In foetuses of 9 and 10 weeks the articular disc presents a more cellular structure
with bands of connective tissue fibres. It is connected with the articular
capsule and lateral pterygoid muscle. During weeks 11 and 12 there is an increase
in collagenous fibres and fusiform cells are located mainly close to the
surface of the disc

A, Wierusz

W, Woźniak

English

Via Medica Journals

Folia Morphol. Vol. 63, No. 2, pp. 185–188Copyright © 2004 Via MedicaISSN 0015–5659www.fm.viamedica.pl O R I G I N A L  A R T I C L E185Early foetal development of the articular discin the human temporomandibular jointAnna Wierusz, Witold WoźniakDepartment of Anatomy, University of Medical Sciences, Poznań, PolandVoivodship Stomatology Centre, Warszawa, Poland[Received 3 January 2004; Accepted 21 February 2004]In foetuses of 9 and 10 weeks the articular disc presents a more cellular struc-ture with bands of connective tissue fibres. It is connected with the articularcapsule and lateral pterygoid muscle. During weeks 11 and 12 there is an in-crease in collagenous fibres and fusiform cells are located mainly close to thesurface of the disc.Key words: human temporomandibular joint, foetal period,development, articular discAddress for correspondence: Prof. Witold Woźniak, Department of Anatomy, University of Medical Sciences, ul. Święcickiego 6,60–781 Poznań, Poland, tel: +48 61 869 91 81 ext. 564, fax: +48 61 865 89 85, e-mail: wwoźniak@usoms.poznan.plINTRODUCTIONThe temporomandibular joint, a distinctivelymammalian feature, consists of the mandibularcondyle, a part of the squamous portion of the tem-poral bone and an intermediate disc. The articulardisc is a fibrous plate that varies in thickness in itsdifferent parts and on the periphery is incorporatedinto the articular capsule, which divides the joint intotwo parts. The upper surface of the articular disc fitsthe articular tubercle and fossa, whereas its inferiorsurface is adapted to the mandibular head.The temporomandibular joint disc is composedof approximately 80% water and 20% fibrous, mainlycollagen, components [17]. Studies on the humandisc have been concerned with its macroscopic struc-ture [2, 5, 8, 15], microscopic and immunohistochem-ical structure [3, 6, 7, 10–12, 18, 19] and the reori-entation of discal fibres to accommodate the direc-tion of tensile stresses [1, 6, 16, 17].The central part of the disc is thinner as com-pared to its periphery. The posterior border is thethickest part and its thickness is correlated to theprominence of the articular eminence. Histologicalstudy shows that the anterior part of the disc is avas-cular and is composed of woven fibrous tissue,whereas the posterior part is of looser texture andmay be subdivided into an upper zone rich in elastictissue and a lower zone, which has many large bloodvessels [2].The variation in structure within the disc has im-portant functional implications. The structural organ-isation of the collagen fibres is thought to correspondto the mechanical function of the disc [6, 16].The foetal development of the disc in the tem-poromanidibular joint has been described in foetus-es from the 12th week onwards [4, 9, 13, 14, 20–22]with particular attention to the relationship of thedisc to the lateral pterygoid muscle.The aim of the present study was to investigatethe shape and histological structure of the articulardisc within the temporomandibular joint in humanfoetuses aged between 9 and 12 weeks.MATERIAL AND METHODSThe study was performed using 14 foetuses rang-ing from 9 to 12 weeks of age (Table 1, 2). All foet-uses were from the collection of the Department ofAnatomy at the University School of Medical Scienc-es in Poznań. 6 foetuses aged 9 to 12 weeks werefixed in 10% buffered formalin, decalcified in 10%186Folia Morphol., 2004, Vol. 63, No. 2EDTA, embedded in paraplast and serially sectionedat 5 µm thickness. In 8 foetuses the temporoman-dibular joint was dissected and the articular disc withthe articular surfaces were taken out, embedded inparaplast and serially sectioned. The sections werestained with haematoxylin and eosin with cresyl vio-let, according to the Mallory method, and impreg-nated with silver salts.In some embryos graphic reconstructions were made.RESULTSIn foetuses at 9 and 10 weeks the formation ofthe articular cavity of the temporomandibular jointcan be observed. Small spaces that are present be-tween the articular disc and the mandibular condylein foetuses aged 9 weeks coalesce during the 10thweek and the lower joint cavity is formed (Fig. 1). Atthis period of development the upper joint cavityappears in the form of discontinuous narrow spacesbetween the articular disc and the ossifying tempo-ral bone. Both joint cavities are seen to be well deve-loped in foetuses of 11 and 12 weeks (Fig. 2, 3).The articular disc in foetuses aged 9 and 10 weekshas a more cellular structure with an irregular ar-rangement of fibres. It is connected to the articularcapsule and the lateral pterygoid muscle (Fig. 1). Infoetuses at the 11th week the disc consists of fusi-form cells, which are located mainly on its surface,and densely arranged collagenous fibres (Fig. 2).During the 12th week the shape of disc changes andat this stage it consisted of a thinner central part anda thickened peripheral part (Fig. 3). During the inves-tigated period of development many blood vesselswere observed in the articular disc of the temporo-mandibular joint, particularly in its posterior part.DISCUSSIONIt is known that the disc blastema of the tem-poromandibular joint is formed at the end of thehuman embryonic period [9, 21].According to Furstman [4], the articular disc isformed between 12 and 14 weeks. At this time, aswas found in our study, the disc is well formed andcompletely separated from the articular surfaces. Italso becomes more fibrous in structure at the end ofthe 12th week.Thilander [19] noted that with the advancementof development there is a progressive decrease in cel-lularity and an increase in collagen in the disc. It isevident that the structural elements of the temporo-mandibular joint develop from different primordia andthat they are widely separated at the beginning.It is evident from the performed investigationsthat the critical period in the development of thearticular disc is between 9 and 12 weeks. During thisperiod the disc becomes a completely separatedstructure and changes in thickness in its central andperipheral parts.REFERENCES1. Berkovitz B (2000) Crimping of collagen in the intra-articular disc of the temporomandibular joint: a com-parative study. J Oral Rehab, 27: 608–613.2. Dixon A (1962) Structure and functional significance ofthe intra-articular disc of the human temporomandib-ular joint. Oral Surg Oral Med Oral Pathol, 15: 48–61.3. Fontenot MG (1985) Viscoelastic properties of human TMJdiscs and discreplacement materials. J Dent Res 6: 163.4. Furstman L (1963) The early development of the humantemporomandibular joint. Am J Orthod, 49: 672–682.5. Griffin CJ, Sharp CJ (1960) The structure of the adulthuman temporomandibular meniscus. Aust Dent J, 5:190–195.6. Griffin CJ, Sharp CJ (1962) Distribution of elastic tissue inthe human temporomandibular meniscus especially inrespect to “compression” areas. Aust Dent J, 7: 72–78.Table 1. Crown–rump length, sex, and age of foetuses inwhich the temporomandibular joint was dissected and re-moved for histological sections; f — female, m — maleNo. Crown-rump length in mm Sex Age in weeks1 34 f 92 38 m 93 55 f 104 60 m 105 65 m 116 75 f 117 77 f 128 79 f 12Table 2. Crown-rump length, sex, and age of foetuseswhich were embedded in toto and sectioned serially;f — female, m — maleNo. Crown-rump length in mm Sex Age in weeks1 33 f 92 40 m 93 49 f 104 68 m 115 75 f 116 80 f 12187Anna Wierusz et al., Human foetal TMJ discFigure 1. Transverse section of the temporomandibular joint in a foetus aged 10 weeks. Stained with haematoxylin and eosin. × 110;a — temporal articular surface, b — articular disc, c — articular capsule, d — lateral pterygoid muscle, e — head of mandible,f — inferior articular cavity.Figure 2. Sagittal section of the temporomandibular joint in a foetus aged 11 weeks. Stained with haematoxylin and eosin. × 110;a — superior articular cavity, b — articular disc, c — head of mandible, d — inferior articular cavity, e — temporal articular surface,f — zygomatic process.188Folia Morphol., 2004, Vol. 63, No. 27. Kopp S (1996) Topographical distribution of sulfated gly-cosaminoglycans in human temporomandibular jointdiscs. J Oral Pathol, 5: 265–276.8. Krogh-Poulsen W, Malhaven A (1957) Om discus ar-ticulationis temporo-manndibulans. Tanlaegebladet,61: 265–271.9. Merida-Velasco JR, Rodriguez-Vazguez JF, Merida-Ve-lasco JA, Sanchez-Montesinos I, Espin-Ferra J, Jimenez--Collado J (1999) Development of the human temporo-mandibular joint. Anat Rec, 255: 20–33.10. Mills DK, Fiandaca DJ, Scapino RP (1994) Morpholog-ic, microscopic, and immunohistochemical investiga-tions into the function of the primate TMJ disc. J Oro-fac Pain, 8: 136–154.11. Minarelli AM, Liberti EA (1997) A microscopic survey ofthe human temporomandibular joint disc. J Oral Rehab,24: 835–840.12. Minarelli AM, Del Santo M, Liberti E (1997) The structureof the human temporomandibular disc: a scanning elec-tron microscopy study. J Orofac Pain, 11: 95–100.13. Ogütcen-Toller M, Juniper RP (1993) The embryologicdevelopment of the human lateral pterygoid muscle andits relationships with the temporomandibular joint discand Meckel’s cartilage. Early Hum Dev, 39: 57–68.14. Ogütcen-Toller M, Juniper RP (1994) The developmentof the human lateral pterygoid muscle and the temporo-mandibular joint and related structures: a three dimen-sional approach. Early Hum Dev, 39: 57–68.15. Schwanalke C (1994) The relationship between temporo-mandibular joint capsule, articular disc, and jaw mus-cles. J Anat, 184: 335–345.16. Scapino RP, Mills DK (1983) Histopathology associatedwith malposition of the human temporomandibular jointdisc. Oral Surg Oral Med Oral Pathol, 55: 382–397.17. Sindelar B, Evanko S, Alonzo T, Herring S, Wight T (2000)Effects of intraoral splint wear on proteoglycans in thetemporomandibular joint disc. Arch Biochem Biophys,379: 64–70.18. Strauss F, Christen A, Weber (1960) The architecture ofthe disk of the human temporomandibular joint. HelvOdontol Acta, 4: 1–4.19. Thilander B (1964) The structure of the collagen of thetemporomandibular disc in man. Acta Odont Scand,22:157–163.20. Wong J, Weinberg S, Symington JM (1985) Morphol-ogy of the developing articular disc of the humantemporomadibular joint. J Oral Maxillofacial Surg, 43:565–569.21. Van der Liden EJ, Burdi A, de Jonge HJ (1987) Criticalperiods in the prenatal morphogenesis of the humanlateral pterygoid muscle, the mandibular condyle, thearticular disc, and medial articular capsule. Am J OrthodDentofacial Orthop, 91: 22–28.22. Yodelis  RA (1966) The morphogenesis of the humantemporomandibular joint and its associated structures.J Dent Res, 45: 182–191.Figure 3. Sagittal section of the temporomandibular joint in a foetus aged 12 weeks. Stained according to the Mallory method. × 110;a — temporal articular surface, b — head of mandible, c — inferior articular cavity, d — articular disc, e — superior articular cavity.

Early foetal development of the articular disc in the human temporomandibular joint

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Early foetal development of the articular disc in the human temporomandibular joint

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