小鼠釉质发育过程中成釉器中间层细胞增殖、凋亡以及组织非特异性碱性磷酸酶的表达

目的:观察小鼠釉质发育过程中成釉器中间层细胞的增殖、凋亡和其组织非特异性碱性磷酸酶(tissue nonspecific alkaline phosphatase,TNSALP)的表达,探讨中间层在釉质形成过程中的可能作用.方法:取出生后1、3、5、7、9、11、15d的BALB/c小鼠56只,解剖分离含下颌第一磨牙区的下颌骨,脱钙,制片,HE染色进行牙釉质发育情况的组织学观察,分别采用原位末端标记法(TUNEL法)、SP免疫组织化学技术、PV二步法观察中间层细胞的凋亡及检测Bcl-2、增殖细胞核抗原(proliferating cell nuclear antigen,PCNA),并对TNSALP进行组织学定位.通过Image-pro plus 6.0图像分析软件.对图像进行半定量分析.采用SPSS13.0软件包进行t检验、单因素方差分析及SNK-q检验.结果:出生后1d.中间层细胞增殖细胞核抗原由比成釉细胞表达高的强阳性表达逐渐降低;至7d时,其表达为阴性,而且中间层细胞随釉质的发育逐渐凋亡.中间层细胞先于成釉细胞表达TNSALP,出生后5d时即呈现强阳性染色,而后其表达又逐步减弱;成釉细胞7d时开始出现阳性,且呈逐渐增强趋势.结论:中间层细胞的增殖和凋亡及其TNSALP的表达与成釉细胞具有相关性,提示中间层细胞有可能参与成釉细胞的分化及釉质形成.

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.