Limits...
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: 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.

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 TNALP (A, B, C) and double stained for TNALP-keratin (D). (C) and (D) are the same section. TNALP and keratin stain brown and purple, respectively. (A) Two dotted lines demarcate sections 1 to 3. In section 1, the dental follicle (DF), particularly in the alveolar bone (AB)-related zone, stains intensely for TNALP. The intact epithelial sheath (arrow) shows no immunoreactivity. In section 2, the intense immunoreactivity extends to the root-related side. Asterisk indicates dentin. DP, dental papilla; OB, odontoblast layer. Bar=40 μm (common in A, B). (B) Section 3. The entire periodontal ligament (PL) shows immunoreactivity for TNALP. Double asterisk indicates cellular cementum. (C and D) Magnification of sections 1 and 2 partitioned by the dotted line. Keratin-positive epithelial cells (white asterisks) show no or only negligible immunoreactivity for TNALP. Dental follicle cells and precementoblasts (black asterisks) show TNALP immunoreactivity on the cell surface (black arrows) and do not show any immunoreactivity for keratin. D, dentin. Bars=10 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection


getmorefigures.php?uid=PMC4491499&req=5

Figure 4: Sections stained for TNALP (A, B, C) and double stained for TNALP-keratin (D). (C) and (D) are the same section. TNALP and keratin stain brown and purple, respectively. (A) Two dotted lines demarcate sections 1 to 3. In section 1, the dental follicle (DF), particularly in the alveolar bone (AB)-related zone, stains intensely for TNALP. The intact epithelial sheath (arrow) shows no immunoreactivity. In section 2, the intense immunoreactivity extends to the root-related side. Asterisk indicates dentin. DP, dental papilla; OB, odontoblast layer. Bar=40 μm (common in A, B). (B) Section 3. The entire periodontal ligament (PL) shows immunoreactivity for TNALP. Double asterisk indicates cellular cementum. (C and D) Magnification of sections 1 and 2 partitioned by the dotted line. Keratin-positive epithelial cells (white asterisks) show no or only negligible immunoreactivity for TNALP. Dental follicle cells and precementoblasts (black asterisks) show TNALP immunoreactivity on the cell surface (black arrows) and do not show any immunoreactivity for keratin. D, dentin. Bars=10 μm.

Mentions: In section 1 (Fig. 4A), the intact epithelial root sheath was negative or only negligibly stained for TNALP. In contrast, the dental follicle, particularly in the alveolar bone-related zone, was stained strongly. In section 2 (Fig. 4A), the intense TNALP immunoreactivity extended towards the root-related side, and in section 3 (Fig. 4B), the entire periodontal ligament, including cementoblasts, exhibited intense TNALP immunoreactivity, whereas cementocytes were negative. At high magnification of section 2 (Fig. 4C, D), dental follicle cells and precementoblasts showed TNALP immunoreactivity on the cell surfaces, and none of these cells were stained for keratin. Keratin-positive epithelial cells showed no or only negligible immunoreactivity for TNALP. Hence, cells possessing double-immunoreactivity for TNALP-keratin were virtually absent. In section 3, TNALP-positive cementoblasts did not show immunoreactivity for keratin (data not shown).


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 TNALP (A, B, C) and double stained for TNALP-keratin (D). (C) and (D) are the same section. TNALP and keratin stain brown and purple, respectively. (A) Two dotted lines demarcate sections 1 to 3. In section 1, the dental follicle (DF), particularly in the alveolar bone (AB)-related zone, stains intensely for TNALP. The intact epithelial sheath (arrow) shows no immunoreactivity. In section 2, the intense immunoreactivity extends to the root-related side. Asterisk indicates dentin. DP, dental papilla; OB, odontoblast layer. Bar=40 μm (common in A, B). (B) Section 3. The entire periodontal ligament (PL) shows immunoreactivity for TNALP. Double asterisk indicates cellular cementum. (C and D) Magnification of sections 1 and 2 partitioned by the dotted line. Keratin-positive epithelial cells (white asterisks) show no or only negligible immunoreactivity for TNALP. Dental follicle cells and precementoblasts (black asterisks) show TNALP immunoreactivity on the cell surface (black arrows) and do not show any immunoreactivity for keratin. D, dentin. Bars=10 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4491499&req=5

Figure 4: Sections stained for TNALP (A, B, C) and double stained for TNALP-keratin (D). (C) and (D) are the same section. TNALP and keratin stain brown and purple, respectively. (A) Two dotted lines demarcate sections 1 to 3. In section 1, the dental follicle (DF), particularly in the alveolar bone (AB)-related zone, stains intensely for TNALP. The intact epithelial sheath (arrow) shows no immunoreactivity. In section 2, the intense immunoreactivity extends to the root-related side. Asterisk indicates dentin. DP, dental papilla; OB, odontoblast layer. Bar=40 μm (common in A, B). (B) Section 3. The entire periodontal ligament (PL) shows immunoreactivity for TNALP. Double asterisk indicates cellular cementum. (C and D) Magnification of sections 1 and 2 partitioned by the dotted line. Keratin-positive epithelial cells (white asterisks) show no or only negligible immunoreactivity for TNALP. Dental follicle cells and precementoblasts (black asterisks) show TNALP immunoreactivity on the cell surface (black arrows) and do not show any immunoreactivity for keratin. D, dentin. Bars=10 μm.
Mentions: In section 1 (Fig. 4A), the intact epithelial root sheath was negative or only negligibly stained for TNALP. In contrast, the dental follicle, particularly in the alveolar bone-related zone, was stained strongly. In section 2 (Fig. 4A), the intense TNALP immunoreactivity extended towards the root-related side, and in section 3 (Fig. 4B), the entire periodontal ligament, including cementoblasts, exhibited intense TNALP immunoreactivity, whereas cementocytes were negative. At high magnification of section 2 (Fig. 4C, D), dental follicle cells and precementoblasts showed TNALP immunoreactivity on the cell surfaces, and none of these cells were stained for keratin. Keratin-positive epithelial cells showed no or only negligible immunoreactivity for TNALP. Hence, cells possessing double-immunoreactivity for TNALP-keratin were virtually absent. In section 3, TNALP-positive cementoblasts did not show immunoreactivity for keratin (data not shown).

Bottom Line: 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.

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