ELECTRON MICROSCOPIC STUDY OF THE MOSSY FIBER ENDING IN THE HIPPOCAMPAL FORMATION AFTER DITHIZONE ADMINISTRATION
1975 年 8 巻 2 号 p. 91-98
詳細
1975 年 8 巻 2 号 p. 91-98
Electron microscopic observations were made of the mossy fiber endings distributed in the hippocampal formation of rats receiving dithizone and of normal controls.
The mossy fiber endings were noted to be enlarged to form terminal synaptic knobs complex in shape, each surrouding a dendritic spine. The synaptic knob contained synaptic vesicles. The portion of the presynaptic membrane of the knob facing a dendritic spine appeared to be markedly thick whereas that of the presynaptic membrane in contact with the smooth surface of a dendrite was not notably thick.
Sections taken at 15 and 30minutes after administration of dithizone frequently showed remarkably dense accumulations of synaptic vesicles in parts of the terminal knobs of mossy fibers.
At 1 and 1.5hours after dithizone, there was evidence of drastic diminution of the synaptic vesicles in the mossy fiber endings and, concomitantly with it, the dendritic spines were seen to have decreased.
The morphologic features of the mossy fiber ending, however, returned almost completely to the normal state by 3 to 5hours after dithizone.
An attempt was made to investigate the interrelation of these ultra-structural alterations with zinc and the mechanism of action of dithizone on the mossy fiber ending has been discussed.
