Identification of potential epithelial stem cells responsible for continuous tooth replacement in the African bichir (Polypterus senegalus), a basal Osteichtyan
In this thesis we wished to test the hypothesis that stem cells are involved in the process of continuous tooth replacement in the basal actinopterygian, Polypterus senegalus (African bichir). First, we studied the morphology of the dentition and the tooth replacement pattern on the premaxillary, ma...
| Main Authors: | , , |
|---|---|
| Format: | Conference Object |
| Language: | English |
| Published: |
2012
|
| Subjects: | |
| Online Access: | https://biblio.ugent.be/publication/8637609 http://hdl.handle.net/1854/LU-8637609 |
| Summary: | In this thesis we wished to test the hypothesis that stem cells are involved in the process of continuous tooth replacement in the basal actinopterygian, Polypterus senegalus (African bichir). First, we studied the morphology of the dentition and the tooth replacement pattern on the premaxillary, maxillary and dentary, using cleared and alizarin red stained heads of juvenile Polypterus. Each of these bones bears one row of functional teeth. In addition, a replacement tooth develops at the lingual and posterior side of each single functional tooth. Functional teeth of a similar stage of maturation tended to be in alternate tooth positions. Two mechanisms are proposed to explain this alternate pattern. Using serially sectioned heads of juvenile fish, we could next reveal the cellular details of the replacement process. The anlage of the replacement tooth is first seen as a local differentiation of the outer dental epithelium of the predecessor, at its postero-lingual side. Throughout the development of the replacement tooth, an epithelial cell population, termed here the ‘middle dental epithelium’, connects the predecessor to the replacement tooth. The bulk of the cells of the ‘middle dental epithelium’ are irregular and separated by small intercellular spaces. In contrast, the cells closely opposed to the inner dental epithelium of the replacement tooth have a stellate reticulum phenotype. The mode of tooth replacement in Polypterus senegalus displays several characters highly similar to those observed in Atlantic salmon (Salmo salar). In the second part of this study we concentrated on the proliferation pattern and the identification of label retaining cells using PCNA (proliferating cell nuclear antigen) and BrdU (bromodeoxyuridine) immunostaining, resp. Proliferation was found in the preodontoblasts and dental organ of the replacement tooth. Strikingly, we found a focus of proliferating cells in the outer dental epithelium of the replacement tooth. This is the presumptive site of initiation of a third tooth ... |
|---|