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Hertwig's Epithelial Root Sheath Fate during Initial Cellular Cementogenesis in Rat Molars.

Yamamoto T, Yamada T, Yamamoto T, Hasegawa T, Hongo H, Oda K, Amizuka N - Acta Histochem Cytochem (2015)

Bottom Line: The advancing root end was divided into three sections, which follow three distinct stages of initial cellular cementogenesis: section 1, where the epithelial sheath is intact; section 2, where the epithelial sheath becomes fragmented; and section 3, where initial cellular cementogenesis begins.Dental follicle cells, precementoblasts, and cementoblasts showed immunoreactivity for vimentin and TNALP.Taken together, these findings suggest that: (1) epithelial sheath cells divide into two groups; one group is embedded in the cementum and thereafter dies by apoptosis, and the other survives on the cementum surface as epithelial cell rests of Malassez; and (2) epithelial sheath cells do not undergo epithelial-mesenchymal transition during initial cellular cementogenesis.

View Article: PubMed Central - PubMed

Affiliation: Department of Developmental Biology of Hard Tissue, Hokkaido University Graduate School of Dental Medicine , Sapporo, Japan.

ABSTRACT
To elucidate the fate of the epithelial root sheath during initial cellular cementogenesis, we examined developing maxillary first molars of rats by immunohistochemistry for keratin, vimentin, and tissue non-specific alkaline phosphatase (TNALP) and by TdT-mediated dUTP nick end labeling (TUNEL). The advancing root end was divided into three sections, which follow three distinct stages of initial cellular cementogenesis: section 1, where the epithelial sheath is intact; section 2, where the epithelial sheath becomes fragmented; and section 3, where initial cellular cementogenesis begins. After fragmentation of the epithelial sheath, many keratin-positive epithelial sheath cells were embedded in the rapidly growing cellular cementum. A few unembedded epithelial cells located on the cementum surface. Dental follicle cells, precementoblasts, and cementoblasts showed immunoreactivity for vimentin and TNALP. In all three sections, there were virtually no cells possessing double immunoreactivity for vimentin-keratin or TNALP-keratin and only embedded epithelial cells showed TUNEL reactivity. Taken together, these findings suggest that: (1) epithelial sheath cells divide into two groups; one group is embedded in the cementum and thereafter dies by apoptosis, and the other survives on the cementum surface as epithelial cell rests of Malassez; and (2) epithelial sheath cells do not undergo epithelial-mesenchymal transition during initial cellular cementogenesis.

No MeSH data available.


Related in: MedlinePlus

Sections stained for vimentin (A, C, E) and double stained for vimentin-keratin (B, D, F). (A) and (B), (C) and (D), and (E) and (F) pairs are the same section. Vimentin and keratin stain brown and purple, respectively. Bar=10 μm (common in A–F). (A and B) Section 1. Cells of dental follicle (DF) and dental papilla (DP) stain for vimentin only and epithelial root sheath (between arrows) stains for keratin only. (C and D) Sections 1 and 2 are partitioned by the dotted line. Precementoblasts (black arrows) stain for vimentin only and epithelial cells (white arrows) stain for keratin only. Asterisk indicates dentin. OB, odontoblast layer. (E and F) Cementoblasts (black arrows) stain for vimentin only. Cells incorporated in the cementum (double asterisk) stain for either vimentin (yellow arrow) or keratin (white arrows). From sections 1 to 3, no cells show double immunostaining.
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Figure 3: Sections stained for vimentin (A, C, E) and double stained for vimentin-keratin (B, D, F). (A) and (B), (C) and (D), and (E) and (F) pairs are the same section. Vimentin and keratin stain brown and purple, respectively. Bar=10 μm (common in A–F). (A and B) Section 1. Cells of dental follicle (DF) and dental papilla (DP) stain for vimentin only and epithelial root sheath (between arrows) stains for keratin only. (C and D) Sections 1 and 2 are partitioned by the dotted line. Precementoblasts (black arrows) stain for vimentin only and epithelial cells (white arrows) stain for keratin only. Asterisk indicates dentin. OB, odontoblast layer. (E and F) Cementoblasts (black arrows) stain for vimentin only. Cells incorporated in the cementum (double asterisk) stain for either vimentin (yellow arrow) or keratin (white arrows). From sections 1 to 3, no cells show double immunostaining.

Mentions: In section 1 (Fig. 3A, B), both dental follicle cells and dental papilla cells stained strongly for vimentin and neither cell type exhibited any keratin immunoreactivity. In contrast, the intact epithelial sheath was only immunoreactive for keratin. Precementoblasts in section 2 (Fig. 3C, D) and cementoblasts in section 3 (Fig. 3E, F) stained strongly for vimentin. Cells embedded in the cementum stained for either vimentin or keratin. In all three sections, no cells on or in the cementum were double immunoreactive for vimentin-keratin.


Hertwig's Epithelial Root Sheath Fate during Initial Cellular Cementogenesis in Rat Molars.

Yamamoto T, Yamada T, Yamamoto T, Hasegawa T, Hongo H, Oda K, Amizuka N - Acta Histochem Cytochem (2015)

Sections stained for vimentin (A, C, E) and double stained for vimentin-keratin (B, D, F). (A) and (B), (C) and (D), and (E) and (F) pairs are the same section. Vimentin and keratin stain brown and purple, respectively. Bar=10 μm (common in A–F). (A and B) Section 1. Cells of dental follicle (DF) and dental papilla (DP) stain for vimentin only and epithelial root sheath (between arrows) stains for keratin only. (C and D) Sections 1 and 2 are partitioned by the dotted line. Precementoblasts (black arrows) stain for vimentin only and epithelial cells (white arrows) stain for keratin only. Asterisk indicates dentin. OB, odontoblast layer. (E and F) Cementoblasts (black arrows) stain for vimentin only. Cells incorporated in the cementum (double asterisk) stain for either vimentin (yellow arrow) or keratin (white arrows). From sections 1 to 3, no cells show double immunostaining.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Figure 3: Sections stained for vimentin (A, C, E) and double stained for vimentin-keratin (B, D, F). (A) and (B), (C) and (D), and (E) and (F) pairs are the same section. Vimentin and keratin stain brown and purple, respectively. Bar=10 μm (common in A–F). (A and B) Section 1. Cells of dental follicle (DF) and dental papilla (DP) stain for vimentin only and epithelial root sheath (between arrows) stains for keratin only. (C and D) Sections 1 and 2 are partitioned by the dotted line. Precementoblasts (black arrows) stain for vimentin only and epithelial cells (white arrows) stain for keratin only. Asterisk indicates dentin. OB, odontoblast layer. (E and F) Cementoblasts (black arrows) stain for vimentin only. Cells incorporated in the cementum (double asterisk) stain for either vimentin (yellow arrow) or keratin (white arrows). From sections 1 to 3, no cells show double immunostaining.
Mentions: In section 1 (Fig. 3A, B), both dental follicle cells and dental papilla cells stained strongly for vimentin and neither cell type exhibited any keratin immunoreactivity. In contrast, the intact epithelial sheath was only immunoreactive for keratin. Precementoblasts in section 2 (Fig. 3C, D) and cementoblasts in section 3 (Fig. 3E, F) stained strongly for vimentin. Cells embedded in the cementum stained for either vimentin or keratin. In all three sections, no cells on or in the cementum were double immunoreactive for vimentin-keratin.

Bottom Line: The advancing root end was divided into three sections, which follow three distinct stages of initial cellular cementogenesis: section 1, where the epithelial sheath is intact; section 2, where the epithelial sheath becomes fragmented; and section 3, where initial cellular cementogenesis begins.Dental follicle cells, precementoblasts, and cementoblasts showed immunoreactivity for vimentin and TNALP.Taken together, these findings suggest that: (1) epithelial sheath cells divide into two groups; one group is embedded in the cementum and thereafter dies by apoptosis, and the other survives on the cementum surface as epithelial cell rests of Malassez; and (2) epithelial sheath cells do not undergo epithelial-mesenchymal transition during initial cellular cementogenesis.

View Article: PubMed Central - PubMed

Affiliation: Department of Developmental Biology of Hard Tissue, Hokkaido University Graduate School of Dental Medicine , Sapporo, Japan.

ABSTRACT
To elucidate the fate of the epithelial root sheath during initial cellular cementogenesis, we examined developing maxillary first molars of rats by immunohistochemistry for keratin, vimentin, and tissue non-specific alkaline phosphatase (TNALP) and by TdT-mediated dUTP nick end labeling (TUNEL). The advancing root end was divided into three sections, which follow three distinct stages of initial cellular cementogenesis: section 1, where the epithelial sheath is intact; section 2, where the epithelial sheath becomes fragmented; and section 3, where initial cellular cementogenesis begins. After fragmentation of the epithelial sheath, many keratin-positive epithelial sheath cells were embedded in the rapidly growing cellular cementum. A few unembedded epithelial cells located on the cementum surface. Dental follicle cells, precementoblasts, and cementoblasts showed immunoreactivity for vimentin and TNALP. In all three sections, there were virtually no cells possessing double immunoreactivity for vimentin-keratin or TNALP-keratin and only embedded epithelial cells showed TUNEL reactivity. Taken together, these findings suggest that: (1) epithelial sheath cells divide into two groups; one group is embedded in the cementum and thereafter dies by apoptosis, and the other survives on the cementum surface as epithelial cell rests of Malassez; and (2) epithelial sheath cells do not undergo epithelial-mesenchymal transition during initial cellular cementogenesis.

No MeSH data available.


Related in: MedlinePlus