ラットの実験的脳腫瘍とその移植腫瘍の病理

Pathology of Experimental Rat Gliomas

　膠腫は頭蓋内腫瘍の約40％を占め，中枢神経系腫瘍のなかで特異な位置を示しているばかりでなく，その組織型，細胞構成，組織由来，局在などをめぐつて多数の未解決の問題を含んでいる。1939年Seligman and Shear^55）が発癌物質をマウス脳内に埋没し，始めて11例の膠腫の実験的形成に成功して以来，膠腫の実験的研究は人の膠腫のもつさまざまな問題を解決する有力な手がかりとして多数の研究者によつて繰り返し行われてきている。特にZimmerman^{61）62）63）64）65）2）}等は1941年以来今日まで，多数の膠腫を実験的に発生させ，継代移植を行い，実験的研究を通じて入の膠腫の細胞構成，組織型とその由来，局在，転移などの諸問題への示唆を与えている。Zimmerman等の精力的な初研究は今日までの膠腫の実験的研究のなかでいわば主流をなすもので，実験的膠腫が種々の組織型の混合構成から成つていて，"Mixed glioma"，"Multiple glioma"が多いというその病理の特徴や，化学的刺激のもとに既存の成熟膠細胞の腫瘍化によつて発生するという組織由来の特徴を指摘している。しかしながら反面実験的膠腫を人の膠腫同様に多数の組織型に分類し，実験的膠腫の諸周題をそのまま人の膠腫の問題として考察を進めている，点にはなお考慮の余地があるように思われる。

　Experimental induction of gliogenous tumorswas carried out by implanting methylcholanthrenc pellets into the brain of rats of Wistar and Donryu strain. A total of 24 tumorswere obtained in Donryu rats in a period of90 to 527 days. With histological examinations, 13 of these tumors were classified asgliomas. Of the others, 2 were meningiomas, 4sarcomas, 1 mixed glioma and sarcoma, 1epidermoid cyst, 2 granulomas and 1 unclassified tumor. By applying the criteria employed in the classification of human glioma, subclassification of experimental gliomaswere made. They consisted of 7 glioblastomas, 3 oligodendrogliomas, 2 astrcytoma-like tumors and 1 ependymoma-like tumor. On studying the induced tumors in serial histologicalsections, by means of metallic impregnationmethods and by transplantation experiments, it is evident that experimental gliomas havepeculiarities in their histological malignancy, and their very mixed character, which arcunable to permit a forced analogy to gliomasin man.

　Meningionias with typical formation ofwhorls were produced in 2 cases. It is arguedthat the arachnoid cells are one of the possible sources of experimental tumors of mesodermal origin.

　Six tumors (4 gliomas, 1 meningioma and1 sarcoma ) were successfully transplanted.They were capable of subsequent transfer into the subcutis, brain, peritoneal cavity andin cases anterior chamber of the eye. Amongthe various histological typs of experimentalgliomas, it is glioblastoma or glioblastoma-like component part of mixed glioma whichis transplanted successfully.

　Electron microscope observations were madeon 2 gliomas, 1 glioma transplant and 2 sarcomas. The cytological malignancy and thediversity of celluar composition as evidencedby light microscopy was in some measurereflected on the ultrastructure of the component cells of experimental gliomas.