development of face, nose and palate (special embryology)
TRANSCRIPT
DEVELOPMENT OF FACE, NOSE AND
PALATE(Page 65)
Dr. Sherif Fahmy
Development of Face• Face is developed from 5 processes (prominences):• One fronto-nasal process, 2 maxillary processes and
2 mandibular processes.• Maxillary process is a foreward growth of dorsal
end if 1st pharyngeal arch.• Mandibular process is a forward growth of ventral
end of 1st pharyngeal arch.• These processes surround stmodeum (primitive
nasal and oral cavities). Bucco-pharyngeal membrane will rupture to allow continuity between oral and pharyngeal cavities.
Bucco-pharyngeal membrane
Cloacal membrane
Cardiogenic area
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Forebrain bulge
Pericardial bulge
Stomodeum
Bucco-pharyngeal membrane
Pharynx
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Maxillary process
Mandibular process
2nd arch
Stomodeum
Forebrain bulge
Fronto-nasal process
Maxillary process
Mandibular process
Stomodeum
Pericardial bulge
Fronto-nasal process
Differentiation & Fusion
Fronto-nasal process
Maxillary process
Mandibular process
Pericardial bulge
Stomodeum
Fronto-nasal process
Maxillary process
Mandibular process
Stomodeum
Pericardial bulge
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Nasal placod
Stomodeum
Fronto-nasal process
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CleftMedial nasal prominence
Lateral nasal prominence
Nasal pit
Maxillary process
Developing eye
Fronto-nasal process
Mandibular process
Dr. Sherif Fahmy
Nasal pits
Cleft
Medial nasal prominence
Lateral nasal prominence
Maxillary process
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Cleft
Medial nasal prominence
Lateral nasal prominence
Maxillary process
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Intermaxillary segment
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Intermaxillary segment
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Medial nasal prominence
Lateral nasal prominenece
Anterior nasal opening
Maxillary process
Mandibular process
Fronto-nasal process
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Fronto-nasal Process• Nasal placode: rounded thickening in the
lower lateral parts of the fronto-nasal process.
• Nasal pits & prominences: invagination of placode will form nasal pits which are surrounded by medial & lateral nasal prominences (folds).
• Intermaxillary segment: from fused medial nasal prominences . It forms intermaxillary segments that form middle part of nose, filtrum, part of upper jaw that carries upper 4 incisors and primary palate.
Maxillary Process• It is separated from side of fronto-nasal
process by naso-lacrimal groove, inside which a cord of ectodermal cells is formed then becomes canalized to form naso-lacrimal duct. Its upper end forms lacrimal sac.
• Maxillary process fuses with fronto-nasal process covering naso-lacrimal duct.
• It forms lower boundary of nasal pit.• It is separated from other maxillary
process by intermaxillary segment.
-It also fuses partially with mandibular process to form the cheek.-Palatine process is formed as inward projection of maxillary process to form secondary palate which divides stomodeum into upper nasal and lower oral cavity.So maxillary process forms upper part of cheek, upper lip except filtrum, upper jaw except part that carries upper incisors and most of hard palate.
Mandibular Process• It forms lower part of cheek, whole lower lip
and lower jaw and floor of mouth.• Development of palate:• 1- Primary palate: from intermaxillary
segment of fronto-nasal process.• 2- Secondary palate: from palatine shelves of
maxillary processes that form most of hard palate and soft palate.
• -Hard palate receives downward growth of nasal septum.
Preimitive maxilla
Secondary maxilla
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Palatine shelves
Nasal septum
Coronal Section
Primitive palate
Palatine shelves
Primary palate
Secondary palate
Medial nasal prominence
Lateral nasal prominenece
Anterior nasal opening
Maxillary process
Palatine process of maxilla (hard palate)
Mandibular process
Fronto-nasal process
Congenital Anomalies of Face & Palate• 1- Dermoid cyst: cystic swelling at line of fusions between
processes of the face.• 2- Oblique facial cleft: failure of fusion between maxillary
and fronto-nasal processes.• 2- Macrostomia or Microstomia : defective or marked
fusion between maxillary and mandibular processes.• 3- Cleft (hare) lip: cleft lip due to failure of fusion between
maxillary process and intermaxillary segment.• 4- Cleft palate: failure of fusion between different parts
that form palate. It could be:– A- Unilateral complete cleft palate.– B- Bilateral complete cleft palate.– C- Partial cleft palate.– D- Cleft uvula.
Dermoid cyst
Dr. Sherif Fahmy
Oblique facial celft
Bilateral cleft lip
MicrostomiaDr. Sherif Fahmy
Macrostomia
Unilateral cleft lip
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Unilateral complete cleft palate
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Bilateral complete cleft palate
Nasal septum
Partial (median) cleft palate
Unilateral partial cleft palate
Hare lip
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Development of Mouth & Salivary glands• Mouth: It is developed from lower part of
stomodeum (below developed hard palate) and anterior part of foregut. Line of demarcation lies behind the gum.
• Salivary glands:– Parotid: from ectodermal outgrowth of buccal
mucosa. Its dorsal part gives several buds to form acini of the gland. Its ventral part is canalized to form the duct.
– Submandibular & sublingual: developed from endodermal buds from floor of mouth.