摘要:

AbstractThe nuclear target of the X zone of the cerebellar cortex was identified in rats as clusters of neurons scattered at the interface between the nuclei medialis (NM) and interpositus (NI). In a previous study, we had outlined these target neurons and termed them “interstitial cell groups” (icg). In order to determine whether the icg should be considered as part of either the NM or the medial NI, we analyzed two efferent pathways from the icg: their nucleocortical and nucleoolivary projections. These were compared to their homologues from the NM and the NI. This analysis is based on mapping retrograde cell labeling and anterograde terminal labeling following microinjections of tracers in either the cerebellar cortex, the cerebellar nuclei, or the inferior olive.Nucleocortical projectionsoriginating from the icg are of the three types described previously: a “reciprocal” projection to the ipsilateral X zone, a “nonreciprocal” projection to the ipsilateral A zone, and a “symmetrical” projection to the contralateral X zone. These features can be considered as the summed characteristics of the nucleocortical projections from the NM and from the medial NI.Nucleoolivary projectionsfrom the icg target the lateral‐rostral portion of the dorsal accessory olive as well as the centrocaudal part of the medial accessory olive. These pathways converge with the nucleoolivary projections from the medial NI and from the NM, respectively. The icg receives olivary afferents from both the regions of the dorsal and medial accessory olives to which it projects.On the basis of similarities shown here between the two types of efferents originating from the icg and those from the NM as well as the medial NI, the icg may be regarded as a “mosaic” of neuron clusters alternately belonging to the NM and the medial NI. Therefore, the icg would be reciprocally connected with the inferior olive.

ISSN:0092-7317    

DOI:10.1002/cne.903630102

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

年代:1995

数据来源: WILEY

摘要:

AbstractHypothalamic arginine vasopressin‐containing neurons are prime elements in central circuits regulating the hypothalamo‐pituitary‐adrenocortical stress response. It is known that release and synthesis of vasopressin are cued by stressful stimuli. The present study was designed to assess effects of stress on vasopressin transcription and mRNA expression in defined populations of vasopressin neurons in the hypothalamic paraventricular (PVN) and supraoptic (SON) nuclei. Intron‐ and exon‐directed in situ hybridization analyses were used to examine stress regulation cf vasopressin heteronuclear (hn) gene transcription and mRNA levels. Actions of glucocorticoids on vasopressin induction were tested using adrenalectomized rats implanted with subcutaneous pellets delivering a constant, physiological dose of corticoste rone. Pellet implantation into adrenalectomized rats allows for normal pituitary‐adrenal tone in the absence of the ability to mount glucocorticoid stress responses. Elevation of vasopressin heteronuclear (hn) RNA in the medial parvicellular PVN was observed in both normal and adrenaleetomized‐corticosterone replaced rats as early as 30 minutes after stress initiation. In control rats, vasopressin hnRNA levels returned to baseline by 120 minutes. In contrast, vasopressin hnRNA remained elevated 120 minutes post‐restraint in adrenalectomized corticosterone replaced rats, indicating that the glucocorticoid stress response acts to rapidly inhibit vasopressin transcription. Significant changes in post‐stress vasopressin mRNA levels were observed in the parvicellular PVN of control rats 90 minutes following restraint induction, returning to normal expression profiles by 120 minutes. Adrenalectomized‐replaced rats showed elevated vasopressin mRNA expression at all time points examined. No changes were observed in magnocellular vasopressin‐containing nuclei at any time point, suggesting that magnocellular vasopressin is not induced by this particular stress paradigm. Thus, in parvicellular paraventricular nucleus neurons the vasopressin gene is rapidly induced by stress. Restraint‐induced up‐regulation of vasopressin transcription is limited by glucocorticoid secretion, consistent with direct actions of glucocorticoid negative feedback on the vasopressin gene in parvicellular neuron

ISSN:0092-7317    

DOI:10.1002/cne.903630103

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

年代:1995

数据来源: WILEY

摘要:

AbstractUrinary bladders of normal adult female guinea pigs were analyzed for anatomical evidence of nerve‐mast cell interaction using light microscopy and electron microscopy. Nerves, ganglia, and individual nerve fibers were visualized on paraffin sections using immunohistochemistry with antisera against the neural antigens neurofilament protein and protein gene product 9.5, and sections were also immunoreacted with antisera against the neuropeptides substance P and calcitonin gene‐related peptide. Separate mast cell populations were identified by counterstain ing with toluidine blue and alcian blue; Mast cells of both types were found within nerves and intramural ganglia and were in close contact with individual nerve fibers displaying substance P‐ and calcitonin gene‐related peptide‐like immunoreactivity. Moreover, serotonin‐immunoreactive mast cells were innervated with nerve fibers that reacted with antiserum against vasoactive intestinal polypeptide. At the ultrastructural level, these fibers were almost exclusively identified as unmyelinated primary sensory afferents. Mast cells contacted these fibers with lamellipodia that wrapped around and enclosed the fibers deeply within the cell. Close association between mast cells, nerves, and vessels was common. Ultrastructural evidence suggests that bidirectional communication occurs between nerve fibers and mast cells. These structures may participate in axon reflexes that regulate normal vascular and detrusor smooth muscle function and cause vasodilation, edema, inflammation, and bladder hyperreactivity. In summary, a close relationship exists between mast cells and peptidergic nerve fibers, including primary sensory afferents. Results suggest that bidirectional interaction could occur between nerves and mast cells. © 1995 Wil

ISSN:0092-7317    

DOI:10.1002/cne.903630104

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

年代:1995

数据来源: WILEY

摘要:

AbstractThis study employed single cell recording and intracellular iontophoretic injection techniques to characterize and label gastric‐ and/or intestine‐sensitive neurons in the rat nucleus of the solitary tract (NST). It was possible to divide our sample of NST neurons into three broad groups based on their response to increased intra‐gastric and intra‐duodenal pressure. Group 1 cells (N=14) were excited by duodenal distention but were not responsive to gastric stimulation. Most of these intestine‐sensitive neurons exhibited a delayed tonic response to the stimulus. Group 2 neurons (N=13) were excited by gastric distention but were not sensitive to distention of the duodenum. The typical Group 2 neuron evidenced a rapid, phasic response to the distention stimulus. Group 3 neurons (N=29) responded tobothgastric and duodenal stimulation. We found that the Group 2 neurons had greater dendritic length and more dendritic branch segments than the Group 1 or Group 3 neurons. Most of the Group 1 neurons were found in the subpostremal/commissural region of the NST, while the majority of the Group 2 neurons were in the gelatinous subnucleus and a disproportionate number of the Group 3 neurons were located in the medial subnucleus. The results of this investigation demonstrate that (1) there are relationships between the morphology and physiology of distention‐sensitive neurons in the NST, and (2) there are distinct functional differences between the gelatinous, medial and commissural subnuclei of this nucleus. © 1995 Wil

ISSN:0092-7317    

DOI:10.1002/cne.903630105

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

年代:1995

数据来源: WILEY

摘要:

AbstractThe development of microglial topography in wholemounts of human retina has been examined in the age range 10–25 weeks gestation (WG) using histochemistry and immunohistochemistry for CD45 and major histocompatibility complex class II antigens. Microglia were present in three planes corresponding to the developing nerve fibre layer/ganglion cell layer, the inner plexiform layer and the outer plexiform layer. Distribution patterns of cells through the retinal thickness and across the retinal surface area varied with gestational age. Microglia were elongated in superficial retina, large and ramified in the middle plane, and small, rounded and less ramified in deep retina. Intensely labeled, rounded profiles seen at thepars caecaof the ciliary processes, the retinal margin and at the optic disc may represent precursors of some retinal microglia. At 10 WG, the highest densities of microglia were present in middle and deep retina in the far periphery and at the retinal margin, with few superficial microglia evident centrally at the optic disc. At 14 WG, high densities of microglia were apparent superficially at the optic disc; microglia of middle and deep retina were distributed at more central locations although continuing to concentrate in the retinal periphery. Microglia appear to migrate into the developing human retina from two mains sources, the retinal margin and the optic disc, most likely originating from the blood vessels of the ciliary body and iris, and the retinal vasculature, respectively. The data suggest that the development of microglial topography occurs in two phases, an early phase occurring prior to vascularization, and a late phase associated with the development of the retinal vasculature. © 1995 Wiley‐Liss,

ISSN:0092-7317    

DOI:10.1002/cne.903630106

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

年代:1995

数据来源: WILEY

摘要:

AbstractSensory neurons can be classified into subpopulations based on a variety of characteristics, including their morphology and physiological modalities. Whether any of these classifications correlates with neurotrophic sensitivities has not been determined, We have recently reported that a subpopulation of large diameter sensory neurons of the rat contain neurotrophin 3‐like immunoreactivity (NT3‐ir). In this study, we have further characterised NT3‐ir sensory neurons by their size, segmental localization, and peripheral projections by combined techniques of retrograde tracing and immunohistochemistry. The size distribution showed that NT3‐ir was localised to a subpopulation of large‐diameter neurons ranging from 560 to 3,120 m Greater numbers of NT3‐ir neurons reside in trigeminal (43% of total), cervical (36%), and lumbar (39%) than in thoracic spinal ganglia (13–17%). In combination with Fluoro‐Gold retrograde tracing, it was found that about 30% of sensory neurons projecting to the tibial muscle were NT3‐ir, compared with 39% for tendon, 50% for whisker hair follicles, 17% for subdermis or epidermis, and only 1% for kidney or adrenal gland. These studies indicate that NT3‐ir sensory neurons mainly project to skin and muscles but not viscera. Thus, the characterization of NT3‐ir spinal sensory neurons suggests that large sensory neurons subserving proprioception and mechanoception require NT3 for the maintenance of normal function.

ISSN:0092-7317    

DOI:10.1002/cne.903630107

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

年代:1995

数据来源: WILEY

摘要:

AbstractThe development of the calcium‐binding protein calretinin (CaR) and its co‐localization with GABA was studied in the striate cortex of Macaca monkeys from fetal day (Fd) 45 to adult. At Fd45, early neurons resembling Cajal‐Retizus cells are stained in the marginal zone (MZ). At Fd55 the MZ is filled with CaR+ Cajal‐Retzius cells and their processes, and scattered CaR+ cells are also found in deep cortical plate (CP), intermediate zone (IZ), and subventricular zone (SVZ). At Fd66, a band of CaR+ fibers appears in the IZ, corresponding to the location of the geniculocortical axons. This fiber band labels heavily until Fd130 but then ceases to be immunoreactive by postnatal (P) 16 weeks. At Fd85–101, the number of CaR+ cells in the CP, SVZ, and ventricular zone (VZ) reaches its highest cell density. After Fd130, CaR+ cells are concentrated in layer II and upper layer III, and this distribution changes little into adulthood. After mid‐gestation, there is a progressive loss of CaR+ cell bodies and processes in the MZ, and these are rare in the adult cortex. Just before birth, a weakly stained CaR+ cell band appears in layer NA at the border between layer NA and IVB, but this band disappears immediately after birth. Another CaR+ cell band appears transiently in upper layer V just below the border with layers IV at P6 months. These results suggest that CaR is expressed early in fetal development in the cell populations that are immunoreactive for CaR in the adult. However, developmental events related to cortical maturation during late prenatal and early postnatal stages result in transient expression of CaR in neurons that are not immunoreactive for CaR in the adult.CaR‐immunoreactivity is colocalized with GABA in almost all CaR+ cells with the exception of Cajal‐Retzius cells in the MZ and some large cells observed at Fd70–101 in the VZ. The band of CaR+ fibers in the IZ is GABA‐. At Fd90, almost all (>96%) CaR+ cells are GABA+ in the CP and he first developed layers V/VI. This percentage declines later, so that on average 80% of CaR+ cells are GABA+ in adult cortex. At Fd135, 53% of GABA+ neurons located in layers II/III are CaR+; this percentage declines to 37% in the adult. These double‐label patterns suggest that early in fetal development the majority of GABA+ cells stain for CaR and that expres of CaR may be related to the migration of these neurons into the cortical plate, Once they attain their final position in the cortex many GABA+ cells loose CaR‐immunoreactivity, so that in postnatal life only a minority of GABA+ neurons contain this calcium‐binding protei

ISSN:0092-7317    

DOI:10.1002/cne.903630108

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

年代:1995

数据来源: WILEY

摘要:

AbstractAn abundance of information is available concerning the spinocerebellar projection in adult mammals. However, only a few studies have attempted a developmental analysis of this important projection system in early postnatal and/or prenatal animals. The present study provides an analysis of the development of the projection from the spinal cord to the cerebellum in fetal mice using anterograde tracing techniques in an in vitro preparation. After applications of biocytin to the caudal cervical spinal cord, anterogradely labelled fibers were present in the brainstem of embryonic day 12 (E12/13) mice, however, there was no indication of label in the cerebellum. At E13/14, labelled fibers were evident in the rostrolateral portions of the cerebellum/isthmus region. By E15/16, labelled spinocerebellar fibers had progressed farther into the cerebellum and were seen crossing the midline in a very superficial position. At older ages, the number of crossing fibers increased, and they became more ventrally positioned within the cerebellum. At E17/18 and E18/19, labelled spinocerebellar fibers were observed to branch and invade deeper portions of the cerebellum including the cerebellar nuclei. However, at E18/19, there was no indication of the parasagittal organization characteristic of this projection in the adult animal. The results of this study indicate that spinocerebellar fibers are present within the cerebellum significantly earlier than the development and differentiation of their primary targets, the granule cells. Furthermore, these data suggest that spinocerebellar fibers may form associations with cerebellar nuclear cells during fetal development. © 1995 Wiley‐Liss, I

ISSN:0092-7317    

DOI:10.1002/cne.903630109

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

年代:1995

数据来源: WILEY

摘要:

AbstractTrigeminothalamic neurons were retrogradely labeled by injection of horseradish peroxidase into the ventroposteromedial nucleus of the thalamus in rats. Jaw‐muscle spindle afferent axons were then physiologically identified and intracellularly stained with biotinamide. The ultrastructure of labeled spindle afferent boutons was then studied in the caudolateral supratrigeminal region (Vsup) and dorsomedial trigeminal principal sensory nucleus (Vpdm). A total of 418 stained spindle afferent boutons were identified in Vsup and Vpdm; approximately 75% of these synapsed with dendrites, 10% synapsed with somata, and 15% synapsed with axons. Most jaw‐muscle spindle afferent boutons were postsynaptic to unlabeled P‐type boutons. Reciprocal synapses between spindle afferent boutons and unlabeled boutons were occasionally observed. A few dendrites in Vsup and Vpdm received synapses from multiple spindle afferent boutons. Conversely, some large (from 3 × 6 to 4 × 8 μm) and giant (from>4 × 8 to 5 × 10 μm) spindle afferent boutons simultaneously contacted two to five dendrites and/or somata. Jaw‐muscle spindle afferent boutons also formed synapses with retrogradely labeled trigeminothalamic neurons in Vsup and Vpdm. Numerous unlabeled S‐and F‐type boutons converged onto the same trigeminothalamic dendrite or soma contacted by a spindle afferent bouton. A small number of synaptic triads consisting of an unlabeled P‐type bouton, a spindle afferent bouton, and either a dendrite or soina were also encountered. These data indicate that sensory feedback from the masticatory muscles is subject to presynaptic inhibition and integration prior to reaching the thalamus. This pathway is likely to be important in the relay of proprioceptive and kinesthetic information from the muscles of mastication to the thalamus. ©

ISSN:0092-7317    

DOI:10.1002/cne.903630110

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

年代:1995

数据来源: WILEY

摘要:

AbstractThe olfactory epithelium, which retains a capacity for neurogenesis throughout life, contains two categories of basal cells, dark/horizontal and light/globose, neither of which is fully characterized with respect to their function during the processes of neurogenesis and epithelial reconstitution after injury. The aim of this study was to define the potential biological role(s) of dark/horizontal basal cells (D/HBCs) in the epithelium by performing immunochemical, electron microscopic, and developmental analyses of this cell population. The D/HBCs express several specific immunochemical characteristics, which include the rat homologues of human cytokeratins 5 and 14, which were identified on the basis of staining with subunit‐ specific monoclonal antibodies and two‐dimensional immunoblot analysis of the immunoreactive proteins. Indeed, the D/HBCs are the only cells in the olfactory mucosa that express these specific cytokeratins. The D/HBCs also express an α‐galactose or α‐N galactosamine moiety to which the Iß4isolectin fromBandeiraea simplicifoliabinds. Moreover, the D/HBCs are heavily labeled by two different antibodies against the EGF receptor and by a monoclonal antibody that binds to phosphotyrosine. These characteristics are also common to the basal cells of respiratory epithelium. The electron microscopic analysis of the basal region of the olfactory epithelium and the light microscopic immunofluorescence observations demonstrate that the D/HBCs provide a bridge between the basal processes of some sustentacular cells and the basal lamina. The most striking ultrastructural feature of the D/HBCa is their enfolding of virtually all bundles of olfactory axons within tunnels formed where D/HBCs arch over the basal lamina. The intimacy of the arrangement between D/HBCs and olfactory axons suggests that signals may pass from axons to D/HBCs or vice‐versa. With respect to the development of D/HBCs, cells that express cytokeratins 5 and 14 and the EGF receptor first appear near the boundary with respiratory epithelium late in development, but do not extend throughout the olfactory epithelium until the middle of the first postnatal week. Taken together, the present findings and previously published data suggest that D/HBCs help to maintain the structural integrity of the olfactory epithelium, participate in its recovery from injury, and may also function to signal the status of the neuronal population of the epithelium. © 1995 Wi

ISSN:0092-7317    

DOI:10.1002/cne.903630111

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

年代:1995

数据来源: WILEY