Prenatal Craniofacial Development

Question 1

Morphogenesis of the face is a complex 3D process involving…

Answer 1

patterning, outgrowth, fusion and moulding of tissues

Question 2

At 22 days, the head and neck region comprise ____ of the embryo

Answer 2

1/2

Question 3

During 4th week, ventral mesoderm condenses into a series of segmented bilaterally paired, mesenchymal swellings called…

Answer 3

pharyngeal (branchial) arches

Question 4

How many pairs of pharyngeal arches are there?

Answer 4

5 pairs

Question 5

What does the first arch make?

Answer 5

mandibular process

Question 6

When does the oropharyngeal membrane break down?

Answer 6

during 4th week

Question 7

First (mandibular) arch and maxillary processes are both ______

Answer 7

paired structures
- grow ventro-laterally around the OM

Question 8

The majority of the growth and morphological change in facial tissue masses is driven by the…

Answer 8

invading cranial neural crest-derived mesenchyme

Question 9

The paired first pharyngeal arches only give rise to the _______ processes

Answer 9

mandibular
(his slide is funky and i hate it)

Question 10

Where do the maxillary processes originate from?

Answer 10

separate (delayed) swellings rostral to the mandibular processes

• distinct population of late migrating CNCC

Question 11

Formation and invagination of nasal placodes (thickening of ectoderm) in…

Answer 11

Frontonasal Prominence (FNP)

Question 12

What is the induction and invagination of nasal placodes similar to?

Answer 12

neural plate induction & invagination

Question 13

What are the two types of morphological processes for “joining” tissue?

Answer 13

• merging
• fusion

Question 14

What is merging?

Answer 14

joining of two masses already partly in contact

Question 15

What is fusion?

Answer 15

joining of two separate tissue masses

Question 16

How do the maxillary (MXP) and lateral nasal processes (LNP) come together?

Answer 16

merging

Question 17

How do the medial nasal processes and maxillary (MXP)/lateral nasal (LNP) come together?

Answer 17

fusion

Question 18

What does the medial nasal processes and maxillary (MXP)/lateral nasal (LNP) form together?

Answer 18

primary palate and nares (nostrils)

Question 19

In what week do the medial nasal processes and maxillary (MXP)/lateral nasal (LNP) fuse together?

Answer 19

6th week

Question 20

What does the secondary palate arise from?

Answer 20

the medial aspects of the MXPs > palatal shelves

Question 21

When does the secondary palate arise?

Answer 21

10th week

Question 22

After immigration of cranial neural crest cells, growth & morphogenesis of the face is controlled by ongoing…

Answer 22

epithelial-mesenchymal interactions

*dont need the rest of the embryo

Question 23

What cells primarily determine facial form/shape?

Answer 23

Cranial neural crest cells (CNCC)

Question 24

There are ______ boundaries of expression in facial ectoderm

Answer 24

defined

Question 25

Neural expression of ______ precedes (and is required for) the ectodermal expression

Answer 25

Shh/Fgf8

Question 26

Secreted factors from the FEZ can direct outgrowth of the underlying CNCC and determines D-V pattern of the

Answer 26

Frontal nasal process (FNP) - but precise shape depends upon pattern information inherent in the neural crest

Question 27

Transplanted ectoderm retains ______ pattern of expression from originating tissue

Answer 27

FGF8/SHH

Question 28

What does the dynamic ectoderm do?

Answer 28

1. support and direct outgrowth of the facial processes 2. guides differeniation of CNC 3. facilitating timely fusion of the facial processes

Question 29

Fusion of the facial processes establishes what?

Answer 29

primary palate and goes on to form the alveolus and lip proper - full fusion is required to ensure the alveolar bone is continuous

Question 30

What is the third most common birth defect?

Answer 30

cleft lip

Question 31

What must occur for secondary palate formation?

Answer 31

1. growth (either side of tongue) 2. elevation and rotation 3. medial growth and fusion at midling with nasal septum

Question 32

Ossification of the secondary palate begins just before...

Answer 32

palatal development complete

Question 33

What are the palatal shelves made of?

Answer 33

condensations of CNCC mesenchyme

Question 34

Secondary palate forms well after the...

Answer 34

primary palate/lip (around 10th week)

Question 35

What can cause cleft secondary palate?

Answer 35

1) poor growth of shelves 2) failed elevation 3) failed fusion

Question 36

It is critical that the ______ lowers to allow the shelves to rotate to a position above it

Answer 36

tongue

Question 37

What can provide a physical barrier to the secondary palate closure?

Answer 37

macroglossia (enlarged tongue)

Question 38

What is indirectly associated with failed secondary palate fusion?

Answer 38

small or retrognathic mandible (tongue is forced backward and elevated) - such as Pierre-Robin sequence

Question 39

Craniofacial cartilage first appears in the ________ and shortly thereafter in the midface and cranial base

Answer 39

mandible

Question 40

What provides structural support for shaping the growing head?

Answer 40

craniofacial cartilage

Question 41

The Meckel's cartilage arises during ___ week

Answer 41

7th - forms the template for the mandible

Question 42

What pharyngeal arch is meckels cartilage from?

Answer 42

PA 1

Question 43

What does PA 1 make besides Meckel's cartilage?

Answer 43

two ear ossicles (parts of the malleus and incus)

Question 44

Like most facial cartilages, most is/is not converted to bone?

Answer 44

is not

Question 45

How does most of the facial cartilage become bone?

Answer 45

parts degenerate

Question 46

Is the ear formed from independent or dependent embryonic structures?

Answer 46

independent

Question 47

External and middle ear derivatives of which pharyngeal arches

Answer 47

PA1 and PA2 - intervening pharyngeal cleft & pharyngeal pouch

Question 48

Inner ear arises from...

Answer 48

thickening of ectoderm (otic placode) dorsal to PA3 at level of hindbrain and subsequent invagination (otic pit)

Question 49

Inner and outer ear malformations often associated with __________ defects

Answer 49

mandibular