摘要:

AbstractNeurones in the striatum and substantia nigra (zona compacta) of the rat were divided into several classes according to differences in morphological appearance and ultrastructural localization of acetylcholinesterase (AChE). To determine which of the neurone types form connections between the substantia nigra and striatum, the ultrastructural localization of AChE was combined with retrograde axonal transport of horseradish peroxidase (HRP). The products of the histochemical reactions for HRP and AChE are localized in separate intracellular compartments and so identification of the efferent cell types was possible.In the striatum there are two morphological classes of AChE‐containing neurone and two or three varieties of cell which do not stain for the enzyme. Only one neurone type projects to the substantia nigra and this is a cell with no AChE which makes up 96% of the total neurone population. In the substantia nigra there are two types of neurone with AChE: a cell with rather variable amounts of AChE which projects to the striatum, and another rarer type, possibly an interneuron

ISSN:0092-7317    

DOI:10.1002/cne.901970202

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe hypothalamic arcuate nucleus (ARCN) was examined ultrastructurally 3 or 21 days after complete deafferentation of the medial basal hypothalamus (MBH) in ovariectomized adult female rats. Axodendritic shaft (SHS) and spine synapses (SPS) were counted in a field of 18,000 μm2in the middle part of the ARCN in each brain. The mean numbers of SHS and SPS at 3 or 21 days after deafferentation were reduced to about half of those in intact control animals. When the ARCNs of the ovariectomized MBH‐island rats were examined 3 days after treatment with estradiol benzoate (EB, 2 μg/day), the numbers of SHS and SPS did not differ from those in ovariectomized MBH‐island rats without EB treatment. However, EB treatment for 21 days produced a marked increase in the number of both SHS and SPS in the ovariectomized MBH‐island females, with the number of SHS in these females being restored to almost 75% of the intact level; the incidence of SPS was also significantly greater than that in the intact control animals. In these EB‐treated, ovariectomized MBH‐island rats, double synapses (spine‐spine and spine‐shaft double synapses) were frequently observed. In ovariectomized females without MBH deafferentation, however, estrogen failed to increase the numbers of SHS, SPS, and double synapses, which were almost comparable to those in intact and ovariectomized controls.These results suggest that estrogen has a facilitatory effect on SHS and SPS formation in the deafferented ARCN, presumably stimulating not only axonal sprouting but also dendritic spine formation by intact arcuate neurons in

ISSN:0092-7317    

DOI:10.1002/cne.901970203

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

年代:1981

数据来源: WILEY

摘要:

AbstractPreviously reported preganglionic‐postganglionic ratios for the sympathetic system are a major part of the evidence for the widely accepted idea that the sympathetic innervation of the viscera is diffuse. Unfortunately, the previous reports did not assess the non‐preganglionic fibers in the nerves examined, and the limitations of light microscopy precluded accurate unmyelinated fiber counts. Thus, a recalculation of these ratios is necessary.The present study recalculates these ratios for the cervical sympathetic system of the rat. All fiber counts are done with the electron microscope which has the resolution necessary for accurately determining axon numbers. Selective surgical procedures establish that 84% of the axons in the cervical sympathetic trunk are preganglionic, 11% are postganglionic, and 5% are sensory. Thus, the numbers of preganglionic fibers can now be accurately assessed and compared to the number of postganglionic neurons in the superior cervical ganglion. When this is done, a preganglionic/postganglionic ratio of approximately 1:4 is obtained. This ratio differs considerably from those previously publis

ISSN:0092-7317    

DOI:10.1002/cne.901970204

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe purpose of this study was to determine the topographical organization of cerebellothalamic projections in the rat. Following stereotaxic injections of3H‐leucine or electrolytic lesions in the cerebellar nuclei, efferent fibers were observed to emerge from the cerebellum through two discrete routes. Fibers from the fastigial nucleus decussated within the cerebellum, formed the crossed ascending limb of the uncinate fasciculus, ascended in the dorsal part of the midbrain tegmentum, and entered the thalamus. Cerebellothalamic fibers from the interpositus and dentate nuclei coursed in the ipsilateral brachium conjuctivum, decussated in the caudal midbrain, and ascended to the thalamus via the crossed ascending limb of the brachium conjunctivum.Cerebellar terminations were observed in the intralaminar, lateral, and ventral tier thalamic nuclei as well as in the medial dorsal nucleus. Projections to the intralaminar nuclei were more pronounced from the dentate and posterior interpositus than from the anterior interpositus and fastigial nuclei. The lateral thalamic nuclei received a projection from the dentate and posterior interpositus nuclei while the fastigial nucleus projected to the medial dorsal nucleus. Within the rostral ventral tier nuclei fastigiothalamic terminations were localized in the medial parts of the ventral medial and ventral lateral nuclei, whereas dentatothalamic projections were concentrated in the lateral parts of the ventral medial nucleus and the medial half of the ventral lateral nucleus. Terminations from the posterior interpositus nucleus were observed ventrally and laterally within the caudal two‐thirds of the ventral medial nucleus and throughout the ventral lateral nucleus, where they were densest in the lateral part of its lateral wing and within the central part of its cap. The anterior interpositus nucleus also projected to the central and lateral parts of the ventral lateral nucleus, but these terminations were considerably less dense than those from the posterior interpositus. A few fibers from the interpositus nuclei terminated in the medial part of the rostral pole of the ventral posterior nucleus.A prominent recrossing of cerebellothalamic fibers from the fastigial, posterior interpositus, and dentate nuclei occurred through the central medial nucleus of the internal medullary lamina. These terminated within the ipsilateral ventral lateral and intralaminar nuclei.These results show that each of the cerebellar nuclei project to the thalamus and that their terminations are topographically organized in the rostral ventral tier nuclei. The clustering of autoradiographic silver grains or terminal degeneration observed in the thalamic nuclei suggests a medial‐to‐lateral organization of this cerebellothalamic

ISSN:0092-7317    

DOI:10.1002/cne.901970205

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

年代:1981

数据来源: WILEY

摘要:

AbstractUnilateral olfactory nerve section was performed in the salamander,Ambystoma tigrinum. An ultrastructural study was performed to investigate the changes occuring during degeneration and replacement of the mature olfactory receptor neurons. Experimental and contralateral control tissues were examined following postoperative survival periods ranging from 12 hours to 90 days. Normal bipolar receptor neurons have a fusiform cell body containing a thin rim of cytoplasm and an ovoid nucleus with a characteristic “checkerboard” chromatin pattern. A single apical dendrite projects to the surface of the epithelium, where numerous cilia extend from its apex into the overlying mucus. A single, unmyelinated, unbranching axon originates at the basal pole of the cell. After nerve section, retrograde degeneration of the mature neurons occurs. Early degenerative changes include pronounced condensation of the nuclear chromatin, increased number of nuclear membrane infoldings, and dilation of the space between the membranes of the nuclear envelope. At a later stage, the cytoplasm of the cell increases in volume and its organelle systems break down, resulting in accumulation of various forms of cell inclusions. Subsequently, proliferation of cells in the basal region of the epithelium occurs. Between 3 week and 2 months following nerve section, these cells differentiate into mature neurons. By 3 months, neurons within the epithelium have resumed their normal ultrastructure. Correlation of the time course of the ultrastructural changes with previously reported neurophysiological studies indicates that neuronal activity of the epithelium is dependent upon the presence of fully differentiated olfactory neur

ISSN:0092-7317    

DOI:10.1002/cne.901970206

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

年代:1981

数据来源: WILEY

摘要:

AbstractUtilizing the retrograde HRP transport method, fibers from anterior and posterior subdiaphragmatic branches of the vagus nerve in the rat were traced to their cells of origin in the brainstem. Efferents to the gut supplied by the subdiaphragmatic vagus nerves derive from cell bodies organized in a viscerotopic, spindle‐shaped longitudinal cell column throughout the longitudinal extent of the classically described dorsal nucleus of the vagus (DNV) and in regions of nucleus commissuralis (NC), caudal to the DNV. This entire longitudinal group of cells is called the DNV cell column. In the caudal one third of the DNV cell column, the cell bodies were found in the midline and paramedian posterior portion of the NC, and in the anterior portion of the caudal DNV, in a horizontally oriented cluster of cells when viewed in cross section. In the middle one third of the DNV cell column, the cell bodies moved laterally, but still maintained their anterior position in the nucleus. In the rostral one third of the cell column, the cell bodies were located at the lateral margin of the DNV. A few scattered cell bodies extended caudally from the DNV cell column into the dorsal region of lamina X of spinal cord, and reached as far caudal as the C5‐C6segments. The anterior subdiaphragmatic branch of the vagus contained axons whose cell bodies were mainly but not exclusively located in the ipsilateral (left) side of the medulla, while the posterior subdiaphragmatic branch of the vagus contained axons whose cell bodies were found bilaterally in the medulla, with a majority (approx. 60%) located on the ipsilateral (right) side, and approximately 40% located on the contralateral (left) s

ISSN:0092-7317    

DOI:10.1002/cne.901970207

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe structural plan of the ventral posterolateral nucleus (VLP) in the rat was analyzed by using a variety of techniques to study the pattern of distribution of the ascending afferent fibers and the synaptology of the neuropil within this somatosensory relay nucleus. Golgi stains, Fink‐Heimer methods, HRP labeling methods, and electron microscopy were all used in the analysis.The neurons in VPL are aligned in rostrocaudal and dorsoventral rows that are roughly parallel to the curvature of the external medullary lamina (EML) and curve partially around the rostral pole of the ventral posteromedial nucleus (VPM). Golgi‐impregnated section reveal that the dendritic trees of the VPL neurons conform in general to the laminar pattern of VPL. Thick proximal dendrites extend about 25 μm from the cell bodies. Most proximal dendrites are aligned with the laminae of VPL but the distal dendrites spread over many laminae within VPL. The inputs from the dorsal column nuclei (DCN) end only on proximal dendrites as large, round‐vesicle terminals. About 20–25% of the small round‐vesicle terminals originate in the cerebral cortex and synapse only on the distal dendrites. The third type of synapse contains many flattened vesicles and is of unknown origin. No serial synapses or vesicle‐containing dendrites were observed. Input from the spinal cord projects to two segregated zones which are transitional between the ventral lateral nucleus (VL) and VPL rostrally and between the posterior thalamic complex (PO) and VPL caudally. Each transition zone contains neurons characteristic of both VPL and the adjacent region. Ascending afferent projections were demonstrated by the antegrade transport of HRP following injections into the ventral mesencephalon and by Fink‐Heimer stains of degeneration resulting from small lesions of the DCN. Both methods indicate that large‐caliber axons course parallel to each other and give off collaterals that diverge to widespread areas of the VPL. The widespread terminal fields that result do not conform to the laminar pattern of the nucleus. Small punctate lesions of DCN result in sparse degeneration that is also widespread in VPL. Structures which appear to be clusters of terminal arborizations of the ascending afferent input were also observed in VPL. These results suggest that somatotopy and modality separation in VPL may be determined either by intrinsic and/or corticothalamic morphological relationships and not by precise topographical ordering

ISSN:0092-7317    

DOI:10.1002/cne.901970208

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

年代:1981

数据来源: WILEY

摘要:

AbstractA survey of diameter spectra in presented for classic neurones of the cat retinal ganglion cell layer. From these, with the aid of retrograde HRP filling for central retina, a set of density distribution maps has been prepared for each of the major modes of the neuronal diameter spectrum. The total population of classical neurones, the presumed ganglion cells of Hughes ('75), confirms published values with a minimum of some 207,000 comprised 5,600 cells in the γ mode, 80,700 cells in the β mode, and 120,700 cells in the γ mode.A proportion of classical neurones in the γ mode do not fill by retrograde transport of HRP from either optic nerve or superior colliculus. Their morphology is characteristic and includes a conspicuous basophilic nuclear bar or fold; they remain subsequent to ganglion cell retrograde degeneration and resemble some prifles of the amacrine layer. It is presumed that they represent a class of displaced amacrine cells.Estimates based on ganglion cell identification by HRP filling indicate populations of about 80,000 cells in both the γ and the β modes and a total count of about 170,000 ganglion cells; a good agreement with Hughes and Wässle's ('76) optic nerve fibre count, but lower than the classic neurone count.It is concluded that the distribution maps for ganglion cells in each of the three modes of the soma diameter spectra are similar in from and resemble that of the total neurone density map. The ganglion cell population of the γ mode in the visual streak isnotfound to increase in proportion relative to that of the β mode, as has been reported e

ISSN:0092-7317    

DOI:10.1002/cne.901970209

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe retrograde transport of horseradish peroxidase (HRP), Golgi impregnations, and electron microscopic (EM) observations have been employed to investigate the intrinsic organization of one cytoarchitectonic subdivision of the feline dorsal column nuclei (DCN): the “clusters” region. Previous studies have demonstrated that neurons arranged in typical cell clusters in the dorsal two‐thirds of the feline DCN project to the ventrobasal complex (VB) of the thalamus. Following injections of HRP in the VB of adult cats, over 90% of the neurons in this region contain detectable reaction product. These thalamic projecting neurons (TPN) are typically round, range from 20 to 35 μm in diameter, and have round nuclei and abundant cytoplasm.In Golgi preparations, TPN are identified by their characteristic arrangement in the cell clusters. Observations of their cytological characteristics in gold‐toned preparations in both 1‐μm‐thick sections, and in thin sections at the EM level, supplement the data from HRP material. The dendrites of TPN in the clusters region characteristically converge in the perikarya‐free center of each cluster, and appendages originate from both proximal and distal portions of the major dendrites of these neurons. These appendages vary in morphology from short‐stalked, occasionally multi‐lobed, bulbous thorns to long‐stalked processes terminating in a single or multilobed swelling. Other appendages often display beaded swellings along their length (moniliform appendages).Neurons in the clusters region unlabelled by HRP injected in the VB have cytological charateristics quite distinct from those of TPN in the same region. Typically located at the periphery of the cell clusters, unlabelled neurons have fusiform perikarya, range in diameter from 8 to 12 μm along their short axis, and have highly indented nuclei and sparse cytoplasm. In Golgi preparations, small fusiform neurons located at the periphery of cell clusters typically have two major dendritic trunks originating from opposite poles of their perikarya. Observations in 1‐μm‐thick plastic sections of re‐embedded Golgi‐impregnated neurons of this type support their identifications as neurons which are unlabelled after HRP injection in VB. Dendritic appendages are present also on this type of neuron, although they do not appear to be as frequent as in the case of the TPN. Although the axon of the small, fusiform neurons have not been impregnated beyond the initial segment in the present Golgi material, thus precluding the classification of this type of neuron as a Golgi type II neuron, a combination of the HRP and Golgi observations suggest that these neurons are distinct from TPN, and are possibly interneurons.In addition to the previously described synaptic complexes of primary afferent terminals associated with, or postsynaptic to, small boutons with flattened vesicles (F‐boutons, of presumed interneuronal origin), EM observations of serial sections demonstrate triadic synaptic arrangements similar to those encountered in other CNS nuclei. In such instances, a primary afferent terminal is presynaptic to a pale profile containing polymorphicvesicles (P‐bouton), and both boutons are presynaptic to a dendrite. In serial sections, P‐boutons are demonstrated to be of dendritic origin, while F‐boutons are observed to arise frommyelinated fibers. By comparison with Golgi observations, P‐boutons are believed to corre‐spond to the dendritic appendages of TPN, suggesting that TPN, as well as interneurons, contribute to the intrin

ISSN:0092-7317    

DOI:10.1002/cne.901970210

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

年代:1981

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.901970201

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

年代:1981

数据来源: WILEY