Cholinesterase Activity in the Dental Epithelium of Hamsters During Tooth Development

Cholinesterase (ChE) is one of the most ubiquitous enzymes and in addition to its well characterized catalytic function, the morphogenetic involvement of ChE has also been demonstrated in neuronal tissues and in non-neuronal tissues such as bone and cartilage. We have previously reported that during mouse tooth development, acetylcholinesterase (AChE) activity is dynamically localized in the dental epithelium and its derivatives whereas butyrylcholinesterase (BuChE) activity is localized in the dental follicles. To test the functional conservation of ChE in tooth morphogenesis among different species, we performed cholinesterase histochemistry following the use of specific inhibitors of developing molar and incisors in the hamster from embryonic day 11 (E11) to postnatal day 1 (P1). In the developing molar in hamster, the localization of ChE activity was found to be very similar to that of the mouse. At the bud stage, no ChE activity was found in the tooth buds, but was first detectable in the dental epithelium and dental follicles at the cap and bell stages. AChE activity was found to be principally localized in the dental epithelium whereas BuChE activity was observed in the dental follicle. In contrast to the ChE activity in the molars, BuChE activity was specifically observed in the secretory ameloblasts of the incisors, whilst no AChE activity was found in the dental epithelium of incisors. The subtype and localization of ChE activity in the dental epithelium of the incisor thus differed from those of the molar in hamster. In addition, these patterns also differed from the ChE activity in the mouse incisor. These results strongly suggest that ChE may play roles in the differentiation of the dental epithelium and dental follicle in hamster, and that morphogenetic subtypes of ChE may be variable among species and tooth types.

In vitro culture and characterization of dental epithelial cells derived from the apical end of rat incisor / 实用口腔医学杂志

Objective:To investigate the biological characteristics of dental epithelial cells derived from cervical-loop epithelium in rat lower incisor. Methods:The apical end of the lower incisor was dissected from two-day-old Sprague-Dawley rats by visual microscopy, and dental epithelial cells were obtained by culture of the apical end explants of the lower incisor. The biological characteristics of dental epithelial cells were determined by morphology and immunocytochemistry fluorescence. Results:Dental epithelial cells emigrated from the cervical loop of rat lower incisor, and epithelium-like morphologies with round-shape or square-shape was observed. Dental epithelial cells had a striking proliferation potential with a high level of BurdU labeling. As a marker of epithelium stem cells, P63 expression was observed in most early cultured cells. However, as cells were subcultured, dental epithelial cells,with the lower level of BurdU labeling,decreasing expression of P63 and increasing expression of alkaline phosphatase, were inclined to terminal differentiation.Conclusion:Stem cells or dental epithelial progenitor cells might reside in the cervical loop of the apical end of the rat lower incisor. The present study may provide an excellent cell source for study on the differentiation of dental epithelial cells and tooth regeneration.