Objectives: The objective of current study is to identify and locate possible stem cell niches in the pharyngeal dentition of medaka, which appear to serve as excellent source of odontogenic stem cells for the study of tooth development and regeneration.
Methods: The upper and lower pharyngeal dentition of adult medaka with or without fluorochrome- or short-and long term-BrdU-labeling were collected and processed for histological, histomorphometrical, and 3D reconstruction studies.
Results: Current data clearly indicated that functional teeth and their successional tooth germs were organized in families up to five generations being aligned at some angles with respect to parasagittal planes on each pharyngeal bone. In vivo calcein and alizarin complexon labeling studies confirmed the replacement cycle of pharyngeal teeth being around 6W in adults and shorter in younger ones. 3D reconstruction of BrdU labeling at various time intervals in adult medaka up to 12W-chase confirmed existence of groups of label-retaining cells posterior to the youngest tooth germ in each tooth family.
Conclusions: Pharyngeal teeth and successional tooth germs comprise well-aligned families of tooth organs, in which stem cell niches are located immediately posterior to the youngest tooth germ in each family.
Keywords: Histology - ultrastructure, Mineralization, Regeneration, Remodeling and Teeth