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抄録 本実験は実験的甲状腺機能低下症(cretinism)ラットの小脳の発達障害について,経時的に電子顕微鏡による検索を行った。経時的検索では,発達期である20日目群に障害が著明であった。この時期の細胞の状態は対照群16日目の発達状態に相当している。成熟期である35日目,60日目には対照群との差は認められなかった。実験群20日目の障害を中心に記すと,細胞成分の変化は,外顆粒細胞の残存と内顆粒細胞の発達遅延が認められた。内顆粒細胞の発達時期(timing)の遅れと成熟度(rate)の不定性が見られた。また,胞体内のmitochondriaに膜様変性所見(主にcristaeの障害)も認められた。白質では,有髄線維の数が少なく,髄鞘形成不全,oligogliaの発達的障害,また,軸索内にmitochondriaの膜様変性とhoneycomblik estructureが認められた。内顆粒細胞(細胞体および突起)の発達遅延は,甲状腺機能低下状態に加え,mitochondriaの変性による,2次的蛋白合成機能低下が原因していると考えられる。また,髄鞘形成不全は,oligogliaの発達障害が関与していると考えられる。
We examined the cerebellum of the rats being the experimental hypothyroidism (cretinism) on the 20th day, 35th day and 60th day by the light and electron microscope. The remarkable findings were observed to the experimental group on the 20 th day. The maturational states of this group correspond to that of the 16th day of the control group. On the other hand, the remarkable pathological findings were not observed on the 35 th and 60 th day of the experimental group.
According to the findings of the experimental rats on the 20 th day, the changes of the cells were the retention of the external granule cells and the maturational changes of the internal granule cells. We recognized the retardation of the matu-rational timing and a disagreement of the matu-rational rate of the internal granule cells. The lamellar bodies being the disturbance of the mito-chondrial cristae were observed. About the white matter, the myelinated nerve fibers were a small quantity in number, and the deficiency of the myelin synthesis, the maturational disturbance of oligoglia were seen. In the several axons, the lamellar bodies and the honeycomb like structures were seen.
It is concluded that the maturational disturbance of the internal granule cells are due to the distur-bance of the secondary protein synthesis by the hypothyroid state and the degeneration of the mitocondria. The deficiency of the myelin synthe-sis is related to the maturational disturbance of oligoglia.
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