Embryology - Development of the Nose and Face

Question 1

State the 4 prominences/sites from which the face develops?

Answer 1

• Frontonasal prominence
• Maxillary prominence
• Mandibular prominence
• Stomotadeum

Question 2

From what structures do the maxillary and Mandibular prominences originate?

Answer 2

The 1st arch

Question 3

Describe briefly how the nose develops (4 marks)

Answer 3

• Nasal placode appears on the Frontonasal prominence
• Placodes sink - forms nasal prominences
• Maxillary prominences grow medially - nasal prominences pushed towards midline
• Maxillary and medial prominences fuse in midline

Question 4

The intermaxillary segment:
What does it come from?
What does it give rise to?

Answer 4

• Comes from fusion of the medial nasal prominences
• Gives rise to:
  Philtrum
  Middle upper jaw + front 4 incisors
  Primary palate

Question 5

What makes up the definitive palate?

Where do these components come from?

Answer 5

1* and 2* palates

• 1* - from medial nasal prominences
• 2* - from maxillary prominences

Question 6

Briefly describe how the palate develops

Answer 6

• Palatal shelves develop from maxillary prominences and grow downwards into mouth
• Mandible develops enough room for tongue to drop
• Palatal shelves grow towards each other and fuse
• Nasal septum grows down midline and fuses with the palate

Question 7

How does a cleft lip and palate come about?

Answer 7

• Failure of fusion of medial nasal and maxillary prominences +/- failure of the Palatal shelves to meet in the midline

Question 8

What are neural crest cells?

Answer 8

Specialised population of cells which originate within the lateral border of neuroectoderm. Migrate into mesoderm.