摘要:

AbstractVibrissal follicle‐sinus complexes (F‐SCs) in the mystacial pad of rodents are heavily innervated by different types of sensory nerve endings. One site in mystacial F‐SCs, the inner conical body (ICB), is uniquely well innervated only in those species, such as the rat, that rhythmically whisk their mystacial vibrissae. In this study, we examined the innervation of rat nonmystacial F‐SCs, which are not whisked. Supraorbital, posteroorbital, lateral cervical, median cervical, submental, and carpal forelimb F‐SCs were cut on a cryostat and were either prepared for anti‐human protein gene product (PGP 9.5) immunofluorescence or stained using the Winkelmann silver technique. Much of the innervation of the nonmystacial F‐SCS is similar to that of mystacial F‐SCs. All are innervated by a large deep vibrissal nerve (DVN) and several smaller superficial vibrissal nerves (SVNs). As in the mystacial pad, the SVNs show a distribution of Merkel and free nerve endings qualitatively similar to the rete ridge collar of all the nonmystacial F‐SCs as well as provide circumferentially oriented endings to the ICBs to all but median‐cervical and carpal F‐SCs. Not only was the ICB innervation relatively sparse in median‐cervical and rpal F‐SCs, but a large portion of the carpal ICB innervation also ascended from the DVNs, which make only a small, ICB contribution in other locations. Similar to mystacial pad F‐SCs, the DVNs provided Merkel and lanceolate endings to the level of the ring sinus as well as reticular and irregular lanceolate‐like endings to the level of the cavernous sinus. However, all but the posteroorbital F‐SCs have relatively few lanceolate endings. Carpal F‐SCs also have relativiely few ring‐sinus Merkel endings, which are diffusely distributed, are limited to the superficial portion of the outer root sheath. They also lack reticular and irregular lanceolate‐like endings in the cavernous sinus. However, carpal F‐SCs have a unique set of corpuscular endings in the ICB, ring sinus, and cavernous sinus that are rrely seen in other F‐SCs. PGP 9.5 immunofluorescence also revealed two sets of fine‐caliber profiles at the level of the ICB and ring sinus that were not previously seen in mystacial F‐SCs. Athough there was no correlation between ICB innervation and whisking, the regional variations in F‐SC innervation suggest that functional differences may exist between vibrissae at differen

ISSN:0092-7317    

DOI:10.1002/cne.903570402

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractInteractions between carbohydrate ligands and their receptors play an important role in cell adhesion and migration in many tissues. Cell‐surface carbohydrates that contain terminal galactose have previously been implicated in primary sensory axon growth in the rodent olfactory system. The aim of the present study was to determine whether galectin‐1, a galactose‐binding receptor, was expressed within the rat primary olfactory pathway. Immunohistochemical and in situ hybridisation analyses revealed expression of galectin‐1 by primary sensory olfactory neurons during the major embryonic period of axonogenesis as well as in maturity. In the adult olfactory bulb, galectin‐1 was expressed by both second‐order projection neurons and interneurons and was selectively localised to the synaptic neuropil layers. Mitral cells, the principal postsynaptic target of primary olfactory axons, began expressing this lectin soon after genesis and maintained high levels into adulthood. The expression of galectin‐1 in the primary olfactory pathway and olfactory bulb neuropil suggests a role for this lectin both in the initial formation and in the subsequent maintenance of neuronal connections between the peripheral and the central olfactory neurons as well as between neurons within the bulb. © 1995 W

ISSN:0092-7317    

DOI:10.1002/cne.903570403

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractBrains of nonmammalian vertebrates typically contain multiple forms of gonadotropinreleasing hormone (GnRH). Until recently, only the mammalian form of GnRH (mGnRH) had been isolated in placental mammals. Biochemical and histological data show that both mGnRH and chicken‐II GnRH (cGnRH‐II) are present in a primitive placental mammal, the musk shrew (Suncus murinus). Similar to the case in nonmammalian species, in the musk shrew, neurons that express cGnRH‐Il are located in a discrete cluster in the midbrain. We have used a combination of radioimmunoassay and immunocytochemistry, analyzed at the light level and with electron microscopy, to describe the distribution of cGnRH‐II cell bodies and fibers in the musk shrew brain. All cGnRH‐II‐immunoreactive (ir) neurons reside in the midbrain, and this area contains the greatest concentration of cGnRH‐II peptide in the brain, At the light and electron micrographic levels, we have identified synaptic terminals containing dense core vesicles that are immunoreactive for cGnRH‐II in the medhd habenula. Radioimmunoassay reveals that this region contains the second greatest concentration of cGnRH‐II in the brain. Widely scattered cGnRH‐II‐ir fibers are present throughout the forebrain, particularly in the medial septum, hypothalamus, and midbrain central gray. Scant cGnRH‐II fibers are present in the median eminence, arcuate nucleus, and infundibular stem, and only low concentrations of the peptide are detected in these areas. Finally, intravenous administration of mGnRH is ten times more effective than cGnRH‐II in promoting ovulation. Taken together, the results suggest that cGnRH‐II is likely to act as a neuromodulator or neurotransmitter in mammals and that the medial habenula is the major site of cGnRH‐II action in mammalian

ISSN:0092-7317    

DOI:10.1002/cne.903570404

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe nuclei of the lateral lemniscus in the echolocating bat,Eptesicus fuscus, are large and highly differentiated. In each nucleus, different characteristic response properties predominate. To determine whether the dissimilar response properties are due in part to dfferential ascending input, we examined the retrograde transport from small deposits of horseradish peroxidase (HRP) or HRP conjugated with wheat germ agglutinin (WGA‐HRP) in the nuclei of the lateral lemniscus.The intermediate nucleus (INLL) and the two divisions of the ventral nucleus (VNLL) receive almost exclusively monaural input from the anteroventral and posteroventral cochlear nuclei and from the medial nucleus of the trapezoid body. Lesser inputs originate in the lateral nucleus of the trapezoid body and the ventral periolivary area. Although the three monaural nuclei of the lateral lemniscus all receive input from the same set of nuclei, and from the same identified cell types in the cochlear nucleus, there is a difference in the relative proportions of input from these sources. The dorsal nucleus (DNLL) receives input mostly from binaural structures, the lateral and medial superior olives and the contralateral DNLL, with only a minor projection from the coc hlear nucleus. The lateral and medial superior olives project bilaterally; the bilateral projection from the medial superior olive is unusual in that it is found in only a few mammalian species.The results show a segregated pattern of binaural projections to DNLL and monaural projections to INLL and VNLL that is consistent with the binaural response properties found in DNLL and the exclusively monaural response properties found in INLL and VNLL. The differences in response properties between monaural nuclei, however, are not due to input from different nuclei or cell types but may be influenced by differing magnitudes of the constituent ascending projections. © 1995 Wiley‐Liss,

ISSN:0092-7317    

DOI:10.1002/cne.903570405

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThis study provides a map of those neurons in the midbrain periaqueductal gray which are activated by chemical stimulation within different subdivisions of the periaqueductal gray. In pentobarbital anesthetized rats, the expression of the c‐FOS protein was detected by immunocytochemistry and was used as a marker of neuronal activity. Microinjections of the γ‐aminobutyric acid (GABAA) receptor antagonist bicuculline (200 pmol in 50 nl) were used to increase selectively the firing rate of neurons originating from the injection site. The pattern of c‐FOS immunoreactivity was highly specific for different injection sites. Dorsal injections were characterized by an extensive distribution of c‐FOS immunoreactivity along the entire rostrocaudal extent of the periaqueductal gray, while ventral injections produced a much more restricted labeling. Following injection into the dorsal subdivision of the rostral periaqueductal gray, c‐FOS immunoreactivity was present bilaterally in the dorsal and dorsolateral subdivisions of the rostral periaqueductal gray and was found in all subdivisions of the caudal periaqueductal gray. Dorsolateral injections at the level of the oculomotor nuclei produced strictly ipsilateral labeling in the dorsal and dorsolateral periaqueductal gray at the level of injection and throughout the ipsilateral half of the periaqueductal gray at more caudal levels. Stimulation in the ventrolateral periaqueductal gray induced FOS in the ventrolateral periaqueductal gray and the adjoining reticular formation. At rostral levels c‐FOS immunoreactivity was also seen in the lateral periaqueductal gray but was absent caudal to the injection site. The identified patterns of activity in the periaqueductal gray provide a new basis for the interpretation of the diverse functional consequences of stimulation at periaqueductal gray sites. © 1995 Wi

ISSN:0092-7317    

DOI:10.1002/cne.903570406

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe prenatal developmental histories of layer I, fibrous (white matter), and protoplasmic (gray matter) astrocytes have been studied in the human neocortex by the rapid Golgi method. The developmental route followed by each of these astrocytes is a distinct process which evolves from a specific precursor, occurs at a different time, and is linked to a specific event. The differentiation of layer I astrocytes is linked to the neocortex external glial limiting membrane (EGLM), that of fibrous astrocytes to the early white matter vascularization and maturation, and that of protoplasmic astrocytes to the late gray matter ascending vascularization and maturation. At the start of development, three glial precursors are established in the neocortex: 1) original radial neuroectodermal cells with nuclei above the primordial plexiform layer (PPL) by losing their ependymal and retaining their pial attachments become early astrocytes of layer I and EGLM components; 2) neuroectodermal cells with nuclei below the PPL that retain their pial and ependymal attachments become type I radial glial cells which are committed to the guidance of neurons and the early EGLM maintenance; and, 3) neuroectodermal cells that lose their pial but retain their ependymal attachment are transformed into type II radial glial precursors. By progressively losing their ependymal attachment, type II radial glia precursors become freely migrating cells, establish vascular contacts, and differentiate into fibrous astrocytes (and into oligodendrocytes?) throughout the subplate, developing white matter, and paraventricular regions. After the formation of the gray matter, additional layer I astrocytes are needed for the EGLM late prenatal and postnatal maintenance because type I radial glia cells start to regress and to reabsorb their EGLM endfeet. A late ependyma‐to‐pia migration of glial precursors progressively repopulates layer I with additional astrocytes and establishes the ephemeral subpial granular layer (SGL) of Ranke. From the 15th week of gestation to the time of birth, late astrocytes of layer I lose their EGLM attachments, migrate freely into the maturing gray matter, establish vascular contacts, and differentiate into protoplasmic astrocytes. The protoplasmic astrocytes of the gray matter evolve from transformation of layer I astrocytes rather than from radial glia cells as is generally believed. © 1995 Wiley‐Lis

ISSN:0092-7317    

DOI:10.1002/cne.903570407

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe development of neuropeptide Y‐immunoreactive (NPY‐IR) cell and fiber systems in the hamster diencephalon was studied. Eight perinatal groups of NPY‐IR neurons develop into 12 distinct sets in nuclei of the adult diencephalon and mesencephalon. NPY‐IR neurons of the thalamic precommissural nucleus, nucleus of the optic tract, and olivary pretectal nucleus are derived from the superior group. Those in the adult magnocellular nucleus of the posterior commissure and deep mesencephalic nucleus are from the dorsal group. An arcuate group contributes neurons to the arcuate nucleus and median eminence and a mammillary group transiently exists in the mammillary, region. A medial group gives rise to two sets of neurons, one that migrates to the intergeniculate leaflet and another that develops in the medial nucleus reuniens. A very large ventral group provides NPY‐IR neurons to the adult medial zona incerta and caudal reticular thalamus. Groups of NPY‐IR neurons also appear in the bed nucleus of the stria terminalis and centromedian thalamic nucleus.Superior group neurons may undergo apoptosis. In several groups, neurons become fewer during development, and NPY‐IR may disappear. NPY‐IR neurons of several groups initially migrate away from the neuroepithelial zone with later emergence of a distinct, persistent set of NPY‐IR neurons in the same neuroepithelial region. The data show that neuropeptide content can be used to identify particular sets of neurons early in development, thereby allowing migration patterns to be followed and principles of brain development to be elucidated. © 19

ISSN:0092-7317    

DOI:10.1002/cne.903570408

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractSurprisingly little is known about the synaptic architecture of the cholinergic innervation in the primate cerebral cortex in spite of its acknowledged relevance to cognitive processing and Alzheimer's disease. To address this knowledge gap, we examined serially sectioned cholinergic axons in supra‐ and infragranular layers of the macaque prefrontal cortex by using an antibody against the acetylcholine synthesizing enzyme, choline acetyltransferase (ChAT). The tissue bound antibody was visualized with both immunoperoxidase and silver‐enhanced diaminobenzidine sulfide (SEDS) techniques. Both methods revealed that cholinergic axons make synapses in all cortical layers and that these synapses are exclusively symmetric. Cholinergic axons formed synapses primarily on dendritic shafts (70.5%), dendritic spines (25%), and, to a lesser extent, cell bodies (4.5%). Both pyramidal neurons and cells exhibiting the morphological features of GABAergic cells were targets of the cholinergic innervation. Some spiny dendritic shafts received multiple, closely spaced synapses, suggesting that a subset of pyramidal neurons may be subject to a particularly strong cholinergic influence. Analysis of synaptic incidence of cholinergic profiles in the supragranular layers of the prefrontal cortex by the SEDS technique revealed that definitive synaptic junctions were formed by 44% of the cholinergic boutons. An unexpected finding was that chohnergic boutons were frequently apposed to spines and small dendrites without making any visible synaptic specializations. These same spines and dendrites often received asymmetric synapses, presumably of thalamocortical or corticocortical origin. Present ultrastructural findings suggest that acetylcholine may have a dual modulatory effect in the neocortex: one through classical synaptic junctions on dendritic shafts and spines, and the other through nonsynaptic appositions in close vicinity to asymmetric synapses. Further physiological studies are necessary to test the hypothesis of the nonsynaptic release of acetylcholine in the Cortex. © 1995 Wiley‐Lis

ISSN:0092-7317    

DOI:10.1002/cne.903570409

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractRetinoic acid (IRA) induces a human teratocarcinoma cell line (NTera‐2 or NT2) to give rise exclusively to post‐mitotic neuron‐like (NT2N) cells, but NT2N cells never acquire a fully mature neuronal phenotype in vitro. To determine whether NT2N cells can mature into adult neuron‐like cells in vivo, purified NT2N cells were grafted into different regions of the central nervous system (CNS) of adult and neonatal athymic mice, and the grafts were examined immunohistochemically by light, confocal, and electron microscopy using antibodies to a panel of developmentally regulated neuronal polypeptides.NT2N grafts were distinguished from endogenous mouse neurons with antibodies that recognize human or murine specific epitopes in selected neuronal polypeptides. Viable NT2N cells were identified in>89% of graft recipients (N=90), and some grafts survived 14 months. Within 3 weeks of implantation, grafted NT2N cells re‐extended their processes, and the location of the grafts (e. g., septum versus neocortex) appeared to determine the extent to which processes were elaborated. Within the early post‐transplantation period, grafted NT2N cells expressed the same neuronal polypeptides as their in vitro counterparts. However, between 6 weeks and 4‐6 months post‐implantation, the grafted NT2N cells progressively acquired the molecular phenotype of fully mature in vivo neurons as evidenced by dramatically increased expression of the most highly phosphorylated isoforms of the heavy neurofilament subunit, and the de novo expression of adult CNS tau. Notably, the time course for the extension of processes and the expression of neuronal polypeptides by NT2N grafts was similar in neonatal and adult mice. Although grafted NT2N cells formed synapse‐like structures and elaborated dendrites and axons, these axons remained unmyelinated. Finally, nbne of the transplanted NT2N cells reverted to a neoplastic state.These studies demonstrate that pure populations of grafted human NT2N cells acquire a fully mature neuronal phenotype in vivo, and that these cells integrate and survive for>1 year post‐implantation in the mouse CNS. These human neuron‐like cells are an attractive model system for studies of neuronal development, polarity and transplantation.

ISSN:0092-7317    

DOI:10.1002/cne.903570410

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.903570401

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY