ISSN:0092-7317    

DOI:10.1002/cne.902670202

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractIn order to determine their local circuit function, we have examined physiologically characterized, intracellularly labeled neurons in laminae I and II with light and electron microscopes. Single neurons in the spinal substantia gelatinosa (lamina II) of the cat and monkey were recorded intracellularly and characterized physiologically. Following characterization, the neurons were labeled with horseradish peroxidase that was iontophoretically ejected from the recording micropipette. After fixation and sectioning, histochemical reaction allowed visualization of the neuron soma, dendrites, and axon. The four nociceptive neurons reported here (three from cats and one from a monkey) had axons that distributed terminal collaterals to deeper laminae of the spinal cord, including laminae III, IV, and V. Electron microscopy of the axons demonstrated that the parent axons were myelinated and that the terminal collaterals established synaptic contact with neurons in the deeper laminae. These results suggest that some substantia gelatinosa neurons relay nociceptive information to neurons in deeper regions of the spinal dorsal horn via myelinated axons.

ISSN:0092-7317    

DOI:10.1002/cne.902670203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractThe present, study was undertaken to define the ultrastructure of synapses of the crossed temporodentate pathway from the entorhinal cortex to the contralateral dentate gyrus and to compare the synapses of the sparse crossed pathway with those of the massive ipsilateral temporodentate pathway. The synapses of the crossed pathway were identified by using EM degeneration and EM autoradiographic techniques. For the degeneration studies, adult male Sprague‐Dawley rats were killed 1, 2, or 4 days following a unilateral entorhinal cortex lesion and prepared for electron microscopy. To identify the synapses by using autoradiographic techniques, four animals received injections of3H‐proline into the entorhinal cortex, were allowed to survive for 3 days, and were prepared for EM autoradiography. Degenerating synapses of the crossed pathway that were found in the molecular layer of the dentate gyrus contralateral to a lesion formed asymmetric synapses on spines and possessed presynaptic organelles indistinguishable from synapses of the ipsilateral temporodentate pathway. The number of degenerating synapses was very low at all survival intervals (14.80 degenerating synapses/10,000μm2at 1 day postlesion and 1.95 degenerating synapses/10,000μm2at 2 days postlesion); no degenerating synapses were found at 4 days postlesion. Ninety‐eight percent of the degenerating synapses found at 1 day postlesion exhibited electron‐lucent degeneration. At 2 days postlesion 83% of the degenerating synapses in the dorsal blade and 18% of those in the ventral blade showed lucent degeneration; the remainder were electron dense. EM autoradiography confirmed the degeneration studies in terms of the type of terminals that were labeled and suggested that the density of the crossed pathway was higher than the degeneration results implied. We conclude that synapses of the crossed temporodentate pathway have a similar ultrastructure to synapses of the ipsilateral temporodentate pathway but exhibit a rapid form of degeneration such that they disappear very rapidly following t

ISSN:0092-7317    

DOI:10.1002/cne.902670204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractThe present study was undertaken to define the ultrastructure of synapses of the crossed temporodentate pathway after they had sprouted to reinnervate the dentate gyrus following the destruction of the normal ipsilateral temporodentate pathway. The synapses of the sprouted crossed temporodentate pathway were identified at the EM level by using autoradiographic techniques and by evaluating the degeneration of the pathway following secondary lesions. Both EM autoradiography and EM degeneration revealed that the terminals of the sprouted crossed temporodentate pathway formed asymmetric synapses on spines; individual terminals appeared to make more synaptic contacts per terminal (multiple synapses) than in the case of the normal crossed pathway. In the two lesioned animals exhibiting the best labeling, labeled terminals made an average of 3.0 ± 2.2 and 2.0 ± 1.3 contacts per terminal. In contrast, labeled terminals in normal animals exhibited only one contact per terminal. The terminals of the sprouted pathway were also larger than those of the normal crossed pathway. The synapses of the crossed temporodentate pathway that degenerated after a secondary lesion of the entorhinal cortex exhibited both electron‐lucent and electron‐dense forms of degeneration at 2 days postlesion. In two animals that were quantitatively analyzed, the density of degenerating synaptic terminals was 281 and 218/10,000 μm2in the terminal field of the sprouted crossed pathway. These values are much higher than in normal animals, where the density of degenerating synaptic terminals was only 2.12/10,000 μm2at 2 days postlesion. Because degenerating terminals were evident at 2 days postlesion, the sprouted crossed pathway does not appear to exhibit the very rapid degeneration that is characteristic of the normal crossed pathway. We conclude that sprouting in this pathway involves terminal proliferation (an increase in the number of presynaptic elements), and terminal hypertrophy (an increase in the size of presynaptic terminals, together with an increase in the number of synaptic contacts formed by individual ter

ISSN:0092-7317    

DOI:10.1002/cne.902670205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractTo learn the distribution of cells projecting to the thalamus, as opposed to the cerebellum, in the mechanosensory nuclei of the dorsal medulla of raccoons, we analyzed the retrograde transport of horseradish peroxidase from the ventrobasal complex of the thalamus and from the cerebellum. We found six nuclear regions projecting heavily to the thalamus with very small projections to the cerebellum: Bischoff's, central cuneate, central gracile, rostral cuneate, rostral gracile nuclei, and cell group z. Two regions showed heavy projections to the cerebellum with no projections to the thalamus: the lateral portion of the external cuneate nucleus and the compact portion of cell group x. Four regions showed more equivalent projections to both target regions: basal cuneate, medial portion of the external cuneate nucleus, medial tongue extension of the external cuneate nucleus, and reticular portion of cell group x. Three more ventral regions were labeled: lateral cervical nucleus from thalamic injections but not from cerebellar injections; central cervical nucleus from cerebellar injections, which crossed the mid‐line, but not from thalamic injections; and lateral reticular nucleus from both target regions. In most medullary regions, most cells project to one target and very few project to the other; we suggest that the cells projecting to the minor target convey samples of the information going to the major targe

ISSN:0092-7317    

DOI:10.1002/cne.902670206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractIn raccoons and other mammals, a pathway for kinesthetic sensation (from muscles, fascia, tendons, and joints) reaches the anterodorsal cap of the ventrobasal thalamus and the anteriormost part of the somatic sensory cerebral cortex. To find the medullary component of this kinesthetic pathway in raccoons, small injections of horseradish peroxidase were made in the thalamus under guidance of simultaneous electrophysiological recording from kinesthetic projections. As determined by retrograde labeling following these injections, kinesthetic thalamic subregions receive projections as follows: caudomedial from cells in the external cuneate nucleus and its medial tongue, rostromedial from cells in basal cuneate nucleus, and rostrolateral from cells in cell group z and the reticular division of cell group x. Electro‐physiological recording showed kinesthetic representations in each of these medullary regions. Labeled cells were also observed in the infratrigeminal subnucleus of the lateral reticular nucleus. Cats have kinesthetic projections to the thalamus from the basal cuneate and cell group z; raccoons (and monkeys) have these plus projections from the external cuneate and cell group x. This suggests that the kinesthetic projection system in raccoons and monkeys is expanded in correlation with their more dextrous use of the han

ISSN:0092-7317    

DOI:10.1002/cne.902670207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractPhysiologically 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 μm × 14 μm. Two to five thick dendrites arose from the somata and frequently gave off branches to form glomerular tufts. The dendrites extended less than 400 μm; 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 morphologi

ISSN:0092-7317    

DOI:10.1002/cne.902670208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractIn the rhesus monkey retina, choline acetyltransferase (ChAT) immunoreactivity has been used to study the localization and synaptic organization of cholinergic neurons by both light and electron microscopy with peroxidase‐antiperoxidase immunohistochemistry. ChAT‐containing neurons are a type of amacrine cell with 97.5% of their cell bodies localized to the ganglion cell layer and the remainder in the inner nuclear layer. Their processes arborize in a single narrow band in the inner plexiform layer in a plane diving the outer two‐thirds from the inner one‐third of this synaptic region. With electron microscopy, ChAT‐immunoreactive amacrine cell processes were observed to be primarily postsynaptic to the diffuse invaginating cone bipolar cells and presynaptic to ganglion cells, although they are both post‐ and presynaptic to immunohistochemically unlabeled amacrine cell profiles and to ChAT‐containing amacrine cell proc

ISSN:0092-7317    

DOI:10.1002/cne.902670209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractPrimary sensory trigeminal projections were investigated in the hagfish following application of horseradish peroxidase (HRP) to the sensory branches. In our control preparations we were able to distinguish five sensory ganglia and their respective nerves. HRP application confirmed the almost exclusive relation of each of these nerves to their respective ganglia, with very little overlap. In normal frontal sections of the medulla oblongata, five columns of fibers surrounded by neuronal cell bodies could be clearly distinguished, but the number is probably fortuitous, for there was no one‐on‐one relationship with the five trigeminal ganglia. From their peripheral connections, we surmised that columns 1 and 3 handle general cutaneous sensation, columns 2, 4, and 5 handle taste sensation, and column 5 handles general mucous cutaneous sensation conveyed by utricular ganglion cells. Dorsally located columns received projections from nerves with dorsal peripheral connections, and more ventrally located columns received projections from nerves with ventral peripheral connections. This relation is the reverse of that seen in other vertebra

ISSN:0092-7317    

DOI:10.1002/cne.902670210

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractThe change with age of cell number in the developing inferior olivary nucleus (ION) of the normal rat, compared to the time course of the regression of the polyneuronal innervation of Purkinje cells by olivary axons (i.e., the climbing fibers), suggests that the involution of the redundant olivocerebellar contacts is caused by a reduction of axonal branching rather than by degeneration of the parent cells, this being also suggested by the normal size of the olivary population in adult rodents whose Purkinje cells retain polyneuronal innervation. However, the similar size of the adult ION population does not necessarily imply that the developmental history is the same in normal and multiply innervated adult rodents. Therefore, cell counts were performed in developing rats which had been repeatedly X‐irradiated from birth until postnatal day 14 and which retained polyneuronal innervation. The results show that, although less marked than during normal development, the evolution of the ION population is also characterized by a phase of cell loss followed by a slow increase. However, the number of cells in X‐irradiated rats is higher than in their controls from birth to postnatal day 15 but becomes identical at 20 days and later. These data confirm that cell death in the ION does not play a major role in the shaping of olivocerebellar connecti

ISSN:0092-7317    

DOI:10.1002/cne.902670211

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY