Development Of The Craniofacial Complex Flashcards
Is the cranial mesoderm segmented or unsegmented?
Unsegmented
What is the fate of the neural crest cells influenced by?
Their position along the A-P axis
What are the derivatives of the cranial neural crest?
- Connective tissues and part of cornea of eye
- Truncoconal septum
- Pharyngeal arch cartilages
- Bones of face
- Odontoblasts
- Dermis of neck and face
- Some cranial nerve ganglia
What are the derivatives of the trunk neural crest?
- Adrenal medulla
- Dorsal root ganglia
- Preaortic ganglia
- Chain ganglia
When do the branchial arches appear?
4-5 weeks
What do the branchial arches consist of?
A bar of mesenchymal tissue, lined on the inside by endoderm and the outside by ectoderm
How many branchial arches are there?
5
Which arch forms the upper and lower jaw?
1st arch
What are the muscle and cartilage derivatives of the 2nd arch?
Muscles of facial expression.
Stapes,styloid process, stylohyoid ligament and lesser horns of hyoid
What are the muscle and cartilages derivatives of the 3rd arch?
Stylopharyngeus.
Greater horns of the hyoid
What are the muscle and cartilage derivatives of the 4th arch?
Constrictors of pharynx.
Cartilages of larynx
What are the muscle and cartilage derivatives of the 6th arch?
Intrinsic muscles of he larynx.
Cartilages of the larynx
What divides the frontonasal prominence into medial and lateral nasal prominences?
Nasal pit
When is the morphology if the face established?
Weeks 4-10
What does bifid nose result from?
Incomplete fusion of the medial nasal prominences
What does cleft chin result from?
Incomplete fusion of the left and right mandibular processes
What happens when the maxillary swellings fail to fuse with the intermaxillary process?
Cleft lip
What is the primary palate formed from?
An extension if the intermaxillary process
What is the secondary palate formed from?
Palatine shelves
When do the palatial shelves fuse?
Weeks 7-10
Which syndrome is classified by a small lower jaw, posterior placement of the tongue and cleft palate?
Pierre-Robin sequence
Mutations in which gene causes Treacher-Collins syndrome?
TCOF1
What happens to neural crest cells in Treacher-Collins syndrome?
There is reduced neural crest migration due to increased apoptosis
Mutations in which signalling molecule causes holoprosencephaly?
Shh
What is the most common environmental cause of holoprosencephaly?
Maternal diabetes
What are the 4 stages of severity of holoprosencephaly?
Alobar, semilobar, lobar, microform
Which signalling pathway is involved in dividing the forebrain?
Shh
Which signalling pathway is key to specifying the midline?
Shh
What facial defects can be caused by
a) low Shh levels
b) high Shh levels
A) cyclopia
B) diprosopus
Which syndrome is classified by an absence of parathyroids, congenital hypoparathyroidism, immune deficiency and tetralogy of Fallot
DiGeorge syndrome
Mutation in which signalling molecule causes DiGeorge syndrome?
FGF8
Which end of the splanchnic mesoderm are cardiogenic precursors found?
Cranial end
Name 4 syndromes associated with craniosynostosis
Muenke syndrome, Apert syndrome, Crouzon syndrome and Pfeiffer syndrome
Mutations in which signalling pathway cause craniosynostosis?
FGF
What is the hallmark of a foetus exposed to retinoic acid?
Absent/defective ears and small jaw
What is the effect of retinoic acid on neural crest cells?
It induces death of neural crest cells
What are 3 characteristics of foetal alcohol syndrome?
Thin upper lip
Rounded, indistinct philtrum
Small eyelids
