Zum Elementaren Bau Der Interneuronalen Synapse

Electron Microscope Histochemical Evidence for a Partial or Total Block of the Tricarboxylic Acid Cycle in the Mitochondria of Presynaptic Axon Terminals

“…The observations are, therefore, suggestive of a block in these mitochondria at an early step of a-oxoglutarate and succinate oxidation, probably at the level of the primary dehydrogenase itself (14) . Lack in the presynaptic mitochondria of succinate oxidation demonstrable both with tetrazolium salt (22) and with ferricyanide (9) fits well into this picture . On the basis of these experiments, it cannot be decided whether the histochemical findings are due to the lack of the enzyme molecule or, conversely, only to blocked activity of the corresponding enzymes .…”

“…Unfortunately, such treatment not only uncouples energy-linked processes but also destroys the fine structure of unfixed tissues so severely that the recognition under the electron microscope of the relevant tissue elements becomes virtually impossible . However, the pioneering work of Szentâgothai (22) carried out on frozen sections of the ciliary ganglion of the chicken, in which the pre-and postsynaptic mitochondria are easily identifiable even at the light microscope level, has already shown a similar lack in SDH activity in the axon terminal mitochondria.…”