Development Of The Branchial Arches

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Course in facial development for European Course in Neuroradiology in Tarragona, Spain, originally on 12 octobre 2008. Revised for November, 2010. For questions, e-mail to etchevers at free dot fr. Download for the animations to take place, as some pictures are covered by others.

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Development Of The Branchial Arches

  1. 1. Development of the branchial arches Heather Etchevers, Ph.D. INSERM
  2. 2. Relation of face to pharynx frontonasal bud maxillary process mandibular process
  3. 3. Pharyngeal arches are also known as branchial or aortic The embryonic dorsal aortae are paired before later fusing at the midline
  4. 4. Pharyngeal arches <ul><li>The arches are metameric structures numbered 1 to 4 and 6 in humans </li></ul><ul><ul><li>“ #5” does not exist as a separate entity </li></ul></ul><ul><li>Each arch is built around the cage of aortic arches between ventral and dorsal aortae </li></ul><ul><li>Each pair = unique complement of: </li></ul><ul><ul><li>Muscles and connective tissue </li></ul></ul><ul><ul><li>Nerves </li></ul></ul><ul><ul><li>Cartilage (bone for PA1-3) </li></ul></ul><ul><ul><li>Segment of the branchial arterial tree </li></ul></ul><ul><ul><li>Endodermal anlage to the neck glands </li></ul></ul>
  5. 5. The first aortic arch is the precursor to all pharyngeal arches Ventral view, human embryonic heart
  6. 6. Rostrocaudal maturation of arches Detrait and Etchevers, 2005
  7. 7. All pharyngeal arch arteries are never present at once Constant remodeling during embryonic life Growth factor guidance of endothelial cells Immature mural coverage Flow pressures and hemodynamics Obliterated 1st PA Maxillary artery Right dorsal aorta Left dorsal aorta 1st PA 2nd PA 3rd PA 4th PA
  8. 8. Craniofacial evolution MOUTH MOUTH r e t i n a s e l e c t i o n o f N C C G n a t h o s t o m e M O U T H p r o s m e s
  9. 9. Volumes and surfaces <ul><li>Outer, notched ectoderm </li></ul><ul><li>Inner, pouched-out endoderm </li></ul><ul><ul><li>Membranes where they meet </li></ul></ul><ul><li>Mesodermal core of muscle and vascular endothelium </li></ul><ul><li>Neural crest mesenchyme </li></ul>hindbrain pros PA1 2 3 4 heart
  10. 10. Pouches and grooves 1 2 Persists as tympanic membrane endoderm ectoderm Persists as intratonsillar cleft bpm midbrain 3
  11. 11. Endoderm and vascular development Dorsal aorta Arterial vitelline plexus Endoderm 1 st pharyngeal pouch Vitelline arteries Pharyngeal arch arteries Internal carotid Umbilical arteries
  12. 12. Endodermal expression of hypoxia-inducible factor 1  <ul><li>HIF1  is a TF activated under hypoxic/growth conditions </li></ul><ul><li>It effects transcription of pro-vascular factors such as VEGF, ET-1 </li></ul>Etchevers, 2003
  13. 13. Endodermal derivatives of pouches Superior parathyroid glands 4 Inferior parathyroid glands and epithelium of thymus 3 Epithelium of tonsil 2 Epithelium of tympanic cavity and auditory tube 1 Derivative Pharyngeal endoderm
  14. 15. Tongue and salivary glands <ul><li>Contributions from most arches </li></ul><ul><li>Endoderm and mesoderm </li></ul><ul><li>First </li></ul><ul><ul><li>oral anterior 2/3 </li></ul></ul><ul><li>Second </li></ul><ul><ul><li>Surface contribution not maintained; tonsillar crypts </li></ul></ul><ul><li>Third </li></ul><ul><ul><li>pharyngeal posterior 1/3 </li></ul></ul><ul><li>Fourth </li></ul><ul><ul><li>Epiglottis and vicinity </li></ul></ul><ul><li>The salivary glands are ectodermal ingrowths of the oral cavity that associate with NC mesenchyme </li></ul>
  15. 16. Structural derivatives Maxillary, palatine, jugal trabecula cranii Superior oblique Abducens Oculomotor muscles Trigeminal nerve (V) 1 Maxillary Incus, ant. lig of malleus palatoquadrate Meckel’s cartilage Muscles of mastication Tensor tympanis Digastric (anterior belly) Trigeminal nerve (V) 1 Mandibular Stapes, hyoid bone Reichert’s cartilage Muscles of facial expression, digastric (posterior belly), styloid Facial nerve (VII) 2 Hyoid Horns of hyoid Thyroid cartilage stylopharyngeas Glossopharyngeal nerve (IX) 3 Cricoid cartilage Striated muscles of oesophagus Laryngeal branches of vagus nerve (X) 4 and 6 Skeletal Derivative Muscle derivative Cranial Nerve Pharyngeal Arch
  16. 17. Cartilage derivatives of arches in 24 wk foetus
  17. 18. Hox segment identity genes are incompatible with facial skeleton Creuzet et al. (2002) Couly et al. 1993
  18. 19. Chicken head vessels are in two sectors
  19. 20. Vascular derivatives - tentative Right proximal pulmonary Left proximal pulmonary Ductus arteriosis 6th Right subclavian (R) Aorta (L) 4th Common and internal carotids 3rd Stapedial 2 nd hyoid Maxillary, mandibular 1 st mandibular Ophthalmic, ethmoid, ramus superior of stapedial 1 st maxillary (shared artery with mandibular) Veins? Arteries Pharyngeal arch
  20. 21. The “cardiac” neural crest is a subpopulation of the cephalic crest
  21. 22. Heart participation of NCC is necessary but transitory © K Sulik and coll.
  22. 23. Oculo-auriculo-vertebral spectrum <ul><li>a.k.a. First arch or Goldenhar syndrome, hemifacial microsomia – though can be bilateral </li></ul><ul><li>Malformation of jaws, ears and face </li></ul><ul><li>Experimentally induced by hemorrhage of 2 nd pharyngeal arch </li></ul><ul><li>Fortuitous genetic mouse model </li></ul><ul><li>Often overlaps with DiGeorge, VACTERL… </li></ul>
  23. 24. Goldenhar, First arch, hemifacial microsomia, oculo-auriculo-vertebral spectrum (MIM 164210) Axial 1-mm 3D FT-CISS MR image through temporal bones. Lemmerling et al., AJNR 2000. Universitätsklinikum Jena semi- circular canals (L) enlarged vestibular aqueduct (R)
  24. 25. Cardiovascular defects in DGS
  25. 26. Main points <ul><li>Pharyngeal arches are metameric structures </li></ul><ul><li>They each contain all germ layers, each of which contributes to distinct structures for each arch </li></ul><ul><li>Hox genes confer identity to differentiate them </li></ul><ul><ul><li>like for other metameric structures (eg. somites) </li></ul></ul><ul><ul><li>not with respect to the facial skeleton </li></ul></ul><ul><li>Arch, facial and heart development are linked </li></ul>
  26. 27. Save the trees! Save your memory! I will make this Powerpoint presentation available and downloadable as of next week on SlideShare. http://www.slideshare.net/Alethea Please comply with fair use (cf Wikipedia if you need to) as the images and photographs are copyrighted by their authors. I will correct any lacunae in attributions if you leave a comment.

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