STUDIES ON THE STEREOTAXIC APPARATUS AND BRAIN ATLAS OF THE HOUSE MUSK SHREW

家麝鼩（Suncusmurinus）是由小田和近藤康介驯化的一种新的实验动物，命名为“臭鼩”。本课题的目的是设计一种适用于假眼的立体定位仪，确定假眼脑的立体定位坐标。假眼的体型与幼鼠相似，但小型啮齿类动物的立体定位仪不能用于假眼，由于鼓膜与啮齿类动物头部的解剖特征有很大不同：（1）鼓泡和外耳道不是骨性的，而是膜性的或部分软骨性的。（2）悬雍垂外听孔向远腹侧移位。两侧孔之间的轴线贯穿喉。本研究设计的适用于悬铃木的耳杆比啮齿类的耳杆粗而短，顶端直径为3mm。基部直径为5mm，长度为5mm，并且将直径为10mm的树脂垫附接到基部。耳杆能将悬雍垂头部固定，不会从侧面压迫喉部，悬雍垂颅骨颞平面在口背轴上不是圆的，而是直的。当通过调整齿杆使颞平面保持水平时，大脑颞表面也保持水平。在上述条件下，通过耳杆0平面的垂直横剖面包括大脑纵裂尾端和乳头体尾端。本研究将此平面作为立体定位坐标的横0平面.与颞平面平行并穿过耳杆或齿杆的平面不能作为水平标准平面。因为它们离大脑太远了。本研究以脑表面作为水平0平面。

The house musk shrew ( Suncus murinus ) has been domesticated by S.Oda and K.Kondo as new laboratory animal, and was named "suncus". It has been revealed that the suncus has various unique characteristics in the central nervous system and endocrinological control systems.The purposes of this project are to contrive a stereotaxic apparatus applicable to the suncus and to decide the stereotaxis coordinate of the suncus brain.Body size of the suncus is similar to those of young rats or mice, but stereotaxic apparatus for small rodents can not be used for suncus, because the suncus has very different anatomical features of head region from rodents:(1) tympanic bulla and external acustic meatus are not bony but membranous or, a part, cartilageous. (2)external acustic pore of the suncus shifts far ventrally. and axis between the pores of both side runs through larynx. Ear-bars contrived to be applicable to the suncus in this study are more thick and short than those used for rodents; apical diameter is 3mm. basal diameter is 5mm and length is 5mm, and resin pad of 10mm diameter is attached to basal part. These ear-bars can fix tightly head of the suncus, and do not put pressure upon larynx from lateral sides.Temporal plane of skull of the suncus is not round but straight on oral-aboral axis. When this temporal plane is kept horizontally by adjustment of teeth-bar, cerebral temporal surface is also kept horizontal. Under above mentioned condition, the vertical transverse profile through ear-bar 0 plane contains caudal end of the longitudinal cerebral fissure and caudal pole of the mamillary body. This plane is used as the transverse 0 plane of stereo- taxic coordinate in this study. Planes which are parallel to the temporal plane and run through ear-bars or teeth-bar can not be used for horizontal standard plane. because those are too ventrally shifted from the brain. Brain surface is used as horizontal 0 plane in this study.