bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrastructure of the horseshoe Bat's organ of corti. II. Transmission electron microscopy
Authors: Vater Marianne , Lenoir Marc , Pujol Remy
Published: January 2005

The fine structure of the organ of Corti was investigated in the echolocating horseshoe bat (Rhinolophus rouxi) by transmission electron microscopy. Particular emphasis was placed on the receptor cells and their supporting cells.

The receptor cells, inner hair cells (IHC) and outer hair cells (OHC), possess the typical mammalian shape, but OHCs are extremely short (length: 12–15 μm in the basal turn and up to 28–30 μm in the apical turn). The afferent innervation of both types of receptor cells and the efferent innervation of the IHC system conform to the general mammalian scheme; however, confirming earlier reports, an efferent innervation to the OHCs is absent. Throughout the cochlea, IHCs and OHCs possess a single layer of subsurface cisternae. Above the level of the nucleus of the OHCs, the arrangements of the subsurface cisternae and their connection to the lateral cell membrane via pillars are highly regular, whereas in IHCs, the cisternae are of irregular shape and the pillar system is much less distinct. In the basal turn of the cochlea, the attachment sites of the OHCs to the supporting cells possess specialized features: (a) in the reticular lamina, the contact sites of the cuticular plates of OHCs with the outer pillar cells and the Deiters cell phalanges are of exaggerated length, and (b) the cup formation of the Deiters cell body, which houses the bottom of the OHC, has a specialized shape and is packed with electron‐dense material and microtubules.

The results are discussed in relation to cochlear ultrastructure in other mammals and in the context of active processes in cochlear mechanics.
Direct W‐like geniculate projections to the cytochrome oxidase (CO) blobs in primate visual cortex: Axon morphology
Authors: Lachica E. A. , Casagrande V. A.
Published: January 2005

The primate lateral geniculate nucleus (LGN) is composed of large, medium, and small cells located, respectively, in magnocellular (M), parvocellular (P), and specialized layers (intercalated and S‐layers in simians, koniocellular (K) layers in prosimians). Several studies have examined the physiology and connections of M and P LGN cells and have concluded that they provide separate contributions to visual perception via separate pathways. Less is known about the structure and contributions of the small LGN cells. This study examined the distribution and structure of K LGN cell axons in the cortex of the prosimian, Galago crassicaudatus. Wheat germ agglutinin conjugated to horseradish peroxidase, or Phaseonlus vulgaris leucoagglutinin, was injected into the LGN K layers to demonstrate the overall axon projection pattern and the details of individual axons, respectively. Location of axons within striate cortex was specified relative to boundaries determined by Nissl or cytochrome oxidase (CO) stains on the same or adjacent sections.

Our results show that K LGN axons end as single complex arbors within one CO blob zone in layer III; they never terminate in interblob zones. These axons also emit a collateral in layer I that arborizes more broadly and spans both CO blob and interblob zones. These data, together with data on K cell physiology and intralaminar cortical connections, suggest that the LGN small cell pathway could modulate the activity of the other two pathways in striate cortex and contribute directly to visual perception. © 1992 Wiley‐Liss, Inc.
Interphotoreceptor matrix in the human retina: Cone‐like domains surround a small population of rod photoreceptors
Authors: Iwasaki Masayuki , Myers Kathy M. , Rayborn Mary E. , Hollyfield Joe G.
Published: January 2005

The interphotoreceptor matrix (IPM) in mammalian retinas is subdivided into rod and cone specific compartments: peanut agglutinin (PNA) binding glycoconjugates are associated with cones, whereas wheat germ agglutinin (WGA) binding glycoconjugates are associated with rods. To establish the identity of a photoreceptor cell type in the human retina with rod dimensions but with a matrix domain which stains with PNA, double label studies, using PNA‐ferritin to decorate the extracellular domains and immunocytochemical techniques using a rod specific anti‐opsin antibody were conducted. The PNA‐binding domains were observed in the cone‐associated IPM as well as in the IPM surrounding a small population of rod‐shaped photoreceptors. The outer segments of these rod‐shaped photoreceptors showed intense labeling with a rod specific anti‐opsin antibody as did all other rods which were free of PNA‐labeling. A quantitative analysis of all retinal quadrants indicates that this novel rod represents approximately 0.3% of the total rod population in the human retina. © 1992 Wiley‐Liss, Inc.
Spatial organization of the auditory nerve according to spontaneous discharge rate
Authors: Kawase Tetsuaki , Liberman M. Charles
Published: January 2005

Auditory‐nerve fibers in mammals have been classified into three functional subclasses according to spontaneous discharge rate (SR). In cat, the peripheral terminals of these SR groups are segregated around the sensory cell circumference (Liberman, '82, Science 216:1239–1241). The present study shows that this spatial segregation is at least partly maintained through the peripheral axonal course from sensory cell to spiral ganglion. Analysis of intracellularly labeled auditory‐nerve fibers shows that peripheral axons and cell bodies of low‐and medium‐SR fibers tend to be found closer to scala vestibuli than high‐SR fibers. Since low‐and medium‐SR fibers tend to be thinner, this SR‐based segregation can also be demonstrated as a fiber‐caliber gradient in the osseous spiral lamina. The issue of SR‐based spatial segregation is relevant to reports that ganglion cells near scala vestibuli project to different regions of the cochlear nucleus than cells near scala tympani (Leake and Snyder, '89, J. Comp. Neurol. 281:612–629). Combining the results of the two studies suggests that there may be some SR‐based spatial segregation of inputs to the cochlear nucleus. © 1992 Wiley‐Liss, Inc.
Ultrastructure of the periaqueductal grey matter of the rat: An electron microscopical and horseradish peroxidase study
Authors: Buma Pieter , Veening Jan , Hafmans Theo , Joosten Henk , Nieuwenhuys Rudolf
Published: January 2005

The neurons of the mesencephalic periaqueductal grey substance (PAG) in the rat are small and medium sized. The cells are frequently located in small clusters, without interdigitating glial elements and may be connected by direct membrane appositions or by gap junctions. The inner zone of the PAG is cell poor. In many cases, the cytoplasm of the cells is filled with extensive rough endoplasmic reticulum, free ribosomes, Golgi apparatus, and large lysosome‐like granules. The nuclei show large indentations. The cells have a high nucleus‐cytoplasm ratio.

The neuropil is very extensive and particularly rich in large numbers of small unmyelinated axons, dendrites, axonal varicosities, and synaptic connections. Myelinated fibres are relatively scarce. The orientation of the fibres was studied in transverse and horizontal sections, in combination with HRP track tracing experiments. It appeared that throughout the PAG most of the fibres were orientated longitudinally. Quantitation showed that most fibres were present in the inner zones of the PAG. Moreover, the diameter of the fibres adjacent to the aqueduct was smaller than that of the fibres in the peripheral parts of the PAG. The thin unmyelinated fibres made extensive synaptic connections within the PAG. Many synaptic varicosities were found in the neuropil of the PAG. There were four types of synaptic varicosities, characterized by different populations of clear and dense‐core secretory granules and by the different morphology of the synaptic specializations. In general, the different types of varicosity were homogeneously distributed in the different parts of the PAG. Electron dense secretory granules, when present, were located at some distance from the synaptic junction. Serial sections revealed varicosities which contained only dense‐core secretory granules, without synaptic specializations.

The dendrites of PAG neurons generally lacked synaptic spines. Many dendrites, particularly those of neurons located in the peripheral parts of the PAG, were directed toward the aqueduct.

The present study shows that the PAG is a very complex brain area. The crisscrossing of axons and dendrites with synaptic connections at considerable distances from the cell bodies render it very difficult to unravel the relationships between the possible sources and destinations of ongoing information. This structure complicates the search for relationships between the functional organization and the cytoarchitectural borders in the PAG area.
Substance P‐immunoreactive sensory axons in the rat respiratory tract: A quantitative study of their distribution and role in neurogenic inflammation
Authors: Baluk Peter , Nadel Jay A. , McDonald Donald M.
Published: January 2005

Substance P is one of the peptides released from sensory nerves that mediate “neurogenic inflammation.” Although substance P‐immunoreactive (SP‐IR) axons are known to be present within the mucosa of the respiratory tract, the relative extent of the innervation of various components of the mucosa is not known. Therefore, we determined the distribution and number of SP‐IR axons in the rat trachea and bronchi, by using immunohistochemistry on tissue whole mounts. Specifically, we sought to learn whether these axons directly innervate the postcapillary venules involved in neurogenic plasma extravasation, the arterioles involved in neurogenic vasodilatation, and the airway smooth muscle involved in bronchoconstriction in pathogen‐free, adult male F344 rats. We found that 90% of the SP‐IR axons were single axons, usually having varicosities. Eighty‐five percent of these were in the epithelium, 6% innervated arterioles, and the remainder elsewhere in the lamina propria. Only 10% of the mediator‐sensitive postcapillary venules (i.e., venules labeled with Monastral blue pigment after challenge with capsaicin or substance P) were within 10 μm of SP‐IR axons. SP‐IR axons were more than 10 times as frequent in the smooth muscle of the distal bronchi as in the trachea. Capsaicin pretreatment (168 mg/kg over 7 days) reduced the number of SP‐IR axons in the trachea by 96%, which is consistent with their being sensory. Unilateral vagotomy reduced the number of SP‐IR axons bilaterally in the trachea and ipsilaterally in the main stem bronchus. Using an antibody to Protein Gene Product 9.5 as a nonspecific marker for all nerves in the trachea, we determined that SP‐IR axons constituted 90% of the axons in the epithelium, 32% of the axons on arterioles, and only 4% of the axons in the smooth muscle. We conclude that most SP‐IR nerves in the trachea are sensory axons and most of these axons end in the epithelium. SP‐IR axons innervate mucosal arterioles, but few innervate postcapillary venules. Therefore, the mechanism by which sensory axons evoke plasma extravasation from these venules is likely to involve the diffusion of the peptide or a secondary mediator from the epithelium or from the arterioles upstream. © 1992 Wiley‐Liss, Inc.
Morphological variations among output neurons of the olfactory bulb in the frog (Rana ridibunda)
Authors: Jiang Tao , Holley André
Published: January 2005

Morphological properties of putative output cells have been studied in detail in the olfactory bulb of frogs (Rana ridibunda). Intracellular injection of Lucifer Yellow was used to reconstruct individual neurons. Ten different anatomical features related to cell shape and position were studied quantitatively. The results show that output cells, generally considered to be a homogeneous group in the olfactory bulb of amphibians, are, in fact, quite different in their morphology. Using multidimensional analysis to examine differences among the output neurons, we found that they might be divided into at least two groups. In one group, the cell somata were located near the glomerular layer and the dendrites lay at large angles with respect to each other. In the other group, the cell somata were farther from the glomerular layer and their dendrites lay at smaller angles. From their morphology, these two cell groups appear to be homologous, respectively, to the superficial/middle tufted cells and deep tufted/mitral cells of mammals.
Glucose metabolism in freshly isolated Müller glial cells from a mammalian retina
Authors: Poitry‐Yamate Carol L. , Tsacopoulos Marcos
Published: January 2005

Glucose metabolism was studied in isolated retinal Müller glial cells from the juvenile guinea pig. Cells, once enzymatically isolated and purified, were identified by morphological criteria, positive vimentin immunoreactivity, and histochemical staining for glycogen. Purified suspensions of Müller cells were obtained in quantities sufficient for biochemical analysis (≈ 2 × 105/pair of retinas) and light microscopic autoradiography. In bicarbonate‐buffered Ringer's medium containing 3H‐2‐deoxyglucose and no glucose, ≥80% of the glucose analogue taken up intracellularly by Müller cells was phosphorylated to 3H‐2‐deoxyglucose‐6‐phosphate. In autoradiographs, this non‐metabolized product provided visual evidence of glucose phosphorylation: the distribution of cell grains mirrored the morphology of individual Müller cells in situ. Exposure to the glycolytic inhibitor iodoacetate (500 μM) caused an 85% decrease in adenosine triphosphate (ATP) content; concomitantly, 3H‐2‐deoxyglucose‐6‐phosphate decreased by 90% and paralleled a dramatic decrease of cell labelling in autoradiographs, while levels of 3H‐2‐deoxyglucose did not change. In the continual absence of glucose, glycogen content decreased with time and this decrease was slowed by 36% in the presence of iodoacetate. This indicated that, in control conditions, glycosyl units from glycogen sustain cellular metabolism, and hence 3H‐2‐deoxyglucose phosphorylation. 3H‐2‐deoxyglucose‐6‐phosphate concentration was 43‐fold less than that of ATP in the control conditions so that depletion of ATP during iodoacetic acid (IAA)‐blocked glycolysis was not due to hexokinase activity. These results demonstrate that this preparation is adequate for quantitative studies of glucose metabolism at the cellular and molecular level in an important metabolic compartment of the mammalian retina.
Organization of the zona incerta in the macaque: A nissl and golgi study
Authors: Ma Terence P. , Hu Xiao‐Jiang , Anavi Yakir , Rafols José A.
Published: January 2005

The zona incerta has been implicated in the control of the initiation of saccadic eye movements in the primate. Complex interactions within the zona incerta must take place to integrate its varied inputs and to produce a coherent efferent signal in order for this function to occur. However, whether the anatomical substrates exist within the zona incerta to allow this integration to take place has not been established. The zona incerta in monkeys (Macaca mulatta) was examined in frontally, horizontally, and sagittally sectioned preparations stained for Nissl, myelinated fibers, or cytochrome oxidase, or impregnated by the Golgi technique. This nucleus can be separated into dorsal and ventral laminae on the basis of staining and morphological differences between these two subdivisions. Neurons are more densely packed, more darkly stained, and larger in the ventral lamina. In addition, the neuropil of the ventral lamina is much more intensely stained after cytochrome oxidase histochemistry. Two neuronal types, principal cells and interneurons, were identified on the basis of neuronal cell body, dendritic, and axonal features in Golgi‐impregnated preparations. Principal cells have fusiform or polygonal somata (long axis from 18 to 40 μm) and dendrites that extend for up to 750 μm within the lamina in which the cell bodies are located. Putative local interneurons have small (12–16 μm), round or oval cell bodies with wavy dendrites (up to 400 μm). Numerous multilobed appendages and axon‐like processes originate from these dendrites and make apparent contacts with other interneurons or with dendrites of principal cells. Dendrites of most neurons in both laminae are oriented preferentially along the principal axis, dorsolateral‐to‐ventromedial, of the nucleus. Therefore, within the limits of light microscopy, the zona incerta appears to possess the morphological heterogeneity to form complex intrinsic interactions. These interactions are hypothesized to form the integrative substrate for the large array of incertal inputs that are utilized to produce an efferent signal involved in the initiation of saccadic eye movements.
Vasopressin‐immunoreactive neurons and neurohemal systems in cockroaches and mantids
Authors: Davis Norman T. , Hildebrand John G.
Published: January 2005

Vasopressin‐like neuropeptides of insects are of special interest because of their possible function as hormones and neuromodulators. Therefore, this study was undertaken by using whole‐mount immunofluorescent staining by two antisera that recognize different types of vasopressin‐like immunoreactive groups of neurons in the cockroaches Periplaneta americana, Leucophaea maderae, Nauphoeta cinerea, Diploptera punctata, and Blaberus discoidalis and in the mantids Litaneuria minor and Tenodera aridifolia sinensis.

Using an antiserum to Arg/vasopressin, only two cells, the paired ventral paramedian (PVP) neurons, were immunostained in the central nervous system (CNS) of the cockroaches. These cells are located in the subesophageal ganglion, project throughout the CNS, and appear to be neurosecretory. Their varicose collaterals extend into the dorsal (motor) neuropil of the segmental ganglia, and this neuropil may be the principal site of the release of their neurosecretion.

The PVP neurons were also stained by an antiserum to Lys/vasopressin; in addition, this antiserum stained several other groups of neurons, most of which appeared to be neurosecretory. Two pairs of Lys/vasopressin‐immunoreactive cells are similar to the PVP neurons in that they are located in the subesophageal ganglion, extend through the ventral nerve cord, have collaterals in the dorsal neuropil of the segmental ganglia, and appear to be neurosecretory within the CNS. In addition, midventral and anteroventral clusters of Lys/vasopressin‐immunoreactive neurosecretory neurons in the subesophageal ganglion project neurohemal release sites on the corpora allata.

Other types of Lys/vasopressin‐immunoreactive neurons include median and lateral neurosecretory cells of the protocerebrum and neurosecretory cells in the tritocerebrum, all of which project to the corpora cardiaca. In the abdominal ganglia there are posterolateral clusters of Lys/vasopressin neurosecretory neurons, and these cells extend to neurohemal release sites on the transverse and lateral cardiac nerves.

In mantids the anti‐Arg/vasopressin and anti‐Lys/vasopressin antisera stained most of the same groups of neurons that these antisera recognized in cockroaches.

The results of this study suggest that there are two or more vasopressin‐like peptides in cockroaches and mantids and that these peptides may be released either as hormones in the blood or as neurosecretions within the CNS. Their function(s) in these insects remains to be determined.
Two types of motoneurons supplying dorsal fin muscles in lamprey and their activity during fictive locomotion
Authors: Shupliakov Oleg , Wallén Peter , Grillner Sten
Published: January 2005

The location and dendritic morphology of motoneurons supplying the dorsal fin muscles were studied in the lamprey spinal cord (Ichtkyomyzon unicuspis). Motoneurons were retrogradely labelled after injection of HRP into the fin muscles or after its application on the cut ends of the ventral roots. HRP‐labelled cells were subsequently reconstructed, in the horizontal and/or transverse planes. Fin motoneurons were also injected intracellularly with Lucifer Yellow and their detailed three‐dimensional structure was analysed by confocal laser‐scanning microscopy.

Unlike myotomal motoneurons, which are closely spaced in the lateral cell column, fin motoneurons were distributed along the spinal cord separately or in pairs. They could be distinguished from motoneurons supplying trunk muscles by having a limited number of dendrites in the lateral part of the spinal cord. In addition, some fin motoneurons extend their dendrites into the dorsal column. The motor cells innervating fin muscles were divided into two types based on their dendritic morphology. Type I have a widespread dendritic tree in the rostrocaudal direction and, with few exceptions, completely restricted to the ipsilateral side. A proportion (25%) of these cells have dendrites extending into the dorsal column. Type II fin motoneurons extend their dendrites both ipsi‐ and contra‐laterally. The contra‐lateral dendrites pass below and above the central canal. The dendrites send off branches into the dorsal columns on both the ipsi‐ and the contra‐lateral sides. Electron microscopic analysis showed that both type I and type II fin motoneurons receive numerous synaptic contacts from dorsal column axons.

During fictive locomotion both types of motoneurons are active in antiphase in relation to myotomal motoneurons and to the main locomotor burst. © 1992 Wiley‐Liss, Inc.
Neurotensin terminals form synapses primarily with neurons lacking detectable tyrosine hydroxylase immunoreactivity in the rat substantia nigra and ventral tegmental area
Authors: Woulfe John , Beaudet Alain
Published: January 2005

A light and electron microscopic double antigen localization technique was employed to examine the fine structural relationship between neurotensin‐containing axon terminals and dopaminergic neurons in the substantia nigra and ventral tegmental area of the rat. At the light microscopic level, neurotensin‐immunoreactive terminals were densely distributed throughout the substantia nigra pars compacta and ventral tegmental area in close proximity to tyrosine hydroxylase‐immunoreactive somata and dendrites. On electron microscopic examination, direct synaptic connections were identified between neurotensin‐immunoreactive axon terminals and tyrosine hydroxylase‐immunopositive perikarya and dendrites. However, only 8.2% and 8.8% of the neurotensin‐immunoreactive axonal profiles detected in the substantia nigra and ventral tegmental area, respectively, were found in direct apposition with tyrosine hydroxylase‐immunostained elements. In turn, only 9.3% and 10.0% of tyrosine hydroxylase immunoreactive dendrites sampled from the substantia nigra and ventral tegmental area, respectively, were seen in contact with neurotensin immunopositive axon terminals. However, neurotensin‐immunoreactive and tyrosine hydroxylase‐immunolabelled elements were frequently identified in close anatomical proximity (<5 μm) to one another. These results are interpreted in light of the selective association of neurotensin receptors with dopaminergic neurons in the substantia nigra and ventral tegmental area to suggest a predominantly parasynaptic mechanism of action for neurotensin in the ventral midbrain.
The influence of inhibitory afferents on the development of postsynaptic dendritic arbors
Authors: Sanes Dan H. , Markowitz Scott , Bernstein Joseph , Wardlow Jesse
Published: January 2005

The growth and maintenance of dendritic form is dependent on normally functioning excitatory afferents. We have now examined the development of dendritic arbors in the gerbil lateral superior olive (LSO), following contralateral cochlear removal at postnatal day 7, a manipulation that substantially eliminates driven inhibitory transmission. Previous studies have demonstrated that the morphology of LSO dendritic arbors varies with tonotopic position and becomes more restricted with age.

The presumed decrease of inhibitory transmission in the contralateral LSO resulted in a hypertrophic response. Quantification of Golgi‐impregnated neurons revealed that dendrites had a significantly greater number of branch points, and their arbors were more spread out along the frequency axis compared to normal. This was especially apparent in the high frequency projection region where the glycine receptor density is known to be 4‐fold higher than in the low frequency projection region. A measure of LSO nucleus size, cross‐sectional area, was identical to control values, indicating no overt signs of degenerative phenomena. Cochlear ablation resulted in a significant atrophy of the ipsilateral LSO, with significant effects on dendritic structure.

We conclude that decreased inhibitory transmission during development does not lead to a net degenerative response. Rather, the postsynaptic neurons exhibit a hypertrophic phenotype that may be due to the persistence of an immature state. These results indicate that activity‐dependent morphogenetic events are a consequence of both excitatory and inhibitory synaptic transmission. © 1992 Wiley‐Liss, Inc.
Morphology of the dorsal cochlear nucleus in C57BL/6J and CBA/J mice across the life span
Authors: Willott James F. , Bross Lori Seegers , McFadden Sandra L.
Published: January 2005

The morphology of the dorsal cochlear nucleus (DCN) was evaluated across the life span in inbred C57BL/6J (C57) and CBA/J (CBA) mice using 5 age groups (young adult to very old). C57 mice exhibit progressive cochlear sensorineural pathology and hearing loss during middle age; CBA mice have only modest sensorineural pathology late in life. DCN layers I, II, and III were evaluated histologically with serial sections stained for Nissl and fibers. DCN volume decreased with age in C57 mice, but the change began earliest and was most pronounced in layer III. In CBA mice, volume increased during the first year of life and decreased only in the oldest mice. All major DCN cell types were found in both strains at all ages. There was an age‐related decrease in the mean size of neurons in C57 mice that was first observed in layer III. In CBA mice, only a nonsignificant trend toward smaller neurons was observed in the oldest mice. An age‐related decline in the number of neurons in layer III (but not in layers I and II) occurred in C57 mice. Aged CBA mice exhibited no significant loss of DCN neurons. Thus, age‐related changes in the DCN were much more pronounced in C57 mice than in CBA mice, and the changes in C57 mice were most pronounced in layer III. Because layer III receives most of the DCN's primary auditory input, it would be directly affected by age‐related hearing loss and degeneration of spiral ganglion cells in C57 mice. This suggests that the age‐related changes observed in DCN layer III of C57 mice are affected by progressive peripheral degenerative changes; when peripheral loss is minimal (CBA mice), less substantial age‐related changes are observed. © 1992 Wiley‐Liss, Inc.
Dual innervation of the rat vibrissa: Responses of trigeminal ganglion cells projecting through deep or superficial nerves
Authors: Waite Phil M. E. , Jacquin Mark F.
Published: January 2005

The rat vibrissal follicle–sinus complex is innervated by a deep vibrissal nerve (DVN) and several smaller fascicles traveling in the dermis [conus or superficial vibrissal nerves, (SVNs)]. The function of the SVNs is unknown, although it has been suggested in a comparative study that they form part of a diffuse, multivibrissal system. Anatomical and electrophysiological methods were used to test this hypothesis and to determine if DVN and SVN fibers have differing response profiles.

No ganglion cells were double‐labeled after retrograde tracer injections in the DVN and SVNs of single follicles. Electron microscopy showed that selective transection of the DVN caused no SVN degeneration or vice versa. Thus, the dual innervation of the vibrissa arises from separate ganglion cells that project through separate nerves.

Ganglion cells with A–row vibrissa receptive fields were studied before and after cutting the DVN and/or SVNs to the responsive vibrissa in order to identify their peripheral trajectories. In this sample, 83% projected through a DVN and 17% via a SVN. SVN or DVN cells were not spontaneously active. All cells responded to single vibrissae only; none were responsive to intervibrissal hairs or skin. Latencies to electrical stimulation were similar for DVN and SVN cells. Adaptation rates and threshold measurements were also similar in the two groups: 60% of the DVN cells and 80% of the SVN cells gave slowly adapting responses to sustained vibrissal displacement; threshold displacements ranged from less than 1° to greater than 15° for both SVN and DVN cells. Direction sensitivity was found in all DVN and SVN slowly adapting cells, with most cells responding to movements in one or two quadrants. For SVN cells, sequential circumferential nerve sections indicated that the fiber's directional sensitivity matched the direction of the fiber's entry into the follicle. The two groups differed in their responses to pushing in or pulling on the hair shaft. All the DVN cells were responsive to both of these stimuli, while for SVN cells pushing activated only 40% and none were responsive to pulling the hair. Another difference in the two groups was that no injury discharges occurred after cutting SVNs, but were present in 44% of DVN cells.

These data suggest that DVN and SVNs are similar in the majority of response properties. There is also no evidence to support the hypothesis that SVNs provide diffuse, multivibrissal inputs. © 1992 Wiley‐Liss, Inc.
Fos‐like immunoreactivity in the brain of homozygous diabetes insipidus brattleboro and normal long‐evans rats
Authors: Guldenaar Stephan E. F. , Noctor Stephen C. , McCabe Joseph T.
Published: January 2005

Water deprivation induces the production of the transcription factor Fos in neurons of the neurohypophysial system. These neurons, which are located primarily in the hypothalamic paraventricular (PVN) and supraoptic nuclei (SON), produce the antidiuretic hormone vasopressin. The present immunocytochemical study has analyzed the distribution of Fos in brain regions involved in osmoregulation and compared the extent of Fos immunoreactivity (Fos‐IR) in vasopressin‐deficient Brattleboro and normal Long‐Evans rats under stimulated and non‐stimulated conditions. Rats were osmotically challenged by means of a single intraperitoneal injection of 1.5 M/L NaCl. Since Fos may be induced by the stress of handling of animals, non‐injected and isotonic saline‐injected rats were used as controls. Faint nuclear Fos immunostaining was found in the organum vasculosum of the lamina terminalis (OVLT), the median preoptic nucleus (MnPO), subfornical organ (SFO), and SON of non‐injected and isotonic saline‐injected Brattleboro but not Long‐Evans rats. Hypertonic saline injection specifically induced Fos‐IR in neurons located in the SFO, OVLT, MnPO, PVN, SON, hypothalamic accessory nuclei (including the nucleus circularis), and arcuate hypothalamic nucleus (Arc) in both Long Evans and Brattleboro rats. No differences in distribution of the induced immunostaining were found between the strains. Stress of handling and (isotonic saline) injection induced Fos‐IR in the lateral septal nuclei, central amygdaloid nuclei, medial amygdaloid nucleus, medial preoptic area, the bed nucleus of the stria terminalis, cingulate‐ and piriform cortex, the lateral hypothalamic area, ventromedial hypothalamic nucleus, and the habenular nucleus. The data are consistent with a role for Fos in the regulation of vasopressin gene expression during acute hyperosmotic stimulation. In addition, this study demonstrated that during chronic osmotic stimulation, as experienced by homozygous Brattleboro rats, Fos‐IR is limited but apparently present constantly and that it increased in these animals following acute osmotic challenge. Our observations suggest that c‐fos regulatory controls in homozygous Brattleboro rats are different from those in Long‐Evans rats. © 1992 Wiley‐Liss, Inc.
Expression of S‐laminin and laminin in the developing rat central nervous system
Authors: Hunter Dale D. , Llinas Rafael , Ard March , Merlie John P. , Sanes Joshua R.
Published: January 2005

The extracellular matrix component, s‐laminin, is a homologue of the B1 subunit of laminin. S‐laminin is concentrated in the synaptic cleft at the neuromuscular junction and contains a site that is adhesive for motor neurons, suggesting that it may influence neuromuscular development. To ascertain whether s‐laminin may also play roles in the genesis of the central nervous system, we have examined its expression in the brain and spinal cord of embryonic and postnatal rats. S‐laminin was not detectable in synapse‐rich areas of adults. However, s‐laminin was present in discrete subsets of three laminin‐containing structures: (1) In the developing cerebral cortex, laminin and s‐laminin were expressed in the subplate, a transient layer through which neuroblasts migrate and cortical afferents grow. Both laminin and s‐laminin disappeared as embryogenesis proceeded; however, laminin was more widely distributed and present longer than s‐laminin. (2) In the developing spinal cord, laminin was present throughout the pia. In contrast, s‐laminin was concentrated in the pia that overlies the floor plate, a region in which extracellular cues have been postulated to guide growing axons. (3) In central capillaries, s‐laminin appeared perinatally, an interval during which the blood‐brain barrier matures. In contrast, laminin was present in capillary walls of both embryos and adults.

To extend our immunohistochemical results, we used biochemical methods to characterize s‐laminin in brain. We found that authentic s‐laminin mRNA is present in the embryonic brain, but that brain‐derived s‐laminin differs (perhaps by a posttranslational modification) from that derived from nonneural tissues. We also used tissue culture methods to show that glia are capable of synthesizing “brain‐like” s‐laminin, and of assembling it into an extracellular matrix. Thus, glia may be one cellular source of s‐laminin in brain. Together, these results demonstrate that s‐laminin is present in the developing central nervous system, and raise the possibility that this molecule may influence developmental processes. © 1992 Wiley‐Liss, Inc.
Normal development and effects of neonatal infraorbital nerve damage upon the innervation of the trigeminal brainstem complex by primary afferent fibers containing calcitonin gene‐related peptide
Authors: Bennett‐Clarke Carol A. , Chiaia Nicolas L.
Published: January 2005

Immunocytochemistry was used to study the normal development and response to infraorbital nerve (ION) damage of the innervation of the trigeminal (V) brainstem complex by axons recognized by an antibody directed against calcitonin gene‐related peptide (CGRP). CGRP‐like immunoreactivity (CGRPLI) was present in axons that occupied the outer V spinal tract (TrV) at all levels of the V brainstem complex. Almost no fibers terminated within V nucleus principalis (PrV), out there was dense CGRPLI in the supratrigeminal nucleus. There was also very little CGRPLI within rostral V subnucleus oralis (SpO). However, in the caudal one‐half of the nucleus, a dense elongated patch of immunoreactivity was consistently present just medial to TrV. Only occasional CGRP‐positive axons could be seen within V subnucleus interpolaris (SpI), but the paratrigeminal nucleus contained dense immunoreactivity. Trigeminal subnucleus caudalis (SpC) also contained CGRPLI that was very dense in lamina I and the outer portion of lamina II. Scattered terminals were also present in layers III and IV and dense terminal clusters were in lamina V. CGRP‐immunoreactive neurons were present in the V ganglion by embryonic (E‐) day 16 and immunoreactive axons could be seen in the V brainstem complex on E–17. At birth, CGRP‐positive axons in the V brainstem complex had achieved a distribution very similar to that in adult rats. The major difference between the patterns of labelling in neonates and adults was the presence of relatively large numbers of CGRP‐positive fibers in ventral PrV and SpO of the former animals. The disappearance of these fibers was completed by the middle of the third postnatal week. Transection of the ION on the day of birth had little effect upon CGRP in SpO, SpI, and SpC, but it did result in an increase in CGRP‐positive fibers in PrV ipsilateral to the damaged nerve. When considered together with previous findings, these results suggest that CGRP‐positive axons express this peptide well after they have entered the V brainstem complex and that the central terminal field of these fibers is not substantially altered by a manipulation which results in the death of nearly 60% of all V primary afferent neurons. © 1992 Wiley‐Liss, Inc.
Three‐dimensional analysis of the structure and composition of CA3 branched dendritic spines and their synaptic relationships with mossy fiber boutons in the rat hippocampus
Authors: Chicurel Marina E. , Harris Kristen M.
Published: January 2005

This paper is the third in a series to quantify differences in the composition of subcellular orgunelles and three‐dimensional structure of dendritic spines that could contribute to their specific biological properties. Proximal apical dendritic spines of the CAS pyramidal cells receiving synaptic input from mossy fiber (MF) boutons in the adult rat hippocampus were evaluated in three sets of serial electron micrographs. These CAS spines are unusual in that they have from 1 to 16 branches emerging from a single dendritic origin. The branched spines usually contain subcellular organelles that are rarely found in adult spines of other brain regions including ribosomes, multivesicular bodies (MVB), mitochondria, and microtubules. MVBs occur most often in the spine heads that also contain smooth endoplasmic reticulum, and ribosomes occur most often in spines that have spinules, which are small nonsynaptic protuberances emerging from the spine head.

Most of the branched spines are surrounded by a single MF bouton, which establishes synapses with multiple spine heads. The postsynaptic densities (PSDs) occupy about 10–15% of the spine head membrane, a value that is consistent with spines from other brain regions, with spines of different geometries, and with immature spines. Individual MF boutons usually synapse with several different branched spines, all of which originate from the same parent dendrite. Larger branched spines and MF boutons are more likely to synapse with multiple MF boutons and spines, respectively, than smaller spines and boutons.

Complete three‐dimensional reconstructions of representative spines with 1, 6, or 12 heads were measured to obtain the volumes, total surface areas, and PSD surface areas. Overall, these dimensions were larger for the complete branched spines than for unbranched or branched spines in other brain regions. However, individual branches were of comparable size to the large mushroom spines in hippocampal area CA1 and in the visual cortex, though the CA3 branches were more irregular in shape. The diameters of each spine branch were measured along the cytoplasmic path from the PSD to the origin with the dendrite, and the lengths of branch segments over which the diameters remained approximately uniform were computed for subsequent use in biophysical models. No constrictions in the segments of the branched spines were thin enough to reduce charge transfer along their lengths. The complex geometry of these spines and their subcellular constituents could modulate postsynaptic responses, however, during synaptic activation or plasticity such as long term potentiation, in ways that can now be evaluated on the basis of the complete dimensions and descriptions reported here. © 1992 Wiley‐Liss, Inc.
Antibody to NGF inhibits collateral sprouting of septohippocampal fibers following entorhinal cortex lesion in adult rats
Authors: Van Der Zee Catharina E. E. M. , Fawcett Jim , Diamond Jack
Published: January 2005

We have used an antiserum raised against mouse 2.5S NGF to examine the involvement of endogenous neurotrophins in the collateral sprouting of septohippocampal fibers in the adult rat brain. The antiserum was administered intraventricularly. Immunocytochemical techniques indicated that the injected antibodies penetrated into brain tissue that included the basal forebrain, cortex, striatum, corpus callosum, and hippocampus. Unilateral lesioning of the entorhinal cortex was done to evoke the sprouting of the cholinergic septohippocampal fibers. At 8 days postlesion, the sprouting was much advanced, as evidenced by an increase in density of the acetylcholinesterase (AChE) staining in the outer molecular layer (OML) of the dentate gyrus and by the associated increase in the absolute number of AChE‐positive fibers in the OML. As well, there was a widening of the inner molecular layer (IML), interpreted as being due to sprouting of noncholinergic axons in that region. In rats injected daily with anti‐NGF or anti‐NGF Fab fragments, no increase in AChE density, or in the population of AChE‐positive fibers, was observed in the OML. In contrast, the widening of the IML seemed to be unaffected by the anti‐NGF treatment. No changes were observed in the AChE related parameters in the dentate gyrus of nonlesioned animals treated similarly for 8 days with anti‐NGF; there was, however, a decrease of choline acetyltransferase (ChAT) immunostaining in the ChAT‐positive cells of the basal forebrain. Our findings and the confirmation that our polyclonal anti‐NGF also recognizes other members of the NGF neurotrophin family, specifically brain‐derived neurotrophic factor and neurotrophin‐3, indicate that at least one of these neurotrophins plays a key role in the collateral sprouting of the cholinergic septohippocampal fibers (but not that presumed to occur within the IML) following an entorhinal cortex lesion. © 1992 Wiley‐Liss, Inc.
An electron microscopical study of calcitonin gene‐related peptide‐like immunoreactive innervation of the anterior pituitary in the dog
Authors: Ju Gong , Zhang Xu
Published: January 2005

Our previous studies have demonstrated the presence of a considerable number of substance P‐, calcitonin gene‐related peptide (CGRP)‐, and galanin‐like immunoreactive (LI) nerve fibers in the anterior pituitary in several mammalian species. The present study investigated the ultrastructure of the CGRP‐LI innervation of this gland in the dog. The CGRP‐LI nerve fibers were unmyelinated, with a wealth of yaricosities containing both small clear synaptic vesicles and large dense‐cored vesicles. They were found to be in direct contact with every cell type of the anterior pituitary. However, only on corticotropes and somatotropes were CGRP‐LI synaptic contacts identified. Most of them were asymmetrical in type. Occasional symmetrical synaptic contacts were also found. It is considered likely that direct neural factors may play a role in the regulation of the anterior pituitary. © 1992 Wiley‐Liss, Inc.
Postnatal development of area 17 callosal connections in Tupaia
Authors: Kretz R. , Rager G.
Published: January 2005

The goal of the present study was to investigate the pattern of maturation of callosal projecting neurons in a well‐studied mammalian visual system with unique structural and functional properties. Studies of the distribution pattern of interhemispheric connections in the adult tree shrew primary visual cortex reveal not only a high concentration of labeled neurons along the area 17/18 border, as in standard experimental animals such as the cat and monkey, but also numerous callosal projecting neurons in the adjacent dorsal part of area 17, which largely corresponds to the binocular visual field (Kretz and Rager, Exp. Brain Res. 82:271, '90).

Callosal projections were anatomically traced in 11 tree shrews (Tupaia belangeri) at various ages between postnatal day 7 (7,9,10,13,15,17,19, and 26 days old) and adulthood (107 days old). In each animal, four injections of wheat germ agglutinin conjugated to horseradish peroxidase were made in a standard configuration into the striate cortex of one hemisphere. In young tree shrews only 7 and 9 days old, heavily labeled terminal axon structures could be seen in the white matter and in layer VI of the opposite hemisphere. Only a few labeled neurons, however, were detected in layer III. The small number of labeled neurons indicated that early in postnatal development, only a few callosal axons had invaded the upper cortical layers. By 10 days of age, the number of supragranular neurons was increasing and the maximal value was counted in a 13‐day‐old tree shrew. A sharp decline in the number of labeled supragranular neurons was noticed—about 94% in our case—between days 13 and 15. In animals more than 15 days old, the distribution pattern and the density of the neurons looked like the pattern seen in the adult Tupaia brain. The labeled cells were mostly concentrated in layers II and III. The majority of neurons resembled typical pyramidal cells. However, some of the neurons in sublayer IIIc had elongated cell bodies oriented parallel to the laminar boundaries. In contrast to the supragranular cells found in all stages investigated, small populations of labeled cells in layer VI were observed in 9‐ to 17‐day‐old tree shrews only. In young postnatal animals 7 to 13 days old, a peculiar cell type was labeled on the ipsilateral side. In coronal sections these cell bodies formed a continuous band that extended from the ventricular wall to the subcortical white matter. These cells might belong to a population of cells still in migration. © 1992 Wiley‐Liss, Inc.
Effects of neonatal transection of the infraorbital nerve upon the structural and functional organization of the ventral posteromedial nucleus in the rat
Authors: Chiaia Nicolas L. , Bauer William R. , Zhang Shujie , King Tod A. , Wright Paul C. , Hobler Scott C. , Freeman Keith A.
Published: January 2005

The present study examined the way in which an indirect partial deafferentation of the medial portion of the ventrobasal complex (VPM/VPL) induced by neonatal transection of the infraorbital nerve (ION) altered the structural and functional properties of its constituent neurons. This manipulation significantly reduced the volume of the contralateral VPM/VPL. In addition, cell counts in Nissl‐stained material revealed a significant reduction of the number of VPM/VPL neurons contralateral to neonatal ION transection. We also analyzed the effect of neonatal ION transection on the soma‐dendritic morphology of individual neurons in the ventral posteromedial nucleus of the thalamus (VPM) by intracellular injection of horseradish peroxidase (HRP) in vivo and Lucifer yellow in fixed slices. Neonatal transection of the ION resulted in increased dendritic length, area, and volume of VPM neurons in both preparations; however only the changes observed in fixed slices reached statistical significance. Alterations in the functional characteristics of VPM neurons were also observed following neonatal nerve damage. There was a significant decrease in the percentage of vibrissae‐sensitive neurons and a corresponding increase in the percentages of neurons responsive to guard hair deflection or that were unresponsive to peripheral stimulation. Neonatal nerve damage also resulted in significantly longer latencies of VPM cells after stimulation of either trigeminal nucleus principalis or subnucleus interpolaris.

The present results indicate that the development of normal response properties and soma‐dendritic morphology of VPM neurons is dependent upon intact afferent input during development. Indirect partial deafferentation of VPM/VPL by neonatal transection of the ION results in reduced neuron number, which may result in decreased competition among the dendrites of these neurons. This proposal is consistent with observations of increased dendritic dimensions of VPM neurons contralateral to neonatal ION damage. © 1992 Wiley‐Liss, Inc.