Application of the whole embryo culture system to the study on the brain development

尽管近年来基因技术取得了很大进展，但哺乳动物脑发育的机制仍不完全清楚。原因之一是难以观察和操纵在母亲子宫内发育的哺乳动物胚胎。本研究利用全胚胎培养系统对小鼠胚胎脑进行了一些实验操作，以阐明脑发育的机制。我们已经研究了小鼠中脑的体内发育，并获得了表明神经细胞粘附分子L1和脑特异性硫酸软骨素蛋白聚糖磷酸蛋白聚糖之间的分子相互作用涉及中脑含多巴胺神经元的迁移的数据（Kawano等人，1997 ; Ohyama等人，1998年出版）。由于L1已被报道在体内结合磷酸蛋白聚糖，这两种分子之间的分子相互作用可能在多巴胺神经元的迁移中发挥重要作用。在此基础上，我们利用全胚胎培养系统，将硫酸软骨素降解酶和抗老化剂L1（antibody ageinst L1）注入E13小鼠胚胎脑室，并进行脑组织学检查。该系统将为研究哺乳动物脑的发育机制提供有用的工具。

In spite of the great advance of the gene technology in recent years, the mechanism of mammalian brain development is not fully known. One of the reasons is the difficulty in observing and manipulating mammalian embryos which develop in the mother's uterus. In the present study, some experimental manupilations were made to the embryonic mouse brain by using the whole embryo culture system to clarify the mechanisms of the brain development. We have already studied the in vivo development of the mouse midbrain and obtained the data which indicate that molecular interactions between neural cell adhesion molecules, L1 and a brain-specific chondroitin sulfate proteoglycan, phosphacan, are involved in the migration of mesencephalic dopamine-containing neurons (Kawano et al., 1997 ; Ohyama et al., 1998 in press). Since L1 have been reported to bind phosphacan in vivo, molecular interaction between the two molecules may play important roles in the migration of dopamine neurons. Based on these observation, we made microinjection of an enzyme which degrades chondrotin sulfate and antibody ageinst L1 into the ventricle of E13 mouse embryos using the whole embryo culture system, and exmined the brain histologically. This system will be a useful tool to study the developmental mechanism of the mammalian brain.