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Studies on unmyelinated axons and varicosities in the olfactory cortex

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Summary

The main afferent input to the olfactory cortex from the olfactory bulbs is via the lateral olfactory tract (LOT). The axons within the lateral olfactory tract are myelinated. On leaving the LOT, they lose their myelination as they fan out over the layer immediately beneath the pial surface to make en passant synaptic connections with dendrites from neurones within the olfactory cortex. Using the guinea-pig, a semiquantitative electron micrographical study was made of the density and dimensions of these unmyelinated axons and the varicosities they create. The unmyelinated axons were very fine (0.17 ± 0.004 μm in diameter) and punctuated at 2 μm intervals by varicosities containing a single type of vesicle. The electrophysiological consequences of this close varicosity spacing is that axonal and varicosity membranes behave electrically as single units.

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Authors and Affiliations

  1. School of Basic Medical Sciences-Physiology, Queens University Belfast, 97 Lisburn Road, BT9 7BL, Belfast, UK

    A. Gracey & C. N. Scholfield

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  1. A. Gracey
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  2. C. N. Scholfield
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Gracey, A., Scholfield, C.N. Studies on unmyelinated axons and varicosities in the olfactory cortex. Exp Brain Res 80, 436–440 (1990). https://doi.org/10.1007/BF00228171

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  • DOI: https://doi.org/10.1007/BF00228171

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