PubMed Health⌕ Search

Biomedical subjects

M Satou

Publications and source records attributed to M Satou.

At least 73 records · Page 4Linked to original sources
PubMed1989

Neuronal organization of the supracommissural ventral telencephalon and the nucleus preopticus periventricularis in the himé salmon (landlocked red salmon, Oncorhynchus nerka): a Golgi study.

The neuronal organization of the supracommissural ventral telencephalon (Vs) and the nucleus preopticus periventricularis (NPP) of the medial preoptic area (MPOA) in the himé salmon (landlocked red salmon, Oncorhynchus nerka) was studied by means of the Nissl staining and the rapid Golgi methods. The Vs was composed of many laterally-orienting spiny neurons and a few sparsely-spined polymorphous neurons. Some of the laterally-orienting neurons extended their dendrites into the lateral forebrain bundle (LFB), suggesting that they may receive inputs from the telencephalofugal and telencephalopetal fibers in the LFB. The NPP consisted of five types of sparsely-spined neurons: laterally-orienting, bipolar, cerebrospinal fluid (CSF)-contacting, commissural, and multipolar neurons. Some of the laterally-orienting neurons extended their dendrites into the medial forebrain bundle (MFB) and regions near the LFB, suggesting that they may also receive inputs from the telencephalofugal and telencephalopetal fibers running there. The presence of the CSF-contacting neurons in the NPP suggests that the NPP may receive humoral informations from the CSF. Involvement of these CSF-contacting neurons in the control of the reproductive functions was discussed. The neuronal organization of the NPP in the himé salmon was compared with that of the MPOA in other vertebrates.

Animals↗
PubMed1988

Morphology of physiologically identified mitral cells in the carp olfactory bulb: a light microscopic study after intracellular staining with horseradish peroxidase.

Physiologically identified mitral cells in the carp olfactory bulb were stained by intracellular injection of horseradish peroxidase in order to study the morphology in detail. The somata were fusiform, elongated, oval, triangular, or irregular. The mean diameters of the somata were 30 microns X 14 microns. Two to five thick dendrites arose from the somata and frequently gave off branches to form glomerular tufts. The dendrites extended less than 400 microns; the dendritic field of single mitral cells in the medial or lateral part of the olfactory bulb was confined within the respective part of the bulb. The axons arose from either the somata or the dendrites and had a conical initial portion, usually with a smooth contour. Some cells had poorly developed intrabulbar axon collaterals. No difference between the mitral cells in the medial part of the olfactory bulb and those in the lateral part was found in the soma diameter, the dendritic diameter at the base, or the number of first-order dendrites. However, there was a difference in the site of the origin of the axon between them: most of the axons of the mitral cells in the medial part arose from the dendrites, while most of the axons of the mitral cells in the lateral part arose from the somata. The morphology of physiologically identified mitral cells is basically consistent with that reported in the Golgi studies of teleosts. The limited dendritic fields of mitral cells may underlie the previously reported functional separation of the olfactory bulb into medial and lateral parts. The results also indicate that the two parts of the teleost olfactory bulb are differentiated not only functionally but also morphologically.

Action Potentials↗
PubMed1988

Neuronal pathways for the lingual reflex in the Japanese toad.

1. Anuran tongue is controlled by visual stimuli for releasing the prey-catching behavior ('snapping') and also by the intra-oral stimuli for eliciting the lingual reflex. To elucidate the neural mechanisms controlling tongue movements, we analyzed the neuronal pathways from the glossopharyngeal (IX) afferents to the hypoglossal (XII) tongue-muscle motoneurons. 2. Field potentials were recorded from the bulbar dorsal surface over the fasciculus solitarius (fsol) to the electrical stimulation of the ipsilateral IX nerve. They were composed of three successive negative waves: S1, S2 and N wave. The S1 and S2 waves followed successive stimuli applied at short intervals (10 ms or less), whereas the N wave was strongly suppressed at intervals shorter than 500 ms. Furthermore, the S1 wave had lower threshold than the S2 wave. 3. Orthodromic action potentials were intra-axonally recorded from IX afferent fibers in the fsol to the ipsilateral IX nerve stimuli. Two peaks found in the latency distribution histogram of these action potentials well coincided with the negative peaks of the S1 and the S2 waves of the simultaneously recorded field potentials. Therefore, the S1 and S2 waves should represent the compound action potentials of two groups of the IX afferent fibers with different conduction velocities. 4. Ipsilateral IX nerve stimuli elicited excitatory postsynaptic potentials (EPSPs) in the tongue-protractor motoneurons (PMNs) and the tongue-retractor motoneurons (RMNs). Inhibitory postsynaptic potentials were not observed. 5. The EPSPs recorded in PMNs had mean onset latencies of 6.4 ms measured from the negative peaks of the S1 wave. The EPSPs were facilitated when paired submaximal stimuli were applied at intervals shorter than 20 ms, but were suppressed at intervals longer than 30 ms. Furthermore, the EPSPs were spatially facilitated when peripherally split two bundles of the IX nerve were simultaneously stimulated. 6. On the other hand, the EPSPs recorded in RMNs had shorter onset latencies, averaging 2.5 ms. In 14 of 43 RMNs, early and late EPSP components could be reliably discriminated. The thresholds for the early EPSP components were as low as those for the S1 waves, whereas for the late EPSP components the thresholds were usually higher than those for the S2 waves.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1987

Direct contacts between glossopharyngeal afferent terminals and hypoglossal motoneurons revealed by double labeling with cobaltic-lysine and horseradish peroxidase in the Japanese toad.

Glossopharyngeal (IX) afferents and hypoglossal (XII) motoneurons of the Japanese toad were simultaneously labeled with cobaltic-lysine and horseradish peroxidase, respectively. Some of the terminal branches of the IX afferents had direct contacts with the dorsal dendrites, the lateral dendrites and the somata of the XII motoneurons, but not with the medial dendrites. Such direct contacts mainly occurred in the rostral region of the dorsomedial XII nucleus, where tongue-retractor motoneurons predominate, but not in the caudal region nor in the ventrolateral XII nucleus.

Animals↗
PubMed1987

Horseradish peroxidase study of the localization of motoneurons in the accessory nucleus (XI) of the Japanese toad.

It has been conventionally accepted that the anuran accessory nerve (nXI) only innervates the musculus cucullaris (C). However, we have found that the nXI of the Japanese toad innervated the musculus interscapularis (IS) in addition to the C. The motoneurons innervating these muscles were labelled by the intramuscular injection of horseradish peroxidase (HRP). In the accessory nucleus (XI), the motoneurons were somatotopically organized: the C motoneurons were localized more rostrally, while the IS motoneurons more caudally.

Accessory Nerve↗
PubMed1987

Cobaltic lysine study of the morphology and distribution of the cranial nerve efferent neurons (motoneurons and preganglionic parasympathetic neurons) and rostral spinal motoneurons in the Japanese toad.

The morphology and distribution of the cranial nerve motoneurons (except III, IV, and VI) and rostral spinal motoneurons were systematically studied in the Japanese toad (Bufo japonicus) by retrograde labelling with cobaltic lysine complex. The cobaltic lysine clearly labelled whole neurons, i.e., cell bodies, proximal and distal dendrites, and axons. The branchial motoneurons (V, VII, IX, and X) had similar morphological characteristics and formed a more-or-less continuous cell column through the brainstem. The dendrites could be grouped mainly into the dorsomedial and the ventrolateral dendritic arrays. The dorsomedial dendrites formed a dendritic plexus in the subependymal gray matter, which extended as far peripherally as beneath the ependymal layer. The ventrolateral dendrites formed a broom-like dendritic plexus in the lateral to ventrolateral white matter. They usually extended as far peripherally as the pial surface. The rostrocaudal extent of the dendritic field was also wide and usually exceeded the motor nuclear boundaries. The hypoglossal motoneurons were grouped into the dorsomedial and ventrolateral cell groups, and the latter was considered to be part of the rostral spinal motoneuron column, from their morphology and distribution. The former had well-differentiated dendrites and occupied a more medial position than the branchial motoneurons. Besides the equivalent of the dorsomedial and ventrolateral dendritic arrays of the branchial motoneurons, they had dorsal and commissural dendrites. The accessory motoneurons had morphological characteristics and a distribution pattern similar to those of the rostral spinal motoneurons rather than the branchial motoneurons. The rostral spinal motoneurons had morphological characteristics somewhat different from the branchial motoneurons and the hypoglossal motoneurons (dorsomedial group). Functional implications of the motoneuron morphology are discussed, mainly based on the present results and earlier anatomical and physiological studies of the spinal motoneurons. The present study also revealed the anatomical features of the preganglionic parasympathetic neurons supplying some cranial nerves. These neurons had small somata with less elaborate dendrites and formed an almost continuous cell column that occupied a more dorsal position than the motoneurons of the corresponding nerve. They are thought to be homologous to the salivatory nucleus and the dorsal motor nucleus of the vagus. The basic anatomical organization of the general visceral efferent column seems to be similar throughout vertebrates.

Accessory Nerve↗
PubMed1987

Distribution of motoneurons involved in the prey-catching behavior in the Japanese toad, Bufo japonicus.

Coordinated activities of several muscles in the head region underlie the prey-catching behavior of anuran amphibians. As a step in elucidating the neural mechanisms generating these activity patterns in the Japanese toad, we labelled the motoneurons innervating 8 behaviorally relevant muscles using intramuscular (i.m.) injection technique of horseradish peroxidase (HRP), and examined their localization within the motor nuclei whose boundaries were determined by HRP application to the nerve trunk. All the motoneurons innervating the two jaw closer muscles (m. masseter major, m. temporalis) and m. submentalis were localized within the rostral subdivision of the trigeminal motor nucleus. The motoneurons innervating the only mouth opener muscle (m. depressor mandibulae) were scattered throughout the facial motor nucleus. The motoneurons innervating tongue (m. hypoglossus, m. genioglossus) and hyoid muscles (m. sternohyoideus, m. geniohyoideus) appeared within the hypoglossal nucleus with distribution patterns characteristic of the target muscles. Thus, we have revealed the neuroanatomical organization of the motoneurons relevant to the prey-catching behavior.

Animals↗
PubMed1987

An improved method for correlative light and electron microscopic examination of cobaltic-lysine-labelled neurons.

We describe an improved method for correlative light and electron microscopic examination of synaptic organization of neurons extracellularly labelled by the axonal transport of cobaltic-lysine (Co-lys). After filling the neurons with Co-lys and precipitating the CoS, the brain is fixed in a double-aldehyde fixative, and thick slices are cut using a Microslicer. The slices are intensified using a physical developer, postfixed in OsO4 and embedded in resin. By cutting alternating semithin and ultrathin sections, it is possible to specify sites and types of synaptic contacts on labelled neuronal profiles.

Animals↗
PubMed1987

Morphology and distribution of the motor neurons of the accessory nerve (nXI) in the Japanese toad: a cobaltic lysine study.

Motoneurons supplying the accessory nerve (nXI) of the Japanese toad were retrogradely labelled by applying the cobaltic lysine to the cut end of the nerve. They had morphological characteristics and a distribution pattern similar to those of the rostral spinal motoneurons rather than the branchial motoneurons. We propose that the anuran nXI is equivalent to the so-called spinal portion of the nXI of other vertebrates, and both should be regarded as part of the rostral spinal nerves rather than the nerve accessory to the vagus nerve.

Accessory Nerve↗
PubMed1987

Morphology and distribution of the preganglionic parasympathetic neurons of the facial, glossopharyngeal and vagus nerves in the Japanese toad: a cobaltic lysine study.

We labelled the preganglionic parasympathetic neurons of the facial, glossopharyngeal and vagus nerves of the Japanese toad by applying the cobaltic lysine to the cut end of the respective nerve, and examined their morphology and distribution. These neurons form an almost continuous cell column consisting of small neurons with less elaborate dendrites, and occupy a more dorsal position than the motoneurons of the corresponding nerves. The results suggest the presence of the amphibian homologues of the salivatory nucleus and the dorsal motor nucleus of the vagus.

Animals↗
PubMed1986

Descending pathways to the spinal cord in the himé salmon (landlocked red salmon, Oncorhynchus nerka).

Distribution and morphology of the cells of origin of the descending spinal pathways and their axonal courses were studied in the himé salmon, using retrograde labelling with cobaltic lysine and horseradish peroxidase (HRP). Following application of the tracers to the cut end of the spinal cord or injection of the tracers at the 10th to 15th spinal segment, neurons mainly labelled via the axons of passage were distributed in the mesencephalon and the rhombencephalon. Mesencephalic cell groups consisted of the nucleus pretectalis, the nucleus fasciculi longitudinalis medialis, and the nucleus ruber. The former two cell groups sent their axons to the fasciculus longitudinalis medialis. The axons of the nucleus ruber formed a separate loose bundle, the "tractus rubrospinalis." The rhombencephalic cell groups consisted of the rhombencephalic reticular formation, the Mauthner cells (one cell for each side), and the octavolateral area. The rhombencephalic reticular formation could be further subdivided into the nucleus reticularis superior, nucleus reticularis medius, and nucleus reticularis inferior. The axons of these cell groups joined the fasciculus longitudinalis medialis and the "tractus bulbospinalis." The Mauthner cell had two main gigantic dendrites, and its giant axons formed a conspicuous fiber of Mauthner throughout the rhombencephalon down to the spinal cord. The octavolateral area could be subdivided into the nucleus vestibularis magnocellularis, nucleus tangentialis, nucleus vestibularis descendens and nucleus intermedius. The axons of the nucleus vestibularis magnocellularis and nucleus intermedius entered the fasciculus longitudinalis medialis and/or the tractus bulbospinalis. Those of the nucleus vestibularis descendens and nucleus tangentialis formed the "tractus vestibulospinalis". The descending spinal pathways of the himé salmon were compared with those of other fishes and other vertebrates. The significance of these descending spinal pathways in the control of locomotion and sexual behavior is also discussed.

Animals↗
PubMed1986

Ascending pathways from the spinal cord in the himé salmon (landlocked red salmon, Oncorhynchus nerka).

The ascending pathways from the spinal cord of the himé salmon were anterogradely labelled by the cobaltic lysine method, and their courses and terminations were examined. Following application of the cobaltic lysine to the cut end of the spinal cord or injection of the cobalt at the 10th to 15th spinal segment, labelled axons were traced from the spinal cord to various regions in the rhombencephalon and the mesencephalon. The axons ascending from the dorsal funiculus gave off many terminals as they ascended to the lower medulla. This terminal area may be homologous to the nucleus funiculi dorsalis of other vertebrates, although cytoarchitectural differentiation of the area is not evident. The dorsal funicular fibers also formed some terminals in the vagus and glossopharyngeal motor nuclei and the nucleus fasciculi solitarii. The axons arising from the anterolateral funiculus ascended as the common trunk of the lemniscus spinalis. The lemniscus spinalis fibers distributed many axon terminals on their way through the lower medulla, and most probably made synaptic contacts with the peripheral dendrites of the cells of origin of the reticulospinal pathways throughout its rostrocaudal extent. They also projected to all the medullary cranial nerve motor nuclei (V, VI, VII, IX, and X). The rostral continuation of the lemniscus spinalis fibers entered the lemniscus lateralis and gave a rostrocaudally elongated terminal area in the nucleus lateralis of the torus semicircularis.(ABSTRACT TRUNCATED AT 250 WORDS)

Afferent Pathways↗
PubMed1986

Glossopharyngeal and tectal influences on tongue-muscle motoneurons in the Japanese toad.

Anuran tongue-muscle motoneurons receive excitatory inputs both from the glossopharyngeal nerve afferents and from the optic tectum. As a step toward elucidating the neural bases for controlling the tongue movements, we searched intracellularly for the neuronal pathways from the glossopharyngeal afferents to the tongue-muscle motoneurons in paralyzed Japanese toads. The electrical stimuli applied to the glossopharyngeal nerve (ipsilateral lingual branch) evoked polysynaptic excitatory postsynaptic potentials (EPSPs) in tongue-protractor motoneurons and mixed mono- and polysynaptic EPSPs in tongue-retractor motoneurons. Furthermore, we investigated the mode of the convergency of the excitatory inputs from the glossopharyngeal nerve and those from the optic tectum. A spatial facilitation was observed between the tectal EPSPs and the glossopharyngeal EPSPs in some motoneurons tested. These results suggest the existence of common excitatory premotor interneurons, on which the tectal descending volleys and the glossopharyngeal afferent volleys converge.

Animals↗