脊髄オリーブ路の経過について

The Course of the Spino-olivary Tract in Cats

I．はじめに

　動物のHelweg三角束は，小川（1943）が正常家兎と猫のPalカルミンまたはBodian染色標本で記載するまで，ほとんど知られていなかつたように思う。その後，Wilson-Magoun（1945）とBrodal-Walberg-Blackstad（1950）は，それぞれMarchi法またはGlees法を用いて，猫の脊髄オリーブ路の存在を確認したが，その経過については詳細でなかつた。Beusekom（1955）はHäggqvist法で，おなじく猫の脊髄オリーブ路を追究したが，我々の結果からみて必ずしも納得できない点がある。小川・草間は，小川によつて記載された猫の三角束との関係を中心として，猫の脊髄とオリーブ核の線維結合をMarchi法で追究し，1954年解剖学総会で報告した。その後原著を発表する機会を失つていたが，小川教授退職記念号が発刊されるに際し，ここに発表して御批判を乞いたいと思う。

　The course of the spino-olivary tract was followed by the Marchi method on adult cats in which C₁, C₂, C₃, C₈ and L₃ of the spinal cord were partially cut by means of small knives, with speical reference to the triangle fasciculus which was reported by Ogawa in intact mammals as corresponding to Helweg's triangle fasciculus in human material. The survival time was 17 to 22 days after operation. The results obtained were as follows.

　1) The spino-olivary tract ascends bilaterally and diffusely through the ventral layer of the ventral funiculus below C₄ or C₅. Above about C₄ or C₅ this tract is gradually collected in the region underneath the pia mater along the ventral margin of the ventral funiculus. At C₁ and C₂ the spino-thalamic tract joins the region of this spino-olivary tract, the two tracts intermingling and together forming a fiber bundle consisting of finer fibers than those surrounding them. This bundle is now recognizable in intact material as the triangle fasciculus. At the level of the pyramidal decussation it lies just laterally to the pyramis, and at the olivary level mainly medially to the hypoglossal root and ventrolaterally to the inferior olive. The spino-olivary tract terminates inthe dorsal and medial accessory olive. Our observations indicate that most of the spino-olivary tract takes the course mentioned.

　2) The opinion of Cajal and Brodal et al. that the spino-olivary tract is formed of collaterals is contrary to our observations.

　3) The difference that the triangle fasciculus in cats is concerned with the accessory olivary nuclei, while that in human material is related with the main nucleus, must be mentioned.