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Biomedical subjects

M Tohyama

Publications and source records attributed to M Tohyama.

At least 595 records · Page 33Linked to original sources
PubMed1979

Tegmentoreticular projections with special reference to the muscular atonia during paradoxical sleep in the cat: an HRP study.

Using the retrograde tracer technique with horseradish peroxidase (HRP), attempts were made to determine the cells of origin and the descending pathway of the tegmentoreticular projections in order to give an anatomical substrate for the physiological phenomenon of the postural atonia observed during paradoxical sleep (PS) in the cat. The HRP was injected into various parts of the pontomedullary reticular formation (RF) including the caudal raphe nuclei, nucleus (n.) reticularis gigantocellularis (Gc), n. reticularis magnocellularis (Mc), and other pontomedullary structures adjacent to the Mc. The results indicated that the HRP injection into the Mc, particularly its caudal and lateral two-thirds, resulted in specific labeling of cells located in an area just medial to the LCa together with those in the most medial part of the LCa. Bilateral lesions of these pontine structures have been reported to suppress the atonia otherwise observed during PS in the normal cat. In addition to the HRP labeled cells, we have also observed HRP filled fiber bundles directed to labeled cells in the medial part of the LCa and immediately adjacent tegmental RF area. The same course of HRP labeled fiber bundles was also observed together with HRP labeled cells in the Mc after HRP injections into the medial part of the LCa area, indicating the existence of an interconnection between the LCa area and the Mc. The location of the tegmentoreticular pathway corresponded to that of the lesions effective to suppress the muscular atonia during PS. HRP injections into the caudal medullar caudal to the Mc, on the other hand, resulted in no or almost no HRP labeled cells in the area medial to the LCa, in spite of the presence of HRP containing neurons in other parts of the pontomedullary RF areas, showing that the tegmentoreticular projections as described above terminate almost exclusively in the Mc.

Animals↗
PubMed1979

Spinal projections from the lower brain stem in the cat as demonstrated by the horseradish peroxidase technique. I. Origins of the reticulospinal tracts and their funicular trajectories.

Using a retrograde tracer technique with horseradish peroxidase (HRP) attempts were made to determine the origins of reticulospinal tracts and their funicular trajectories. Reticulospinal tracts originating from the mesencephalic reticular formation (RF) were composed of: (1) descending projections arising from the cluster of cells located just lateral to the periaqueductal gray that course in the anterior funiculus (AF) and ventral part of the lateral funiculus (LF) with ipsilateral predominance; and (2) projections from the cluster of cells located dorsal to the brachium conjunctivum that course in the ipsilateral LF. Origins of the pontine reticulospinal tracts arising from the n. reticularis pontis oralis (Poo) have been divided qnto three parts: (1) medial one-third; (2) middle; and (3) ventrolateral. The axons from the medial part descend ipsilaterally via the medial part of the AF, while the axons from the ventrolateral part of the Poo give rise to diffuse descending projections in the AF and LF. The middle part of the Poo has been further subdivided into: (1) dorsal part that gives rise to spinal projections ipsilaterally in the ventrolateral funiculus (VLF); and (2) ventral, particularly its upper part, whose axons descend bilaterally via the DLF. Origins of reticulospinal tracts from the n. reticularis pontis caudalis (Poc) could be divided into three parts: (1) medial; (2) dorsolateral; and (3) ventrolateral. The medial part of the Poc is a source of axons via the medial part of the ipsilateral AF, while the ventrolateral part of the nucleus is a source of axons via the contralateral LF. The spinal projections from the dorsolateral part of the Poc appears to course diffusely in the AF and LF, but with DLF predominance. The n. reticularis gigantocellularis (Gc) was found to be a main medullary source of the spinal projections in the ipsilateral AF, while n. reticularis magnocellularis (Mc) is the major source of the fibers coursing ipsilaterally in the VLF. The most medial part of the Mc descends ipsilaterally via the medial part of the AF, while the ventrolateral part of the nucleus together with the n. reticularis lateralis of Meesen and Olszewski descends ipsilaterally via the DLF. It has also been found that the axons from the n. reticularis paramedianus pass via both the AF and LF with ipsilateral predominance, while the n. reticularis dorsalis and ventralis course via the LF with ipsilateral predominance.

Animals↗
PubMed1979

[Medulloblastoma with extracranial metastases--a case report (author's transl)].

A case of medulloblastoma with extracranial metastases was reported. A 20-year-old woman was operated on for cerebellar medulloblastoma twice during the past 5 years and a half. Two years after the second operation, she revealed the metastases to the cervical, axillar and inguinal lymphnodes, and to the skeletal system, such as the skull, scapula, humerus, sternum, spine, pelvis and femur. The cause of extracranial metastases in the very core in this case. While the tumor was located deep in the cerebellar hemisphere at the first operation, it spread over the cerebellar surface at the after the second operation, so that the tumor cells became infiltrative to the dura mater. Thus through lymphatic and circulatory system extracranial metastases occurred. The location of the tumor seems important in this case.

Adult↗
PubMed1978

Afferent fiber connections from lower brain stem to hypothalamus studied by the horseradish peroxidase method with special reference to noradrenaline innervation.

Attempts were made to determine the afferent projections to the anterior hypothalamus including the preoptic area from the lower brain stem by means of the horseradish peroxidase method combined with monoamine oxidase staining to identify noradrenaline (NA) neurons. In addition to this technique, a histofluorescence analysis was performed. NA fibers in the medial part of the anterior hypothalamus were mainly supplied by A1 and A2 NA neuron groups, while the lateral part and periventricular zone received NA terminals from both pontine and medulla oblongata NA neuron groups. Furthermore, the present study indicated that there were direct projections to the anterior hypothalamus from non-noradrenergic neurons in the lower brain stem: nuclei raphe dorsalis, centralis superior, cells in the mesencephalic and pontine central gray matter, nuclei parabrachialis lateralis and medialis, cells around fasciculus longitudinalis medialis.

Afferent Pathways↗
PubMed1978

Cellular organization of locus coeruleus in the rat as studied by Golgi method.

The locus coeruleus (LC) of rats at different ages was studied in sections stained by the Golgi-rapid method. The LC is composed of two types of neurons, medium-sized (20mu x 35mu) and small cells (10mu x 15mu). The medium-sized cells are mainly fusiform in shape and occupy the dorso-caudal part of the nucleus, while pyramidal or multipolar cells frequently occur in the ventral part. Both types of cells bear a moderate to large number of spines on the surface of their soma, which form the main criterion for identifying the LC neurons. Though they radiate several relatively short dendrites in different directions, which bifurcate once or twice, the medio-ventral ramification is prevailing, extending beyond the limit of cells to the pontine central gray adjacent to the LC. The latter region might constitute the principal receptive sites of LC for inputs from various origins. Axons of LC neurons take their initial course either latero-rostral- or latero-caudalwards, while some axons divide dichotomously rostral- and caudalwards. Fine axon collaterals are frequently demonstrated within the LC and sometimes seem to contact with dentrites of LC neurons. Besides this, two kinds of afferents of unknown origins are observed between LC neurons. At least three kinds of small oval neurons are occasionally impregnated, though their axonal distributions cannot be demonstrated.

Animals↗
PubMed1978

Organization and projections of the neurons in the dorsal tegmental area of the rat.

The organization and projection of the neurons in the dorsal tegmental area at the locus coeruleus level of the rat have been investigated by means of the horseradish peroxidase (HRP) method, combined with monoamine oxidase staining to identify the noradrenaline (NA) neurons. Judging from the anatomical aspects elucidated in this study, this area is composed of various different cell groups. Although the functional role of these neuronal groups remains to be determined, the present study strongly suggests that the dorsal tegmental area participates in important regulation of several brain functions.

Animals↗
PubMed1978

Afferent fiber connections from the lower brain stem to the rat cerebellum by the horseradish peroxidase method combined with MAO staining, with special reference to noradrenergic neurons.

The origin of cerebellar noradrenaline (NA) was investigated by means of the horseradish peroxidase (HRP) method, combined with the monoamine oxidase (MAO) staining method to identify the NA neurons. The present study gives clear cut evidence that the main source for cerebellar NA in the rat is the locus coeruleus (Lc), both the dorsal and ventral parts which innervate the entire cerebral cortex and hypothalamus respectively. The present study clearly demonstrates the pontine NA neurons such as the nucleus subcoeruleus (sc) NA neurons also send their axons to the cerebellum. The fact that some neurons in the nucleus dorsalis nervi vagi and the nucleus commissuralis were labeled by HRP indicates strong possibility that A2 NA neurons also innervate the cerebellum, though direct proof was lacking in this study. Furthermore, some unknown afferent fibers to the cerebellum were found in this study. These are as follows: (1) non-noradrenergic neurons in the Sc area, (2) nucleus reticularis gigantocellularis and nucleus reticularis parvocellularis, (3) group 1 (of Meessen and Olszewski), (4) a cell group extending to the ventrolateral region of the reticular formation of the pons, (5) nucleus ambiguug, (6) nucleus nervi facialis.

Animals↗
PubMed1977

Noradrenaline innervation of the spinal cord studied by the horseradish peroxidase method combined with monoamine oxidase staining.

The origin of the spinal cord noradrenaline (NA) has been investigated by means of the horseradish peroxidase (HRP) method, combined with monoamine oxidase staining (Glenner) to identify the NA neurons. Following the injection of HRP to the various levels of rat spinal cord, cervical to sacral cord, A1-3, 5-7 NA neuron groups were labeled with HRP. They showed almost the same distribution pattern regardless of difference in the injected segment. Labeled NA neurons in A6 were concentrated in the ventral division of the locus coeruleus, which continued to the labeled NA neurons in the subcoeruleus area. The HRP positive neurons in the pons outnumbered those of the medulla oblongata. As the NA neurons described above were considered to be the source of NA in the forebrain, such as the hypothalamus and preoptic area, the possibility that the same NA neurons might innervate both the forebrain and spinal cord has been presented.

Adrenergic Fibers↗
PubMed1977

Catecholamine innervation of the forebrain in the bull frog, Rana catesbiana.

The innervation of forebrain catecholamine (CA) were experimentally investigated with use of sensitive fluorescence method of glyoxylic acid formaldehyde in the brain of the bull frog, Rana catesbiana. The CA of the olfactory bulb is supplied by CA neurons situated in olfactory bulb. And CA neurons in the hypothalamus contribute the main source for the forebrain CA except olfactory bulb. The hypothalamic CA neurons also give rise to long descending axons to innervate the brain stem. Judging from their anatomical aspects it seems that the structure homologous to mammalian nigro-neostriatal dopamine or mesolimbic dopamine system is not present in amphibian brain.

Animals↗
PubMed1977

Comparative anatomy of the topography of catecholamine containing neuron system in the brain stem from birds to teleosts.

The distribution of catecholamine (CA) containing neurons and nerve terminals in the brain stem from birds to teleosts were studied by means of histofluorescence technique of glyoxylic acid-formaldehyde combining method. The present study revealed that there exists marked differences in topography of CA neurons between higher vertebrates (birds and reptile) and lower vertebrates (amphibia and teleosts). Tegmental CA neurons in the birds and reptile are much more developed than those of amphibia and teleosts. Furthermore, huge collection of CA neurons (presumably dopamine) in the midbrain tegmentum could not be found in the amphibia and teleosts. On the other hand, distribution of CA nerve terminals in the brain stem is essentially similar throughout the vertebrate brains, though there exist modifications by secondary pattern distortions which correspond to various conditions of their lives. Some possible significance of CA neurons on development of central nervous system was discussed.

Animals↗
PubMed1977

Fine structure of noradrenaline containing nerve fibers in the median eminence of female rat demonstrated by in situ fixation of potassium permanganate.

Fine structure of noradrenaline (NA) terminals in the internal layer of the median eminence (ME) was elucidated by in situ fixation of potassium permanganate. The NA terminals in ME contained relatively large cored vesicles (about 1000 A) together with a large number of small core vesicle (400-600 A). The most dominant feature that NA terminals show is the closed contact with ependymal cells and their processes. In the bulging abutting on the contact membrane, some of core vesicles fused or touched the membrane appearing to release the content into intercellular space or take up NA from the space. This finding shows that the NA terminals abutting on the ependymal cells and their processes have a close contact with them and give an important influence on regulation of ependymal function. Our present study further revealed that the NA terminals also had a close contact not only with the axon terminals in which ordinary spherical non-cored vesicles were exclusively present but also with the axonal fibers of neurosecretary system. These findings would infer complicated function of NA in ME.

Animals↗
PubMed1976

Comparative anatomy of cerebellar catecholamine innervation from teleosts to mammals.

The cerebellar innervation of the catecholamine (CA) neurons was experimentally investigated with histofluorescence method in the brains of the vertebrates from teleosts to mammals. In the teleosts the source for the cerebellar CA are composed of three CA neuron groups. Hypothalamic CA neuron group contributes mainly to innervation in the valvula cerebelli whose development is dependent on the high degree of the development of the lateral-line organ. CA neurons in the medulla oblongata might innervate the vestibulo-lateral lobe and corpus cerebelli. These two CA neuron groups appear to constitute the main source for the cerebellar CA, though it is certain that rhombencephalic CA neurons also send their axons to innervate the cerebellum. In the tailless amphibian which is devoid of the lateral-line nerves, cerebellar CA especially in the corpus cerebelli is supplied mainly by the rhombencephalic CA neurons which still remain in less developed stage in phylogenetic scale. In the bird, ascending CA neuron system is maintained by long axons and the anlage of locus coeruleus (LC) appear first in this class. A large number of CA nerve terminals in the cerebellum of the bird are supplied by both CA neurons of the dorsal part of the tegmentum and CA neurons disseminated in the tegmental reticular formation. In the mammals showing the highest development of the cerebellar and cerebral cortices, LC is well developed and cerebellar CA is supplied mainly by LC, though cerebellum is innervated by other CA neurons besides LC. Possible significance of the CA neurons on the development of the cerebellum in phylogeny was discussed.

Animals↗
PubMed1976

Comparative anatomy of the locus coeruleus. II. Organization and projection of the catecholamine containing neurons in the upper rhombencephalon of the frog, Rana catesbiana.

The organization and projection of the catecholamine (CA) containing neurons in the upper rhombencephalon were experimentally investigated with histofluorescence method in the brain of the bullfrog, Rana catesbiana. A small number of catecholamine containing neurons are located in the upper rhombencephalon. These neurons do not send ascending fibers to contribute CA projection to the forebrain, but give rise to relatively short axons to innervate the cerebellum and neighbouring reticular formation. Judging from their anatomical aspects, it seems that the structure homologous to the mammalian locus coeruleus is not present in the amphibian brain.

Animals↗