Development of face with diagrams
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development of the face embryology stages diagram
Let me pull the detailed content from "The Developing Human" (best embryology source) and the ENT textbook, plus search for facial development images with different terms.
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pharyngeal arches facial prominences frontonasal process embryo
Continuing to read the full section on face development.
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9780323611541_block*.md in /textbooks/9780323611541
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Excellent - found the key diagrams. Let me continue reading the section to get full content on nose, palate, and clinical correlations.
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I have solid content and diagram URLs. Let me finish with a bit more on the final fusion (upper lip, intermaxillary segment) and check for a quick recent evidence supplement.
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craniofacial development neural crest
Development of the Face
Facial development is one of embryology's most visually striking processes — occurring almost entirely between the 4th and 8th weeks of gestation, driven by growth and fusion of five primary facial prominences around the primitive mouth (stomodeum). Source: The Developing Human: Clinically Oriented Embryology (Moore, Persaud & Torchia).
1. The Five Facial Prominences (Week 4)
Early in the fourth week, the facial primordia appear as swellings around the stomodeum, driven by the inductive influence of the forebrain (via sonic hedgehog signaling), the frontonasal ectodermal zone, and the developing eye. Five prominences form:
- 1 frontonasal prominence — surrounds the forebrain; gives rise to the forehead and, later, the nose
- 2 maxillary prominences (paired) — form the lateral boundaries of the stomodeum
- 2 mandibular prominences (paired) — form the caudal boundary of the stomodeum
The maxillary and mandibular prominences are derivatives of the first pharyngeal arch, populated mainly by Hox-negative neural crest cells migrating from the midbrain and rostral hindbrain — these become the connective tissue, cartilage, bone, and ligaments of the face.
2. Nasal Placodes and Nasal Prominences (End of Week 4 - Week 5)
By the end of week 4, bilateral thickenings of surface ectoderm — the nasal placodes — develop on the inferolateral parts of the frontonasal prominence. Mesenchyme proliferation around each placode produces horseshoe-shaped elevations: the medial and lateral nasal prominences, with the placode itself sinking into a depression, the nasal pit (primordium of the nostril and nasal cavity).
- The lateral nasal prominences form the alae (sides) of the nose
- The medial nasal prominences will later form the nasal septum, philtrum, and premaxilla
Each lateral nasal prominence is separated from the maxillary prominence by the nasolacrimal groove — the future site of the nasolacrimal duct.
3. Growth and Merging of Prominences (Weeks 5-8)
As mesenchyme proliferates, the maxillary prominences enlarge and grow medially, pushing the medial nasal prominences toward the midline (regulated by PDGFRA signaling). By the end of the fifth week, auricular hillocks also appear, beginning ear development.
By the end of week 6: each maxillary prominence begins to merge with the lateral nasal prominence along the nasolacrimal groove, joining the side of the nose to the cheek.
Between weeks 7 and 10: the medial nasal prominences merge with each other and with the maxillary prominences. Fusion requires disintegration of contacting epithelia and intermingling of the underlying mesenchyme. This:
- establishes continuity of the upper jaw and lip
- separates the nasal pits from the stomodeum
As the medial nasal prominences fuse, they form the intermaxillary segment, which gives rise to:
- The philtrum (middle part of the upper lip)
- The premaxillary part of the maxilla and its gingiva
- The primary palate
(The upper lip itself is formed mainly by the maxillary prominences, with the philtrum from the intermaxillary segment.)
, the face has an unmistakably human appearance, though the eyes are still widely spaced and the ears are low-set — final facial proportions continue refining through the fetal period.
Timeline Summary
| Week | Event |
|---|---|
| 4 (early) | Five facial prominences appear around stomodeum: 1 frontonasal, 2 maxillary, 2 mandibular |
| 4 (late) | Nasal placodes form on frontonasal prominence -> medial & lateral nasal prominences + nasal pits |
| 5 | Maxillary prominences enlarge, grow medially; auricular hillocks appear |
| 6 | Maxillary prominence fuses with lateral nasal prominence (nasolacrimal groove closes) |
| 7-10 | Medial nasal prominences fuse with each other and maxillary prominences -> intermaxillary segment -> philtrum, premaxilla, primary palate |
| 8 (end) | Face has recognizably human appearance |
| Fetal period | Refinement of facial proportions (eyes converge, ears ascend) |
Clinical Note
Failure of the maxillary prominence to fuse with the medial nasal prominence results in unilateral or bilateral cleft lip; failure of the palatal shelves (from the maxillary prominences) to fuse in the midline, or with the primary palate, produces cleft palate. These are among the most common congenital craniofacial anomalies and directly reflect disruption of the fusion events described above.
All diagrams and micrographs above are from The Developing Human: Clinically Oriented Embryology (Moore, Persaud & Torchia), Fig. 9.25-9.32, pp. 511-523.
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