Prenatal Craniofacial Development Flashcards
- During what week does the ventral mesoderm condense into a series of segmented bilaterally poured, mesenchymal swellings?
Week 4
- How many pharyngeal (branchial) arches are there?
5
- What facial prominences surround the stomodeum?
a. Frontonasal prominence
b. First arch (mandibular process)
c. Maxillary process
- The 1st mandibular arch and maxillary process are both
a. Paired structures
- The mandibular and maxillary processes are both derived from what branchial arch?
Arch 1
- The majority of growth and morphological change in facial tissue masses is driven by what?
a. Invading cranial neural crest-derived mesenchyme (CNCC)
- The 1st paired pharyngeal arches only give rise to what?
a. Mandibular processes
- Do maxillary processes originate as (separate) swellings from the mandibular process?
Yes
- You get the formation and invagination of nasal (nostrils) placodes (thickening of ectoderm)
where?
a. Frontonasal prominence (FNP)
- What are the 2 types of morphological processes for ‘joining’ tissues?
a. 1st merging
b. 2nd fusion
- This is the joining of 2 masses already partly in contact
a. 1st merging
- What types of ‘merging’ occur?
a. merging of Maxillary (MXP) and Lateral nasal processes (LNP)
b. Medial merging of mandibular processes (MNP)
- This is the joining of 2 separate tissue masses
a. 2nd fusion
- This forms the primary palate and nares (nostrils)
a. Contact-dependent fusion between MNP and MXP/LNP
- The 2nd palate arises later from the medial aspects of the MXP which are
a. Palate shelves
- The 2nd palate arises later from what?
a. Medial aspects of MXP
- These primarily determine facial form/shape
a. CNCC
- These give the pattern of growth in the ectoderm
a. FGF8/SHH
- FGF8/SHH come from what zone?
a. Frontonasal ectoderm zone (FEZ)
- When you translate the ectoderm, what happens to FGF8/SHH?
a. Retains the expression pattern from the original tissue
- SHH is what ectoderm?
a. Ventral facial ectoderm
- FGF8 is what ectoderm?
a. Dorsal facial ectoderm
- Secreted factors from the ectoderm (FGF8/SHH) can direct outgrowth of the underlying CNCC and determine what pattern?
a. D-V pattern of the FNP
- Fusion of the facial ectoderm establishes what?
a. Primary palate
- Fusion of the facial ectoderm establishes the primary palate and goes on to form what?
a. Alveolus and lip proper
- What is required to ensure that the alveolar bone is continuous?
a. Full fusion
- This is the 3rd most common birth defect
a. Cleft lip/cleft palate
- The palatal shelves are formed due to what?
a. Condensations of CNCC mesenchyme
- What week does the 2nd palate form?
Week 10
- What week does the primary palate form?
Week 7
- Ossification of the 2nd palate begins just before what?
a. Palatal development is complete
- How does the 2nd palate develop?
a. Growth (either side of the tongue)
b. Elevation and rotation
c. Medial growth and fusion at the midline and with nasal septum
- Defects on the palatal shelf fusion can result from
a. Poor growth of shelves
b. Failed elevation
c. Failed fusion
- Secondary palate failure can occur from
a. Macroglossia (too big tongue)
b. Small or retrognathic mandible
c. Primary palate problem
d. Problem with CNCC
- This can provide a physical barrier to 2nd palate closure
a. Macroglossia (big tongue)
- This is associated with failed palatal fusion and small retrognathic mandible
a. Pierre-robin sequence
- This provides structural support for shaping the growing head
a. Craniofacial skeleton/cartilage
- Craniofacial ___ precedes ossification
a. Cartilage
- This forms the template for the mandible
a. PA1 (Meckel cartilage)
- When does PA1 (Meckel’s cartilage) arise?
a. Week 7
- PA1 contributes to what 2 ear ossicles?
a. Malleus and incus (and ligaments)
- The external and middle ear are derivatives of what?
a. PA1
b. PA2
- The inner ear arises from what?
a. Thickening of the ectoderm (otic placode) dorsal to PA3 at the level of the hindbrain
- What branchial arches affect ear formation?
a. Arch 1 and 2
