摘要:

AbstractAn antibody raised in rabbits against a GABA‐BSA conjugate was used together with the PAP technique to label elements in the neostriatum of three Old World monkeys. Light microscopy revealed numerous immunoreactive medium‐size neurons of various staining intensities, some of which had indented nuclei, as well as an occasional large cell. The neuropil showed a plexus of fine processes with frequent puncta, Ultrastructurally, the medium‐size GABA‐positive neurons were of two types: one with smooth nuclei and scanty cytoplasm, similar to spiny I cells, the other with invaginated nuclear envelopes and more abundant perikaryon, resembling the aspiny type. Correspondingly, labeled dendrites were either spiny or varicose. Some stained axons were myelinated, and the boutons had either large and ovoid, or small and pleomorphic vesicles. All of these boutons formed symmetric synapses, the former type with GABA‐positive dendritic shafts but also with unlabeled dendrites; the latter type usually with GABA‐negative elements, either dendrites, dendritic spines, or somata. Synapses were also observed between unreactive boutons and immunostained dendrites. Terminals with densely packed, small round vesicles that established asymmetric synapses with spines were always GABA‐negative. Glial elements were consistently unlabeled, save, for some astroglial endfeet. These findings provide positive evidence for the existence of two classes of GABAergic striatal neurons corresponding to a long‐axoned spiny I type and an aspiny interneuron. Furthermore, the simultaneous labeling of GABA‐immunoreactive presynaptic and postsynaptic profiles offers possible morphologic bases for the various kinds of intrastriatal inhibitory processes, including the feedforward, feedback, and

ISSN:0092-7317    

DOI:10.1002/cne.902700202

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe ultrastructure of large neurons in the stratum griseum intermedium of the cat superior colliculus was examined following injections of horseradish peroxidase (HRP) into the dorsal tegmental decussation. Four HRP‐labeled cells were selected, and the synaptology of their cell bodies and selected regions of proximal and distal dendrites was examined. The four neurons represent four morphologically distinct cell types: multipolar radiating, tufted, large vertical, and medium‐sized trapezoid radiating. These four neurons correspond with cell types X1, X2, X3, and T1respectively, according to the recent classification of neurons in the superior colliculus of the cat by Moschovakis and Karabelas (J. Comp Neurol.239:276–308, '85).The three X type neurons are similar in having 83% of their somata and over 74% of their proximal dendrites contacted by synaptic profiles. Distal dendrites of the X type neurons, however, receive fewer synaptic contacts. In contrast, in the T1cell, only 69% of the soma membrane is contacted by synaptic profiles, and the synaptic coverage on proximal and distal dendrites does not vary much from this. Of the eight types of synaptic terminals described in the stratum griseum intermedium of the cat superior colliculus by Norita (J. Comp. Neurol.190:29–48, '80), only five are found in contact with the X and T type efferent neurons described here. There are some regional differences in terminal distribution, although each terminal is represented on each cell. Type III terminals (small, contain mostly pleomorphic vesicles, and make symmetrical contacts) are the most abundant on cell bodies and dendrites of all four cell types. Terminal types II (medium‐sized, containing round and flattened vesicles, and making asymmetrical contacts), and IV (medium to large in size, containing flattened vesicles, and making symmetrical contacts) are well represented. In general, terminal types I (small, containing densely packed round vesicles/and making asymmetrical contacts) and VI (small and irregular in shape, containing flattened vesicles and making symmetrical contacts) are found infrequently. The identity of different types of synaptic terminal is

ISSN:0092-7317    

DOI:10.1002/cne.902700203

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractA new technique of retrograde labeling of ganglion cells with horseradish peroxidase (HRP) has been developed, based on orbital injections of HRP combined with a detergent (lysolecithin). When injections are followed by an appropriate survival time, dense staining of a small number of widely scattered cells results in Golgi‐like filling of each neuron. This technique, as well as a variation which causes mass staining of ganglion cell somas, has been used to analyze the morphology of mudpuppy retinal ganglion cells. Morphological analysis has relied on computer reconstruction techniques for display, analysis of dendritic sublamination pattern, and morphometric analysis of the dendrites and soma.Based on morphological criteria, the mudpuppy retina contains a rich variety of ganglion cell types which vary according to soma placement, dendritic field size, polar vs. non‐polar dendritic fields, dendritic branching pattern, and dendritic sublamination. The mudpuppy retina contains both conventional and displaced ganglion cells: the latter constitute about 15% of the total ganglion cell population. Both conventional and displaced ganglion cells show morphological diversity of dendritic sublamination branching pattern; cells from each group have a dendritic branching pattern confined to either distal or proximal divisions of the inner plexiform layer, whereas other cells have dendrites which branch in both sublaminae. Using morphological criteria, two subtypes of ganglion cells were identified, which have a distinctive branching pattern and dendritic tree size.The size and distribution of ganglion cell somas were analyzed from retinas in which mass staining of ganglion cells was present. The total number of ganglion cells was estimated at approximately 14,500 cells per retina. There was a tendency for soma size and density to decrease near the optic disk. The somas of displaced ganglion cells are smaller than their conventional counterparts, at the same retinal eccentricity.The somas of all HRP filled cells swell when compared to those of unstained fixed and freshly dissected retinas. The degree of swelling is proportional to the length of exposure to HRP. Cell swelling was evident for both retrograde labeling and intracellularly injected HRP. This artifact of HRP staining could influence the interpretation of studies in which quantitative differences in soma sizes are based on the use of HRP label

ISSN:0092-7317    

DOI:10.1002/cne.902700204

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe projections of the medial preoptic nucleus (MPN) were examined by making injections of the anterogradely transported lectinPhaseolus vulgarisleucoagglutinin (PHA‐L) into the MPN and charting the distribution of labeled fibers. The evidence indicates that the MPN projects extensively to widely distributed regions in both the forebrain and brainstem, most of which also supply inputs to the nucleus. An important neuroendocrine role for the MPN is underscored by its extensive projections to almost all parts of the periventricular zone of the hypothalamus, including the anteroventral periventricular, anterior part of the periventricular, paraventricular (PVH), and arcuate nuclei, and a role in autonomic mechanisms is indicated by projections to such regions as the dorsal and lateral parvicellular parts of the PVH, the lateral parabrachial nucleus, and the nucleus of the solitary tract. Other projections of the MPN suggest participation in the initiation of specific motivated behaviors. For example, inputs to two nuclei of the medial zone of the hypothalamus, the ventromedial and dorsomedial nuclei, may be related to the control of reproductive and ingestive behaviors, respectively, although the possible functional significance of a strong projection to the ventral premammillary nucleus is presently unclear. The execution of these behaviors may involve activation of somatomotor regions via projections to the substantia innominata, zona incerta, ventral tegmental area, and pedunculopontine nucleus. Similarly, inputs to other regions that project directly to the spinal cord, such as the periaqueductal gray, the laterodorsal tegmental nucleus, certain medullary raphe nuclei, and the magnocellular reticular nucleus may also be involved in modulating somatic and/or autonomic reflexes. Finally, the MPN may influence a wide variety of physiological mechanisms and behaviors through its massive projections to areas like the ventral part of the lateral septal nucleus, the bed nucleus of the stria terminalis, the lateral hypothalamic area, the supramammillary nucleus, and the ventral tegmental area, all of which have extensive connections with regions along the medial forebrain bundle.Although the PHA‐L method does not allow a clear demonstration of possible differential projections from each subdivision of the MPN, our results suggest that each of them does give rise to a unique pattern of outputs. This pattern of projections was found to be essentially the same in female rats and appears to be unique to the MPN, since injections of PHA‐L into the lateral preoptic or anterior hypothalamic areas, or into other nuclei within the medial preoptic area showed quite different patterns of ou

ISSN:0092-7317    

DOI:10.1002/cne.902700205

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe laterodorsal tegmental nucleus (ntdl) contains a cluster of cells located just medial to the locus coeruleus in the pontine brainstem. The ntdl has been shown to project both rostrally to the forebrain and diencephalon and caudally to the spinal cord. In an effort to characterize this region neurochemically, the present study was conducted to identify a variety of neurochemicals localized within perikarya and fibers of the ntdl and surrounding nuclei. Rats were perfused with formalin, and brain sections were processed for fluorescence immunocytochemistry and acetylcholinesterase (AChE). Of the neurochemicals screened, atrial natriuretic factor (ANF), choline acetyltransferase (ChAT), cholecystokinin (CCK), calcitonin gene‐related peptide (CGRP), dynorphin B (Dyn B), galanin, somatostatin, substance P, neurotensin (NT), neuropeptide Y (NPY), vasopressin, vasoactive intestinal polypeptide (VIP), serotonin (5HT), glutamic acid decarboxylase (GAD), and tyrosine hydroxylase (TH) were studied. AChE and ChAT staining revealed that the ntdl contains mostly cholinergic neurons. In addition, brightly reactive substance P and galanin and paler staining CRF, ANF, CGRP, NT, VIP, and Dyn B cell bodies were found within the ntdl. Varicose fibers in this nucleus also contained these peptides in addition to CCK, GAD, TH, 5HT, and NPY. The dorsal tegmental nucleus, dorsal raphe nucleus, locus coeruleus, and the parabrachial region contained a dense and varied assortment of peptides with distinct positions and patterns. This multiplicity of neurochemicals within this area suggests a possible influence on a variety of functions modulated by the ntdl and other closely associated tegmental nucle

ISSN:0092-7317    

DOI:10.1002/cne.902700206

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe distribution of motoneurons innervating the upper cervical muscles, biventer cervicis, splenius capitis, complexus, rectus capitis dorsalis, rectus capitis lateralis, and rectus capitis ventralis in the chicken was examined by retrograde transport of horseradish peroxidase. Labeled motoneurons supplying upper neck muscles ranged from 30 to 60 μm in diameter and were located within two subnuclei in the brainstem. The rostrocaudal distributions of motoneurons projecting to individual cervical muscles ranged from 3 to 9 mm in length, both rostral and caudal to the obex. Detailed analysis of the data showed that the more dorsally positioned subnucleus projected mainly to the hypaxial muscles, i.e., the rectus capitis ventralis and lateralis, whereas the ventral subnucleus supplied chiefly the epaxial muscles, i.e., the biventer cervicis and splenius capitis. The complexus and rectus capitis dorsalis were innervated by both of these subnuclei.Historically these dorsal and ventral subnuclei, respectively, have been called the nucleus hypoglossus ventralis and the nucleus hypoglossus ventralis ventrolateralis. In view of the observation that these nuclei do not undergo retrograde degeneration following section of the hypoglossal nerves, this older nomenclature is misleading. In agreement with other authors, we suggest that these motoneuron groups should be collectively referred to as the nucleus supraspinalis

ISSN:0092-7317    

DOI:10.1002/cne.902700207

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractCone photoreceptor movements in lower vertebrates are regulated by the interaction of the light‐dark cycle and an endogenous circadian clock. We have suggested that melatonin and dopamine interact to regulate dark‐ and light‐adaptive movements, respectively, and that melatonin affects cones indirectly by inhibiting dopamine release. In fact, any factor modulating dopaminergic neurons in the retina may have effects on either cone elongation or contraction. We have utilized anin vitroeyecup preparation from the African clawed frog,Xenopus laevis, to evaluate a possible role of the neurotransmitter GABA, which is thought to tonically suppress dopamine release. GABA agonists mimic the effects of darkness and induce cone elongation; the effects of GABA agonists are blocked by dopamine. Muscimol‐induced cone elongation occurs at low light intensity but is inhibited by bright light in eyecups prepared from cyclic‐light‐maintained animals. Although neither melatonin nor muscimol stimulates cone elongation in bright light, simultaneous application of both drugs induces elongation. The GABA antagonist picrotoxin induces cone contraction which is blocked by the dopamine receptor antagonist spiroperidol, which suggests that GABA may affect cone movement inXenopusby regulating dopamine neurons. Consistent with this, picrotoxin‐induced cone contraction is Ca+2dependent and is blocked by high Mg+2or the Ca+2antagonist nifedipine. Pharmacological analysis suggests that the effects of GABA may result from its action at more than one receptor subtype. Our results support the hypothesis that dopamine is part of the light signal for cone contraction and that its suppression is part of the signal for co

ISSN:0092-7317    

DOI:10.1002/cne.902700208

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractGlycoconjugates, including glycolipids, glycoproteins, and proteoglycans, are present in the plasma membrane of photoreceptor cells and in the interphotoreceptor matrix surrounding photoreceptor cell ellipsoids and outer segments. Although the precise function of these molecules is unknown, they may be important in mediating photoreceptor–pigment epithelial cell interactions, outer segment membrane assembly, and/or disc shedding. Lectins, affinity ligands for defined carbohydrate sequences, have proven particularly useful in studying the glycoconjugate composition of the interphotoreceptor matrix. The peanut lectin selectively binds to domains of the interphotoreceptor matrix surrounding cone (“cone matrix sheaths”), but not rod inner and outer segments. This is evidence for the existence of chemical and structural heterogeneity within the interphotoreceptor matrix.The studies described herein utilized ultrastructural pre‐embedding histochemical labeling to assess whether, in addition to the surrounding interphotoreceptor matrix, peanut lectin binding is associated directly with the plasma membrane of cone inner and outer segments. This study confirms that ferritin‐conjugated peanut agglutinin binds to cone matrix sheaths, and, in addition, provides ultrastructural evidence for the presence of binding to the plasma membrane surrounding cone inner and outer segments. The data suggest that cone membrane–associated peanut agglutinin–binding molecules may differ from those located within cone m

ISSN:0092-7317    

DOI:10.1002/cne.902700209

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractLow‐threshold mechanosensory nerves in the adult rat differ both from their counterparts in lower vertebrates and fromhigh‐threshold nociceptive nerves in mammals in that they appear not to undergo collateral sprouting into adjacent denervated skin, although they will clearlyregenerateinto it after they are damaged. We have now studied the growth capabilities of the low‐threshold nerves supplying touch domes, the visible mechanosensory structures scattered throughout the hairy skin. Touch domes in the rat are often multiply innervated. A serendipitous observation on such domes allowed us to investigate the possibility that a functional collateral sprouting of their nerves can indeed occur, but only to a spatially very restricted extent, e.g., within the confines of a partially denervated dome. We used a “prodder” with a tip diameter of 16 μm to examine the mechanosensory profile across single domes that were preselected as being supplied by only two axons, one running in each of two adjacent dorsal cutaneous nerves (DCNs). Simultaneous recordings were made of the afferent discharges evoked in these nerves when the prodder was applied at about 17 or more locations on a selected dome; the spatial resolution was better than 55 μm. We found that within such a shared dome, one axon can supply a discrete territory (its “domain”), which may or may not overlap with the corresponding domain of the other axon. In a preliminary electron microscopic study, we found no evidence for a sharing of single Merkel cells, which are the specialized sensory cells in touch domes, even in the regions of a shared dome where two domains overlapped; each innervated Merkel cell appeared to be contacted by a single nerve ending, implying that in a shared dome each axon probably supplies an exclusive subpopulation of the Merkel cells. We tested for functional collateral sprouting by eliminating one nerve to a shared dome, and at a selected time thereafter mapping the domain of the remaining axon to see whether it had enlarged. The result was the same whether the two domains initially had a region of overlap or not; no expansion of the surviving domain occurred over postoperative periods up to 4 months (an expansion of the domain by 55 μm would have been detected). Thus functional collateral sprouting had failed to occur. In contrast, when the entire DCN containing one of the axons was surgically eliminated, and that containing the other axon crushed and allowed toregenerate, invariably the axon that grew into the now totally denervated dome invaded it extensively, restoring mechanosensitivity to both former domains.The likelihood that these and related results imply that collateral sprouting and regeneration are evoked by different mechani

ISSN:0092-7317    

DOI:10.1002/cne.902700210

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.902700201

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY