A quantitative electron microscope study of cerebellar axon terminals on the magnocellular red nucleus neurons in the cat

doi:10.1016/0006-8993(78)90769-2

Brain Research

Volume 147, Issue 1, 19 May 1978, Pages 17-27

https://doi.org/10.1016/0006-8993(78)90769-2 Get rights and content

Abstract

In the red nucleus (RN) of the cat, the bouton covering ratio (BCR: the ratio of whole somatic surface length and that covered with axon terminals) and the density of axon terminals in contact with somatic profiles (DAST: the number of axosomatic terminals per 100 μm of somatic surface membrane) were calculated in each neuronal somatic profile over 60 μm in diameter. The mean BCR was61.4±1.43 (S.E.M.) %. The mean DAST of axosomatic terminals filled with spherical synaptic vesicles (S-terminals) was27.7±0.95, and that of terminals with plemorphic and/or flattened vesicles (F-terminals) was 10.3±1.12.

Subsequently, sequential changes of the BCR and DAST of intact terminals were examined in the RN deafferented from the cerebellorubral fibers. The mean BCR and DAST were decreased most markedly during the survival period of 4–7 days; thus decrease was chiefly due to degeneration of S-terminals (BCR:16.7±1.17%, DAST of S-terminals: 7.1±1.12, DAST of F-terminals: 5.8±1.22). In the RN 11–63 days after the operation, both the BCR and DAST tended to re-increase slightly and the majority of the re-increased terminals appeared to be F-terminals. Possible meanings of this re-increase of axosomatic terminals are discussed.

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