Mapping of a candidate gene for the absence of third molars in EL/mice

(1)牙胚发育组织学观察：5、7.10日龄的EL/kw（对照小鼠）和EL/sea（突变小鼠）下颌骨置于Bouin固定液中24h， 14% EDTA脱钙1周，脱水后包埋石蜡。切片用苏木精和伊红染色，光镜下观察。在5日龄时，EL/sea的3^<rd>臼齿（M3）牙胚发育较EL/kw慢。但牙冠形态发生正常。7日龄时发现M3牙胚畸形，EL/sea观察到M3牙胚发育停滞。出生后10天，牙胚在EL/sea中几乎消失，与正常发育的EL/kw相比。(2) m3的免疫组化。组织用4%多聚甲醛4℃固定过夜，12.5% EDTA脱钙。它们被脱水，包埋在石蜡中。5、7、10日龄的EL/kw。left 1在M3的牙胚及周围细胞中表达。另一方面，Lef 1在EL/sea小鼠中随5、7和10日龄的变化而变化。在7日龄EL/海鼠中，M3牙胚中检测到强烈的lef1表达。在5日龄和10日龄时，lef1表达几乎完全下调。5、7、10日龄EL/kw和EL/sea小鼠中，EGF的表达均无显著差异。结果表明，Lef - 1可能在抑制M3病菌发育中起重要作用。

(1) Histological findings for the tooth germ developmentThe mandibles obtained from the EL/kw (control mouse) and EL/sea (mutant mouse) mice at 5, 7.10 days of age were in Bouin's fixtative for 24h, decalcified in 14% EDTA for 1 week, dehydrated, and then embedded in paraffin. The section were stained with hematoxylin and eosin, and observed under a light microscope. The development of the 3^<rd> morlar (M3) tooth germ of EL/sea was slower than EL/kw at 5 days of age. However, tooth crown morphogenesis was progressing normally. The malformation of the M3 tooth germ was found on 7 days of age and arrest of M3 tooth germ development was observed in EL/sea. When it was the ten days after birth, the tooth germ almost disappeared in EL/sea, compared with normal development in EL/kw.(2) Immunohistochemistry for the M3The tissues were fixed in 4% paraformaldehyde at 4℃ overnight, and decalcified in 12.5% EDTA. They were dehydrated, embedded in paraffin. In EL/kw of 5, 7 and 10 days of age. Lef 1 was expressed in a tooth germ of M3 and the surrounding cells. On the other hand, the expression of Lef 1 was varied by 5, 7 and 10 days of age in EL/sea mice. In 7-day-old EL/sea mice, strong Lef 1 expression was detected in the tooth germ of M3. In both 5 and 10 days of age, Lef 1 expression was down regulated almost completely. In both EL/kw and EL/sea mice of 5, 7 and 10 days of age, there were observed no significant differences in the expression of EGF. From the result, it was suggested that Lef 1 may play an important role in arrest of the germ development of M3.