Gliomaの成り立ち及びその頭蓋外転移について，主としてRatの実験的脳腫瘍から

The Nature of Gliomas, with Special Reference to the Experimental Brain Tumor of Rats

　原発性頭蓋内腫瘍の約半数を占めるGliomaは，BAILEY及びCUSHING^3）により1926年初めて混沌の世界から輝かしい体系を附されて以来，脳腫瘍病理学としても，脳神経外科としても，その研究に既に30有余年の歴史をもつに至った。然るにも拘らずgliomaは尚多くの問題を残し頭蓋内腫瘍としての重要性と興味，更に一般腫瘍学解明への道を拓くという意昧に於ても一層の研究努力を要することが明かである。それは，gliomaが単に統計上頭蓋内腫瘍の主位を保つということだけでなく，第1にその組織発生をめぐる諸問題は尚錯雑として諸家の論争の的であり，またその分類法の不統一性，任意性に基づく紅織診断の混乱，その好発部位と腫瘍像との関連の有無，悪性腫瘍の通則を逸脱するuniqueなgliomaの特性と考えられて来た自然的頭蓋外転移有無をめぐる問題等，今後解決を要する問題の少くないことを知る。

　著者等はこれらの諸問題を解明する目的で，腫瘍生成には，miceよりも不適当とされるratの頭蓋内にcarcinogen：Methylcholanthreneを手術的に埋没し，約1ケ年に亘り時と共にそれらの四囲に惹起される諸相を病理組織学的に追跡し，その若干例に明かにgliomaを含む脳腫瘍形成に成功した。

The implantation experiments with chemical carcinogen in the central nervous system of mice to induce neoplasia have been engaged in by several researchers so as to throw some light on the problems of gliomas, that is, questions as to the histogenesis and the lack of spontaneous, extracranial metastasis of glioma.

Pellets of 50% 3-Methylcholanthrene were implanted in the right cerebral hemispheres and cerebella of 108 crossbred rats of both sexes, in which it has been found more difficult to produce neoplasia than in mice.

The resulting tumors of 63 rats in all as well as the tumor producing process in latent period were examined histopathologically for 321 days. Most cases of the rats in which, no tumor was produced have revealed the fact that in the surrounding brain tissues of the pellets different types of morphological adult, glial cells including not only astrocytes and oligodendrocytes, but also ependymal cells occurred to proliferate almost simultaneously, Of all the cases showing the effects above men-tioned, 5 cerebral gliomas, 2 meningeal sarcomas and 1 cholesteatoma appeared.

The gliomas produced by this means were almost never pure gliomas composed of cells of one type, but mixtures of cells of several diffe-rent types, and different parts of them presen-ted diversified cellular populations ; i. e., mainly spongioblastoma, astroblastoma, astrocy-toma and oligodendroglioma. The proliferat-ing picture of several different adult glial cells, which were very analogous to those grown,around the pellets, were seen in the adjacent brain tissues of the gliomas.

The histological examination of some human glioma cases which have been diagnosed as ependymoma or medulloblastoma-these types were not seen in this experiment due to the location of the pellet-has suggested that most of human gliomas are also composed of the pre dominant type picture together with several different types.

This experimental evidence has approved of Zimmerman's opinion regarding glioma prob-lems;"under chemical stimulation many different adult glial cells begin to proliferate almost simultaneously to produce a glioma in the animal brain. The resulting tumor is almost never a pure glioma composed of cells of one type, but rather a mixture of cells of several different types."

But the authors have reached the opinion that the glioma progenitors may not be always adult but could also be immature cells in nature, as the result of histogenetic studies of the progenitors of human gliomas.

Twenty mg. of experimentally induced rat's glioma tissue consisting of such various kinds of glioma picture was homogenised in lcc. of Guy's B.Solution, Then O.Icc. of the glioma homogenates was injected into the upper sagit-tal sinus of three rats. As a result of autopsy 81 days later, in one animal metastatic gliomas which were grown extra- or intra pulmonal and mainly composed of astrocytes and oligoden-drocytes were perceived, but their anaplasia in nature was less distinctive than that of the original glioma.

The literatures on the problem of the extra-cranial metastases in spontaneous human gli-omas ever reported have been gathered and evaluated.