Ultrastructural analysis of axosomatic contacts on functionally identified primate spinothalamic tract neurons

S. M. Carlton, C. C. Lamotte, C. N. Honda, D. J. Surmeier, N. Delanerolle, W. D. Willis

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    Abstract

    The morphology and frequency of axosomatic contacts on three functionally identified primate spinothalamic tract (STT) cells were analyzed at the electron microscopic level. The STT cells analyzed were wide‐dynamic‐range neurons responsive to activation of low‐ and high‐threshold cutaneous afferents innervating the foot. The somas were located in the lateral border of lamina V; the dendritic trees were oriented dorsally and were very extensive. Numerous spinelike appendages were observed emanating from two of the cell bodies. Terminal types contacting the cell bodies were categorized at several different layers through each neuron. Six morphologically different terminal types were established following analysis of serial sections. Profiles classified as round (R) terminals containing round clear vesicles and zero or one densecore vesicle made up over 50% of the total population in contact with the STT somas. Profiles containing round clear vesicles and two to four small‐diameter dense‐core vesicles (D1 category) made up approximately 10% of the population in contact with each soma. Flat (F) terminals with oblong or flattened clear vesicles made up approximately 8% of the population. The remaining three categories (D2, L1, and L2) distinguished by the number and size of the dense‐core vesicles made up a small percentage of the total population in contact with the cell bodies. The distribution of terminal types on the soma proper versus somatic spines was also determined for one cell. The proportions of the six terminal types contacting the soma of these cells were very similar, although the physiological characteristics of each cell were different. However, the relative proportions of terminal types on these three lamina V STT cell bodies were different from those previously reported contacting somata in lamina V, suggesting that there may be a unique innervation of STT cells that differentiates them from other cell types in lamina V.

    Original languageEnglish (US)
    Pages (from-to)555-566
    Number of pages12
    JournalJournal of Comparative Neurology
    Volume281
    Issue number4
    DOIs
    StatePublished - Mar 22 1989

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    Keywords

    • ascending systems
    • electron microscopy
    • nociception

    ASJC Scopus subject areas

    • Neuroscience(all)

    Cite this

    Carlton, S. M., Lamotte, C. C., Honda, C. N., Surmeier, D. J., Delanerolle, N., & Willis, W. D. (1989). Ultrastructural analysis of axosomatic contacts on functionally identified primate spinothalamic tract neurons. Journal of Comparative Neurology, 281(4), 555-566. https://doi.org/10.1002/cne.902810406