Tongue Development

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Contents

Introduction

Tongue position within the oral cavity.

The tongue's embryonic orgin is derived from all pharyngeal arches contributing different components. As the tongue ((Latin, lingua; Greek, glossa) develops "inside" the floor of the oral cavity, it is not readily visible in the external views of the embryonic (Carnegie) stages of development. Tongue muscle cells originate from somites, while muscles of mastication derive from the unsegmented somitomeres. This current page gives a brief overview of early tongue development.

The dorsal tongue is covered by a stratified squamous epithelium, with numerous papillae and taste buds. There are also 8 to 12 circumvallate papillae arranged in an inverted V-shape towards the base of the tongue. These notes cover development of the muscular tongue, not the sense of taste.


Taste Links: Introduction | Student project | Tongue Development | Category:Taste | Gastrointestinal Tract | Category:Tongue


Historic Embryology: 1902 Tongue | 1921 Tongue

Some Recent Findings

  • Noncanonical transforming growth factor β (TGFβ) signaling in cranial neural crest cells causes tongue muscle developmental defects[1] "Microglossia is a congenital birth defect in humans and adversely impacts quality of life. In vertebrates, tongue muscle derives from the cranial mesoderm, whereas tendons and connective tissues in the craniofacial region originate from cranial neural crest (CNC) cells....Thus, our data indicate that CNC-derived fibroblasts regulate the fate of mesoderm-derived myoblasts through TGFβ-mediated regulation of FGF and BMP signaling during tongue development."
  • Mice with TGFβ activated kinase 1 (Tak1) deficiency in neural crest lineage exhibit cleft palate associated with abnormal tongue development[2] "The repressive effect of the Tak1-mediated noncanonical TGFβ signaling on Fgf10 expression was further confirmed by inhibition of p38, a downstream kinase of Tak1, in the primary cell culture of developing tongue. Tak1 thus functions to regulate tongue development by controlling Fgf10 expression and could represent a candidate gene for mutation in human PRS clefting." Fibroblast Growth Factor
  • Bone morphogenetic protein-2 functions as a negative regulator in the differentiation of myoblasts, but not as an inducer for the formations of cartilage and bone in mouse embryonic tongue[3] "In vitro studies using the myogenic cell line C2C12 demonstrate that bone morphogenetic protein-2 (BMP-2) converts the developmental pathway of C2C12 from a myogenic cell lineage to an osteoblastic cell lineage. Further, in vivo studies using null mutation mice demonstrate that BMPs inhibit the specification of the developmental fate of myogenic progenitor cells. ...BMP-2 functions as a negative regulator for the final differentiation of tongue myoblasts, but not as an inducer for the formation of cartilage and bone in cultured tongue, probably because the genes related to myogenesis are in an activation mode, while the genes related to chondrogenesis and osteogenesis are in a silencing mode."
  • Shh and ROCK1 modulate the dynamic epithelial morphogenesis in circumvallate papilla development[4] "In rodents, a circumvallate papilla (CVP) develops with dynamic changes in epithelial morphogenesis during early tongue development. Molecular and cellular studies of CVP development revealed that there would be two different mechanisms in the apex and the trench wall forming regions with specific expression patterns of Wnt11 and Shh. ...Wnt, a well known key molecule to initiate taste papillae, would govern Rho activation and cytoskeleton formation in the apex epithelium of CVP. In contrast, Shh regulates the cell proliferation to differentiate taste buds and to invaginate the epithelium for development of von Ebner's gland (VEG)."

Pharyngeal Arch Contributions

The tongue has contributions from all pharyngeal arches which changes with time. The tongue initially begins as swelling rostral to foramen cecum, the median tongue bud.

Animation shows the sequence of development of the tongue. The different colours represents the relative contribution from each pharyngeal arch.

  • Arch 1 - oral part of tongue (anterior 3/2)
  • Arch 2 - initial contribution to surface is lost
  • Arch 3 - pharyngeal part of tongue (posterior 1/3)
  • Arch 4 - epiglottis and adjacent regions
Tongue.gif
Tongue 001 icon.jpg
 ‎‎Tongue
Page | Play

Week 4

Stage13 sem3.jpg Gray0979.jpg


Links: Carnegie stage 13 | Week 4

Week 8

The four images below are from the Carnegie Stage 22 human embryo during week 8 of development.

Stage 22 image 060.jpg Stage 22 image 061.jpg
Stage 22 image 062.jpg Stage 22 image 063.jpg
Links: Carnegie stage 22 | Week 8

Tongue Muscles

  • Tongue muscles originate from the somites.
    • Masticatory muscles (MM) originate from the somitomeres. These muscles develop late and are not complete even at birth.
  • Tongue muscles develop before masticatory muscles and complete by birth.

Developing muscle fibers within the tongue. Note the multinucleated appearance of each muscle fiber and their overall organization. Muscle goes through the same developmental changes as other skeletal muscle.

See also: Embryonic and postnatal development of masticatory and tongue muscles.[5]

Skeletal muscle histology 017.jpg Skeletal muscle histology 018.jpg


Links: Skeletal Muscle Histology

Tongue Innervation

The hypoglossal nerve (CN XII) provides the motor innervation of the intrinsic and extrinsic tongue muscles allowing protrusion, retrusion, and changes in the shape of the tongue. Motor units within the hypoglossal motor system can be categorized as predominantly fast fatigue resistant.[6]

The human tongue innervation has been recently analysed histologically and described as extremely dense and complex.[7] The structure of the motor endplate junctions (neuromuscular junctions) was found to be of the multiple en grappe (grapelike cluster) form. The transverse muscle group that comprises the core of the tongue was found to have the most complex innervation. The pattern of innervation of the human tongue also has specializations not found in other mammalian tongues, this allows for fine motor control of tongue shape.

The pathway of the hypoglossal nerve can be imaged using magnetic imaging (MRI) while computer tomography (CT) can show the bony anatomy of the neurovascular foramina of the skull base. Clinically, the nerve pathway can be divided into three regions: intra-axial, cisternal, skull base and extracranial segments.[8]

Lingual Frenulum

Inferior side of tongue with right side superficial dissection.

Frenulum is a general term for a small fold of integument (skin) or mucous membrane that limits the movements of an organ or part. There are several anatomical frenula associated with the genital system, while the lingual frenulum is associated with the inferior side of the tongue.

The lingual frenulum length (short) and position of insertion (anterior) can lead to speech disorders and may affect postnatal feeding.[9] Interestingly, it is the prevalence of pain in mothers breastfeeding infants with ankyloglossia that presents many problems in breastfeeding.[10]

Children with a frenulum length of more than 2 cm do not show these speech problems. Ankyloglossia (tongue-tie) is the general clinical term for the short frenulum which limits the range of movement of the tongue, there is still no accurate classification for this condition.[11] Frenotomy, frenectomy, and frenuloplasty are the main surgical treatment options to release or remove an ankyloglossia.

Histology

Abnormalities

Macroglossia

Macroglossia associated with congenital hypothyroidism.

Term means an abnormally large tongue. Macroglossia is more common than microglossia and can be associated with a number of genetic abnormalities including: trisomy 21 (Down syndrome), acromegaly, Beckwith-Wiedemann syndrome, mucopolysaccharidoses and primary amyloidosis. There is also an association with congenital hypothyroidism and diabetes.

Beckwith-Wiedemann syndrome macroglossia.jpg

Macroglossia associated with Beckwith-Wiedemann syndrome.

Links: Trisomy 21 | Medlineplus - Macroglossia

Microglossia

Term means an abnormally small tongue.

Ankyloglossia

Ankyloglossia (tongue-tie) is the general clinical term for the short lingual frenulum (less than 2 cm), that limits the range of movement of the tongue, prevalence ranges between 4.2% and 10.7%. This is associated with speech development disorders and has been suggested as also associated with feeding disorders. There is still no accurate classification for this condition.[11] Frenotomy, frenectomy, and frenuloplasty are the main surgical treatment options to release or remove an ankyloglossia, though there is still discussion about surgical intervention.

A short lingual frenulum is also associated with a number of genetic syndromes such as: ROR2-Related Robinow Syndrome, Dystrophic Epidermolysis Bullosa, Oral-Facial-Digital Syndrome Type I, Opitz Syndrome (X-Linked Opitz G/BBB Syndrome) and Van der Woude syndrome.


Links: Medline Plus - Tongue tie | ROR2-Related Robinow Syndrome | Dystrophic Epidermolysis Bullosa | Oral-Facial-Digital Syndrome Type I | X-Linked Opitz G/BBB Syndrome

Additional Images

Historic

Human Embryology and Morphology. Keith, A. (1902) London: Edward Arnold.

Anatomy of the Human Gray, H. (1918) Philadelphia: Lea & Febiger.

Text-Book of Embryology Bailey, F.R. and Miller, A.M. (1921). New York: William Wood and Co. - Tongue Development

References

  1. Jun-Ichi Iwata, Akiko Suzuki, Richard C Pelikan, Thach-Vu Ho, Yang Chai Non-canonical transforming growth factor beta (TGFb) signaling in cranial neural crest cells causes tongue muscle developmental defects. J. Biol. Chem.: 2013; PMID:23950180
  2. Zhongchen Song, Chao Liu, Junichi Iwata, Shuping Gu, Akiko Suzuki, Cheng Sun, Wei He, Rong Shu, Lu Li, Yang Chai, Yiping Chen Mice with Tak1-deficiency in neural crest lineage exhibit cleft palate associated with abnormal tongue development. J. Biol. Chem.: 2013; PMID:23460641
  3. Kayoko Aoyama, Akira Yamane, Takeo Suga, Erika Suzuki, Tadayoshi Fukui, Yoshiki Nakamura Bone morphogenetic protein-2 functions as a negative regulator in the differentiation of myoblasts, but not as an inducer for the formations of cartilage and bone in mouse embryonic tongue. BMC Dev. Biol.: 2011, 11();44 PMID:21736745
  4. Jae-Young Kim, Min-Jung Lee, Kyoung-Won Cho, Jong-Min Lee, Yeun-Jung Kim, Ji-Youn Kim, Hye-In Jung, Je-Yoel Cho, Sung-Won Cho, Han-Sung Jung Shh and ROCK1 modulate the dynamic epithelial morphogenesis in circumvallate papilla development. Dev. Biol.: 2009, 325(1);273-80 PMID:19014928
  5. A Yamane Embryonic and postnatal development of masticatory and tongue muscles. Cell Tissue Res.: 2005, 322(2);183-9 PMID:16041600
  6. J Chadwick Smith, Stephen J Goldberg, Mary Snyder Shall Phenotype and contractile properties of mammalian tongue muscles innervated by the hypoglossal nerve. Respir Physiol Neurobiol: 2005, 147(2-3);253-62 PMID:16087149
  7. Liancai Mu, Ira Sanders Human tongue neuroanatomy: Nerve supply and motor endplates. Clin Anat: 2010; PMID:20607833
  8. Pedro Alves Imaging the hypoglossal nerve. Eur J Radiol: 2010, 74(2);368-77 PMID:20347541
  9. Irene Queiroz Marchesan Lingual frenulum: classification and speech interference. Int J Orofacial Myology: 2004, 30();31-8 PMID:15832860
  10. Lauren M Segal, Randolph Stephenson, Martin Dawes, Perle Feldman Prevalence, diagnosis, and treatment of ankyloglossia: methodologic review. Can Fam Physician: 2007, 53(6);1027-33 PMID:17872781
  11. 11.0 11.1 Valérie G A Suter, Michael M Bornstein Ankyloglossia: facts and myths in diagnosis and treatment. J. Periodontol.: 2009, 80(8);1204-19 PMID:19656020

Articles

R Achiron, A Ben Arie, U Gabbay, S Mashiach, Z Rotstein, S Lipitz Development of the fetal tongue between 14 and 26 weeks of gestation: in utero ultrasonographic measurements. Ultrasound Obstet Gynecol: 1997, 9(1);39-41 PMID:9060129


Search PubMed

Search PubMed: Tongue Development | Macroglossia | Microglossia

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Cite this page: Hill, M.A. (2014) Embryology Tongue Development. Retrieved April 23, 2014, from http://embryology.med.unsw.edu.au/embryology/index.php?title=Tongue_Development

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Dr Mark Hill 2014, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G
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