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Cellular turnover in epithelial rests of M alassez in the periodontal ligament of the mouse molar
Author(s) -
Oka Kyoko,
Morokuma Masakazu,
ImanakaYoshida Kyoko,
Sawa Yoshihiko,
Isokawa Keitaro,
Honda Masaki J
Publication year - 2012
Publication title -
european journal of oral sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.802
H-Index - 93
eISSN - 1600-0722
pISSN - 0909-8836
DOI - 10.1111/eos.12003
Subject(s) - periodontal fiber , tunel assay , immunocytochemistry , lgr5 , microbiology and biotechnology , molar , immunohistochemistry , stem cell , biology , periodontal ligament stem cells , chemistry , pathology , immunology , endocrinology , medicine , dentistry , alkaline phosphatase , biochemistry , paleontology , cancer stem cell , enzyme
Fragments of H ertwig's epithelial root sheath persist in the periodontal ligament ( PDL ) in small clusters known as epithelial rests of Malassez ( ERM ). It is generally agreed that ERM are maintained as a quiescent and exclusively dental epithelial cluster in PDL . However, we speculate that homeostasis and cellular turnover underlies cluster maintenance. We also hypothesize that the fate of ERM clusters – diminishing or remaining – might be regulated via the presence or absence of epithelial stem cells therein. Histological analysis of aging mouse molar PDL showed that ERM clusters gradually increase in size with increasing age. Immunocytochemistry and cell culture revealed that ERM clusters contained K i67‐positive cells and were able to expand when brought in culture. The T d T ‐mediated biotin– dUTP nick‐end labeling ( TUNEL ) procedure also detected signs of apoptosis. Finally, we identified putative epithelial stem cells in the clusters by 5‐bromo‐2′‐deoxyuridine (BrdU) pulse–chase experiments and immunohistochemistry, using the stem‐cell marker leucine‐rich repeat‐containing G‐protein‐coupled receptor 5 (Lgr5). The results suggest that ERM clusters are maintained in the PDL, via cellular turnover, throughout life.