HELICAL FILAMENTS IN ASTROCYTIC MITOCHONDRIA OF THE CORPUS STRIATUM IN THE RAT.

Astrocytic mitochondria have been studied in serial electron micrographs of the corpus striatum. Special filaments have been found inside several of these mitochondria located in both the cell body and the processes. They were particularly frequently observed in the pericapillary end-feet. The filaments occur within dilated intracristal spaces provided with several communications with the outer chamber, and form helices which are oriented approximately in the same direction. Each filament is about 30 A thick, the diameter of the helix is 140 A, and the pitch is 120 A. Their possible nature and significance are briefly discussed. There is no clear relationship between these mitochondria and other unusual forms of mitochondria previously described in astrocytes from other regions.