Letter | Published:

Characteristics of Excitatory and Inhibitory Synapses in the Central Nervous System of the Cat

Naturevolume 207pages642643 (1965) | Download Citation



ELECTRON microscopic investigations by Gray1,2, De Lorenzo3 and Hamlyn4 suggest that there are three types of patches of membrane density in the synaptic contacts of the central nervous system, of which only two are functional (Gray's type 1 and type 2). However, no criterion has yet been established to distinguish the excitatory synapses from the inhibitory ones. In the peripheral autonomic nervous system two types of synaptic vesicles (cholinergic and adrenergic) have been found, the former having a diameter of 500 Å with clear content, while the latter have a diameter of 1000 Å with granular cores5–7. So-called granulated vesicles have also been discovered by Shimizu8 in the hypothalamus of mammals. Gray's classification hints that the type 1 synapse is excitatory, whereas the type 2 is inhibitory9.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.


  1. 1

    Gray, E. G., J. Anat., 93, 420 (1959).

  2. 2

    Gray, E. G., J. Anat., 95, 345 (1961).

  3. 3

    De Lorenzo, A. J., Bull. Johns Hopkins Univ., 108, 258 (1961).

  4. 4

    Hamlyn, L. H., J. Anat., 96, 112 (1962).

  5. 5

    Wolfe, D. E., et al., Science, 440 (1963).

  6. 6

    Uchizono, K., Jap. J. Physiol., 14, 210 (1964).

  7. 7

    Uchizono, K., Jap. J. Physiol., 14, 587 (1964).

  8. 8

    Shimizu, N. (submitted for publication).

  9. 9

    Eccles, J. C., Physiology of Synapses, 16 (Springer, Berlin, 1964).

Download references

Author information


  1. Department of Physiology, Faculty of Medicine, University of Tokyo



  1. Search for KOJI UCHIZONO in:

About this article

Publication history

Issue Date



Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.