Syndecan-1 immunohistochemistry in the dental follicle of postnatal mouse teeth

Objectives: Syndecan (syn)-1 is cell surface heparan sulfate proteoglycan and involved in the formation of junctional epithelium (Dias et al. J periodont 76:696-704, 2005). In this study, the syn-1 protein expression in the dental follicle and dental pulp of postnatal mouse teeth by immunohistochemistry. Methods: ICR mice, E 18.5 to d 21, were used in this study. Each mandible was fixed with 4% paraformaldehyde, decalcified with EDTA and routinely embedded in paraffin. Frontal or sagittal sections were cut and M1 and lower incisors were analyzed by syn-1 immunohistochemistry. Results: At E 18.5, M1 was at late bell stage and syndecan-1 immunostaining was detected in enamel organ and weakly in the dental follicle. At d 4, Hertwig's epithelial sheath (HERS) started to be formed in M1 and enhanced syndecan-1 immunostaining was detected in the dental follicle and adjacent dental pulp between buccal and lingual HERS. Sundecan-1 positive areas looked to plug the apical foramens surrounded by HERS. This staining pattern continued until d 14. At d 21, eruption of M1 was almost completed and syn-1 immunostaining was no longer detected in the dental follicle. Meanwhile, immunostaining was continuously detected in the dental follicle and adjacent dental pulp between the apical loops of lower incisor at 21 d. In incisor, immunostaining was also detected in the dental pulp around capillaries. In addition, cell membrane localization of syn-1 was confirmed in the dental follicle and pulp cells by immunoelectron microscopy. Conclusions: syn-1 in the dental follicle seems to be involved in the root formation through the interaction with HERS, and this molecule in the dental pulp seems to be related to supply of capillaries.