Development of the facial prominences

1. Facial Prominences
ALWALEED ABUSHANAN, BDS
PEDIATRIC DENTAL RESIDENT
UNIVERSITY OF BRITISH COLUMBIA
BC CHILDREN’S HOSPITAL

2. Objectives:
 To present the sequence of developmental
events that take place during normal lip closure.
 Show an animation of facial prominences
coming together to form the lip.

3. The Formation of Facial Prominences
During the 4th week 5 swellings
appear and contribute the
formation of the face.
 Frontonasal prominence
 Medial Nasal Process
 2 Lateral Nasal Processes
 2 Maxillary prominences
 2 Mandibular prominences
Dixon et al. (2011) Nature Reviews Genetics 12, 167-178

4. Which part of the face forms
first ?
Which structures divide the
frontonasal mass?
Moore, Keith L., T.V.N. Persaud. The Developing Human: Clinically Oriented Embryology, 9th Edition. W.B. Saunders Company, 2013
Development of the
Facial Prominences
24 – 35 days

5. Facial Prominences
• Moore, Keith L., T.V.N. Persaud. The Developing Human: Clinically Oriented Embryology, 9th Edition. W.B. Saunders Company, 2013
Frontonasal Process
Mandibular Process
Maxillary Process
Lateral nasal prominence Medial nasal
Prominence
Nasal pits

6. Moore, Keith L., T.V.N. Persaud. The Developing Human: Clinically Oriented Embryology, 9th Edition. W.B. Saunders Company, 2013
Transformation into the face

7. Facial prominences fuse and merge to make the upper lip
fnp – frontonasal process, lnp – lateral nasal prominence, man – mandibular prominence, mnp – medial nasal
prominence
Hinrichsen K. 1985. The early develop- ment of morphology and patterns of the face in the human embryo. Adv Anat Embryol Cell Biol 98:1–79.

8. Facial prominences fuse and
merge to form the upper lip
Larson, WJ. Human Embryology

9. Formation of The Lip
https://www.youtube.com/watch?v=oz1kJexvEFE

10. Steps in the process of lip formation
 FUSION
1. Outgrowth and contact between facial prominences
2. Formation of a bilayered epithelial seam
3. Seam removal
4. Formation of a mesenchymal bridge
 MERGING
1. Proliferation of the mesenchyme to smooth out the grooves
(merging)
Cox, T. C., 2004. Taking it to the max: the genetic and developmental mechanisms coordinating midfacial morphogenesis and dysmorphology. Clin Genet. 65, 163-7

11. 2. Then a mesenchymal bridge1. First a bilayered epithelial seam
LNP
MNPMxp
Mxp
LNP
Steps in lip formation
Mesenchymal
bridge
• Images
from Dr.
Diewert

12. Looking at the inside of the mouth
• Moore, Keith L., T.V.N. Persaud. The Developing Human: Clinically Oriented Embryology, 9th Edition. W.B. Saunders Company, 2013
• Jiang, R., Bush, J. O., Lidral, A. C., 2006. Development of the upper lip: morphogenetic and molecular mechanisms. Dev Dyn. 235, 1152-66.
• The maxillary processes continue
to grow rapidly and push the
nasal pits and medial nasal
processes mesiofrontally
• The groove between the Medial
Nasal Process becomes
gradually shallow and eventually
smooth (merging) and becomes
the philtrum

13. Animal models to study lip fusion
We can study the
genes and
molecules that
control lip fusion in
mouse and
chicken because
the facial
prominences are
conserved in
evolution
Abramyan and Richman, 2015, Recent insights into the morphological diversity in the amniote primary and secondary palates. Dev Dyn. doi: 10.1002/dvdy.24338

14. References
 Abramyan and Richman, 2015, Recent insights into the
morphological diversity in the amniote primary and secondary
palates. Dev Dyn. doi: 10.1002/dvdy.24338
 Dixon et al. (2011) Nature Reviews Genetics 12, 167-178
 Moore, Keith L., T.V.N. Persaud. The Developing Human: Clinically
Oriented Embryology, 9th Edition. W.B. Saunders Company, 2013
 Cox, T. C., 2004. Taking it to the max: the genetic and
developmental mechanisms coordinating midfacial morphogenesis
and dysmorphology. Clin Genet. 65, 163-76.