[Proliferation, apoptosis and expression of tissue non-specific alkaline phosphatase in cells of stratum intermedium during amelogenesis in postnatal stage of BALB/c mouse.]

PURPOSE: To study the apoptosis and expression of proliferating cell nuclear antigen(PCNA),tissue non-specific alkaline phosphatase(TNSALP) of stratum intermedium cell in postnatal stage of BALB/c mouse. METHODS: Fifty six BALB/c mice in different developmental days were sacrificed and their bilateral mandibular first molar germs with surrounding alveolar bone were taken out, then the tissues were fixed with 4% paraformaldehyde at 4degrees centigrade overnight, dehydrated, embedded in paraffin and serially sectioned at 5mum.Tdt-mediated Dutp nick end labeling (TUNEL) and immunohistochemical assay were adopted to determine the tissue distribution and cellular localization of bcl-2, PCNA and TNSALP,respectively. Image-pro plus 6.0 software was used to evaluate the histological sections and the data was analyzed by Students\’t test,one-way ANOVA and SNK-q test with SPSS 13.0 software package. RESULTS: The expression of PCNA in stratum intermedium was higher than ameloblast at postnatal day 1, but it gradually decreased and was negative at postnatal day 7. The apoptosis of stratum intermedium cells increased during enamel development.The expression of TNSALP appeared at postnatal day 3 and was most obvious at postnatal day 5 in stratum intermedium, then gradually decreased. However, the expression of TNSALP appeared at postnatal day 7 in ameloblasts, then gradually increased. CONCLUSIONS: There is a significant linear correlation between stratum intermedium cell and ameloblast in apoptosis and expression of PCNA and TNSALP.It is suggested that the stratum intermedium participate in the differentiation of ameloblast and formation of enamel.

Tang KL, Li S, Xiao CJ, Wang J, Yu L, Yu XJ.

Department of Periodontology, School of Stomatology, Shandong University,Jinan 250012,Shandong Province,China.E-mail: lishu@sdu.edu.cn.