissure lengths
• Smooth philtrum
• Thin upper lip
• Brain damage

Question 21

What is teratology?

Answer 21

Study of birth defects/congenital malformations

Question 22

Where is inhibin A produced?

Answer 22

Foetus and placenta

Question 23

Sacrococcygeal teratomas

Answer 23

Remnants of primitive streak persist and form tumours

Question 24

Situs inversus

Answer 24

Transposition of visceral organs

Question 25

Sirenomelia

Answer 25

Legs stuck together like mermaid

Question 26

Caudal dysplasia

Answer 26

due to mesodermal insufficiency in caudal-most region of embryo which contributes to formation of lower limbs, urogenital system and lumbosacral vertebrae
- Affected child exhibits a variable range of defects including: hypoplasia and fusion of lower limbs, vertebral abnormalities, renal agensis, imperforate anus, abnormalities or genital organs