摘要:

AbstractThe innervation of the rat hard palate and the bordering part of the soft palate was studied after anterograde transport of horseradish peroxidase conjugated to wheat germ agglutinin (WGA‐HRP) and to choleragenoid (B‐HRP) in separate experiments. WGA‐HRP labeling showed leakage from several types of nerve endings, whereas B‐HRP did not. Both conjugates gave rise to heavy labeling of a variety of nerve endings. Intragemmal and, especially, perigemmal fibers were labeled in chemosensory corpuscles, which were most common in the medial wall of the incisive canal and in the most anterior part of the soft palate. Ruffini endings of different sizes were labeled in the incisive papilla. Other subepithelial endings forming elongated expanded profiles with medium‐to large‐caliber source fibers were most common in protruding parts of the palate. Labeled intraepithelial endings included Merkel endings, which were most frequent in the incisive papilla and the rugae. Other labeled profiles were medium‐caliber afferents giving rise to irregular, beaded, and sometimes branched endings often located far superficially in the epithelium. Such endings were present both within and between protruding parts of the palate. Fine‐caliber intraepithelial endings were labeled almost exclusively in WGA‐HRP experiments. © 19

ISSN:0092-7317    

DOI:10.1002/cne.903510402

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

年代:1995

数据来源: WILEY

摘要:

AbstractSomatostatin, neuropeptide Y, and nicotinamide adenine dinucleotide phosphatediaphorase are colocalized within a small population of medium aspiny neurons in the caudate‐putamen of the rat. The extent of colocalization, however, appears to be in dispute. In order to examine the question of colocalization between these three neuroactive substances, a series of double‐labelling experiments was performed. This was accomplished by combining immunocytochemistry for somatostatin or neuropeptide Y or enzyme histochemistry for nicotinamide adenine dinucleotide phosphate‐diaphorase with in situ hybridization for somatostatin and/or neuropeptide Y mRNA. The results of such analysis indicate that nicotinamide adenine dinucleotide phosphate‐diaphorase and somatostatin mRNA are 100% colocalized throughout the caudate‐putamen, except for the area bordering the globus pallidus. All neurons that contain neuropeptide Y contain somatostatin message. Only 84% of the neurons that contain somatostatin mRNA, however, also contain neuropeptide Y. Neurons that contain somatostatin 28 but not neuropeptide Y are found throughout the caudate‐putamen. These results indicate that the somatostatin neuron population in the rat caudate‐putamen is not homogeneous. Instead, the medium aspiny neuron population is actually composed of several subpopulations based on the content of neuroactive substances. © 1995 W

ISSN:0092-7317    

DOI:10.1002/cne.903510403

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

年代:1995

数据来源: WILEY

摘要:

AbstractThe cathecholaminergic (CA) systems have been described as appearing early in the development of the mammalian central nervous system (CNS), but their exact distribution in humans has been studied only following gestational week (g.w.) 13. Furthermore, it is not known when CA fibers initially penetrate the developing cerebral cortex. In this study, the CA cells groups and fibers are described in the human central nervous system from 6 to 13 g.w. as revealed with immunocytochemical techniques, with antibodies raised against three synthetic enzymes of the catecholamine (CA) pathway: tyrosine hydroxylase (TH), dopamine‐β‐hydroxylase (DBH), and phenylethanolamine‐N‐methyltransferase (PNMT). At 6 g.w., TH‐like immunoreactive (TH‐IR) cell groups were widespread through the caudorostral extension of the CNS corresponding to the different dopaminergic mesencephalic and hypothalamic groups. Noradrenergic groups also were labeled in the medulla oblongata and in the locus coeruleus as well as in other areas in the pons. Additional TH‐IR cell groups might represent a transient developmental expression of TH similar to that observed in the rat. DBH immunoreactivity labeled primarily the noradrenergic pontic cell groups and, to a lesser extent, groups located in the medulla oblongata. Rare PNMT‐IR neurons were detected in the medulla oblongata only at 13 g.w. The main CA bundles described in the adult were also observed in human embryos and fetuses. At 6 g.w., TH‐IR pathways extended caudorostrally within the central tegmental tract and the dorsal tegmental bundle, the latter merging with the dopaminergic mesotelencephalic pathway giving rise to the medial forebrain bundle in the basal forebrain. At 7–8 g.w., TH‐IR fibers extended to the basal ganglia and the telencephalic wall. The first TH‐IR and, to a much lesser extent, DBH‐IR fibers penetrated the frontal lateral cortical anlage through the intermediate zone and sparsely through the marginal zone but not through the thin cortical plate. A second stream entered the telencephalic anlage frontomedially, ventral to the septal area. At 11 g.w., numerous TH‐IR fibers invaded the subplate layer, but they penetrated the cortical plate only at 13 g.w. At that time, TH‐IR and DBH‐IR fibers had reached the occipital cortex in a rostrocaudal gradient. The appearance of well‐organized CA system already in embryonic stages in humans could be of great importance for normal shaping of the nervous system as well as for development of cortical

ISSN:0092-7317    

DOI:10.1002/cne.903510404

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

年代:1995

数据来源: WILEY

摘要:

AbstractThe star‐nosed mole possesses a conspicuous specialization of its snout in the form of 22 fleshy appendages that fan out from around the nostrils. These appendages are used by the mole to explore its underground environment and are repeatedly brought into contact with objects of interest to the mole. This report describes the structure, innervation, and distribution of the sensory organs on the star of the star‐nosed mole and briefly describes the behavioral use of the star. Each of the 22 appendages of the star is covered with a continuous array of Eimer's organs. These sensory receptors are modifications of the epidermal surface that take the form of bulbous papillae. Each Eimer's organ contains a column or stack of epidermal cells accompanied by nerve processes that originate from myelinated fibers in the underlying dermis. These neural processes travel through the cell column and form terminal swellings just below the outer layer of keratinized epidermis. Each Eimer's organ also contains a single Merkel cell‐neurite complex within the cell column and a single lamellated corpuscle immediately below the cell column in the connective tissue of the dermis. There are approximately 30,000 Eimer's organs on the snout of this mammal, making this structure perhaps the most sensitive tactile organ yet discovered for its size. The segregation of these organs to individual appendages, not unlike the fingers of primates. affords an intriguing model for the study of somatosensory systems in mammals. © 1995 Willy‐L

ISSN:0092-7317    

DOI:10.1002/cne.903510405

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

年代:1995

数据来源: WILEY

摘要:

AbstractThe nose of thestar‐nosed mole consists of a star‐like array of 22 fleshy appendages that radiate from the nostrils and are moved about to explore the environment. The surface of each appendage, or ray, is densely packed with bulbous receptor organs (Eimer's organs) that are highly responsive to tactile stimulation. Here, we report that these rays have corresponding morphological specializations in somatosensory cortex. Using a stain for the metabolic enzyme, cytochrome oxidase (CO), to reveal subdivisions of cortex, we disclosed a complex pattern of CO‐dense stripes or bands separated by sharp lines or septa of low CO staining. Multiunit microelectrode recordings of neural activity evoked by light tactile stimuli in somatosensory cortex of anesthetized moles allowed us to mark some of the bands and other CO‐dark regions with small electrolytic lesions and later relate recording results to the CO pattern. The results suggest that the primary somatosensory cortex, S1, has an unusual ventrolateral location and orientation with representations of mouth, nose rays, facial vibrissae, forepaw, and trunk in a rostrocaudal sequence. Within this presumptive S1, the 11 rays of the contralateral nose are represented as a rostral‐to‐caudal cortical pinwheel of 11 stripes. Cortex ventral to the primary set of stripes contains a second rostrocaudal representation of the rays as a mirror image of the first. This second set of stripes may be part of the second somatosensory area, S2. A third pattern of CO stripes appears to merge partially with caudal stripes of the first two patterns, so that a full pattern of 11 stripes is not obvious. This representation may correspond to the ventral somatosensory area, VS, of other mammals. An extensive area of cortex separated from the nose by a large septum was responsive to stimulation of the forelimb. Auditory cortex is unusually caudal in this mole, and the presumptive primary visual area is relatively small. These specializations of somatosensory cortex in star‐nosed moles may be more patent examples of the consequences of more general factors in brain development. The observations are consistent with the general rule that the terminations of sensory projections with discorrelated activity segregate. © 1995 W

ISSN:0092-7317    

DOI:10.1002/cne.903510406

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

年代:1995

数据来源: WILEY

摘要:

AbstractThis study has examined the ascending projections of the periaqueductal gray in the rat. Injections of Phaseolus vulgaris‐leucoagglutinin were placed in the dorsolateral or ventrolateral subregions, at rostral or caudal sites. From either region, fibers ascended via two bundles. The periventricular bundle ascended in the periaqueductal and periventricular gray matter. At the posterior commissure level, this bundle divided into a dorsal component that terminated in the intralaminar and midline thalamic nuclei, and a ventral component that supplied the hypothalamus. The ventral bundle formed in the deep mesencephalic reticular formation and supplied the ventral tegmental area, substantia nigra pars compacta, and the retrorubral field. The remaining fibers were incorporated into the medial forebrain bundle. These supplied the lateral hypothalamus and forebrain structures, including the preoptic area, the nuclei of the diagonal band, and the lateral division of the bed nucleus of the stria terminalis.The dorsolateral subregion preferentially innervated the centrolateral and paraventricular thalamic nuclei and the anterior hypothalamic area. The ventrolateral subregion preferentially innervated the parafascicular and central medial thalamic nuclei, the lateral hypothalamic area, and the lateral division of the bed nucleus of the stria terminalis. Although the dorsolateral and ventrolateral subregions gave rise to differential projections, the projections from both the rostral and caudal parts of either subregion were similar. This suggests that the dorsolateral and ventrolateral subregions are organized into longitudinal columns that extend throughout the length of the periaqueductal gray. These columns may correspond to those demonstrated in recent physiological studies. © 1995 Willy‐Liss,

ISSN:0092-7317    

DOI:10.1002/cne.903510407

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

年代:1995

数据来源: WILEY

摘要:

AbstractThe descending projections of the periaqueductal gray (PAG) have been studied in the rat using the anterograde tracer Phaseolus vulgaris‐leucoagglutinin. The tracer was injected into the dorsolateral or ventrolateral subdivisions of the PAG at rostral or caudal sites. It was found that the patterns of the descending projections of the rostral and caudal parts of the dorsolateral PAG were the same and that the patterns of the descending projections of the rostral and caudal parts of the ventrolateral PAG were the same. However, the patterns of projections of the dorsolateral and ventrolateral PAG subregions were substantially different. These results suggest that the dorsolateral and ventrolateral parts of the PAG are organized into longitudinal columns that extend throughout the length of the PAG. The axons of PAG neurons descended through the pons and medulla via two routes. A small fiber bundle was present in the periaqueductal gray and in the periventricular area. This bundle distributed fibers and terminals locally within the periaqueductal gray and in the locus coeruleus and Barrington's nucleus. A larger bundle had a diffuse arrangement in the pontine reticular formation, however, and it had a more restricted distribution in the medulla, where it occupied a position dorsolateral to the pyramid. This bundle supplied structures in the pontine and medullary tegmentum. The dorsolateral column preferentially supplied the locus coeruleus, subcoeruleus, the gigantocellular nucleus pars alpha, the rostral part of the paragigantocellular nucleus, and the region of the A5 noradrenergic cell group. The ventrolateral column preferentially supplied the nucleus raphe magnus, the caudal part of the lateral paragigantocellular nucleus, and the rostroventrolateral reticular nucleus. © 1995 Willy‐Liss,

ISSN:0092-7317    

DOI:10.1002/cne.903510408

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

年代:1995

数据来源: WILEY

摘要:

AbstractWe analyzed the development of the hippocamposeptal projection and the morphology of the neurons giving rise to this projection. The fluorescent tracer Dil was injected into the septal region or the hippocampus in fixed brains of embryonic and early postnatal rats. Anterogradely labeled hippocampal axons first reached the septal region at E16. They ran along the midline of the brain, thereby approaching the medial septum. Axons to the lateral septum were first observed around E18/19. The lateral septum is partly innervated by collaterals of axons that travel to the medial septum. The projection to the lateral septal nuclei becomes more massive during early postnatal stages, whereas that to the medial septum becomes smaller. Cells in the medial septum retrogradely labeled by injection into the hippocampus were first observed at E18. Thus, the hippocamposeptal projection is established earlier than the septohippocampal projection.The first hippocampal projection neurons are nonpyramidal neurons that appear to pioneer the pathway to the septum. Pyramidal cell axons follow this first cohort of axons into the medial septum. Pyramidal cells could be retrogadely labeled from the medial septum during the perinatal period but then diminished in number. At P10, only nonpyramidal cells were labeled by medial septal injections. This indicates that the pyramidal component of this projection is transient and is removed shortly after birth. However, as is known from ther studies, hippocampal pyramidal cells give rise to a powerful projection to the lateral septum in adult animals. Our results show that there is a considerable remodeling of the projection from the hippocampus to the septum during ontogenetic development. © 1995 Willy‐Liss, I

ISSN:0092-7317    

DOI:10.1002/cne.903510409

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

年代:1995

数据来源: WILEY

摘要:

AbstractRegulation of protein function through tyrosine phosphorylation is critical in the control of many developmental processes, such as cellular proliferation and differentiation. Growing evidence suggests that tyrosine phosphorylation also regulates key events in neural development. Although a large body of data has demonstrated that protein tyrosine kinases play an important role in neural development, much less is known about their counterparts, protein tyrosine phosphatases (PTPases). Using polymerase chain reaction (PCR) with degenerate primers and a neonatal rat cortex cDNA library, we have identified seven PTPases expressed in the developing rat brain. Four of these are transmembrane PTPases: LAR, LRP, RPTPγ, and CPTP1. Three are nonreceptor PTPases: PTP‐1, P19‐PTP, and SHP. Northern hybridization analysis demonstrates that only CPTP1 is preferentially expressed in neural tissues, whereas the others are found abundantly in nonneural tissues as well as in the brain.Within the embryonic and early postnatal brain, the seven PTPases have overlapping, yet unique, distributions. For example, LAR mRNA is highly expressed by both proliferating and postmitotic cells in the cerebral cortex at embryonic day 17 and in all layers of the cortex at postnatal day 4. In contrast, RPTPγmRNA is expressed by postmitotic neurons in the embryo and predominantly by neurons in the superficial layers of the postnatal cortex.Several of the PTPases examined here are expressed at very high levels in the embryonic cortical plate and postnatal neocortex, including the subplate and subventricular zone. The spatial and temporal regulation of PTPase agene expression suggests that these PTPases have important roles in signal transduction during early neuronal differentiation and neural development. © 1995 Willy‐L

ISSN:0092-7317    

DOI:10.1002/cne.903510410

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

年代:1995

数据来源: WILEY

摘要:

AbstractThe lateral superior olive and medial superior olive give rise to pathways that terminate in the dorsal nucleus of the lateral lemniscus and central nucleus of the inferior colliculus. In most mammals, neurons in both the medial and lateral superior olives are binaural, but in the mustached bat most neurons in the medial superior olive are monaural. The aims of this study were to determine how the inputs to the medial superior olive contribute to its monaurality and to determine whether the ascending projections from the lateral and medial superior olives overlap or rema in segregated at their targets. Injections of two different tracers were placed in tonotopically matched areas of the lateral and medial superior olives in the same animal. Retrograde transport from injections in the medial superior olive labeled spherical cells in the contralateral anteroventral cochlear nucleus and principal cells in the ipsilateral medial nucleus of the trapezoid body. Few cells were labeled in ipsilateral cochlear nucleus. Anterograde transport resulted in tonotopically specific distributions of label with the same laterality as in nonecholocating mammals. In the dorsal nucleus of the lateral lemniscus, label from the lateral and medial superior olives largely overlapped. In the inferior colliculus, label from the two sources overlapped in the high and low frequency ranges, but in the frequency range around 60 kHz, label from the medial superior olive extended more dorsally than that from the lateral superior olive. These results indicate that projections of the lateral and medial superior olives overlap extensively at their targets. © 1995 Willy‐Liss, I

ISSN:0092-7317    

DOI:10.1002/cne.903510411

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

年代:1995

数据来源: WILEY