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Efferent projections from medial pallidal segment in the monkey: An anterograde tracing study with biotinylated dextran
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SERIAL RECONSTRUCTION OF ENTOPEDUNCULAR AFFERENTS TO THE VENTRAL ANTERIOR NUCLEUS IN THE CAT. YASUHISA NAKAMURA AND FUMI SATO. Dept. of Anat., Fat. of Med., Tokyo Med. and Dent. Univ., Yushima, Bunkyo-ku, Tokyo 113, Japan. 1624
Neuronal interrelation in the ventral anterior nucleus (VA) of the cat thalamus was analyzed by a serial electron microscopic reconstruction technique. Synaptic relationships among entopeduncular terminals (EPTs), dendrites of thalamocortical projection neurons (TCNs) and presynaptic dendrites (PSDs) of local circuit neurons (LCNs) were investigated. In the Nembutal-anesthetized cat, 4% WGA-HRP or 5% biocytin was stereotaxically injected into the entopeduncular nucleus to label EPTs anterogradely, and at the same time WGA-HRP was also injected into the medial part of the anterior sigmoid gyrus to label TCNs retrogradely. Specimens were embedded for electron microscopy after histochemical procedures. Serial ultrathin sections were observed and photographed, and labeled axon terminals and their surrounding components were reconstructed by means of a computer graphic program. Labeled axon terminals showed grape-like bouton terminaux type or bouton en passant type. These terminals contained pleomorphic vesicles and made symmetric synapses mostly with proximal and distal dendrites. Occasionally synapses between labeled terminals and PSDs were encountered, but typical glomerular structure was found rarely. These data were compared with those of the cerebellothalamic projection observed in the ventral lateral nucleus.
1625
EFFERENT PROJECI’IONS FROM THE MEDIAL PALLIDAL SEGMENT IN THE MONKEY: AN ANTEROGRADE TRACING STUDY WITH BIOTINYLATED DEXTRAN. KATSUMA NAKANO. TETSURO KAYAHARA. YASUO HASEGAWA AND HIROSHI USHIRO. 1st. Dent. of Anat.. Mie Univ. Sch. of Med. Edobashi, Tsu. 514. Janan. In the previous study, we indicated the topographical distribution of the pallidal neurons projecting to each subgroup of the motor thalamic nuclei by using the retrograde axonal transport technique of WGA-HRP. However, it remains an anterogmde tracing study to elucidate this topographical organization. In the present study, small injections of biotinylated dextran, PHAL. or WGA-I-IRP were made into the various parts of the medial pallidal segment (GPm) in adult monkeys (A4acacafuscutu). The results confirm and extend findings of the previous study. The caudal and ventrolateral2/3 parts of the GPm projects to the nucleus ventrahs lateralis pars oralis (VLo), nucleus ventralis lateralis pars caudalis (VLc), nucleus ventralis lateralis pars medialis (VLm), nucleus centromedianus (CM) and the lateral habenular nucleus, and to other extrathalamic nuclei such as substantia nigra pars reticulata and pedunculopontine nuclei. These pallidal efferents course dorsomedially, pierce the internal capsule and reach to the Forel’s field H through the lenticular fasciculus. Major fibers continue dorsally and terminate in the target areas. The pallidohabenular fibers take a different course passing dorsally in front of the anterior thalamic pole, then enter the stria medullaris thalami to reach the lateral habenular nucleus. Several fibers break off from the Forel’s field H, course ventromedially and terminate in the middle third portion of the substantia nigra, mainly in its pars reticulata. The rostromedial portion of the GPm sends projection fibers ventrally and medially through the ansa lenticularis to terminate in the medial portion of nucleus ventralis anterior pars principalis (VApc). The lateral portion of the VApc receives pallidal afferents from the dorsomedial GPrn.
THREE DIMENSIONAL ANALYSIS OF SINGLE CEREBELLAR TERMINALS AND THEIR SURROUNDING STRUCTURES IN THE CAT VENTRAL LATERAL NUCLEUS. FUMI SATO’, YASUHISA NAKAMURA’ AND YOSHIRAZU SHINODA2, Dept. of Anat.’ and Physiol.2, Fat. of Med., Tokyo Med. and Dent. Univ., Yushima, Bunkyo-ku, Tokyo, 113, Japan. 1626
Neuronal interrelation in the ventral lateral nucleus (VL) of the cat thalamus was quantitatively analyzed using serial electron microscopic technique. Relationships among cerebellar terminals (CTs), dendrites of thalamocortical projection neurons (TCNs) and presynaptic dendrites (PSDs) of local circuit neurons (LCNs) were investigated. In the Nembutal-anesthetized cat, single axons originating from the cerebellar nuclei were electrophysiologically identified and injected with HRP iontophoretically. Specimens were enabled for electron microscopy. Serial ultrathin sections were observed and labeled CTs were three dimensionally reconstructed by means of a computer graphic program. Light microscopically, a few swellings occurred along the course of the axon. One terminal swelling was also observed at the end of the axon. In electron microscopy, CTs of a bouton terminal type and of a bouton en passant type and their postsynaptic components were photographed through consecutive sections and reconstructed. Although electron-dense reaction product was filled within these terminals, spherical vesicles were obviously discernible in them. Both types of terminals made synaptic contacts with one TCN dendrite and several PSDs. In some cases, PSDs participated in triadic arrangements; the PSD is postsynaptic to the CT and presynaptic to the TCN dendrite which is also postsynaptic to the same CT. Typical glomerulus as described before was rarely encountered in this nucleus.
SERIAL RECONSTRUCTION OF ENTOPEDUNCULAR AFFERENTS TO THE VENTRAL ANTERIOR NUCLEUS IN THE CAT. YASUHISA NAKAMURA AND FUMI SATO. Dept. of Anat., Fat. of Med., Tokyo Med. and Dent. Univ., Yushima, Bunkyo-ku, Tokyo 113, Japan. 1624
Neuronal interrelation in the ventral anterior nucleus (VA) of the cat thalamus was analyzed by a serial electron microscopic reconstruction technique. Synaptic relationships among entopeduncular terminals (EPTs), dendrites of thalamocortical projection neurons (TCNs) and presynaptic dendrites (PSDs) of local circuit neurons (LCNs) were investigated. In the Nembutal-anesthetized cat, 4% WGA-HRP or 5% biocytin was stereotaxically injected into the entopeduncular nucleus to label EPTs anterogradely, and at the same time WGA-HRP was also injected into the medial part of the anterior sigmoid gyrus to label TCNs retrogradely. Specimens were embedded for electron microscopy after histochemical procedures. Serial ultrathin sections were observed and photographed, and labeled axon terminals and their surrounding components were reconstructed by means of a computer graphic program. Labeled axon terminals showed grape-like bouton terminaux type or bouton en passant type. These terminals contained pleomorphic vesicles and made symmetric synapses mostly with proximal and distal dendrites. Occasionally synapses between labeled terminals and PSDs were encountered, but typical glomerular structure was found rarely. These data were compared with those of the cerebellothalamic projection observed in the ventral lateral nucleus.
1625
EFFERENT PROJECI’IONS FROM THE MEDIAL PALLIDAL SEGMENT IN THE MONKEY: AN ANTEROGRADE TRACING STUDY WITH BIOTINYLATED DEXTRAN. KATSUMA NAKANO. TETSURO KAYAHARA. YASUO HASEGAWA AND HIROSHI USHIRO. 1st. Dent. of Anat.. Mie Univ. Sch. of Med. Edobashi, Tsu. 514. Janan. In the previous study, we indicated the topographical distribution of the pallidal neurons projecting to each subgroup of the motor thalamic nuclei by using the retrograde axonal transport technique of WGA-HRP. However, it remains an anterogmde tracing study to elucidate this topographical organization. In the present study, small injections of biotinylated dextran, PHAL. or WGA-I-IRP were made into the various parts of the medial pallidal segment (GPm) in adult monkeys (A4acacafuscutu). The results confirm and extend findings of the previous study. The caudal and ventrolateral2/3 parts of the GPm projects to the nucleus ventrahs lateralis pars oralis (VLo), nucleus ventralis lateralis pars caudalis (VLc), nucleus ventralis lateralis pars medialis (VLm), nucleus centromedianus (CM) and the lateral habenular nucleus, and to other extrathalamic nuclei such as substantia nigra pars reticulata and pedunculopontine nuclei. These pallidal efferents course dorsomedially, pierce the internal capsule and reach to the Forel’s field H through the lenticular fasciculus. Major fibers continue dorsally and terminate in the target areas. The pallidohabenular fibers take a different course passing dorsally in front of the anterior thalamic pole, then enter the stria medullaris thalami to reach the lateral habenular nucleus. Several fibers break off from the Forel’s field H, course ventromedially and terminate in the middle third portion of the substantia nigra, mainly in its pars reticulata. The rostromedial portion of the GPm sends projection fibers ventrally and medially through the ansa lenticularis to terminate in the medial portion of nucleus ventralis anterior pars principalis (VApc). The lateral portion of the VApc receives pallidal afferents from the dorsomedial GPrn.
THREE DIMENSIONAL ANALYSIS OF SINGLE CEREBELLAR TERMINALS AND THEIR SURROUNDING STRUCTURES IN THE CAT VENTRAL LATERAL NUCLEUS. FUMI SATO’, YASUHISA NAKAMURA’ AND YOSHIRAZU SHINODA2, Dept. of Anat.’ and Physiol.2, Fat. of Med., Tokyo Med. and Dent. Univ., Yushima, Bunkyo-ku, Tokyo, 113, Japan. 1626
Neuronal interrelation in the ventral lateral nucleus (VL) of the cat thalamus was quantitatively analyzed using serial electron microscopic technique. Relationships among cerebellar terminals (CTs), dendrites of thalamocortical projection neurons (TCNs) and presynaptic dendrites (PSDs) of local circuit neurons (LCNs) were investigated. In the Nembutal-anesthetized cat, single axons originating from the cerebellar nuclei were electrophysiologically identified and injected with HRP iontophoretically. Specimens were enabled for electron microscopy. Serial ultrathin sections were observed and labeled CTs were three dimensionally reconstructed by means of a computer graphic program. Light microscopically, a few swellings occurred along the course of the axon. One terminal swelling was also observed at the end of the axon. In electron microscopy, CTs of a bouton terminal type and of a bouton en passant type and their postsynaptic components were photographed through consecutive sections and reconstructed. Although electron-dense reaction product was filled within these terminals, spherical vesicles were obviously discernible in them. Both types of terminals made synaptic contacts with one TCN dendrite and several PSDs. In some cases, PSDs participated in triadic arrangements; the PSD is postsynaptic to the CT and presynaptic to the TCN dendrite which is also postsynaptic to the same CT. Typical glomerulus as described before was rarely encountered in this nucleus.