bluuebunny/crossref_metadata_2025 huggingface dataset:
Laterality of superior olive projections to the inferior colliculus in adult and developing ferret
Authors: Henkel Craig K. , Brunso‐Bechtold Judy K.
Published: January 2005

The laterality of projections from the lateral superior olivary nucleus (LSO) to the inferior colliculus was studied in adult and immature postnatal ferrets. In the adult ferret, large unilateral injections of horseradish peroxidase (HRP) in the inferior colliculus labeled about equal proportions of cells in the ipsilateral and contralateral lateral superior olivary nuclei. The contralateral labeled cells consistently were more densely labeled than those on the ipsilateral side. Double labeling experiments using fluorescent dyes indicated that only about 3% of LSO cells in the adult give rise to collaterals ending in the inferior colliculus on both sides. As expected, the distribution of labeled cells varied topographically in the LSO as a function of the injection site in the inferior colliculus. Dorsolateral inferior collicular injections labeled cells in the lateral limb of the LSO, whereas ventromedial injections labeled cells in the medial limb of the LSO. The proportion of ipsilateral and contralateral labeled cells also varied across the lateral‐medial axis of the LSO in some cases. A gradient in laterality was observed in these cases with the lateral limb of the LSO containing the highest proportion of contralateral labeled cells, and the medial limb, the highest proportion of ipsilateral labeled cells. Larger inferior collicular injections resulted in greater proportions of ipsilateral labeling in LSO than smaller injections. Finally, ipsilateral labeled cells tended to be in the marginal region of the LSO, whereas contralateral labeled cells were more common within the core region of the LSO, irrespective of the location along the lateral‐medial axis of LSO. The contralateral predominance of labeled cells, greater density of labeling in contralateral cells, different topographic distribution, and regional segregation of ipsilateral and contralateral labeled cells were typical of the LSO in ferret kits by birth, one month before the onset of hearing. Nevertheless, the relative proportion of ipsilateral and contralateral projection cells appears to change during postnatal development. © 1993 Wiley‐Liss, Inc.
Morphological and quantitative evaluation of olfactory bulb development in Xenopus after olfactory placode transplantation
Authors: Byrd Christine A. , Burd Gail D.
Published: January 2005

We found previously that the number of olfactory axons is correlated with the number of mitral/tufted cells (output neurons of the olfactory bulb) during normal larval development. To examine the significance of this quantitative relationship, we evaluated the effects of transplanting an extra olfactory placode on the development of the larval olfactory bulb. We found that the transplanted tissue retained the normal, pseudostratified, columnar appearance and had the same cell types as normal olfactory epithelium, and the olfactory bulbs had the same laminar organization as control bulbs. With gross examination of the olfactory bulb, the side innervated by the transplant appeared slightly larger than the contralateral side in animals analyzed at a young larval stage (stage 50) and in 2 of the 9 animals examined at late larval stages (57/58). Tissue sections and area measurements, however, revealed that the volume of the olfactory bulbs in animals with a transplant was not significantly different from control values.

Our quantitative analysis also showed that in stage‐50 animals with a transplant, the total number of olfactory axons (in nerves from the transplanted and host olfactory organs) appeared to be greater than in control animals, but not to a statistically significant level. The number of mitral/tufted cells was not different from controls. In animals examined at stage 57/58, there was no differnce from controls in either the total number of olfactory axons, total number of mitral/tufted cells, or convergence ratio of olfactory axons onto mitral/tufted cells. Thus, in the late‐stage larvae, the quantitative relationship between olfactory axons and mitral/tufted cells was not altered by the experimental manipulation. These results suggest that the olfactory bulb can regulate the number of affernt fibers. © 1993 Wiley‐Liss, Inc.
Ventral subicular interaction with the hypothalamic paraventricular nucleus: Evidence for a relay in the bed nucleus of the stria terminalis
Authors: Cullinan William E. , Herman James P. , Watson Stanley J.
Published: January 2005

The axonal projections of the ventral subiculum to the bed nucleus of the stria terminalis (BST) were examined in the rat with the anterograde neuronal tracer Phaseolus vulgaris‐ leucoagglutinin (PHA‐L). Axons originating in the ventral subiculum coursed to the BST through either the fimbria‐fornix, or a pathway involving the stria terminalis via the amygdala. Ventral subicular axons gave rise to dense terminal networks that were preferentially distributed in medial and ventral subregions of the BST. The distribution of subicular fibers and terminals was examined in relation to BST neurons that project to the hypothalamic paraventricular nucleus (PVN). In these cases, discrete iontophoretic injections of the retrograde tracer Fluoro‐gold were made in the PVN, with PHA‐L delivered to the ipsilateral ventral subiculum. An immunocytochemical double‐labeling protocol was then employed for the simultaneous detection of PHA‐L and Fluoro‐gold, and provided light microscopic evidence for subicular input to PVN‐projecting cells located within the BST.

In a second series of experiments, the γ‐amino butyric acid (GABA)ergic nature of the BST was examined by in situ hybridization histochemistry for detection of transcripts encoding GAD67 mRNA. The studies revealed that a high proportion of BST neurons express GAD67 transcripts. Also, experiments combining Fluoro‐gold tracing with GAD67 in situ hybridization suggested that a proportion of PVN‐projecting neurons in the BST are GABAergic. Taken together, the results of these sets of studies suggest that the inhibitory influences of the hippocampus on the PVN might be relayed through specific portions of the BST. These findings may have important implications for our understanding of the neural regulation of the hypothalamic‐pituitary‐adrenal axis. © 1993 Wiley‐Liss, Inc.
GABA‐ and glycine‐immunoreactive neurons in the spinal cord of the carp, Cyprinus carpio
Authors: Uematsu Kazumasa , Shirasaki Makiko , Storm‐Mathisen Jon
Published: January 2005

γ‐Aminobutyric acid (GABA) and glycine are the two main inhibitory transmitter amino acids in the central nervous system of vertebrates. The distribution of cells containing GABA and glycine in the carp spinal cord was examined by using specific antisera raised against the two amino acids conjugated to bovine serum albumin. The immunoreaction on serial paraffin sections was visualized by a streptavidin‐biotin method. Both antisera gave highly specific labellings of cells. At least three types of GABA‐immunoreactive cells were found. They were small cells in the dorsal grey matter, various sized cells in the central and ventral grey, and some ependymal cells contacting the central canal. In addition, very small cells and neuropil structures in the dorsal horn were strongly immunoreactive to the GABA serum. Certain cells in the ventral horn have moderate numbers of labelled synaptic boutons on the perikarya, but very few GABA‐labelled terminals were found on putative motoneurons. The immunoreactive ependymal cells appeared to have a ventrolaterally directed axon. The glycine antiserum labelled small and intermediate cells in the dorsal grey, large, elongated cells in the median region, and varying sized cell sin the ventral grey. The numbers and density of immunoreactive cells and neuropil strucures in the ventral horn were fewer and lower than in GABA‐stained sections. The median large cells had a thick venrolateral process. The ventral intermediate cells were often found near putative motoneurons. Labelled synaptic boutons were present on most ventral cells including putative motoneurons and interneurons. Abundant distribution of cells immunoreactive to both antisera suggest important roles of both GABA and glycine as neurotransmitters for controlling swimming movements in teleosts. © 1993 Wiley‐Liss, Inc.
Intersegmental ascending interneurones controlling uropod movements of the crayfish Procambarus clarkii
Authors: Nagayama Toshiki , Isogai Yukihiro , Sato Motoaki , Hisada Mituhiko
Published: January 2005

The premotor effects of intersegmental ascending interneurones upon uropod motor neurones in the crayfish Procambarus clarkii (Girard) are examined with intracellular recording and staining techniques. We show that many ascending interneurones can affect the activity of the antagonistic opener and closer motor neurones in the terminal ganglion. Based upon soma position, ascending interneurones are divided into three groups of rostral, medial, and caudal interneurones. Twenty‐four ascending interneurones are characterized physiologically according to their inputs from the tailfan and their output effects on the uropod motor neurones of both sides. Each interneurone is identifiable as a unique individual by means of overall shape, soma position, number of main branches, the commissure in which primary neurites cross the midline, axon position in the 5th–6th abdominal connective and physiological responses. They are classified into six classes; coactivating, coinhibiting, reciprocally closing, reciprocally opening, variably effective, and not effective interneurones, according to their premotor effects on the uropod motor neurones. These ascending interneurones seem to act as multifunctional units conveying sensory information from the tailfan to the anterior abdominal ganglia and, at the same time, influencing the uropod motor pattern in the terminal abdominal ganglion. © 1993 Wiley‐Liss, Inc.
Striatal connections of the parietal association cortices in rhesus monkeys
Authors: Yeterian Edward H. , Pandya Deepak N.
Published: January 2005

The corticostriatal connections of the parietal association cortices were examined by the autoradiographic technique in rhesus monkeys. The results show that the rostral portion of the superior parietal lobule projects predominantly to the dorsal portion of the putamen, whereas the caudal portion of the superior parietal lobule and the cortex of the upper bank of the intraparietal sulcus have connections with the caudate nucleus as well as with the dorsal portion of the putamen. The medial parietal convexity cortex projects strongly to the caudate nucleus, and has less extensive projections to the putamen. In contrast, the medial parietal cortex within the caudal portion of the cingulate sulcus projects predominantly to the dorsal portion of the putamen, and has only minor connections with the caudate nucleus. The rostral portion of the inferior parietal lobule projects mainly to the ventral sector of the putamen, and has only minor connections with the caudate nucleus. The middle portion of the inferior parietal lobule has sizable projections to both the putamen and the caudate nucleus. The caudal portion of the inferior parietal lobule as well as the lower bank of the intraparietal sulcus project predominantly to the caudate nucleus, and have relatively minor connections with the putamen. The cortex of the parietal opercular region also shows a specific pattern of corticostriatal projections. Whereas the rostral portion projects exclusively to the ventral sector of the putamen, the caudal portion has connections to the caudate nucleus as well. Thus, it seems that parietostriatal projections show a differential topographic distribution; within both the superior and the inferior parietal region, as one progresses from rostral to caudal, there is a corresponding shift in the predominance of projections from the putamen to the caudate nucleus. In addition, with regard to the projections to the putamen, the superior parietal lobule is related mainly to the dorsal portion, and the inferior parietal lobule to the ventral portion. The striatal projections of the cortex of the caudal portion of the cingulate gyrus (corresponding in part to the supplementary sensory area) and of the rostral parietal opercular region (corresponding in part to the second somatosensory area) are directed almost exclusively to the dorsal and ventral sectors of the putamen, respectively. This pattern resembles that of the primary somatosensory cortex. The results are discussed with regard to the overall architectonic organization of the posterior parietal region. Possible functional aspects of parietostriatal connectivity are considered in the light of physiological and behavioral studies. © 1993 Wiley‐Liss, Inc.
Ultrastructural characteristics of enkephalin‐immunoreactive boutons and their postsynaptic targets in the shell and core of the nucleus accumbens of the rat
Authors: Meredith G. E. , Ingham C. A. , Voorn P. , Arbuthnott G. W.
Published: January 2005

The present study compared the ultrastructural morphology of enkephalin‐immunoreactive boutons and their postsynaptic targets in different territories of the nucleus accumbens in the rat. The synaptic bouton profiles were identified by antibodies directed against [leu5]enkephalin. Ninety‐five percent of the synaptic contacts were symmetric in configuration and the remaining 5% were asymmetric. Axosomatic contacts comprised 6% of all enkephalin‐immunoreactive junctions and were distributed equally in all parts of the nucleus. Most (76%) synaptic terminals contacted dendrites but they contacted proportionally fewer dendrites in the shell (71%) than in the core (78%). Moreover, enkephalin‐immunoreactive synaptic boutons in the shell (19%) and caudal enkephalin‐rich areas (17%) of the core contacted twice as many spines than in the remaining parts of the core (8.5%). In the core, long pallidum‐like dendrites were occasionally found ensheathed in enkephalin‐immunoreactive terminal boutons.

We conclude that the differential arrangement of enkephalinergic contacts in the shell and core could have important functional consequences, especially when considered in relation to other known morphological and neurochemical differences between these regions. © 1993 Wiley‐Liss, Inc.
Localization of NADPH diaphorase activity in monoaminergic neurons of the rat brain
Authors: Johnson Mark D. , Ma Pokay M.
Published: January 2005

Nitric oxide has recently been implicated as a neurotransmitter, and may modulate synaptic transmission, cerebral blood flow, and neurotoxicity. NADPH diaphorase histochemistry has been shown to be a reliable marker for nitric oxide synthase, the enzyme that synthesizes nitric oxide, in the nervous system. Because monoaminergic neurons frequently contain co‐transmitters, we examined whether these cells also exhibit NADPH diaphorase activity. Frozen sections from postnatal and adult rat brains were stained for NADPH diaphorase activity and either serotonin‐like immunoreactivity or tyrosine hydroxylase‐like immunoreactivity. Numerous neurons in the mesopontine serotoninergic cell groups (including the caudal linear, dorsal, median, supralemniscal, and pontine raphe nuclei) contained both serotonin‐like immunoreactivity and NADPH diaphorase activity. Within the dorsal raphe nucleus, approximately 70% of the serotoninergic neurons in the medial subnuclei displayed NADPH diaphorase activity, while less than 10% of the serotoninergic neurons in the lateral subnuclei were doubly labeled. Retrograde labeling with fluorescent microspheres indicated that many raphe‐cortical neurons contained NADPH diaphorase activity. No NADPH diaphorase activity was detected in serotoninergic neurons in the medullary nuclei (including the raphe magnus, raphe pallidum, and raphe obscurus). Only a small proportion of tyrosine hydroxylase‐like immunoreactive neurons in the periaqueductal gray, rostral linear nucleus, and rostrtrodorsal ventral tegmental area contained NADPH diaphorase activity. Tyrosine hydroxylase‐like immunoreactive neurons in the substantia nigra, locus coeruleus, hypothalamus, olfactory bulb, and dorsal raphe nucleus did not contain detectable NADPH diaphorase activity. The observation that many mesopontine (but not medullary) serotoninergic neurons contain NADPH diaphorase activity suggests that these neurons may release both serotonin and nitric oxide. © Wiley‐Liss, Inc.
Ultrastructural localization and afferent sources of corticotropin‐releasing factor in the rat rostral ventrolateral medulla: Implications for central cardiovascular regulation
Authors: Milner Teresa A. , Reis D. J. , Pickel V. M. , Aicher S. A. , Giuliano R.
Published: January 2005

We investigated the ultrastructural localization, afferent sources, and arterial pressure effects of corticotropin‐releasing factor (CRF) in the nucleus reticularis rostroventrolateralis (RVL), a region of the ventrolateral medulla containing C1 adrenergic neurons and sympatho‐excitatory reticulospinal afferents to sympathetic preganglionic neurons. A polyclonal antibody, to CRF was localized in acrolein‐fixed sections through the rat RVL by the peroxidase–antiperoxidase (PAP) method. Light microscopy showed that 1–7 perikarya/30 μm section and numerous varicose processes contained CRF‐like immunoreactivity (CRF‐LI). By electron microscopy, CRF‐LI was most intensely localized to large (80–100 nm) dense‐core vesicles within numerous terminals and a few perikarya and large dendrites. Approximately half of the terminals containing CRF‐LI were in direct contact with unlabeled perikarya or dendrites; the remainder were in apposition to either unlabeled terminals or astrocytes. Most synaptic specializations were asymmetric synapses on small, unlabeled dendrites.

To examine potential extrinsic sources of CRF‐containing terminals in the C1 area of the RVL, PAP immunocytochemical localization of CRF was combined with retrograde transport of wheat germ agglutinin‐conjugated horseradish peroxidase (WGA‐HRP). In all cases examined, a number of dually labeled neurons were found in the paraventricular nucleus (PVN) of the hypothalamus and a few dually labeled neurons were observed in the nuclei of the solitary tract; these labeled neurons were ipsilateral to the unilateral injection of WGA‐HRP into the C1 area. Fewer dually labeled perikarya were detected in the lateral hypothalamic area and the lateral parabrachial nuclei, ipsilateral to the WGA‐HRP injection.

Additional physiological studies showed that bilateral microinjections of CRF into the C1 area of the RVL of urethane‐anesthetized rats elicited a dose‐related increase in arterial pressure. The results suggest that within the C1 area of the RVL, CRF released from terminals, arising predominantly from the PVN of the hypothalamus and probably from local neurons as well, may excite sympathoexcitatory reticulospinal neurons. © 1993 Wiley‐Liss, Inc.
Retinal degeneration in the nervous mutant mouse. I. Light microscopic cytopathology and changes in the interphotoreceptor matrix
Authors: LaVail Matthew M. , White Mary P. , Gorrin Gregg M. , Yasumura Douglas , Porrello Kathryn V. , Mullen Richard J.
Published: January 2005

Nervous is an autosomal recessive mutation in mice (gene symbol, nr) that produces a progressive cerebellar and retinal degeneration. We have examined various cytopathological features of the photoreceptor degeneration by light microscopy. An increase in the number of pyknotic photoreceptor nuclei in the outer nuclear layer (ONL) is first seen at postnatal day (P) 11. Between P13 and P19 there is a rapid loss of photoreceptors, with the ONL about 60% the thickness of littermate controls at P19. Between P19 and 2.5 months of age, photoreceptor cell loss is minimal, and there is a relatively slow loss of these cells between 3 and 7.5 months of age. At 7.5 months, the ONL consists of single row of nuclei, most of which are lost over the ensuing months, although a few photoreceptor nuclei persist at 17 months of age and older. Both rods and cones are lost at comparable rates for the first 2 months of life, but rods are somewhat preferentially lost at later ages. A very slight central‐to‐peripheral gradient of photoreceptor degeneration exists in the nr/nr retina, but no superior‐inferior hemispheric differences are evident. The rate, spatiotemporal gradient, and hemispheric similarity in photoreceptor degeneration are the same in albino nr/nr mice reared either in cyclic light or in the dark, and in pigmented nr/nr mice. Autoradiographic analysis of rod outer segment renewal shows that outer segment membranes are synthesized in nervous homozygotes. Rhythmic outer segment disc shedding and phagocytosis by the retinal pigment epithelium occur at approximately normal rates in nr/nr mice.

Histochemical and immunocytochemical study of the interphotoreceptor matrix (IPM) reveals the exclusion of stainable IPM from the outer segment zone by lamellar whorls of outer segment membrane, accumulation of stainable IPM in the basal region of the outer segment zone, and the absence of an intense band of stainable IPM at the apical surface of the retinal pigment epithelium. These changes in the IPM are similar to those seen in the Royal College of Surgeons rat. However, comparison of cytopathological changes in these two mutants reveals that the IPM defect probably is not the primary cause of photoreceptor cell death in nr/nr mice, and that similar phenotypic appearance does not necessarily signify similar pathological processes. © 1993 Wiley‐Liss, Inc.
Collateral sprouting in the electrosensory lateral line lobe of weakly electric teleosts (Gymnotiformes) following ricin ablation
Authors: Lannoo Michael J. , Maler Leonard , Hawkes Richard
Published: January 2005

Sprouted collateral axons were observed in the electrosensory lateral line lobe (ELL) of gymnotiform teleosts (Apteronotus leptorhynchus:) following the ablation of the supraorbital branch of the anterior lateral line nerve. Ablation was accomplished by using microinjections of the toxic lectin ricin. Sprouted axons were followed for up to 26 weeks postablation. Ricin exposure severely reduced axonal numbers and the peripheral electroreceptors in the region innervated by these fibers. To visualize sprouted fibers, intact lateral line afferent nerve branches were anterogradely labelled with the neuronal tract tracers horseradish peroxidase or cobalt chloride, or the monoclonal antibody Q26A3.

Within the four somatotopically organized ELL segments, sprouted collaterals were first observed two weeks after ricin injection in the medial and centromedial segments, and four weeks postinjection in the centrolateral and lateral segments. Sprouting involved intrasegmental, horizontally directed axons from adjacent nerve branch terminal fields, and mixed intra‐and extrasegmental, dorsally directed axons from the ELL deep fiber layer. The sprouting response was robust but variable in its timing, peaking between 6 and 12 weeks. Subsequently, the intrasegmental, horizontally directed fibers were retained but the mixed dorsally directed fibers, including all extrasegmental axons, were retracted. Therefore, this sprouting response appears to consist of a collateral overproduction followed by a selective axonal retraction. In our view, the most likely explanation for this axonal retraction is that the descending inputs from the isthmus and the cerebellum, as well as commissural fibers from the contralateral ELL, maintain established somatotopic relationships by eliminating somatotopically mismatched sprouted collaterals. © 1993 Wiley‐Liss, Inc.
Development of the olfactory organ in the zebrafish, Brachydanio rerio
Authors: Hansen Anne , Zeiske Eckart
Published: January 2005

The development of the olfactory organ of the zebrafish, from the forming of the early placode to the adult organ, was investigated by electron microscopy and DiI labeling. The olfactory placode is formed by a subepidermal layer of cells. These cells differ from those of the epidermis as well as from brain cells, and they do not mingle either with epidermal or with brain cells. No migration of cells from the brain or the epidermis towards the subepidermal cell layer has been observed. The cells of the subepidermal layer seem to form all cell types of the olfactory mucosa, i.e., basal cells, ciliated and microvillous receptor cells, supporting cells, and ciliated nonsensory cells. Axons grow into the forebrain at a very early stage when the epidermis still covers the placode completely. Dendrites grow out when the epidermis separates, building the olfactory pit. This process implicates neither cell lysis nor cell degeneration. The olfactory pit forms a rosette with a midline raphe and olfactory lamellae. The incurrent nostril is separated from the excurrent nostril by a funnel‐shaped structure. Differentiation of the olfactory placode in the embryo is accomplished very quickly, whereas the development into the adult organ during larval stages is a slow process. © 1993 Wiley‐Liss, Inc.
Organization and synaptic connections of cholinergic fibers in the cat superior colliculus
Authors: Jeon Chang‐Jin , Spencer Robert F. , Mize R. Ranney
Published: January 2005

The cat superior colliculus (SC) receives a dense cholinergic input from three brainstem nuclei, the pedunculopontine tegmental nucleus, the lateral dorsal tegmental nucleus, and the parabigeminal nucleus (PBG). The tegmental inputs project densely to the intermediate gray layer (IGL) and sparsely to the superficial layers. The PBG input probably projects only to the superficial layers. In the present study, the morphology of choline acetyltransferase (ChAT)‐immunoreactive axons and synaptic endings in the superficial and deep layers of the SC was examined by light and electron microscopy to determine whether these cholinergic afferents form different types of synapses in the superifical and deep layers.

Two types of fibers were found within the zonal (ZL) and upper superficial gray layers (SGL): small diameter fibers with few varicosities and larger diameter fibers with numerous varicosities. Quantitative analysis demonstrated a bimodal distribution of axon diameters, with one peak at approximately 0.3–0.5 μm and the other at 0.9–1.0 μm. On the other hand, ChAT‐immunoreactive fibers in the IGL were almost all small and formed discrete patches within the IGL.

Two types of ChAT‐immunoreactive synaptic profiles were observed within the ZL and upper SGL using the electron microscope. The first type consisted of small terminals containing predominantly round synaptic vesicles and forming asymmetric synaptic contacts, mostly on dendrites. The second type was comprised of varicose profiles that also contained round synaptic vesicles. Their synaptic contacts were always symmetric in profile. ChAT‐immunoreactive terminals in the IGL patches contained round or pleomorphic synaptic vescles, and the postsynaptic densities varied from symmetric to asymmetric, including intermediate forms. However, no large varicose profiles were observed.

This study suggests that cholinergic fibers include at least two differnt synaptic morphologies: small terminals with asymmetric thickenings and large varicose profiles with symmetric terminals. The large varicose profile in the superficial layers is absent in the IGL. This result suggests that the cholinergic inputs that innervate the superficial layers and the patches in the IGL of the cat SC differ in their synaptic organization and possibly also in their physiological actions. © 1993 Wiley‐Liss, Inc.
Differential expression of N‐ and R‐cadherin in functional neuronal systems and other structures of the developing chicken brain
Authors: Redies Christoph , Engelhart K. , Takeichi M.
Published: January 2005

Cadherins are a family of cell surface molecules mediating calcium‐dependent cell–cell adhesion in a variety of tissues. More than a dozen cadherins are expressed in the vertebrate brain. To obtain insight into the biological significance of this diversity in cadherin expression, we mapped the expression of N‐and R‐cadherin in the brain of the developing chicken embryo (days 2–19 of incubation) by immunohistochemical and in situ hybridizaiton techniques.

Whereas the expression of N‐ and R‐cadherin is relatively uniform or weak in early (about 2–5 days of incubation) and late development (15 days of incubation to hatching stage), these two molecules are differentially expressed in specific nuclei and fiber tracts between days 6–11 of incubation. For example, in the mes‐ and diencephalon, one of the tectofugal pathways and its target nuclei, here called the tecto‐pretecto‐rotundal system, express N‐cadherin. R‐cadherin is expressed by a different tectofugal system, the tectoisthmic pathway. The other tectofugal systems express neither N‐ nor R‐cadherin. In addition, a small number of other mes‐ and diencephalic nuclei express N‐ or R‐cadherin. On the basis of these results and experimental evidence from other studies, we speculate that the two cadherins are involved in the formation and segregation of particular functional systems within the vertebrate central nervous system (CNS) by regulating the formation of nuclei, and the pathfinding and/or the selective fasciculation of neurites.

Apart from neuronal elements, a variety of vascular and ependymal structures also express N‐cadherin or R‐cadherin, e.g., the parenchymal blood vessels, the choroid plexus, the floor and roof plates, and the ventricular lining. These findings suggest that the two cadherins play a variety of roles during the development of neuronal and nonneuronal epithelial structures throughout CNS development. © 1993 Wiley‐Liss, Inc.
Neuroanatomical alterations in the rat nucleus of the solitary tract following early maternal NaCl deprivation and subsequent NaCl repletion
Authors: King Camille Tessitore , Hill David L.
Published: January 2005

Restricting the NaCl content in the rat maternal and preweaning diet results in a significant and specific reduction (60%) of chorda tympani nerve responsiveness to sodium stimuli in the offspring. Repletion of dietary sodium at any time during postnatal development results in a complete and persistent recovery of chorda tympani nerve function. To learn whether the maturation of postsynaptic cells are also affected by the early dietary manipulation, dendritic morphology, neuronal and glial densities and numbers were studied within the area of the nucleus of the solitary tract (NTS).

Examination of dendritic morphologies in Golgi‐Cox stained neurons revealed that cells with multipolar and fusiform somata in the rostral NTS exhibited longer dendrites following dietary NaCl deprivation during development (deprived rats) than in controls. These changes were generally maintained in rats initially deprived of NaCl and then fed a NaCl‐replete diet postweaning (“recovered” rats). In contrast, ovoid neurons were not affected by NaCl deprivation but had increases in the lengths of their dendrites following “recovery” Along with dendritic alterations, the packing density of neurons in the rostral NTS was greater in NaCl‐deprived rats than in controls, but was similar to controls following “recovery” Glial packing density also increased following deprivation and remained high in “recovered” rats.

These results indicate that activity‐dependent events as well as events not related to afferent activity (e.g., hormonal changes) may influence the morphological development of NTS neurons. In addition, significant interactions among primary afferent fibers, central neurons, and glia may direct development within the central gustatory system. © 1993 Wiley‐Liss, Inc.
Morphological correlations between spontaneously discharging primary vestibular afferents and vestibular nucleus neurons in the cat
Authors: Sato Fumi , Sasaki Hiroshi
Published: January 2005

Synaptic connections between physiologically classified primary vestibular afferents (PVAs) and their target vestibular nucleus (VN) neurons were examined by a combination of intra‐axonal staining and electron microscopic techniques. PVAs originating from the horizontal semicircular canal were electrophysiologically classified as either regular‐ or irregular‐type based on the regularity of their spontaneous discharge patterns, and were intra‐axonally labeled with horseradish peroxidase (HRP). HRP‐labeled PVAs of both types had many swellings along their course that contacted VN neurons. These swellings contained spherical synaptic vesicles and showed asymmetric postsynaptic specialization. Target VN neurons of both types of PVAs were distributed primarily in the superior, medial, and inferior VN. Irregular‐type PVAs made more axosomatic contacts than did regular‐type PVAs. The soma size of target VN neurons and the number of terminal boutons per target VN neuron were larger for irregular‐type PVAs than for regular‐type PVAs. Large VN neurons (presumably kinetic neurons) were innervated exclusively by irregular‐type PVAs. Small VN neurons were innervated by PVAs of the regular‐type and the irregular‐type. These results demonstrate that there is a correlation between the physiological properties and morphological characteristics of PVAs and their target VN neurons. © 1993 Wiley‐Liss, Inc.
Species‐specific patterns of glycoprotein expression in the developing rodent caudoputamen: Association of 5′‐nucleotidase activity with dopamine islands and striosomes in rat, but with extrastriosomal matrix in mouse
Authors: Schoen Siegfried W. , Graybiel Ann M.
Published: January 2005

The glycoprotein 5′‐nucleotidase is a cell surface phosphatase and represents a new marker for striosomes in the adult rat caudoputamen. We report here on its developmental expression in the rat and mouse striatum, and show an unexpected converse 5′‐nucleotidase chemoarchitecture of the caudoputamen in these closely related species.

In the rat, 5′‐nucleotidase activity was first visible as neuropil staining in tyrosine hydroxylase‐positive dopamine islands of the midstriatum on postnatal day 1, and by the end of the first postnatal week, 5′‐nucleotidase‐positive dopamine islands also appeared rostrally. This compartmental pattern persisted thereafter, so that in adult animals, in all but the caudal caudoputamen, zones of enhanced 5′‐nucleotidase staining were restricted to calbindin‐D28k‐poor striosomes. Weak 5′‐nucleotidase activity also emerged in the matrix.

In striking contrast, in the mouse striatum, enhanced 5′‐nucleotidase activity was preferentially associated with extrastriosomal tissue. Enzymatic reaction first appeared on embryonic day 18, and developed over the first postnatal week into a mosaic pattern in which the matrix was stained but the dopamine islands were unstained. The matrix staining itself was heterogeneous. After the second postnatal week, most of the caudoputamen was stained, and in adult mice only rostral striosomes expressed low 5′‐nucleotidase activity.

We conclude that in rats, 5′‐nucleotidase represents one of the few substances that maintains a preferential dopamine island/striosome distribution during striatal development. In mice, 5′‐nucleotidase activity is expressed preferentially in the matrix during development, and its compartmental pattern is gradually lost with maturation, except very rostrally. These findings do not suggest an instructive role of the enzyme in striatal compartment formation in either species, but do suggest the possibility that 5′‐nucleotidase contributes to the differentiation of striatal compartments during development. © 1993 Wiley‐Liss, Inc.
Comparison of the immunocytochemical localization of DARPP‐32 and I‐1 in the amygdala and hippocampus of the rhesus monkey
Authors: Barbas H. , Gustafson E. L. , Greengard P.
Published: January 2005

Dopamine and adenosine 3′:5′‐monophosphate (cAMP) regulated phosphoprotein of Mr32 kDa (DARPP‐32) and phosphatase inhibitor 1 (I‐1) have been associated with intracellular signal transduction processes and share several biochemical features. Localization of each phosphoprotein in distinct neural structures will aid investigation of their physiologic properties and help identify their unique roles in the nervous system. We have compared the distribution of the two phosphoproteins in the amygdala and hippocampus of the rhesus monkey with the aid of immunocytochemical procedures. Neurons immunoreactive to antibodies raised against the phosphoproteins DARPP‐32 and I‐1 were noted in the cortical, central, and components of the basal group, including the basomedial, the lateral, and to a lesser extent, the basolateral amygdaloid nuclei. Within the large basal nuclei positive neurons were found preferentially in their medial and ventral subdivisions. By making a direct comparison in the same animals, we observed differences in the distribution of the two phosphoproteins in the amygdala. DARPP‐32 and I‐1 positive neurons overlapped partially in the basal nuclei, to a lesser extent in the cortical, but were segregated in the central amygdaloid nucleus with neurons positive for DARPP‐32 noted laterally, and for I‐1 medially.

In contrast to the amygdala, where numerous DARPP‐32 and I‐1 positive neurons were observed, only I‐1 had a notable presence in the hippocampus. Moreover, I‐1 associated label was found only in neurons in the granule cell layer of the dentate gyrus, their dendritic plexus, and axons which innervate hilar and CA3 neurons. DARPP‐32 and I‐1 are intracellular messengers associated with signal transduction. Their regional distribution in the amygdala and the hippocampus suggests an involvement in the level of excitability of specific components of these limbic structures. Moreover, our results suggest that I‐1 has a unique role in the intrinsic circuitry of the hippocampal formation and indicate a system where the physiologic properties of I‐1 may be studied in isolation. © 1993 Wiley‐Liss, Inc.
Cortical modules in the posteromedial barrel subfield (Sml) of the mouse
Authors: White Edward L. , Peters Alan
Published: January 2005

An antibody to MAP2 was used on sections through the posteromedial barrel subfield (PMBSF) of primary somatosensory cortex to reveal the distributions of cell bodies and dendrites. It was found that apical dendrites of layer VI neurons form irregular bundles or sheets that break up in layer IV, where most of these dendrites form their terminal tufts. In contrast, the apical dendrites of layer V pyramidal neurons form clusters that ascend into layer II/III where they are joined by apical dendrites of the superficial pyramidal neurons. In layer IV the clusters of the layer V apical dendrites are more concentrated in barrel walls than in hollows. Thus, in layer IV the average center to center spacing between the clusters is about 25 m̈m in the barrel hollows, and about 22 m̈m in the barrel walls. In part, this differential distribution of the apical dendritic clusters is brought about because the apical dendrites of layer V pyramids beneath the periphery of the barrel hollows arc towards the barrel walls as they pass from layer V into layer IV.

Based on previous analyses of the three‐dimensional organization of the primary visual areas in the monkey, cat, and rat, it has been proposed that neurons in these cortices are organized into modules that are centered on the clusters of apical dendrites belonging to layer V pyramidal neurons. Mouse PMBSF cortex is composed of similar pyramidal cell modules and the organization of neurons in these modules is similar to that in visual cortex. This suggests that the pyramidal cell modules are fundamental neuronal units that exist throughout the cerebral cortex, and implies that the various functional areas of the cortex in different species are organized according to a common, basic plan. © 1993 Wiley‐Liss, Inc.
Peripheral peptidergic fibers of the trigeminal nerve in the olfactory bulb of the rat
Authors: Finger Thomas E. , Böttger Bärbel
Published: January 2005

Axons immunoreactive for calcitonin gene‐related peptide (CGRP) and substance P are present in the olfactory nerve, although few, if any, olfactory receptor cells contain immunocytochemically detectible levels of these peptides. The possible trigeminal origin of these fibers was tested by performing unilateral stereotaxic lesions of the ophthalmic division of the trigeminal nerve, followed 2–25 days later by immunocytochemistry for CGRP and substance P. As reported previously, free nerve endings immunoreactive for both peptides were found transversing the nasal epithelium on the unlesioned side. Also on the unlesioned side, peptidergic axons, immunoreactive for both CGRP and substance P, could be traced from the olfactory nerve into the glomerular layer throughout the olfactory bulb, but especially into its rostral third. Ipsilateral to the trigeminal ganglion lesion, such peptide‐immunoreactive fibers were absent or markedly reduced in the bulb, nerve, and epithelium. These results indicate that the peripheral branches of the ophthalmic branch of the trigeminal nerve enter the olfactory bulb along with the olfactory nerve and terminate in the glomerular layer along with the olfactory axons. Ultrastructural analysis of the CGRP‐immunoreactive terminals in the glomeruli reveal vesicle‐filled axonal processes terminating in the absence of obvious pre‐ or postsynaptic specializations. Whether the trigeminal fibers in the bulb are functional, e.g., convey information to the olfactory bulb via an axon reflex, or relay information from the olfactory bulb to the brainstem trigeminal nuclei is unclear. © 1993 Wiley‐Liss, Inc.
Calbindin D‐28k‐ and substance P‐immunoreactive primary sensory neurons: Peripheral projections in chick hindlimbs
Authors: Duc Christophe , Barakat‐Walter Ibtissam , Droz Bernard
Published: January 2005

The peripheral projections of two distinct subpopulations of primary sensory neurons, expressing either calbindin D‐28k or substance P, were studied in chick hindlimbs by immunodetecting calbindin D‐28k with a rabbit antiserum and substance P with a mouse monoclonal antibody. Calbindin D‐28k‐immunoreactive axons provided an innervation restricted to specific mechanoreceptors such as muscle spindles, Herbst and Merkel corpuscles, or collars of feather follicles but were absent from Golgi tendon organs. In contrast, substance P‐positive axons spread out diffusely in muscles and skin, formed loose plexuses, and extended free branches to the endomysium, arteries, superficial dermis, or dermal pulp of feather follicles.

The present results show that calbindin D‐28k‐ and substance P‐immunoreactive primary sensory neurons provide distinct modes of innervation to selective targets in peripheral tissues. The results suggest a possible correlation between CaBP‐expressing nerve endings and rapidly adapting mechanoreceptors. © 1993 Wiley‐Liss, Inc.
Distribution of GABA‐immunoreactive nerve fibers and cells in the cervical and thoracic paravertebral sympathetic trunk of adult rat: Evidence for an ascending feed‐forward inhibition system
Authors: Wolff J. R. , Kása P. , Dobó E. , Römgens H. J. , Párducz Á. , Joó F. , Wolff A.
Published: January 2005

Neurochemical and immunohistochemical evidence suggests that the superior cervical ganglion (SCG) contains all components of a gamma‐aminobutyric acid (GABA)ergic transmission system, which includes GABAergic axons of unknown origin. The number of nerve fibers with and without GABA‐like immunoreactivity was determined in interganglionic connectives at all cervical and thoracic levels of the paravertebral sympathetic trunk. In addition, the distribution of GABA‐immunoreactive (IR) neurons was established within the ganglion chain and compared with the relative frequency of principal neurons richly innervated by GABA‐IR axon terminals.

The following results were obtained: (1) the total number of nerve fibers in cross sections did not significantly vary between the cervical levels, but it increased steadily from upper to lower thoracic segments; (2) in contrast, the number of GABA‐IR fibers decreased from the cervical sympathetic trunk below the SCG (∼300 fibers) down to the seventh to tenth thoracic ganglion, below which no such fiber was seen; (3) GABA‐IR nerve fibers originate from a subclass of GABA‐IR cells; these are small, bipolar neurons with predominantly ascending, unmyelinated axon‐like processes; (4) the number of principal neurons richly innervated by GABA‐IR nerve fibers decreased from the SCG to the upper thoracic ganglia, and was very small below; and (5) apart from basket‐like innervation, GABA‐IR axons also formed diffuse networks around GABA‐negative principal neurons predominantly in cervical and upper thoracic ganglia. These data suggest that the GABAergic innervation of paravertebral sympathetic ganglia is more complex than previously suspected. What appears as preganglionic afferents from several spinal segments (C8‐Th7) innervate GABAergic neurons in the sympathetic trunk which have ascending axons and focus their inhibitory effects on the cervical sympathetic ganglia, predominantly the SCG. These data suggest that GABAergic small interganglionic neurons form a feed‐forward inhibition system, which may be driven by multisegmental spinal input in the paravertebral sympathetic ganglion chain. © 1993 Wiley‐Liss, Inc.
Restoration of substance P and calcitonin gene‐related peptide in dorsal root ganglia and dorsal horn after neonatal sciatic nerve lesion
Authors: Nothias Fatiha , Tessler Alan , Murray Marion
Published: January 2005

Dorsal root ganglion (DRG) neurons decrease their substance P (SP) synthesis after peripheral nerve lesions. Levels in the dorsal horn also decline but return to normal if regeneration is successful. In adults, when regeneration is prevented, recovery of SP in the dorsal horn is slow and incomplete, whereas in newborns, recovery is rapid and complete even though retrograde cell death of DRG neurons is greater than in adults. We have examined the mechanisms that might account for the rapid and complete recovery of SP and calcitonin‐gene related peptide (CGRP) in the dorsal horn after peripheral nerve injury in newborns. Peptides were compared in the L4 and L5 DRG and spinal cord segments of normal rats and in rats surviving 6 days to 4 months after sciatic nerve section/ligation within 24 hours of birth.

Sciatic nerve section/ligation produced 50% neuron death in L4 and L5 DRGs, but immunocytochemical methods showed that both SP‐immunoreactivity (‐IR) and CGRP‐IR recovered completely in dorsal horn. Radioimmunoassay confirmed that recovery of SP was not an artefact due to shrinkage. β‐Preprotachykinin (PPT)‐mRNA hybridization and SP‐IR were observed mostly in small neurons; α‐CGRP‐mRNA‐hybridized and CGRP‐IR neurons were more heterogeneous. The percentage of DRG neurons that contained SP (∼ 25%) or CGRP (∼ 50%) was the same in normal newborn and adult rats. Neither selective cell survival nor change in neuron phenotype was likely to contribute to the recovery seen in the dorsal horn, and DRG neurons ipsilateral to the lesion exhibited the same level of hybridized β‐PPT‐mRNA and α‐CGRP‐mRNA as intact DRG neurons. Because neither the constitutive level of expression of the genes nor peptide levels increased above those observed in intact DRG neurons, these mechanisms were also not responsible. Axotomized DRG neurons, however, contributed to recovery. Recovery was also due to sprouting by neurons in intact DRGs rostral and caudal to L4 and L5. © 1993 Wiley‐Liss, Inc.