小鼠牙胚裸鼠体内移植的形态学观察

A histological innovative study of Balb/c mouse tooth germ transplanted to nude mouse in vivo

目的:观察小鼠牙胚裸鼠体内移植后的形态学变化。方法:将出生后5天的小鼠的下颌第一磨牙牙胚异位移植到成年裸鼠背部肌层中,在移植后第7天和第14天分别取出植入的牙胚,常规制片,HE染色,显微镜下观察。另取出生后12天和19天的小鼠各1只,常规制片,HE染色,作移植后不同时间的对照。结果:肉眼观察发现,移植后牙胚生长于肌浅层,组织相容性好,表面有丰富的毛细血管;组织学观察表明:移植后的牙胚可继续发育,但比正常发育的牙胚速度减慢。牙本质层较薄,移植后形成大量牙本质小管、排列不规则的牙本质。虽然上皮根鞘位置变化不明显,但牙根可继续根向延伸。髓室底形成,髓腔缩小,根部钙化程度明显增强。移植后第7天,牙胚内外均有炎细胞浸润;但移植后第14天的牙胚,均未见明显的炎症现象。结论:小鼠牙胚裸鼠肌浅层移植后有一定的发育趋势,可以短期用于牙根发育的研究。

PURPOSE： To observed the changes of the developed mouse＇s dental germs after transplanting into nude mouse and find some theoretical foundation for establishing an innovative experimental model. METHODS： Eight tooth germs from four 5^th day postnatal Balb/c mice were transplanted to the back muscles of the adult nude mice. At seventh and fourteenth day after grafting, the germs were collected, fixed, demineralized, dehydrated, and embedded in wax. Serial sections of 5μm thick were made following the routine methods, stained with haematoxylin-eosin dying solution, and observed under a light microscope. The mandibular first molars were taken out from the 12^th and 19^th day postnatal mouse. Serial sections of 5μm thick were made following the routine methods, then compared with the germs after graft. RESULTS： All implantations were located in the superficial muscles with abundant capillary vessels. The dental germs could further developed after grafting under the microscope, but slower than dental germs self-development. The layer of dentin was thin,plenty of dentin with disorganized dentin tubule formed after grafting. Although the location of Hertwig＇s epithelial root sheath hardly moved, the roots developed further. The floor of pulp chamber could form and the pulpchambers were shrinking. The degree of calcification in the area of root increased very clearly. The inflammatory reaction was found at 7^th day while hardly noted at 14^th day after grafting. CONCLUSIONS： It suggests that late development of mouse tooth germs could further develop after heterotopic transplantation within the superficial muscles of the nude mouse. This model is useful for study of tooth root development in short time.Supported by National Natural Science Foundation of China（Grant No.3037153） and Award Fund for Excellent Young and Middle-Aged Scientists of Shandong Province（Grant No.02BS096）.