Structural and functional relations between the connective tissue and epithelium of enamel organ and their role during enamel maturation

Abstract

The morphological and possible functional interactions between the connective tissue and enamel organ cells were examined during the maturation phase of enamel formation, using immunohistochemical techniques. Decalcified mandibular sections (10 µm) including incisors were used from Wistar rats ages 10–12 weeks. Sections were incubated with one or two primary antibodies targeting cell cytoskeleton (vimentin, α-actin, α-tubulin), dendritic marker (OX6), gap junctions (cx-43), enzymes (nitric-oxide synthase (nos1) and cyclooxygenase (cox1)), and the ion transporters (Na+/H+ exchanger (NHE1) and Na+/Ca2+ exchanger (NCX)) for 24 h, before incubation with the appropriate conjugated fluorescent secondary antibodies. Sections were examined by fluorescence microscopy. Haematoxylin–eosin slides were also employed. Cellular heterogeneity and morphological modulations were identified within enamel organ cells and connective tissue covering suggesting complex cellular interactions and indicating a new functional concept and possible complementary role during enamel maturation. Also, some ion transportation activity, and nos1 and cox1 signalling pathways have been identified, indicating intercellular communication between these regions. A hypothesis is suggested, to explain the morphological modulation of ameloblasts and papillary cells during enamel maturation which functions to increase the transporting membrane surface area to accomplish faster and bulker ion transportation to achieve controlled pH and to direct Ca2+ towards enamel.

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Acknowledgements

The authors would like to thank Dr. John M. Whitworth (Professor of Endodontology at the School of Dental Sciences/Newcastle University) for his support of this work and Mrs D.S. Jones for proofreading the final manuscript.

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No funding was received for conducting this study.

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All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by [Anas F. Mahdee], and [James I. Gillespie]. The first draft of the manuscript was written by [Anas F. Mahdee] and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.

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Correspondence to Anas F. Mahdee.

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The animal work was performed according to the schedule 1, UK Home Office guidelines, within the facilities of the Oral Biology Department in the Institute of Cellular Medicine, Newcastle University. All applicable international, national, and/or institutional guidelines for the care and use of animals were followed.

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Mahdee, A.F., Ali, A.H. & Gillespie, J.I. Structural and functional relations between the connective tissue and epithelium of enamel organ and their role during enamel maturation. J Mol Histol (2021). https://doi.org/10.1007/s10735-021-09992-y

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Keywords

  • Enamel organ
  • Enamel maturation
  • Interstitial cells
  • Ameloblast
  • Papillary layer
  • Connective tissue