Term
| How do the medial and lateral nasal prominences arise? How does their formation relate to bilateral or unilateral cleft upper lips? |
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Definition
As the ectdodermal placodes invaginate, they divide the lowerfrontonasal prominence into two medial and two lateral nasal prominences.
Cleft upper lip arises when the medial nasal prominences do not fuse appropriately with the maxillary prominences. |
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Term
| How do the ears arise in terms of the middle ear bones, the inner ear and the external auditory meatus? |
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Definition
Middle ear bones- malleus and incus (1st branchial arch), stapes (2nd branchial arch)
External auditory meatus- 1st branchial groove
Inner ear- otic placodes (just above 1st and 2nd arches) |
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Term
| Neural crest cells give rise to the bones and cartilage of the face jaws and ears when they populate branchial arches. For each arch, which structures do crest cells contribute to? |
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Definition
frontonasal prominence- nasal, orbital and frontal bones
Arch 1- Malleus and Incus, maxillary and mandibular bones and cartilages of external ears.
Arch 2- Stapes, upper hyoid
Arch 3- Lower hyoid
Arch 4- laryngeal cartilages |
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Term
| Each branchial arch consists of a core mesenchyme surrounds by surface ectoderm. What tissues are contained within the mesenchyme, and how do they contribute differently to cranial development? |
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Definition
1) Neural crest and Head mesoderm
2) Neural crest gives rise to viscerocranium cartilage structures and the head mesoderm gives frise to unique set of muscles. |
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Term
| At 4-5 weeks, the pharyngeal gut gives rise to pharyngeal pouches that lie between branchial arches. What structures arise from each pouch? |
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Definition
Pouch 1) Tympanic cavity and auditory tube and form tympanic membranes with 1st branchial crest.
Pouch 2) Palatine tonsils
Pouch 3) Thymus and inferior parathyroids
Pouch 4) Superior parathyroids |
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Term
| Where is Shh expressed in neural development. What role does Shh play in forebrain development? |
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Definition
1) Expressed in prechordal mesoderm and ventral forebrain.
2) Required for 1st branchial arch formation (inner ear bones, maxillary and mandibular prominences) and survival of first crest (external auditory meatus) |
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Term
| Where is FGF expressed in neural development. What roles does it serve? |
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Definition
1) Anterior edge of forbrain
2) Outgrowth and specification of fore. Also in the migration and proliferation of neural crest required for surivival of branchial arch mesenchyme |
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Term
| What role does RA play in neural development? Where is it found? |
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Definition
1) Regulates FGF and Shh expression, thereby affecting forebrain cell development. Also important for survival of head mesenchyme
2) Detected in early forebrain and frontonasal regions |
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Term
| What roles to Hox genes play in neural development? Where are they found? |
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Definition
1) Defining particular skeletal elements that arise from each branchial arch.
2) In neural crest cells that populate branchial arches 2-4 |
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Term
Where does the anterior palate originate from?
Where does the posterior palate originate from?
How do you get anterior vs. posterior cleft palate? |
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Definition
1) Ectodermal placodes that invaginate to form medial nasal prominence
2) Formed behind premaxilla, originating bilaterally from maxilla in the form of palatal shelves.
3) Anterior- premaxillary segment doesn't fuse with posterior shelves
Posterior- two palatine shelves arising from maxilla do not fuse. |
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Term
| How can cleft palates arise (molecular interpretation) |
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Definition
1) Neural crest cell populations
2) Disruption in forebrain induction (reduction in size of medial nasal prominences)
3) TGFB for fusion
4) Tongue and/or lower jaw development (palatal shelves cannot elevate) |
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Term
Treacher Collins
1) Defective tissue
2) Gene/Protein |
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Definition
1) Neural crest contributing to 1st branchial arch
2) TCOF1/treacle |
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Term
Digeorge/Velocardiofacial
1) Chromosome of interest
2) Gene/Protein
3) Symptoms |
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Definition
1) micro deletions in 22q11 causing neural crest issues
2) TBX1 (not expressed in cranial neural crest!)
3) Tetralogy of fallot, facial dysmorphia, cleft palate |
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Term
Holoprosencephaly
1) Molecule of interest
2) Symptoms |
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Definition
1) Shh- prechordal mesoderm function-induction of cranial neural plate (also can be caused by RA)
2) Midline development issue |
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Term
Fetal Alcohol Syndrome
1) Gene/Protein
2) Symptoms |
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Definition
1) Ethanol inhibits migration of prechordal mesoderm cells and is associated with Shh signaling
2) Hypoplastic philtrum, this upper lip, median cleft lip, short papebral fissues |
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Term
RA Embryopathy
1) Gene/Molecule
2) Symptoms |
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Definition
1) Neural crest (head and heart) particularly sensitive to Vitamin A derivatives. RA can effect Shh and Hox gene expression
2) craniofacial, mental retardation, narrow forehead, flat nasal bridge, VSD/ASD |
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