Three-dimensional structure of Tomes' processes and enamel prism formation in the kitten.

Wakita, Minoru; Gunji, Takahide; Kobayashi, Shígeo

doi:10.1679/aohc1950.44.285

Cited by 24 publications

(15 citation statements)

References 16 publications

(24 reference statements)

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“…Many investigations have examined the three-dimensional features and arrangement patterns of Tomes' processes (Skobe, 1976(Skobe, , 1977Wakita et al, 1981), Tomes' process pits on the developing enamel surface (Boyde, 1964(Boyde, ,1969Warshawsky et al,1981;Nishikawa, 1992), or resin replicas of Tomes' process pits corresponding to the structure of Tomes' processes (Kindaichi et al, 1981;Ohara et al, 1990) by scanning electron microscopy. These studies reported that the direction and arrangement of the secretory faces of Tomes' processes shifted periodically and clamed that ameloblasts could be characterised as those with Tomes' processes having secretory faces inclined in the same direction (Boyde, 1964(Boyde, , 1969Kindaichi et al,1981;Wakita et al,1981). However, the microscopic images of Tomes' processes and their related structures in these studies were often unclear, most probably due to mechanical damage during preparation.…”

Section: Light Microscopymentioning

confidence: 99%

“…The enamel prism sheath represents a fossilized path traced by the Tomes' processes during enamel secretion (Boyde,1967), and the secretory face of Tomes' process is at right angles to the longitudinal axis of prisms (Boyde, 1967(Boyde, ,1969Wakita et al, 1981;Hanaizumi et al, 1994). Considering this, the direction of enamel prisms here was estimated from the inclination of the top of the crosscut images of prisms sheaths; and the prisms oriented to the right were colored blue, and prisms oriented to the left were colored green (Fig.…”

Section: Three-dimensional Reconstructionmentioning

confidence: 99%

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The initial process of enamel prism arrangement and its relation to the Hunter-Schreger bands in dog teeth

Hanaizumi

Yokota

Domon

et al. 2010

Archives of Histology and Cytology

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belt-like zones, corresponding to the parazone or the diazone of the Hunter-Schreger bands.Reversed images of scanning electron-micrographs of the exposed surfaces of the developing enamel revealed round and bulb-like profiles of Tomes' processes at early amelogenesis and its changes into a characteristic structure combined with flat secretory and enclosing nonsecretory faces that dictated the orientation of corresponding enamel prisms.The results suggest that the groups of enamel prisms oriented in sideward directions first appear as small island-like specks near the enamel-dentin junction, which later merge and form alternating horizontal belt-like zones as a consequence of morphological changes of the Tomes' processes. However, the mechanisms whereby the functional grouping of secretory ameloblasts with similarly oriented Tomes' processes is induced are yet to be determined.

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Section: Light Microscopymentioning

confidence: 99%

Section: Three-dimensional Reconstructionmentioning

confidence: 99%

The initial process of enamel prism arrangement and its relation to the Hunter-Schreger bands in dog teeth

Hanaizumi

Yokota

Domon

et al. 2010

Archives of Histology and Cytology

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“…That crystals tend to orient themselves perpendicular to the secretory surface of the Tomes' process has been a useful theory for understanding the organization of crystals in the enamel of humans and other mammals [30][31][32]. The situation in rat enamel clearly does not conform to this theory [9], which casts doubt on its validity.…”

Section: Discussionmentioning

confidence: 99%

TEM Observations on the Ameloblast/Enamel Interface in the Rat Incisor

Risnes

Septier

Periere

et al. 2002

Connective Tissue Research

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The structure of rat incisor enamel is established at the topographically complex interface between secretory ameloblasts and forming enamel. The aim of this study was to gain additional information on this interface by sectioning parallel with the rows and the long axis of Tomes' processes and prisms. Rats were sacrificed and fixed by glutaraldehyde/paraformaldehyde perfusion. After dissection, demineralization and embedding transverse jaw/incisor segments were cut, reembedded, and reoriented. Sections were prepared for and observed in the transmission electron microscopy (TEM). The intraenamel part of Tomes' process was about 18 microns long. The forming prism occupied a longitudinally grooved invagination on its apical aspect. The parts of Tomes' process forming the side walls of the groove were attenuated and showed variation in extent and outline. Prism growth occurred over the whole grooved area. An estimation of Tomes' process secretory area in rat compared with data from humans suggests that there may be a relationship between secretory area and rate of prism formation. Prism crystals were oriented obliquely or parallel to the secretory surface of Tomes' process. At interprism growth sites matrix deposition was irregular and required some redistribution to conform to the pattern of interprism sheets.

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“…Boyde (1964Boyde ( ,1976 has proposed a hypothesis for the formation of the varicosities of prisms, which would also be applicable to the formation of the staircasetype Retzius lines; due to a diminished rate of matrix production and ameloblast movement, growth of enamel at the pit wall is enhanced, resulting in an increase in the interprism at the expense of the prisms. However, it has recently been appreciated that the aspect of the Tomes' process facing the pit wall is nonsecretory (Kallenbach, 1977;Skobe et al, 1981;Wakita et al, 1981;Warshawsky et al, 1981;Sasaki and Higashi, 1983;Nanci and Warshawsky, 1984). This indicates that the overgrowth of interprism associated with the staircase-type Retzius lines is related to a n increase in the interprismatic growth region as the Tomes' process is constricted.…”

Section: Discussionmentioning

confidence: 99%

Structural characteristics of staircase‐type retzius lines in human dental enamel analyzed by scanning electron microscopy

Risnes

1990

Anat. Rec.

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Based on a scanning electron microscopic (SEM) analysis of adjoining, acid-etched planes cut through human cervical enamel, the structural characteristics of staircase-type Retzius lines have been clarified. Structural features associated with this type of Retzius lines--such as cleftlike defects, decreased dimension of prisms, increased interprism, club-shaped appearance of prisms, oblique ridges, and triangular regions--have been incorporated into a unifying, three-dimensional model. A continuous discontinuity defect, involving both prisms and interprism, is a prominent feature of this type of Retzius lines. Prisms and interprism facing the deep aspect of the cleftlike defect show an enlarged, flat surface that encroaches on the cervically situated prisms being rebuilt from the same cleft. The initial part of a prism taking off from the cleft is of distorted shape. As the prism reaches the level of the interprism cleft, it abruptly regains its normal size and shape. The relationship between this type of Retzius lines and the carious process is discussed, and it is suggested that the discontinuity defect may retard the carious lesion due to a protective effect of its supposed organic content. The developmental events creating staircase-type Retzius lines are discussed, and it is suggested that Tomes' processes are constricted near their bases with a corresponding increase in interprismatic growth region. Tomes' processes will have to reshape plastically as they move out of the constricted pits, trailing the parent ameloblasts as they resume enamel production and move in the direction of the prisms.

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Three-dimensional structure of Tomes' processes and enamel prism formation in the kitten.

Cited by 24 publications

References 16 publications

The initial process of enamel prism arrangement and its relation to the Hunter-Schreger bands in dog teeth

The initial process of enamel prism arrangement and its relation to the Hunter-Schreger bands in dog teeth

TEM Observations on the Ameloblast/Enamel Interface in the Rat Incisor

Structural characteristics of staircase‐type retzius lines in human dental enamel analyzed by scanning electron microscopy

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