Prenatal & Craniofacial Development- Cox Flashcards
Morphogenesis of the face is a complex 3D process involving:
patterning, outgrowth, fusion and molding of tissues
at around 22 days (3 weeks), head and neck regions comprise:
nearly half of the embryo
During the 4th week, ventral mesoderm condenses into a series of segmented bilaterally paired:
mesenchymal swellings
During the 4th week, ventral mesoderm condenses into a series of segmented bilaterally paired mesenchymal swellings also known as:
pharyngeal (branchial) arches
There are ultimately ___ pairs of pharyngeal (branchial) arches arising in a ____ order
cranial-caudal
Cranial-caudal can also be referred to as:
anterior-posterior
Thinking of the face itself now, initially __ prominences (tissue masses) surround the ___
5; stomodeum
The first mandibular arch and maxillary processes are both ___
paired structures
The first mandibular arch and maxillary processes are both paired structures and grow:
Ventro-laterally around the OM
The oropharyngeal membrane breaks down during:
4th week
(pharyngeal arch growth) The majority of growth and morphological change in facial tissue masses is driven by:
invading cranial neural crest-derived mesenchyme
The ____ forms first, then forms into the ___ . Then the ___ splits off
branchial arch 1; mandibular portion; maxillary portion
contrary to textbook literature, the paired first pharyngeal arches only give rise to ____.
mandibular processes
____ originate as separate (delayed) swellings rostral to the mandibular processes
maxillary processes
Maxillary processes occur due to the invasion by a distinct population of:
late migrating CNCC
Formation and invagination of ____ (thickening of ectoderm) in the frontonasal prominence (FNP) occurs after the maxillary and mandibular swellings occur
nasal placodes
Induction and invagination of ___ is similar to neural plate induction and invagination
nasal placodes
(morphogenesis of the midface): there are two types of morphological processes for “joining tissues” including:
- merging
- fusion
Joining of two masses already partly in contact
merging
What structures are involved in the morphological process of “merging”
- merging of maxillary and lateral nasal processes
- medial merging of mandibular processes
In morphogenesis of the midface, ___ occurs between the maxillary and lateral nasal processes (MXP & LNP)
merging
In morphogenesis of the midface, ____ occurs with the mandibular processes (MNP)
medial merging
In morphogenesis of the midface, merging occurs during the ___ week of human development
5th week
Joining of two separate tissue masses:
fusion
During formation of the primary and secondary palates, ____ occurs between the MNP, MXP/LNP:
contact-dependent fusion
Contact dependent fusion between the MNP (medial nasal process), and MXP/LNP (maxillary nasal process/Lateral nasal process) forms the:
primary palate and nares (nostrils)
Contact dependent fusion between the MNP (medial nasal process), and MXP/LNP (maxillary nasal process/Lateral nasal process) forms the primary palate and nares during the ___ week of human development
6th week
The ____ arises later rom the medial aspects of the MXPs leading to palatal shelves
secondary palate
The secondary palate (future roof of mouth) arises later from the medial aspects of the __ which lead to ___.
MXPs; palatal shelves
The secondary palate forms during the ___ week of human development
10th
The secondary palate forms during the 10th week of development through a ___ event
fusion
after immigration of cranial neural crest cells, growth and morphogenesis of the face is controlled by ongoing:
epithelial-mesenchymal interactions
responsible for determining facial form/shape:
cranial neural crest cells
in addition to CNCCs primarily determining facial form/shape, ___ also play a role
ectoderm
How does the ectoderm play a role in determining facial form/shape:
defines boundaries of gene expression
What are two examples of neural expression signals provided by the ectoderm for role in facial form/shape:
Shh & Fgf8
juxta-positioned FGF8/SHH leads to:
frontonasal ectoderm zone (FEZ)
The growth factor secreted by ventral facial ectoderm:
Shh
The growth factor secreted by the dorsal facial ectoderm:
Fgf8
Ectodermal factors instruct:
facial D-V patterning
secreted factors from the FEZ can direct outgrowth of the underlying CNCC and determines:
D-V pattern of FNP
The precise shape of the frontonasal process depends upon pattern information inherent in the:
neural crest
List three other functions of the ectoderm (in addition to gene expression/patterning signals):
- support and direct outgrowth of facial processes
- Guides differentiation of CNC through growth factors
- facilitates fusion of facial processes
fusion between what 3 components of the embryo must occur in order to form the primary palate:
- medial nasal tissue
- lateral nasal process
- maxillary process
for the medial nasal tissue, lateral nasal process, and maxillary process to fuse to form the primary palate, what is absolutely required?
ectodermal cells
Fusion establishes the primary palate which goes on to form the:
alveolus and lip proper
How do we know that fusion of the medial nasal tissue of the frontal nasal process, the lateral nasal process and the maxillary process are improtant?
because defects in this fusion result ini cleft lip and palate
full fusion is required to ensure the ___ is continuous
alveolar bone
third most common birth defect and occurs in ~1 in 700 births world-wide
cleft lip +/- cleft primary palate
forms through a similar fusion mechanism as the primary palate:
secondary palate
When does the primary palate form? when does the secondary palate form?
7th week; 10th week
condensations of CNCC mesenchyme are:
palatal shelves
Secondary palate formation involves: (3)
- growth of maxillary extensions (either side of tongue)
- Elevation and rotation
- medial growth and fusion at midline with nasal septum
___ of the secondary palate begins just before palatal development is complete:
ossification
Palatal shelves are condensations of:
CNCC mesenchyme
What is required in order to have complete mesenchyme over the bridge to form the bony part in the formation of a secondary palate:
movement and disintegration of epithelia
Defects in palatal shelf fusion would result in:
cleft secondary palate
Cleft primary palate occurs in :
Cleft secondary palate occurs in:
1/700 births
1/1000 births
Cleft secondary palate can result from:
- poor growth of shelves
- failed elevation
- failed fusion
What is critical for the tongue and secondary palate closure?
critical that the tongue lower to allow the shelves to rotate to a position above the tongue
Macroglossia (enlarged tongue) can provide a physical barrier to:
secondary palate closure
____ is also associated with failed palatal fusion (such as in pierre-robin sequence)
small or retrognathic mandible
A small or retrognathic mandible results in the tongue being:
force backward ad elevated
craniofacial cartilage first appears in the ____ and shortly thereafter in the ____ and ____
mandible; midface & cranial base
Provides structural support for shaping the growing head:
craniofacial cartilage
Unlike the axial skeleton, craniofacial cartilage:
is not typically replaced by bone
Cartilage of pharyngeal arch 1:
Meckel’s Cartilage
When does meckel’s cartilage arise and what does it form?
7th week of human development; template for the mandible
Pharyngeal arch 1 also contirbutes to two:
ear ossicles (parts of malleus and incus)
If a patient has a mandibular defect, what also should you check for?
inner ear deficiencies
portion of the ear:
- derivatives of PA1 and PA2
- intervening pharyngeal cleft
- pharyngeal pouch
external and middle ear
portion of the ear:
- arises from thickening of ectoderm (otic placode) dorsal to PA3 at the level of the hind brain and subsequent invagination (otic pit)
Inner ear
During the development of the ear, region between PA1 and PA2 undergo a morphological change to create bulge like structures called:
Hillocks of His
Inner and outer ear malformations are often associated wtih:
mandibular defects
ossification of the mandible and maxilla start occurring around day ____ of development
day 52
cranial neural crest cells give rise to the bony structures of the ___ & ___ but not the ____ as those are derived from a mesoderm component
face and frontal bone; NOT parietal bone
