The Experts below are selected from a list of 243 Experts worldwide ranked by ideXlab platform

Gorm Danscher - One of the best experts on this subject based on the ideXlab platform.

  • ZEN Pathways, and Pools of Zinc Ions in a Multitude of Other ZEN Cells Zinc-specific Autometallographic In Vivo Selenium Methods: Tracing of Zinc-enriched (ZEN) Terminals,
    2013
    Co-Authors: Gorm Danscher, Meredin Stoltenberg
    Abstract:

    SUMMARY In vivo–applied Sodium Selenide or Sodium selenite causes the appearance ofzinc–selenium nanocrystals in places where free or loosely bound zinc ions are present.These nanocrystals can in turn be silver enhanced by autometallographic (AMG) develop-ment. The selenium method was introduced in 1982 as a tool for zinc-ion tracing, e.g., invesicular compartments such as synaptic vesicles of zinc-enriched (ZEN) terminals in thecentral nervous system, and for visualization of zinc ions in ZEN secretory vesicles of, e.g.,somatotrophic cells in the pituitary, zymogene granules in pancreatic acinar cells, beta-cellsof the islets of Langerhans, Paneth cells of the crypts of Lieberkuhn, secretory cells of thetubuloacinar glands of prostate, epithelium of parts of ductus epididymidis, and osteo-blasts. If Sodium Selenide/selenite is injected into brain, spinal cord, spinal nerves contain-ing sympathetic axons, or intraperitoneally, retrograde axonal transport of zinc–seleniumnanocrystals takes place in ZEN neurons, resulting in accumulation of zinc–selenium nano-crystals in lysosomes of the neuronal somata. The technique is, therefore, also a highly spe-cific tool for tracing ZEN pathways. The present review includes an update of the 1982 pa-per and presents evidence that only zinc ions are traced with the AMG selenium techniquesif the protocols are followed to the letter.

  • zinc specific autometallographic in vivo selenium methods tracing of zinc enriched zen terminals zen pathways and pools of zinc ions in a multitude of other zen cells
    Journal of Histochemistry and Cytochemistry, 2005
    Co-Authors: Gorm Danscher, Meredin Stoltenberg
    Abstract:

    In vivo-applied Sodium Selenide or Sodium selenite causes the appearance of zinc-selenium nanocrystals in places where free or loosely bound zinc ions are present. These nanocrystals can in turn be silver enhanced by autometallographic (AMG) development. The selenium method was introduced in 1982 as a tool for zinc-ion tracing, e.g., in vesicular compartments such as synaptic vesicles of zinc-enriched (ZEN) terminals in the central nervous system, and for visualization of zinc ions in ZEN secretory vesicles of, e.g., somatotrophic cells in the pituitary, zymogene granules in pancreatic acinar cells, beta-cells of the islets of Langerhans, Paneth cells of the crypts of Lieberkuhn, secretory cells of the tubuloacinar glands of prostate, epithelium of parts of ductus epididymidis, and osteoblasts. If Sodium Selenide/selenite is injected into brain, spinal cord, spinal nerves containing sympathetic axons, or intraperitoneally, retrograde axonal transport of zinc-selenium nanocrystals takes place in ZEN neuron...

  • Zinc-specific autometallographic in vivo selenium methods: tracing of zinc-enriched (ZEN) terminals, ZEN pathways, and pools of zinc ions in a multitude of other ZEN cells.
    The journal of histochemistry and cytochemistry : official journal of the Histochemistry Society, 2005
    Co-Authors: Gorm Danscher, Meredin Stoltenberg
    Abstract:

    In vivo-applied Sodium Selenide or Sodium selenite causes the appearance of zinc-selenium nanocrystals in places where free or loosely bound zinc ions are present. These nanocrystals can in turn be silver enhanced by autometallographic (AMG) development. The selenium method was introduced in 1982 as a tool for zinc-ion tracing, e.g., in vesicular compartments such as synaptic vesicles of zinc-enriched (ZEN) terminals in the central nervous system, and for visualization of zinc ions in ZEN secretory vesicles of, e.g., somatotrophic cells in the pituitary, zymogene granules in pancreatic acinar cells, beta-cells of the islets of Langerhans, Paneth cells of the crypts of Lieberkuhn, secretory cells of the tubuloacinar glands of prostate, epithelium of parts of ductus epididymidis, and osteoblasts. If Sodium Selenide/selenite is injected into brain, spinal cord, spinal nerves containing sympathetic axons, or intraperitoneally, retrograde axonal transport of zinc-selenium nanocrystals takes place in ZEN neurons, resulting in accumulation of zinc-selenium nanocrystals in lysosomes of the neuronal somata. The technique is, therefore, also a highly specific tool for tracing ZEN pathways. The present review includes an update of the 1982 paper and presents evidence that only zinc ions are traced with the AMG selenium techniques if the protocols are followed to the letter.

  • Retrograde tracing of zinc-enriched (ZEN) neuronal somata projecting to the olfactory bulb.
    Brain research, 2002
    Co-Authors: Yong Kuk Kim, Zhan-you Wang, Gorm Danscher
    Abstract:

    Zinc ions seem to be important to several neurological functions and have been connected to the pathophysiology of epilepsy, neuronal cell death after seizure or stroke, and Alzheimer's disease. Both epilepsy and Alzheimer's disease are clinical conditions believed to involve the olfactory bulb. The mammalian olfactory bulb is densely innervated by zinc-enriched (ZEN) neurons, and the distribution of the ZEN terminals in the mouse olfactory bulb has previously been described. The aim of this study was to describe the origins of ZEN terminals projecting into the main olfactory bulb of the rat. Selective labeling of ZEN terminals was accomplished by intracerebral infusion of Sodium Selenide, whereby zinc selenium clusters are created in the ZEN terminals. Some of these clusters move by retrograde axonal transport to the somata where they can be silver-enhanced by autometallography (AMG). After infusion of Sodium Selenide into the main olfactory bulb, retrogradely labeled ZEN somata were found (1) ipsilaterally in all anterior olfactory nuclei, taenia tecta, piriform cortex and lateral entorhinal cortex, and (2) contralaterally in anterior olfactory nuclei except the external division. The ipsilateral anterior olfactory nucleus had the densest population of ZEN somata, and it was found that these somata originated mainly from pyramidal neurons in layers II and III of each area. The olfactory-related centrifugal afferents to the main olfactory bulb are discussed.

  • Localization of zinc-enriched neurons in the mouse peripheral sympathetic system.
    Brain research, 2002
    Co-Authors: Zhan-you Wang, Gorm Danscher, Annica Dahlström
    Abstract:

    Growing evidence supports the notion that zinc ions located in the synaptic vesicles of zinc-enriched neurons (ZEN) play important physiological roles and are involved in certain pathological changes in the central nervous system. Here we present data revealing the distribution of zinc ions and the co-localization of zinc transporter 3 (ZnT3) and tyrosine hydroxylase (TH) in crush-operated sciatic nerves and lumbar sympathetic ganglia of mice, using zinc Selenide autometallography (ZnSe(AMG)) and ZnT3 immunofluorescence combined with confocal scanning microscopy, respectively. Six hours after the crush operation, ZnSe(AMG) grains and ZnT3 immunoreactivity were predominantly present in a subpopulation of thin unmyelinated sciatic nerve axons. In order to identify the type(s) of ZEN axons involved, double labeling with ZnT3 and (1) TH, (2) vesicular acetylcholine transporter (VAChT), (3) calcitonin gene-related peptide (CGRP), and (4) neuropeptide Y (NPY) was performed. Confocal microscopic observations showed that ZnT3 was located in a subpopulation of sciatic axons in distended parts proximal and distal to the crush site. Most, if not all, ZnT3-positive axons contained TH immunofluorescence, a few showed co-localization of ZnT3 and VAChT with very weak immunostaining, while no congruence was observed between ZnT3 and CGRP or NPY. Studies of the lumbar sympathetic ganglia showed that not more than 5% of the neurons were ZnT3-positive and that almost all of these were TH-positive. Furthermore, approximately 5% of total lumbar sympathetic ganglionic cells were ZnSe(AMG) positive, 48 h after a local injection of Sodium Selenide into the sciatic nerve. The present data support the notion that a subgroup of mouse sympathetic postganglionic neurons are ZEN neurons.

Zhan-you Wang - One of the best experts on this subject based on the ideXlab platform.

  • Retrograde tracing of zinc-enriched (ZEN) neuronal somata projecting to the olfactory bulb.
    Brain research, 2002
    Co-Authors: Yong Kuk Kim, Zhan-you Wang, Gorm Danscher
    Abstract:

    Zinc ions seem to be important to several neurological functions and have been connected to the pathophysiology of epilepsy, neuronal cell death after seizure or stroke, and Alzheimer's disease. Both epilepsy and Alzheimer's disease are clinical conditions believed to involve the olfactory bulb. The mammalian olfactory bulb is densely innervated by zinc-enriched (ZEN) neurons, and the distribution of the ZEN terminals in the mouse olfactory bulb has previously been described. The aim of this study was to describe the origins of ZEN terminals projecting into the main olfactory bulb of the rat. Selective labeling of ZEN terminals was accomplished by intracerebral infusion of Sodium Selenide, whereby zinc selenium clusters are created in the ZEN terminals. Some of these clusters move by retrograde axonal transport to the somata where they can be silver-enhanced by autometallography (AMG). After infusion of Sodium Selenide into the main olfactory bulb, retrogradely labeled ZEN somata were found (1) ipsilaterally in all anterior olfactory nuclei, taenia tecta, piriform cortex and lateral entorhinal cortex, and (2) contralaterally in anterior olfactory nuclei except the external division. The ipsilateral anterior olfactory nucleus had the densest population of ZEN somata, and it was found that these somata originated mainly from pyramidal neurons in layers II and III of each area. The olfactory-related centrifugal afferents to the main olfactory bulb are discussed.

  • Localization of zinc-enriched neurons in the mouse peripheral sympathetic system.
    Brain research, 2002
    Co-Authors: Zhan-you Wang, Gorm Danscher, Annica Dahlström
    Abstract:

    Growing evidence supports the notion that zinc ions located in the synaptic vesicles of zinc-enriched neurons (ZEN) play important physiological roles and are involved in certain pathological changes in the central nervous system. Here we present data revealing the distribution of zinc ions and the co-localization of zinc transporter 3 (ZnT3) and tyrosine hydroxylase (TH) in crush-operated sciatic nerves and lumbar sympathetic ganglia of mice, using zinc Selenide autometallography (ZnSe(AMG)) and ZnT3 immunofluorescence combined with confocal scanning microscopy, respectively. Six hours after the crush operation, ZnSe(AMG) grains and ZnT3 immunoreactivity were predominantly present in a subpopulation of thin unmyelinated sciatic nerve axons. In order to identify the type(s) of ZEN axons involved, double labeling with ZnT3 and (1) TH, (2) vesicular acetylcholine transporter (VAChT), (3) calcitonin gene-related peptide (CGRP), and (4) neuropeptide Y (NPY) was performed. Confocal microscopic observations showed that ZnT3 was located in a subpopulation of sciatic axons in distended parts proximal and distal to the crush site. Most, if not all, ZnT3-positive axons contained TH immunofluorescence, a few showed co-localization of ZnT3 and VAChT with very weak immunostaining, while no congruence was observed between ZnT3 and CGRP or NPY. Studies of the lumbar sympathetic ganglia showed that not more than 5% of the neurons were ZnT3-positive and that almost all of these were TH-positive. Furthermore, approximately 5% of total lumbar sympathetic ganglionic cells were ZnSe(AMG) positive, 48 h after a local injection of Sodium Selenide into the sciatic nerve. The present data support the notion that a subgroup of mouse sympathetic postganglionic neurons are ZEN neurons.

  • Retrograde tracing of zinc-enriched (ZEN) neuronal somata in rat spinal cord.
    Brain research, 2001
    Co-Authors: Zhan-you Wang, Gorm Danscher, Yuxiu Shi, Henrik Daa Schrøder
    Abstract:

    The zinc Selenide autometallographic (ZnSeAMG) technique for tracing the retrograde axonal transport of zinc ions in zinc-enriched (ZEN) neurons was used to map the distribution of ZEN neuronal somata in rat spinal cord. After a local injection of Sodium Selenide into the dorsal or ventral horn, ZnSeAMG-labeled ZEN neurons appeared in Rexed's laminae V, VII and X while laminae I and II were void. A few scattered ZEN somata were observed in the remaining laminae. The labeled neurons differed in shape and size, and the relatively high level of labeled somata around the injection site suggests that many ZEN neurons have relatively short axons or boutons en passage close to the neuronal origin. Ultrastructurally, the retrogradely transported zinc Selenide clusters were found in the lysosomes of ZEN somata and proximal dendrites. Electron microscopic studies also revealed two different kinds of ZEN terminals: (1) terminals with flat synaptic vesicles making symmetric synaptic contacts; and (2) terminals with round vesicles making asymmetric synaptic contacts. The present study suggests the existence of propriospinal systems of ZEN neurons comprising both segmental and intersegmental ZEN connections and having either inhibitory or excitatory ZEN terminals. The ZEN neurons seem to form a vast network of terminals located primarily in the gray matter, but also contacting dendrites radiating into the white matter. Important functions of this rather massive system of ZEN terminals can not be deduced from our present knowledge, but the systems appear to be involved in both motor and sensory functions.

  • Research report Retrograde tracing of zinc-enriched (ZEN) neuronal somata in rat
    2001
    Co-Authors: Zhan-you Wang, Gorm Danscher, Yuxiu Shi, Henrik Daa Schrøder
    Abstract:

    AMG The zinc Selenide autometallographic (ZnSe ) technique for tracing the retrograde axonal transport of zinc ions in zinc-enriched (ZEN) neurons was used to map the distribution of ZEN neuronal somata in rat spinal cord. After a local injection of Sodium Selenide into AMG the dorsal or ventral horn, ZnSe -labeled ZEN neurons appeared in Rexed's laminae V, VII and X while laminae I and II were void. A few scattered ZEN somata were observed in the remaining laminae. The labeled neurons differed in shape and size, and the relatively high level of labeled somata around the injection site suggests that many ZEN neurons have relatively short axons or boutons en passage close to the neuronal origin. Ultrastructurally, the retrogradely transported zinc Selenide clusters were found in the lysosomes of ZEN somata and proximal dendrites. Electron microscopic studies also revealed two different kinds of ZEN terminals: (1) terminals with flat synaptic vesicles making symmetric synaptic contacts; and (2) terminals with round vesicles making asymmetric synaptic contacts. The present study suggests the existence of propriospinal systems of ZEN neurons comprising both segmental and intersegmental ZEN connections and having either inhibitory or excitatory ZEN terminals. The ZEN neurons seem to form a vast network of terminals located primarily in the gray matter, but also contacting dendrites radiating into the white matter. Important functions of this rather massive system of ZEN terminals can not be deduced from our present knowledge, but the systems appear to be involved in both motor and sensory functions. © 2001 Elsevier Science B.V. All rights reserved.

Meredin Stoltenberg - One of the best experts on this subject based on the ideXlab platform.

  • ZEN Pathways, and Pools of Zinc Ions in a Multitude of Other ZEN Cells Zinc-specific Autometallographic In Vivo Selenium Methods: Tracing of Zinc-enriched (ZEN) Terminals,
    2013
    Co-Authors: Gorm Danscher, Meredin Stoltenberg
    Abstract:

    SUMMARY In vivo–applied Sodium Selenide or Sodium selenite causes the appearance ofzinc–selenium nanocrystals in places where free or loosely bound zinc ions are present.These nanocrystals can in turn be silver enhanced by autometallographic (AMG) develop-ment. The selenium method was introduced in 1982 as a tool for zinc-ion tracing, e.g., invesicular compartments such as synaptic vesicles of zinc-enriched (ZEN) terminals in thecentral nervous system, and for visualization of zinc ions in ZEN secretory vesicles of, e.g.,somatotrophic cells in the pituitary, zymogene granules in pancreatic acinar cells, beta-cellsof the islets of Langerhans, Paneth cells of the crypts of Lieberkuhn, secretory cells of thetubuloacinar glands of prostate, epithelium of parts of ductus epididymidis, and osteo-blasts. If Sodium Selenide/selenite is injected into brain, spinal cord, spinal nerves contain-ing sympathetic axons, or intraperitoneally, retrograde axonal transport of zinc–seleniumnanocrystals takes place in ZEN neurons, resulting in accumulation of zinc–selenium nano-crystals in lysosomes of the neuronal somata. The technique is, therefore, also a highly spe-cific tool for tracing ZEN pathways. The present review includes an update of the 1982 pa-per and presents evidence that only zinc ions are traced with the AMG selenium techniquesif the protocols are followed to the letter.

  • zinc specific autometallographic in vivo selenium methods tracing of zinc enriched zen terminals zen pathways and pools of zinc ions in a multitude of other zen cells
    Journal of Histochemistry and Cytochemistry, 2005
    Co-Authors: Gorm Danscher, Meredin Stoltenberg
    Abstract:

    In vivo-applied Sodium Selenide or Sodium selenite causes the appearance of zinc-selenium nanocrystals in places where free or loosely bound zinc ions are present. These nanocrystals can in turn be silver enhanced by autometallographic (AMG) development. The selenium method was introduced in 1982 as a tool for zinc-ion tracing, e.g., in vesicular compartments such as synaptic vesicles of zinc-enriched (ZEN) terminals in the central nervous system, and for visualization of zinc ions in ZEN secretory vesicles of, e.g., somatotrophic cells in the pituitary, zymogene granules in pancreatic acinar cells, beta-cells of the islets of Langerhans, Paneth cells of the crypts of Lieberkuhn, secretory cells of the tubuloacinar glands of prostate, epithelium of parts of ductus epididymidis, and osteoblasts. If Sodium Selenide/selenite is injected into brain, spinal cord, spinal nerves containing sympathetic axons, or intraperitoneally, retrograde axonal transport of zinc-selenium nanocrystals takes place in ZEN neuron...

  • Zinc-specific autometallographic in vivo selenium methods: tracing of zinc-enriched (ZEN) terminals, ZEN pathways, and pools of zinc ions in a multitude of other ZEN cells.
    The journal of histochemistry and cytochemistry : official journal of the Histochemistry Society, 2005
    Co-Authors: Gorm Danscher, Meredin Stoltenberg
    Abstract:

    In vivo-applied Sodium Selenide or Sodium selenite causes the appearance of zinc-selenium nanocrystals in places where free or loosely bound zinc ions are present. These nanocrystals can in turn be silver enhanced by autometallographic (AMG) development. The selenium method was introduced in 1982 as a tool for zinc-ion tracing, e.g., in vesicular compartments such as synaptic vesicles of zinc-enriched (ZEN) terminals in the central nervous system, and for visualization of zinc ions in ZEN secretory vesicles of, e.g., somatotrophic cells in the pituitary, zymogene granules in pancreatic acinar cells, beta-cells of the islets of Langerhans, Paneth cells of the crypts of Lieberkuhn, secretory cells of the tubuloacinar glands of prostate, epithelium of parts of ductus epididymidis, and osteoblasts. If Sodium Selenide/selenite is injected into brain, spinal cord, spinal nerves containing sympathetic axons, or intraperitoneally, retrograde axonal transport of zinc-selenium nanocrystals takes place in ZEN neurons, resulting in accumulation of zinc-selenium nanocrystals in lysosomes of the neuronal somata. The technique is, therefore, also a highly specific tool for tracing ZEN pathways. The present review includes an update of the 1982 paper and presents evidence that only zinc ions are traced with the AMG selenium techniques if the protocols are followed to the letter.

Henrik Daa Schrøder - One of the best experts on this subject based on the ideXlab platform.

  • Retrograde tracing of zinc-enriched (ZEN) neuronal somata in rat spinal cord.
    Brain research, 2001
    Co-Authors: Zhan-you Wang, Gorm Danscher, Yuxiu Shi, Henrik Daa Schrøder
    Abstract:

    The zinc Selenide autometallographic (ZnSeAMG) technique for tracing the retrograde axonal transport of zinc ions in zinc-enriched (ZEN) neurons was used to map the distribution of ZEN neuronal somata in rat spinal cord. After a local injection of Sodium Selenide into the dorsal or ventral horn, ZnSeAMG-labeled ZEN neurons appeared in Rexed's laminae V, VII and X while laminae I and II were void. A few scattered ZEN somata were observed in the remaining laminae. The labeled neurons differed in shape and size, and the relatively high level of labeled somata around the injection site suggests that many ZEN neurons have relatively short axons or boutons en passage close to the neuronal origin. Ultrastructurally, the retrogradely transported zinc Selenide clusters were found in the lysosomes of ZEN somata and proximal dendrites. Electron microscopic studies also revealed two different kinds of ZEN terminals: (1) terminals with flat synaptic vesicles making symmetric synaptic contacts; and (2) terminals with round vesicles making asymmetric synaptic contacts. The present study suggests the existence of propriospinal systems of ZEN neurons comprising both segmental and intersegmental ZEN connections and having either inhibitory or excitatory ZEN terminals. The ZEN neurons seem to form a vast network of terminals located primarily in the gray matter, but also contacting dendrites radiating into the white matter. Important functions of this rather massive system of ZEN terminals can not be deduced from our present knowledge, but the systems appear to be involved in both motor and sensory functions.

  • Research report Retrograde tracing of zinc-enriched (ZEN) neuronal somata in rat
    2001
    Co-Authors: Zhan-you Wang, Gorm Danscher, Yuxiu Shi, Henrik Daa Schrøder
    Abstract:

    AMG The zinc Selenide autometallographic (ZnSe ) technique for tracing the retrograde axonal transport of zinc ions in zinc-enriched (ZEN) neurons was used to map the distribution of ZEN neuronal somata in rat spinal cord. After a local injection of Sodium Selenide into AMG the dorsal or ventral horn, ZnSe -labeled ZEN neurons appeared in Rexed's laminae V, VII and X while laminae I and II were void. A few scattered ZEN somata were observed in the remaining laminae. The labeled neurons differed in shape and size, and the relatively high level of labeled somata around the injection site suggests that many ZEN neurons have relatively short axons or boutons en passage close to the neuronal origin. Ultrastructurally, the retrogradely transported zinc Selenide clusters were found in the lysosomes of ZEN somata and proximal dendrites. Electron microscopic studies also revealed two different kinds of ZEN terminals: (1) terminals with flat synaptic vesicles making symmetric synaptic contacts; and (2) terminals with round vesicles making asymmetric synaptic contacts. The present study suggests the existence of propriospinal systems of ZEN neurons comprising both segmental and intersegmental ZEN connections and having either inhibitory or excitatory ZEN terminals. The ZEN neurons seem to form a vast network of terminals located primarily in the gray matter, but also contacting dendrites radiating into the white matter. Important functions of this rather massive system of ZEN terminals can not be deduced from our present knowledge, but the systems appear to be involved in both motor and sensory functions. © 2001 Elsevier Science B.V. All rights reserved.

Yuxiu Shi - One of the best experts on this subject based on the ideXlab platform.

  • Retrograde tracing of zinc-enriched (ZEN) neuronal somata in rat spinal cord.
    Brain research, 2001
    Co-Authors: Zhan-you Wang, Gorm Danscher, Yuxiu Shi, Henrik Daa Schrøder
    Abstract:

    The zinc Selenide autometallographic (ZnSeAMG) technique for tracing the retrograde axonal transport of zinc ions in zinc-enriched (ZEN) neurons was used to map the distribution of ZEN neuronal somata in rat spinal cord. After a local injection of Sodium Selenide into the dorsal or ventral horn, ZnSeAMG-labeled ZEN neurons appeared in Rexed's laminae V, VII and X while laminae I and II were void. A few scattered ZEN somata were observed in the remaining laminae. The labeled neurons differed in shape and size, and the relatively high level of labeled somata around the injection site suggests that many ZEN neurons have relatively short axons or boutons en passage close to the neuronal origin. Ultrastructurally, the retrogradely transported zinc Selenide clusters were found in the lysosomes of ZEN somata and proximal dendrites. Electron microscopic studies also revealed two different kinds of ZEN terminals: (1) terminals with flat synaptic vesicles making symmetric synaptic contacts; and (2) terminals with round vesicles making asymmetric synaptic contacts. The present study suggests the existence of propriospinal systems of ZEN neurons comprising both segmental and intersegmental ZEN connections and having either inhibitory or excitatory ZEN terminals. The ZEN neurons seem to form a vast network of terminals located primarily in the gray matter, but also contacting dendrites radiating into the white matter. Important functions of this rather massive system of ZEN terminals can not be deduced from our present knowledge, but the systems appear to be involved in both motor and sensory functions.

  • Research report Retrograde tracing of zinc-enriched (ZEN) neuronal somata in rat
    2001
    Co-Authors: Zhan-you Wang, Gorm Danscher, Yuxiu Shi, Henrik Daa Schrøder
    Abstract:

    AMG The zinc Selenide autometallographic (ZnSe ) technique for tracing the retrograde axonal transport of zinc ions in zinc-enriched (ZEN) neurons was used to map the distribution of ZEN neuronal somata in rat spinal cord. After a local injection of Sodium Selenide into AMG the dorsal or ventral horn, ZnSe -labeled ZEN neurons appeared in Rexed's laminae V, VII and X while laminae I and II were void. A few scattered ZEN somata were observed in the remaining laminae. The labeled neurons differed in shape and size, and the relatively high level of labeled somata around the injection site suggests that many ZEN neurons have relatively short axons or boutons en passage close to the neuronal origin. Ultrastructurally, the retrogradely transported zinc Selenide clusters were found in the lysosomes of ZEN somata and proximal dendrites. Electron microscopic studies also revealed two different kinds of ZEN terminals: (1) terminals with flat synaptic vesicles making symmetric synaptic contacts; and (2) terminals with round vesicles making asymmetric synaptic contacts. The present study suggests the existence of propriospinal systems of ZEN neurons comprising both segmental and intersegmental ZEN connections and having either inhibitory or excitatory ZEN terminals. The ZEN neurons seem to form a vast network of terminals located primarily in the gray matter, but also contacting dendrites radiating into the white matter. Important functions of this rather massive system of ZEN terminals can not be deduced from our present knowledge, but the systems appear to be involved in both motor and sensory functions. © 2001 Elsevier Science B.V. All rights reserved.