Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 7-Day Trial for You or Your Team.

Learn More →

Monosynaptic projections from the nucleus retroambiguus to motoneurons supplying the abdominal wall, axial, hindlimb, and pelvic floor muscles in the female rhesus monkey

Monosynaptic projections from the nucleus retroambiguus to motoneurons supplying the abdominal... The nucleus retroambiguus (NRA) consists of premotor neurons in the caudal medulla. It is involved in expiration, vomiting, vocalization, and probably reproductive behavior by means of projections to distinct motoneuronal cell groups. Because no information is available about the NRA and its efferent pathways in primates, the present study examines NRA projections to the lumbosacral spinal cord in female rhesus monkeys. To identify the NRA, wheat germ agglutinin‐horseradish peroxidase (WGA‐HRP) was injected into the lumbosacral cord in three monkeys. To study the distribution of NRA axons in the lumbosacral cord, WGA‐HRP injections were made into the NRA in seven monkeys. To identify motoneuronal cell groups receiving input from the NRA, the same seven monkeys also received cholera toxin subunit b (CTb) injections into different hindlimb, axial, and pelvic floor muscles. The results show that NRA neurons projecting to the lumbosacral cord are mainly located between 1 to 4 mm caudal to the obex. They send numerous axons to external oblique and pelvic floor motoneurons, whereas projections to iliopsoas and axial motoneurons are less numerous. The projections are bilateral, but show a clear contralateral predominance in the iliopsoas, axial, and pelvic floor motoneuronal cell groups. At the ultrastructural level, NRA‐terminal profiles make asymmetrical contacts with labeled and unlabeled dendrites in these motoneuronal cell groups and contain large amounts of spherical and a few dense core vesicles. It is concluded that the NRA is well developed in the monkey and that there exists a direct pathway from the NRA to lumbosacral motoneurons in this species. The finding that the NRA projects to a somewhat different set of motoneuronal cell groups compared with other species fits the concept that it is not only involved in expiration‐related activities but also in species specific receptive and submissive behavior. J. Comp. Neurol. 424:233–250, 2000. © 2000 Wiley‐Liss, Inc. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Comparative Neurology Wiley

Monosynaptic projections from the nucleus retroambiguus to motoneurons supplying the abdominal wall, axial, hindlimb, and pelvic floor muscles in the female rhesus monkey

Download PDF
18 pages

Loading next page...
 
/lp/wiley/monosynaptic-projections-from-the-nucleus-retroambiguus-to-motoneurons-D0DvshIhvV

References (63)

Publisher
Wiley
Copyright
"Copyright © 2000 Wiley Subscription Services, Inc., A Wiley Company"
ISSN
0021-9967
eISSN
1096-9861
DOI
10.1002/1096-9861(20000821)424:2<233::AID-CNE4>3.0.CO;2-C
Publisher site
See Article on Publisher Site

Abstract

The nucleus retroambiguus (NRA) consists of premotor neurons in the caudal medulla. It is involved in expiration, vomiting, vocalization, and probably reproductive behavior by means of projections to distinct motoneuronal cell groups. Because no information is available about the NRA and its efferent pathways in primates, the present study examines NRA projections to the lumbosacral spinal cord in female rhesus monkeys. To identify the NRA, wheat germ agglutinin‐horseradish peroxidase (WGA‐HRP) was injected into the lumbosacral cord in three monkeys. To study the distribution of NRA axons in the lumbosacral cord, WGA‐HRP injections were made into the NRA in seven monkeys. To identify motoneuronal cell groups receiving input from the NRA, the same seven monkeys also received cholera toxin subunit b (CTb) injections into different hindlimb, axial, and pelvic floor muscles. The results show that NRA neurons projecting to the lumbosacral cord are mainly located between 1 to 4 mm caudal to the obex. They send numerous axons to external oblique and pelvic floor motoneurons, whereas projections to iliopsoas and axial motoneurons are less numerous. The projections are bilateral, but show a clear contralateral predominance in the iliopsoas, axial, and pelvic floor motoneuronal cell groups. At the ultrastructural level, NRA‐terminal profiles make asymmetrical contacts with labeled and unlabeled dendrites in these motoneuronal cell groups and contain large amounts of spherical and a few dense core vesicles. It is concluded that the NRA is well developed in the monkey and that there exists a direct pathway from the NRA to lumbosacral motoneurons in this species. The finding that the NRA projects to a somewhat different set of motoneuronal cell groups compared with other species fits the concept that it is not only involved in expiration‐related activities but also in species specific receptive and submissive behavior. J. Comp. Neurol. 424:233–250, 2000. © 2000 Wiley‐Liss, Inc.

Journal

The Journal of Comparative Neurology – Wiley

Published: Sep 21, 2001

Keywords: ; ; ; ; ;

There are no references for this article.