The motoneurons of the spinal cord of the frog

Silver, Maurice L.

doi:10.1002/cne.900770102

Cited by 96 publications

(34 citation statements)

References 11 publications

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“…4A, arrowhead). We did not find clear separation between ventromedial (axial) and ventrolateral (limb) MN groups that have been described for the frog (Silver, 1942;Kennard, 1959;Stensaas and Stensaas, 1971;Szekely, 1976). However, the largest MN somata (30 -50 m) tended to occur more laterally than somewhat smaller cells (20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)Figs.…”

Section: Motoneuronscontrasting

confidence: 72%

“…4, 15A) that has been described for fish and amphibians (Silver, 1942;Kennard, 1959;AriensKappers et al, 1960;Szekely, 1976;Szekely and Czeh, 1976;Cajal, 1995). Terminal branches of MN dendrites approached the pial membrane with radial orientation but then bent in various directions finally to run more or less parallel to the surface after splitting into fine terminal twigs.…”

Section: Subpial Plexusmentioning

confidence: 88%

“…1, 3) was quite unexpected, given available descriptions of amphibian spinal cords (Silver, 1942;Kennard, 1959;Stensaas and Stensaas, 1971;Szekely, 1976;Szekely and Czeh, 1976;Cajal, 1995). It remains to be seen whether this is a feature of other neotenic amphibians that are sexually mature but retain certain larval features, such as external gills.…”

Section: Gray Mattermentioning

confidence: 97%

“…With the exception of work on axial motoneurons (Fetcho, 1986) and marginal neurons (Schroeder and Egar, 1990), the available information is scarce and pertains mostly to the early stages of development in related species, including Ambystoma (Coghill, 1913;Herrick, 1948), Salamandra (van Gehuchten, 1897; see also Cajal, 1995, for other references), and Triturus (Blight, 1978;Harper and Roberts, 1993). In contrast to a relatively extensive literature on spinal cord anatomy in anurans (Silver, 1942;Kennard, 1959;Stensaas and Stensaas, 1971;Llinas and Precht, 1976;Szekely, 1976;Szekely and Czeh, 1976;Schotland and Tresch, 1997), there is less information in classical anatomical studies of tailed amphibians (Urodele). Herrick's monumental work on Ambystoma (1948) and Necturus (see Herrick, 1948, for references) omits this region, and to date detailed morphological features of the brachial spinal cord in adult Necturus have not been described.…”

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confidence: 99%

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Morphology of brachial segments in mudpuppy (Necturus maculosus) spinal cord studied with confocal and electron microscopy

Jovanovic

Burke

2004

J of Comparative Neurology

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The isolated brachial spinal cord of Necturus maculosus is useful for studies of neural networks underlying forelimb locomotion, but information about its cellular morphology is scarce. We addressed this issue by using confocal and electron microscopy. Remarkably, the central region of gray matter was aneural and consisted exclusively of a tenuous meshwork of glial fibers and large extracellular spaces. Somata of motoneurons (MNs) and interneurons (INs), labeled by retrograde transport of fluorescent tracers from ventral roots and axons in the ventrolateral funiculus, respectively, were confined within a gray neuropil layer abutting the white matter borders, whereas their dendrites projected widely throughout the white matter. About one-third of labeled INs were found contralaterally, with axons crossing ventral to a thick layer of ependyma surrounding the central canal. Lateral MN dendrites proliferated under the pial surface to form a dense, thin (1-2 m) plexus immediately beneath a thin layer of glial fibrillary acidic protein-positive glia limitans. The latter contained arrays of unusual tubular structures (diameter 200 -400 nm, length 3 m) that resembled mitochondria but lacked double membranes or cristae. Dorsal roots (DRs) produced dense presynaptic arbors within a wedge-shaped afferent termination zone medial to the dorsal root entry, within which dendrites of MNs and INs mingled with dense collections of synaptic boutons. Our data suggest that a major fraction of synaptic interactions takes place within the white matter. This study provides a detailed foundation for designing electrophysiological experiments to study the neural circuits involved in locomotor pattern generation.

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Section: Motoneuronscontrasting

confidence: 72%

Section: Subpial Plexusmentioning

confidence: 88%

Section: Gray Mattermentioning

confidence: 97%

mentioning

confidence: 99%

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Morphology of brachial segments in mudpuppy (Necturus maculosus) spinal cord studied with confocal and electron microscopy

Jovanovic

Burke

2004

J of Comparative Neurology

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“…The latter authors also failed to see an excitant action of curare on the preparation, as described by Eccles (1946) (Eccles, Fatt & Koketsu, 1954;Eccles, Eccles & Fatt, 1956;Curtis, Phillis & Watkins, 1961b). The presence of motor axon collaterals in the frog has been confirmed by Silver (1942 (Straughan, 1960;Krnjevi6 & Mitchell, 1961) and cerebral cortex (Mitchell, 1962 Calabro, 1933;Bergami, 1936;and Lissak, 1939) A similar argument can be applied to the result obtained with direct stimulation of the spinal cord. The greatest density of motoneurones in the amphibian spinal cord lies in the regions of brachial and lumbar enlargements from which the nerve plexuses to the limbs arise (Silver, 1942), with fewer in the intervening area.…”

Section: Discussionmentioning

confidence: 76%

Cholinergic Transmission in the Frog Spinal Cord

Mitchell

Phillis

1962

British Journal of Pharmacology and Chemotherapy

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The effect of acetylcholine and other drugs has been tested on the isolated and sagittally hemisected spinal cord of the frog (Rana temporaria). The release of acetylcholine from this preparation during stimulation of the spinal roots and whole hemicord has also been studied. After inactivation of the tissue cholinesterases acetylcholine was released spontaneously from the preparation at a steady rate of about 5.5 pmole/15 min/preparation. No increase in this release was obtained by stimulating the dorsal roots, but antidromic stimulation of the ventral roots always gave an increase in the rate of acetylcholine release up to 2.3 times the spontaneous level. Direct stimulation of the spinal cord did not alter the rate of acetylcholine release. Acetylcholine (1 mm) and eserine (10 mM) had weak excitatory actions and prolonged the reflex response of the preparation during dorsal root stimulation, but dihydro-,8-erythroidine and atropine had no effect. The response evoked by antidromic ventral root stimulation was potentiated by eserine (10 rM) and depressed by acetylcholine (10 MM) and dihydro-18-erythroidine (1 lAM) as in the toad preparation.The evidence supporting cholinergic transmission at some synapses in the spinal cord is discussed in relation to these results.In a previous paper (Kiraly & Phillis, 1961) it was suggested that the slow depolarizing dorsal root potentials evoked by stimulation of adjacent ventral roots of the toad spinal cord were generated along a neuronal pathway containing at least one cholinergic synapse. It was further suggested that this synapse might be similar, anatomically and pharmacologically, to the synapse between motor axon collaterals and Renshaw cells in the cat.It is generally considered (Crossland, 1957;Paton, 1958) that, to qualify as a synaptic transmitter agent, the postulated substance should be released during stimulation of the appropriate pre-synaptic elements. Hence it was felt that the demonstration of an increased acetylcholine content in the solution bathing the isolated frog spinal cord during ventral root stimulation would provide further evidence of cholinergic synapses in the ventral root-dorsal root pathway.

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Organization of lumbosacral motoneuronal cell groups innervating hindlimb, pelvic floor, and axial muscles in the cat

1997

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In a study on descending pathways from the nucleus retroambiguus (NRA) to hindlimb motoneurons (see accompanying paper), it appeared impossible, using data from the literature, to precisely determine which muscles were innervated by the motoneurons receiving the NRA fibers. This lack of data made it necessary to produce a detailed map of the lumbosacral motoneuronal cell groups in the cat. Therefore, 50 different muscles or muscle compartments of hindlimb, pelvic floor and lower back were injected with horseradish peroxidase (HRP) in 135 cases. The respective muscles were divided into ten groups: I, sartorius and iliopsoas; II, quadriceps; III, adductors; IV, hamstrings; V, gluteal and other proximal muscles of the hip; VI, posterior compartment of the distal hindlimb; VII, anterior compartment of the distal hindlimb; VIII, long flexors and intrinsic muscles of the foot; IX, pelvic floor muscles; and X, extensors of the lower back and tail. The L4-S2 segments were cut and incubated, and labeled motoneurons were counted and plotted. A new method was developed that made it possible, despite variations in size and segmental organization between the different cases, to compare the results of different cases. The results show that the spatial interrelationship between the hindlimb and pelvic floor lumbosacral motoneuronal cell groups remains constant. This finding enabled the authors to compose an accurate overall map of the location of lumbosacral motoneuronal cell groups. The general distribution of the motoneuronal cell groups is also discussed in respect to their dorsoventral, mediolateral, and rostrocaudal position within the lumbosacral ventral horn.

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The motoneurons of the spinal cord of the frog

Cited by 96 publications

References 11 publications

Morphology of brachial segments in mudpuppy (Necturus maculosus) spinal cord studied with confocal and electron microscopy

Morphology of brachial segments in mudpuppy (Necturus maculosus) spinal cord studied with confocal and electron microscopy

Cholinergic Transmission in the Frog Spinal Cord

Organization of lumbosacral motoneuronal cell groups innervating hindlimb, pelvic floor, and axial muscles in the cat

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