Prenatal Craniofacial Development

Question 1

1. During what week does the ventral mesoderm condense into a series of segmented bilaterally poured, mesenchymal swellings?

Answer 1

Week 4

Question 2

2. How many pharyngeal (branchial) arches are there?

Answer 2

5

Question 3

3. What facial prominences surround the stomodeum?

Answer 3

a. Frontonasal prominence
b. First arch (mandibular process)
c. Maxillary process

Question 4

4. The 1st mandibular arch and maxillary process are both

Answer 4

a. Paired structures

Question 5

5. The mandibular and maxillary processes are both derived from what branchial arch?

Answer 5

Arch 1

Question 6

6. The majority of growth and morphological change in facial tissue masses is driven by what?

Answer 6

a. Invading cranial neural crest-derived mesenchyme (CNCC)

Question 7

7. The 1st paired pharyngeal arches only give rise to what?

Answer 7

a. Mandibular processes

Question 8

8. Do maxillary processes originate as (separate) swellings from the mandibular process?

Answer 8

Yes

Question 9

9. You get the formation and invagination of nasal (nostrils) placodes (thickening of ectoderm)
   where?

Answer 9

a. Frontonasal prominence (FNP)

Question 10

10. What are the 2 types of morphological processes for ‘joining’ tissues?

Answer 10

a. 1st merging
b. 2nd fusion

Question 11

11. This is the joining of 2 masses already partly in contact

Answer 11

a. 1st merging

Question 12

12. What types of ‘merging’ occur?

Answer 12

a. merging of Maxillary (MXP) and Lateral nasal processes (LNP)
b. Medial merging of mandibular processes (MNP)

Question 13

13. This is the joining of 2 separate tissue masses

Answer 13

a. 2nd fusion

Question 14

14. This forms the primary palate and nares (nostrils)

Answer 14

a. Contact-dependent fusion between MNP and MXP/LNP

Question 15

15. The 2nd palate arises later from the medial aspects of the MXP which are

Answer 15

a. Palate shelves

Question 16

16. The 2nd palate arises later from what?

Answer 16

a. Medial aspects of MXP

Question 17

17. These primarily determine facial form/shape

Answer 17

a. CNCC

Question 18

18. These give the pattern of growth in the ectoderm

Answer 18

a. FGF8/SHH

Question 19

19. FGF8/SHH come from what zone?

Answer 19

a. Frontonasal ectoderm zone (FEZ)

Question 20

20. When you translate the ectoderm, what happens to FGF8/SHH?

Answer 20

a. Retains the expression pattern from the original tissue

Question 21

21. SHH is what ectoderm?

Answer 21

a. Ventral facial ectoderm

Question 22

22. FGF8 is what ectoderm?

Answer 22

a. Dorsal facial ectoderm

Question 23

23. Secreted factors from the ectoderm (FGF8/SHH) can direct outgrowth of the underlying CNCC and determine what pattern?

Answer 23

a. D-V pattern of the FNP

Question 24

24. Fusion of the facial ectoderm establishes what?

Answer 24

a. Primary palate

Question 25

25. Fusion of the facial ectoderm establishes the primary palate and goes on to form what?

Answer 25

a. Alveolus and lip proper

Question 26

26. What is required to ensure that the alveolar bone is continuous?

Answer 26

a. Full fusion

Question 27

27. This is the 3rd most common birth defect

Answer 27

a. Cleft lip/cleft palate

Question 28

28. The palatal shelves are formed due to what?

Answer 28

a. Condensations of CNCC mesenchyme

Question 29

29. What week does the 2nd palate form?

Answer 29

Week 10

Question 30

30. What week does the primary palate form?

Answer 30

Week 7

Question 31

31. Ossification of the 2nd palate begins just before what?

Answer 31

a. Palatal development is complete

Question 32

32. How does the 2nd palate develop?

Answer 32

a. Growth (either side of the tongue) b. Elevation and rotation c. Medial growth and fusion at the midline and with nasal septum

Question 33

33. Defects on the palatal shelf fusion can result from

Answer 33

a. Poor growth of shelves b. Failed elevation c. Failed fusion

Question 34

34. Secondary palate failure can occur from

Answer 34

a. Macroglossia (too big tongue) b. Small or retrognathic mandible c. Primary palate problem d. Problem with CNCC

Question 35

35. This can provide a physical barrier to 2nd palate closure

Answer 35

a. Macroglossia (big tongue)

Question 36

36. This is associated with failed palatal fusion and small retrognathic mandible

Answer 36

a. Pierre-robin sequence

Question 37

37. This provides structural support for shaping the growing head

Answer 37

a. Craniofacial skeleton/cartilage

Question 38

38. Craniofacial ___ precedes ossification

Answer 38

a. Cartilage

Question 39

39. This forms the template for the mandible

Answer 39

a. PA1 (Meckel cartilage)

Question 40

40. When does PA1 (Meckel’s cartilage) arise?

Answer 40

a. Week 7

Question 41

41. PA1 contributes to what 2 ear ossicles?

Answer 41

a. Malleus and incus (and ligaments)

Question 42

42. The external and middle ear are derivatives of what?

Answer 42

a. PA1 b. PA2

Question 43

43. The inner ear arises from what?

Answer 43

a. Thickening of the ectoderm (otic placode) dorsal to PA3 at the level of the hindbrain

Question 44

44. What branchial arches affect ear formation?

Answer 44

a. Arch 1 and 2