Development of face
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The face develops from the third to eighth week of gestation as the pharyngeal arches, pouches and clefts form. The pharyngeal arches contribute mesenchymal tissue that gives rise to structures of the head and neck. Neural crest cells migrate into the arches and determine the skeletal structures that develop. Each arch is associated with a cranial nerve and blood vessel. Structures of the face, ears, tongue, larynx and thyroid develop from the differentiation and fusion of the pharyngeal arches and clefts.
![Development of face
The embryonic period extends from the beginning of the fourth week till
the end of the eighth week.
● The trilaminar embryonic area differentiates as follows:
1] ectoderm providing protection,
2] endoderm providing nutrition ,
3] mesoderm forming skeletal tissue ,muscle and blood vascular
system.
● The fourth week is characterized by the differentiation of the three
germ layers and the folding of the embryo.
● In the second month the organs and tissues are laid down and the
embryo has a distinct human appearance.](https://image.slidesharecdn.com/developmentofface-190208171816/85/Development-of-face-12-320.jpg)
Development of face
- 1. Development of Face Dr. Sudeep Madhusudan Chaudhari 1st year PG Department of Paedodontics & Preventive Dentistry
- 2. ● Introduction ● Fertilization ● Formation of germ layers ● Development of face – Pharyngeal arches, pouch & clefts ● Development of nose ● Development of lips ● Conclusion ● References Contents
- 3. The face is the anatomical feature which is truly unique to each human. The development of the face refers to the development of the structures from the third to eighth week that give rise to the future head and neck. The head and neck is not really a system, but structurally quit different in origin from the body. The head and neck are one of the most complicated structures that embryo forms, with special intermediate structures, contribution from all three germ layers and significantly, a major contribution from neural crest. Introduction
- 4. FERTILIZATION ● A process by which male and female gametes fuse ● Occurs in ampullary region of uterine tube
- 5. RESULTS OF FERTILIZATION ● Restoration of diploid number of chromosomes ● Initiation of cleavage ● Determination of sex in individual 44 + X + X44 + X + X 22 + X22 + X 22 + X22 + X FemaleFemale 22 + X22 + X 22 + Y22 + Y 44 +X + Y44 +X + Y spermspermovumovum MaleMale ovumovum spermsperm
- 6. Cleavage ● After fertilization – 2 cell stage – undergo series of division – called cleavage. Zygote – TWO CELL STAGE (30 hrs) 4 CELL STAGE (40 hrs) After 3 days of fertilization – 16 cell stage–MORULA
- 7. zona pellucida Outer cell mass Which give rise to trophoblast Small fluid passes into the morula from uterine cavity Partially separates the cells of inner & outer cell mass i.e. trophoblast Cells of trophoblast become flattened Inner cell mass comes to be attached to the inner side of the trophoblast on one side only Morula become cyst – so called as blastocyst & the cavity called as blastocoele Inner cell mass Which give rise to embryo proper. Therefore also called as embryoblast.
- 8. Zona pellucida disappears when the blastocyst reaches uterine lumen Implantation
- 9. Formation of germ layers Some cells from inner cell mass differentiates into flattened cells Forms endoderm (1st germ layer) Remaining cells of inner cell mass becomes columnar Forms ectoderm Space appears between ectoderm & trophoblast – amniotic cavity Endoderm spread inside the blastocoele – give rise to primary yolk sac Cells of trophoblasts proliferate & forms extra embryonic mesoderm
- 10. Some ectodermal cells proliferate & form a bulge into amniotic cavity – called as primitive streak These cells pushes themselves between ectoderm & endoderm Forms intraembryonic mesoderm Intraembryonic mesoderm spread throughout the disc except in the region of the prochondral plate Where ectoderm & endoderm – in contact This forms bucco-pharyngeal membrane
- 11. Applied anatomy Beginning of 3rd week: highly sensitive stage ● Holoprosencephaly (HPE) – is a cephalic disorder in which the prosencephalon (the forebrain of the embryo) fails to develop into two hemispheres. – high doses of alcohol – damage of cells in mid-line of germ disc or mutation in the gene encoding the Sonic Hedgehog protein (SHH). ● Sacrococcygeal Teratoma – persistence of remnants of primitive streak in saccrococcygeal region. – most common tumor present in newborn.
- 12. Development of face The embryonic period extends from the beginning of the fourth week till the end of the eighth week. ● The trilaminar embryonic area differentiates as follows: 1] ectoderm providing protection, 2] endoderm providing nutrition , 3] mesoderm forming skeletal tissue ,muscle and blood vascular system. ● The fourth week is characterized by the differentiation of the three germ layers and the folding of the embryo. ● In the second month the organs and tissues are laid down and the embryo has a distinct human appearance.
- 13. ● The most typical feature in the development of the head and neck is formed by the pharyngeal or branchial arches. ● These arches appear in the 4th and 5th week of development and contribute to the characteristic external appearance of the embryo. ● Initially there are bars of mesenchymal tissue separated by deep clefts known as pharyngeal or branchial clefts. ● With the development of the arches and clefts, a number of outpocketings arise, the pharyngeal pouches. ● Although the development of pharyngeal arches, clefts, and pouches resembles formation of gills in fish and amphibia, in the human embryo; real gills (branchia)are never formed. Therefore the term pharyngeal has been adapted.
- 14. ● When the embryo is 41⁄2 weeks old five mesenchymal prominenses can be recognised. ● The frontonasal prominence, a slightly rounded elevation cranial to the stomodeum. ● The maxillary prominences (dorsal portion of the 1st arch), lateral to the stomodeum. ● The mandibular prominences, caudal to the stomodeum. ● Development of face is later complemented by the formation of the nasal prominences. Mandibular prominences Frontonasal prominence Maxillary prominences Stomodeum
- 15. Pharyngeal arches ● 4 and 5 week IU life. ● Lateral plate mesoderm : Pharyngeal arches. ● Mesodermal core – augmented by neural crest tissue. ● Pharyngeal arches decreases in size – from cranial to caudal. ● Each pharyngeal arch is characterized by its own muscular components, their nerve component and it’s own arterial component.
- 16. Pharyngeal arches ● Each arch contain – a cartilaginous bar, an aortic arch and a cranial nerve. ● Each cranial nerve supplies the structures that develop from the arch. ● The mesenchyme of the arches is derived from paraxial mesoderm in the hindbrain region, lateral mesoderm, and neural crest cells from nearby midbrain and hindbrain regions. ● The cartilages and bones that develop in the arches mainly come from neural crest cells, while blood vessels, some connective tissue and laryngeal cartilages are from lateral mesoderm.
- 17. Pharyngeal arches ● Neural crest cells also contribute to the dermis of the skin in this region and to other connective tissue. Muscle develops from the paraxial mesoderm. ● Paraxial mesoderm from occipital somites also contributes to the laryngeal muscles of arches 4 and 6. However, these muscles are innervated by Xth cranial nerve and are considered branchiomeric muscles.
- 18. Pharyngeal arches ● Neural crest cells are also responsible for the specification of the arches and the different structures they make. These cells express homeobox (HOX) genes and other homeodomain transcription factors even before they migrate from the developing midbrain and hindbrain. ● Neural crest cell differentiation into the skeletal structures in the different arches is determined by homeobox (HOX) genes and other transcription factors as well as secreted growth factors such as fibroblast growth factor (FGF).
- 19. Pharyngeal arches ● Treacle ribosome biogenesis factor 1 (TCOF1) gene is involved in pharyngeal arch development. Its protein, Treacle, is expressed most intensely in the first pharyngeal arch during times of critical craniofacial development, including the formation and fusion of the pharyngeal arches with the rest of the face. Treacle is involved in ribosomal RNA production in prefusion neural folds during early embryogenesis.
- 20. Pharyngeal arches ● T-box transcription factor (TBX1) gene has a wide variety of functions. It regulates proper neural crest cell migration in the posterior pharyngeal arches, stabilizes the structural patterns of the middle and inner ear during their development, regulates the onset of the development of jaw and neck muscles, controls the proper patterning of cells in the jaw, supports proper proliferation of cells fated to become part of the cardiac outflow tract, and is required for the formation of the division between the aorta and the pulmonary artery.
- 21. II. HYOID ARCH REICHERT’S: (45-48 DAY IU) Stapes, partly – malleus, incus, styloid process, stylohyoid lig, lesser horn and cranial part of hyoid bone Cranial somitomere-6 Stapedius, stylohyoid, post. Belly of digastric Seventh cranial N – facial N Spec. sensory: chorda tympani – pretrematic for Iarch Stapedial A ECA PHARYNGEAL ARCH CARTILAGE MUSCULATURE NERVE ARTERY I MANDIBULAR ARCH MECKEL: (41 -45 day IU) ●Malleus ●Incus ●Anterior ligament of malleus ●Sphenomandi-bular ligament ●Cranial somitomere -4 ●Muscles of mastication ●Mylohyoid muscle ●Anterior belly of digastric ●Tensor tympani ●Tensor veli palatini ●Mandibular division of trigeminal nerve ●Maxillary artery ●External carotid artery II HYOID ARCH REICHERT’S:(45-48 DAY IU) ●Stapes, partly – malleus, incus ●Styloid process ●Stylohyoid ligament ●Lesser horn cranial part of hyoid bone ●Cranial somitomere-6 ●Stapedius ●Stylohyoid ●Posterior belly of digastric ●Seventh cranial nerve – facial nerve ●Special sensory: chorda tympani – pretrematic for I arch ●Stapedial artery ●External carotid artery
- 22. PHARYNGEAL ARCH CARTILAGE MUSCULATURE NERVE ARTERY III ARCH ●Greater cornu and caudal part of hyoid bone ●Cranial somitomere-7 ●Stylopharyngeus muscle ●Mucosa of posterior third of tongue ●IX- glossopharyng eal nerve ●Common carotid artery ●Part of internal carotid artery IV ARCH ●Thyroid cartilage ●Occipital somites-2 and 4 ●Cricothyroid ●Constrictors of pharynx ●Palatopharyngeus ●Levator veli palatini ●Muscles of soft palate ●Palatoglossus ●X(vagus) branch- superior laryngeal nerve ●Left side-arch of aorta ●Right side-Right subclavian and brachicephalic artery
- 23. VI ARCH ●Cricoid and arytenoid cartilage of larynx ●Occipital somites-1 and 2 ●Intrinsic muscles of larynx ●X (vagus N) branch- recurrent laryngealnerve ●Pulmonaryartery ●Ductus arteriosus of fetus – ligamentum arteriosum -V Pharyngeal arch : disappears soon as it forms -does not contribute to any permanent structural formations
- 24. PHARYNGEAL POUCH PHAR- YNGEAL POUCH STRUCTURES FORMED First Auditory tube Second Tonsillar fossa – palatine tonsil
- 25. Fifth Endoderm –ultimobronchial body Calcitonin secreting cells – parafollicular cells in thyroid gland Third Ventral diverticulum - endoderm proliferate and migrate on each side –thymus gland Dorsal diverticulum – inferior parathyroid gland Fourth Ventral diverticulum-Fate uncertain- thymus or thyroid tissue Dorsal diverticulum – superior parathyroid gland
- 26. PHARYNGEAL CLEFTS ● The first pharyngeal cleft enlarges to form the external auditory meatus. ● The ectoderm from the cleft, which is in close proximity to the first pharyngeal pouch, will contribute to the tympanic membrane as well. ● The second (hyoid) arch enlarges and grows inferiorly so that by the 6th week it overlaps the 3rd , 4th and 6th arches exteriorly and covers them.
- 27. ● As a consequence, the second arch also covers the openings of the 2nd , 3rd , & 4th pharyngeal clefts, which together form a remnant called the cervical sinus. The cervical sinus is gradually obliterated, but occasionally it will persist and can enlarge and form fluid-filled lateral cervical cysts. ● Sometimes the cervical sinus can fail to close externally, leaving a fistula open to the external surface. More rarely, the pharyngeal membrane can rupture internally, leaving the cervical remnant connected to the pharynx by a sinus. A fistula that runs entirely from the external to the internal surface is called a branchial fistula. PHARYNGEAL CLEFTS
- 28. ● The ectodermal covering of the 2nd arch contributes to the epithelium of the auricle and external auditory canal (meatus), and some of the epithelium behind the ear. Since the second arch is innervated by facial nerve, its derivatives are innervated by the VII nerve. PHARYNGEAL CLEFTS
- 29. ● The stomodeum (primitive mouth) forms primarily through the longitudinal folding of the early embryo as the buccopharyngeal membrane, and some of the ectoderm adjacent to it, comes to lie inside the oral cavity. The membrane, which will rupture, is located at the boundary of the first and second arches. Thus, the epithelium of the first arch inside the oral cavity is derived from ectoderm. This epithelium will also give rise to the parotid gland, enamel of the teeth, epithelium of the body of the tongue. Structures that develop from the first arch ectoderm are innervated by cranial nerve V. PHARYNGEAL CLEFTS
- 30. ● A portion of the pituitary gland also comes from ectoderm in the oral cavity. The pituitary gland consists of two parts, the anterior and posterior. During the fourth week, ectoderm in the roof of the oral cavity forms a diverticulum, Rathke's pouch, which will eventually become the anterior portion of the gland. The pouch continues to migrate toward the developing brain. As it does so, it makes contact with a diverticulum growing down from the floor of the forebrain called the infundibulum, which is destined to become the posterior pituitary. As the pouch moves up toward the brain, the thin stalk of tissue that connected it to the oral cavity involutes. PHARYNGEAL CLEFTS
- 31. PHARYNGEAL ARCH ANOMALIES • Branchial cysts ➢Second branchial arch fails to grow caudally over third and fourth arches. ➢Found on lateral aspect of neck – anterior to sternocleidomastoid muscle. • Branchial fistula ➢ Anomalies in the development of branchial clefts can lead to four unique but closely related lesions, cysts, external sinuses, internal sinuses and complete fistulas. Complete branchial fistulas are extremely uncommon with only very few reported cases in literature. ➢ Branchial fistulae are formed due to the abnormal persistence of the embryonic second branchial cleft. Branchial fistulae arising from second and third arches are common than from first and fourth arches. •
- 32. • Ectopic thymus - Cervical thymic anomalies may occur as a consequence of an arrest in descent during the 9th week of embryonic growth, a sequestration of thymic tissue during descent or a failure of involution. • Ectopic parathyroid tissue MRI coronal view demonstrating a right- sided, anteriorly-located 6 cm cervical mass, inferior to the parotid gland, intimately connected to the carotid sheath
- 33. First arch syndrome - congenital defects caused by a failure of neural crest cells to migrate into the first pharyngeal arch. -first arch syndromes include Treacher Collins syndrome and Pierre Robin syndrome ● Treacher Collins syndrome ➢ Malar hypoplasia ➢ Mandibular hypoplasia ➢ Slanting palpebral fissures ➢ Lower eyelid colobomas ➢ Malformed external ear ● Pierre Robin syndrome ➢ Micrognathia ➢ Cleft palate ➢ Glossoptosis Treacher Collins syndrome Pierre Robin syndrome
- 34. • Digeorge anomaly: ➢ Congenital absence of parathyroid glands and thymus ➢ Metabolic defects and immune disorders ➢ Spectrum of disorders: Thymic hypoplasia Abnormal facies Hypocalcemia Cleft palate Cardiac defects
- 35. Hemifacial Microsomia / Goldenhar Syndrome: -It is associated with anomalous development of the first branchial arch and second branchial arch. ➢ Anomalies involving: maxillary, temporal and zygotic bone – small and flat ➢ Microtia/anotia ➢ Dermoids in eyeball ➢ Spina bifida ➢ Cardiac defects
- 36. Eagle’s Syndrome ● Elongation of the styloid process or calcification of the stylohyoid ligament. ● Sharp, shooting pain in the jaw, back of the throat, base of the tongue, ears, neck and/or face ● Difficulty swallowing ● Sensation of having a foreign object in throat
- 37. Development of face ● The development of the face is dependent on the development of the nearby forebrain and the prechordal plate mesoderm. ● The prechordal plate, which originated from axial mesoderm migrating through the primitive node, acts as the organizer of face development. ● Growth factors, including sonic hedgehog (SHH) secreted by the prechordal plate, induce forebrain (prosencephalon) development and the eventual development of the right and left lobes. ● The forebrain, in turn, sends signals (also including SHH) back to the mesoderm to induce the growth of a prominence in the midline, the frontonasal prominence, which overhangs the cranial end of the oral cavity and develops at the end of the sixth week.
- 38. ● The homeobox-containing transcription factor MSX-1 is also important for face development and is expressed in the mesenchyme at the tips of the face primordia. ● In addition, retinoic acid (RA) is a secreted molecule related structurally to vitamin A that is heavily involved in the development of the lower part of the face and first arch structures. Retinoic acid (RA) binds to specific receptors within cells that regulate the transcription of a number of genes, including homeobox (HOX) genes. ● Retinoic acid (RA), if taken during pregnancy, increases the incidence of abnormalities in the head and neck region of the fetus, presumably by premature activation of retinoic acid (RA) signaling pathways.
- 39. • The development of the face occurs mainly between 5th – 8th weeks. • The lower jaw (mandible) is the first to form (4th week). • The facial proportions develop during the fetal period (9th week to birth). • During infancy & childhood, following the development of teeth and paranasal sinuses, the facial skeleton increases in size and contribute to the definitive shape of the face.
- 40. ● Face consists of a few primordial tissue masses partially surrounding the future oral region. ● The oral cavity (stomodeum) is an ectodermal depression separated from the foregut by the oral plate formed of ectoderm on one side and endoderm on the other. ● The face is dominated by the frontal prominence of the overhanging forebrain. ● Laterally, the maxillary processes of the 1st branchial arch are visible. 4 weeks 5 weeks 5.5 weeks 6 weeks 7 weeks 8 weeks
- 41. ● On either side of the frontal prominence are horseshoe-shaped elevations are found around the nasal placodes. a. Medial limbs are nasomedial processes b. Lateral limbs are nasolateral processes ● The maxillary processes growing toward midline, approaching mandibular arches and merging with them at the angle of the mouth. a. Maxillary processes grow to crowd the nasal processes closer together. b. Nasomedial processes grow quickly, pushing the frontal prominence, then fuse with the maxillary processes to complete the arch of the upper jaw. c. Nasomedial tissues give rise to philtrum of lip. 4 weeks 5 weeks 5.5 weeks 6 weeks 7 weeks 8 weeks
- 42. Development of Nose ● By the end of 4th week, bilateral oval- shaped ectodermal thickenings called ‘nasal placodes’ appear on each side of the lower part of the frontonasal prominence. ● Nasal placodes are primordia of the nose and nasal cavities. ● Mesenchymal cells proliferate at the margin of the placodes and produce horse-shoe shaped swellings around these. ● The sides of these swellings are called ‘medial’ and ‘lateral’ nasal prominences ● The placodes now lie in the floor of a depression called ‘nasal pits’.
- 43. ● Each lateral nasal prominence is separated from the maxillary swelling by nasolacrimal groove. ● Obstructed Duct - failure of duct to canalize; is opened surgically for tears to drain to nasal cavity. 6 weeks
- 44. ● By the end of 6 th week, nasal pits deepen and form nasal sacs. ● Initially the nasal sacs are separated from the oral cavity by oronasal membrane. ● The oronasal membrane ruptures by the 6 th week, communicating the primitive nasal cavities with the oral cavity.
- 45. ● These communications are called the primitive choana and are located posterior to the primary palate. ● After the development of the secondary palate, the choana change their position and become located at the junction of nasal cavity and the pharynx.
- 46. ● The nasal septum develops as a downgrowth from the internal parts of merged medial nasal prominences. ● Fuses with the palatine process in 9th -12th weeks, superior to the hard palate.
- 47. ● The superior, middle and inferior conchae develop on the lateral wall of each nasal cavity. ● The ectodermal epithelium in the roof of each nasal cavity becomes specialized as the olfactory epithelium.
- 48. ● The olfactory cells of the olfactory epithelium give origin to olfactory nerve fibers that grow into the olfactory bulb.
- 49. Development of lips ● Lower lip :The mandibular processes of the two sides grow towards each other and fuse in the midline, they form the lower margin of the stomatodeum. ● Upper lip :Each maxillary process grows medially and fuses, first with the lateral nasal process and the with the medial nasal process.
- 50. ● The mesodermal basis of the lateral part of the lip is formed from the maxillary process. ● The overlying skin is derived from the ectoderm covering this process. ● The mesodermal basis of the medial part of the lip(Philtrum) is formed from he frontonasal process. ● The muscles of the face (including those of the lips) are derived from the 2nd branchial arch and are supplied by the facial nerve.
- 51. Developmental Anomalies of Craniofacial Region ● Cleft lip and/or palate ● A congenital fissure in the roof of the mouth, resulting from incomplete fusion of the palate during embryonic development. ● Cleft lip - A congenital deformity characterized by a vertical cleft or pair of clefts in the upper lip, with or without involvement of the palate.
- 52. Nasal Deformities:- Losee et al (2004)- Type I - Hypoplasia and atrophy (represents paucity, atrophy, or underdevelopments of skin, subcutaneous tissue, muscle, cartilage, and/or bone) Type II - Hyperplasia and duplications (represents anomalies of excess tissue, ranging from duplications of parts to complete multiples) Type III - Clefts (The comprehensive and widely used Tessier classification of craniofacial clefts is applied.) Type IV - Neoplasms and vascular anomalies (Both benign and malignant neoplasms are found in this category.)
- 53. Apert Syndrome ● A genetic disorder characterizedby the premature fusion of certain skull bones(craniosynostosis). This early fusion prevents theskull from growing normally and affects the shape of the head and face. In addition, a varied numberof fingers and toes are fused together (syndactyly). ● Hearing loss ● Possible, slow intellectual development ● Prominent or bulging eyes ● Severe under-development of the mid-face ● Mandibular prognathism ● Narrow palate ● Crowding of the teeth
- 54. Conclusion The human face is a fascinating study of physiology and psychology. The amount of information a human face can relay is unending. Face is the mirror of one’s personality. It is our most useful and most underestimated tool for communication. Face is the most beautiful and attractive part of body which is most likely to develop malformations. So, the knowledge of normal development of face will aid in understanding the potential reasons for preventing or treating of anamolies.
- 55. References ● Singh I. Human embryology. 7th Edition, JP Medical Ltd; 2014 Sep 30. ● Frisdal A, Trainor PA. Development and evolution of the pharyngeal apparatus. Wiley Interdisciplinary Reviews: Developmental Biology. 2014 Nov;3(6):403-18. ● Som PM, Naidich TP. Illustrated review of the embryology and development of the facial region, part 1: early face and lateral nasal cavities. American Journal of Neuroradiology. 2013 Dec 1;34(12):2233-40. ● Dixon J, Jones NC, Sandell LL, Jayasinghe SM, Crane J, Rey JP, Dixon MJ, Trainor PA. Tcof1/Treacle is required for neural crest cell formation and proliferation deficiencies that cause craniofacial abnormalities. Proceedings of the National Academy of Sciences. 2006 Sep 5;103(36):13403-8. ● Passos‐Bueno MR, Ornelas CC, Fanganiello RD. Syndromes of the first and second pharyngeal arches: a review. American Journal of Medical Genetics Part A. 2009 Aug;149(8):1853-9. ● Trainor PA, Krumlauf R. Hox genes, neural crest cells and branchial arch patterning. Current opinion in cell biology. 2001 Dec 1;13(6):698-705.
- 56. Thank You