Neural Crest Cell / orthodontic courses by Indian dental academy

NEURAL CREST CELL & DEVELOPMENT OF SOFT

TISSUE OF FACE INDIAN DENTAL ACADEMY

Leader in continuing dental education www.indiandentalacademy.com

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Embryogenesis is divided into three

phases• Pre implantation period (first 7 days)

• Embryonic period (next 7 weeks)

• Fetal period (3 – 9 months)


Neural crest cells

Neural plate

Notochord

Primitive streak

Ectodermal cells

Germ layers

Morula

zygote


Embryology– first week


Second week

Bilaminar embryonic disc

Epiblast / ectoderm2nd germ layerEmbryo resembles disc


Second week

Heusers membranewww.indiandentalacademy.com

Second week• FORMATION OF PROCHORDAL PLATE

Bilaminar discHypoblast cells- columnarIndicates the future site of mouthCranial region of embryo


3rd week

Rapid developmentPrimitive streak formation3rd germ layer formationNotochordTrilaminar embryo


3rd week

Prochordal plateHead regionHypoblast

Primitive streak Tail regionEpiblast


Formation of notochord

• Primitive streak• Primitive knot• Canalization of cord cells


Primitive streak and node


Migration of cells b/w hypoblast and epiblast




3rd week – Notochord

Notochord is the structure around which the vertebral column forms

Developing notochord induces the overlying ectoderm to form neural plate


Neurulation

• End of 3 week• Formation of neural tube and neural plate


Formation of neural tube


Neurulation


Neurulation


Neural crest cells• Ectomesenchymal in nature

• Major source of connective tissue components, including cartilage, bone and ligaments of facial and oral region

• Contribute to muscles and arteries of this region


• Ectomesenchymal tissue termed neural crest cells appears in the intermediate zone between the surface ectoderm and the neural tube during neurulation.



Migraton is so excessive & their role is so imp Considered as fourth primary germ layerwww.indiandentalacademy.com

Source and pattern of migration to the developing

face and branchial arch system

As they migrate from rhombomeres ,carry with them homeobox geneFrom the site.


Characteristics of neural crest cells.

Pluripotent cells Migration Cyto-differentiation


Neural crest cells

Derivatives

Connective tissue Muscles Nervous tissues

Sensory ganglia

ANS

Pigment cells Endocrine tissues


Derivatives of neural crest cells.

Connective tissue-

- Ectomesenchyme of facial prominences and branchial arches

- Bones and cartilages of facial visceral skeleton


annotated_embryo.mov


-Dermis of face and neck -Stroma of salivary ,thymus thyroid,parathyroid and

pituitary gland -Corneal mesenchyme -Aortic arch arteries


-Dental papilla

-Portions of periodontal ligament ,Cementum

Muscle tissue-

-Ciliary muscles

-Covering connective tissue of branchial arch

muscles


Nervous tissue- -Leptomeninges. -Schwann sheath cells


Endocrine tissues

• Adrenomedullary cells

• carotid body


Pigment cells

• Melanocytes in all tissues

• Melanophores of iris


Neural crest cells

Derivatives

Connective tissue Muscles Nervous tissues

Sensory ganglia

ANS

Pigment cells Endocrine tissues


Sensory ganglia- -Autonomic ganglia. -Spinal dorsal root ganglia. -Sensory ganglia.

ANS- -Sympathetic ganglia. -Parasympathetic ganglia.


Factors affecting migration

• Extra cellular molecules: like fibronectin

• Vitamin A,isotretinoin

• 13 cis-retinoic acid

• Mutant geneswww.indiandentalacademy.com

Factors effecting the normal growth of neural

crest derivatives

• Number of cells leaving the neural tube

• Rate of migration• Proportion of dividing• Minimal period between successive divisions

• Number of cells that diewww.indiandentalacademy.com

Characteristics of neural crest cells

• Regulation


Significance of neural crest cells

• In craniofacial region

Differentiate to form most of the connective tissue of head - ectomesenchyme


Significance in development of dentition

• Neural crest is primary material for odontogenesis.

• Interaction between neural crest, pharyngeal endoderm and oral ectoderm produces the dental lamina.

• Neural crest provides material for dentin, pulp and cementum.


Altered Neural Crest Development

• Mandibulofacial Dysostosis


• Hemifacial Microsomia


•Fetal alcohol syndrome

• Due to deficiences of midline tissues of the neural plate ,caused by very high level of ethanol.


Branchial arches or pharyngeal arches



Each pair of branchial arches contain a basic set of structure

• Cartilage component• Muscular component• Vascular component• Nervous component


Branchial arches• Develops due to neural crest migration in the 4th week

• Mesenchyme of each branchial arch gives rise to muscles, cartilages and bone


First branchial arch(mandibular arch)


1st branchial arch

MANDIBULAR ARCH

Muscles

Skeletal structures

Ligaments Cartilage

Nerve


COMPONENTS OF 1st ARCH

• Cartilage : MECKEL’S CARTILAGE --Arises 41st – 45th Day I.U --It provides a template for subsequent development of the mandible.


Structures formed by cartilaginous component





Nerve supply


2nd branchial arch

HYOID ARCH

Muscles

Skeletal structures

Ligaments Cartilage

Nerve


Second branchial arch (Hyoid Arch) Components:

• Cartilage : Reichert’s Cartilage (45th – 48th I.U) -- Stapes -- Styloid process of the temporal bone. _ _Stylohyoid ligament. -- Lessor horn of sphenoid. -- Cranial part - Body of Hyoid.



• Muscles :

-- Stapedius -- Stylohyoid -- Post. Belly of Digastric -- auricular -- muscles of facial expression

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• Nerve : -- Facial / VII Cranial nerve.

-- Chorda tympani nerve (Ant 2/3rd of Tongue) Artery : -- Stapedial artery -- Transient i.e. disappears during fetal life


Nerve supply


3rd branchial arch

3rd Arch

9th CN Stylopharyngeous

Greater cornu of hyoidLower part of body of hyoid


4th & 6th branchial arch

4TH & 6TH Arch

Sup. Laryngeal NRec. Laryngeal N

ThyroidCricoidArytenoidCorniculateCunieform

cricothyroidconstrictors of pharynxLaryngeal muscles


Ectodermal clefts

Epi. Lining of ext. acoustic meatusAuricle


Ectodermal clefts

Branchial cyst Branchial sinus


Endodermal pouches



Branchial arch malformations• Branchial cyst

• Branchial sinus

• Branchial fistula


Thanxwww.indiandentalacademy.com

Development of Tongue


Tongue


Tongue



Tongue Papillae and taste buds

• End of 8th week – vallate & foliate( 9th CN)????

Relation to terminal branches OF 9th CN


Tongue• Fungiform papillae – develop near termination of chorda

tympani Filiform

• Appear in early fetal life• No taste buds• Sensitive to touch


Tongue

Nerve supply

Lingual N Chorda tympani

Glossopharyngeal N

Vagus N


Tongue Important points

• 2nd branchial arch does not contribute to tongue formation Chorda tympani supplies fungiform papillae????


Tongue


Tongue


Tongue

Lymphatic drainagewww.indiandentalacademy.com

Tongue


Clinical correlation

• Tongue tie• Macroglossia• Microglossia• Bifid tongue• Fissured tongue• Rhomboid tongue


Malformations of tongue

Ankyloglossia



Fissured tongue



Bifid tongue



Median rhomboid glossitis



Macroglossia



Hypertrophy of papillae


Development of the face


• Face is derived from the following structures that lie around the stomatodaeum:

• Frontonasal process• First pharyngeal arch


Facial prominences






Upper lip maxillary process with medial & lateral nasal process

Frontonasal process becomes narrow

Lower lip and jaw Mand. Prominences


Nose medial & lateral nasal process (rt & lt)

Eye lens placode


• Dev. Of the face starts at the end of 4 week





Facial Malformations








References

• The Developing Human - Keith L Moore• Craniofacial Embryology - G.H.Sperber

• Human Embryology - I.B.Singh• Color Atlas of Oral Path - Robinson, Miller


Thank you

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Documents

Neural Crest Cell / orthodontic courses by Indian dental academy