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Spinal termination of functionally identified primary afferent neurons with slowly conducting myelinated fibers

Spinal termination of functionally identified primary afferent neurons with slowly conducting... Single primary afferent myelinated fibers from cutaneous receptors of cat and monkey were functionally identified by recording from the spinal cord with micropipettes filled with horseradish peroxidase (HRP). Relatively slowly conducting fibers (< 40 m/sec) from high threshold mechanoreceptors (mechanical nociceptors) and two types of low threshold mechanoreceptor (D‐hair and field) were selected for staining. Iontophoresis of the HRP and subsequent histochemical reaction stained the axons recorded from and their collaterals, including terminations, for several millimeters. The termination patterns in the two species proved essentially identical. Ipsilaterally, the mechanical nociceptor fibers terminated principally in the dorsal horn's marginal zone and in the ventral parts of the nucleus proprius (lamina V in the cat). Some of these nociceptors also had terminals in the midline just dorsal to the central canal, contralaterally in the marginal zone, and at the base of the opposite nucleus proprius. In contrast, the D‐hair primary afferent axons terminated in the dorsal part of the nucleus proprius overlapping into the innermost portion of the substantia gelatinosa. The field receptor fibers terminated predominantly in the middle part of the nucleus proprius. These results suggest that there is a highly specialized central projection of primary afferent endings which is related to sensory function and not to fiber diameter. The marginal zone and most dorsal parts of the substantia gelatinosa receive direct projections from cutaneous nociceptors but do not have direct input from cutaneous receptors transmitting activity initiated by innocuous stimulation. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Comparative Neurology Wiley

Spinal termination of functionally identified primary afferent neurons with slowly conducting myelinated fibers

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References (60)

Publisher
Wiley
Copyright
"Copyright © 1979 Wiley Subscription Services, Inc., A Wiley Company"
ISSN
0021-9967
eISSN
1096-9861
DOI
10.1002/cne.901860203
pmid
109477
Publisher site
See Article on Publisher Site

Abstract

Single primary afferent myelinated fibers from cutaneous receptors of cat and monkey were functionally identified by recording from the spinal cord with micropipettes filled with horseradish peroxidase (HRP). Relatively slowly conducting fibers (< 40 m/sec) from high threshold mechanoreceptors (mechanical nociceptors) and two types of low threshold mechanoreceptor (D‐hair and field) were selected for staining. Iontophoresis of the HRP and subsequent histochemical reaction stained the axons recorded from and their collaterals, including terminations, for several millimeters. The termination patterns in the two species proved essentially identical. Ipsilaterally, the mechanical nociceptor fibers terminated principally in the dorsal horn's marginal zone and in the ventral parts of the nucleus proprius (lamina V in the cat). Some of these nociceptors also had terminals in the midline just dorsal to the central canal, contralaterally in the marginal zone, and at the base of the opposite nucleus proprius. In contrast, the D‐hair primary afferent axons terminated in the dorsal part of the nucleus proprius overlapping into the innermost portion of the substantia gelatinosa. The field receptor fibers terminated predominantly in the middle part of the nucleus proprius. These results suggest that there is a highly specialized central projection of primary afferent endings which is related to sensory function and not to fiber diameter. The marginal zone and most dorsal parts of the substantia gelatinosa receive direct projections from cutaneous nociceptors but do not have direct input from cutaneous receptors transmitting activity initiated by innocuous stimulation.

Journal

The Journal of Comparative Neurology – Wiley

Published: Mar 15, 1980

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