The disribution of ganglioside sialidase on developing mouse tooth germ

神经节苷类唾液酸酶是动物唾液酸酶的一种，根据生物学定义，其活性天生定位于细胞膜上。本项目旨在确认该酶的形态定位和生物学作用。免疫细胞化学研究证实该酶在转染牛cDNA的COS细胞和用人cDNA表达的转基因小鼠骨骼肌细胞的细胞膜上定位。为了阐明该酶的生物学作用，对上述转基因小鼠的门牙进行了组织学研究。老鼠的门牙在动物的一生中不断生长。因此，我们可以在动物生命的任何时刻研究某些实验条件对牙齿形成的影响。由于多聚甲醛不充分的组织固定，转基因小鼠的牙釉质器官和牙齿的组织学变化不明确。为了获得良好的组织学特征，需要改进组织固定方法。麻醉小鼠用化学固定剂固定，化学固定剂通过导管通过蠕动泵注入左心室。将沿血管循环的固定物从右心房切开排出。手术时间较短，留置导尿管进入左侧。就能得到更好的组织学特征。为缩短手术时间，设计了导管。最好的导管是直径0.9mm的聚乙烯管，一端连接金属针（26号）。开胸后用针穿刺左心室。为了将针固定在合适的位置，心脏和针被用一种外科胶水Aron Alpha A （Toagosei Co., Ltd）粘住。组织固定方法的改进花费了大量时间，组织学研究尚未完成。

Ganglioside sialidase is one type of the animal sialidases, whose activity is innately localized on cell membrane by biological definition. This project aimed at confirming the morphological localization and biological role of this enzyme. An immunocytochemical study proved the enzyme being localized on cell membrane of COS cells transfected with bovine cDNA of the enzyme, and of skeletal muscle cells in transgenic mice expressed with the human cDNA. To elucidate a biological role of the enzyme, a histological study was done in incisors of abovementioned transgenic mice. Mouse incisors continue to grow during the animal life. Therefore we can study an effect of some experimental condition on tooth formation at any time of the animal life. The histological changes of the enamel organ and tooth were ambiguous in the transgenic mice because of inadequate tissue fixation with paraformaldehyde. To get good histological features, the tissue fixation method needed to be improved. Mice under anesthetization were fixed with the chemical fixative which was infused into the left ventricle through a catheter by using a peristaltic pump. The fixative circulating the body along blood vessels was drained from the right atrium cut open. The shorter surgical operation time to insert a catheter into the left. ventricle you will take, the better histological features you will get. A catheter was devised for shortening the surgical operation time. The best catheter was a polyethylene tubing 0.9mm in diameter connected to a metal needle (26 gauge) at the one end. The left ventricle was punctured by the needle after thoracotomy. To hold the needle in place the heart and needle were glued by using Aron Alpha A (Toagosei Co., Ltd.), one of surgical glues. Taking much time for improving the tissue fixation method, the histological study has not yet been completed.