Shh及其受体Ptc1、Ptc2在鼠帽状期磨牙的基因表达

目的 观察信号分子Sonic Hedgehog(Shh)及其受体Ptcl、Ptc2在小鼠下颌第一磨牙帽状期的基因表达，以探讨Shh信号路径在牙胚形态发育早期的作用。方法 制备昆明小鼠磨牙形态发育早期标本(E10．5～E15．5)，常规HE染色观察组织形态。免疫组化SP法对增殖细胞核抗原(proliferating cell nuclear antigen，PCNA)进行定位研究。原位杂交法分析Shh、Ptcl、Ptc2 mRNA在牙胚中的表达与分布。结果 E14．5，内、外釉上皮，星网状层及牙乳头细胞PCNA阳性，大部分釉结细胞PCNA阴性，少量釉结细胞PCNA阳性。Shh、Ptcl、Ptc2 mRNA在内、外釉上皮、星网状层及釉结中均有表达。结论 在帽状期，信号分子Shh可能经自分泌或旁分泌途径作用于釉结以外的上皮和间充质，促进其增殖。

Expression of Shh、Ptc1、Ptc2 mRNA in the cap stage of mouse molar

OBJECTIVE: To investigate the expression of Shh and its receptors Ptc1 and Ptc2 mRNA in the cap stage of mouse molar and discuss its role in early tooth morphogenesis. METHODS: The embryonic mouse heads of early tooth development (E10.5 - E15.5) were obtained and 5 micro m serial sections were made. Immunohistochemical staining of PCNA was carried out by SP method. The expression pattern of Shh, Ptc1, and Ptc2 mRNA was analysed by in situ hybridization. RESULTS: E14.5, outer dental epithelium, inner dental epithelium, stellate reticulum and underlying dental mesenchyme were PCNA positive. Most of the enamel knot cells were PCNA negative. A few of the enamel knot cells were PCNA positive. Shh, Ptc1, and Ptc2 mRNA were strongly expressed in outer dental epithelium, inner dental epithelium, stellate reticulum and the enamel knot. CONCLUSION: In the cap stage, Shh as a paracrine and autocrine signaling molecule might stimulate epithelium and mesenchyme proliferation.