bluuebunny/crossref_metadata_2025 huggingface dataset:
Location, morphology, and central projections of mesencephalic trigeminal neurons innervating rat masticatory muscles studied by axonal transport of choleragenoid‐horseradish peroxidase
Authors: Raappana Pentti , Arvidsson Jan
Published: January 2005

Retrograde and transganglionic transport of horseradish peroxidase conjugated to the B‐fragment of cholera toxin (B‐HRP) was used to study the location, morphology, and central projections of mesencephalic trigeminal (Me5) neurons innervating rat masticatory muscles. Labeled Me5 cell bodies were found throughout the Me5 nucleus from a level slightly caudal to the trigeminal motor nucleus to the level of the superior colliculus 5 mm further rostrally. Occasionally, labeled Me5 cells were observed in the anterior medullary velum, in the cerebellum, and in the brainstem contralateral to the B‐HRP injection. The vast majority of the labeled Me5 cells were pseudounipolar, but multipolar cells were also found. Extensive central projections from labeled Me5 cells could be seen extending from the nucleus of Darkschewitsch rostrally to the C2 segment caudally. Small but consistent projections from Me5 neurons were observed in nuclear islands among the incoming Me5 root fibers. Trigeminal and hypoglossal motor nuclei received direct projections from Me5 cells, but not the facial motor nucleus. The most prominent Me5 projections appeared in the brainstem reticular formation, including the supratrigeminal nucleus. Smaller projections also extended into the main sensory trigeminal nucleus, trigeminal subnucleus oralis, and the nucleus of the solitary tract. © 1993 Wiley‐Liss, Inc.
Pre‐ and postnatal development of efferent connections of the cochlear nucleus in the rat
Authors: Kandler Karl , Friauf Eckhard
Published: January 2005

Although the connections of the auditory brainstem nuclei are well described in adult mammals, almost nothing is known concerning how and when these connections develop. The purpose of the present study was to describe the development of the efferent projections of the cochlear nucleus (CN), the first central relay station in the ascending auditory pathway of mammals. We used two tracers in rats aged between embryonic day 15 (E15) and postnatal day 14 (P14; birth in the rat is at E22 = P0). The carbocyanine dye DiI was applied into the CN in aldehyde‐fixed tissue. The second tracer, biocytin, was applied into the ventral acoustic stria in an in vitro slice preparation.

The ontogeny of the efferent projections from the CN could be divided into three periods. The first period (E15–E17) is characterized by axonal outgrowth. Axons traverse nuclei in the superior olivary complex and the lateral lemniscus and finally grow up into the inferior colliculus, but axon collaterals do not from during this period. The second period (E18–P5) is marked by pronounced collateral branching of CN fibers in auditory brainstem nuclei. Collateralisation in the contralateral inferior colliculus starts shortly before that in the ipsilateral superior olivary complex. The remaining auditory nuclei become successively innervated, as indicated by collaterals found in them. During the third period (P5–P14) terminal structures mature further, as shown by the morphological changes of the calyces of Held in the medial nucleus of the trapezoid body.

In conclusion, our results show that the efferent connections from the cochlear nucleus form over a period of almost two weeks and are laid down without forming aberrant internuclear connections. On a nuclear level, an adult‐like projection pattern is already achieved one week prior to the onset of physiological hearing. © 1993 Wiley‐Liss, Inc.
Astrocyte subtypes in the rat olfactory bulb: Morphological heterogeneity and differential laminar distribution
Authors: Bailey Mary S. , Shipley Michael T.
Published: January 2005

Despite increased recognition of the importance and heterogeneity of astrocyte functions throughout the central nervous system (CNS) relatively little attention has been paid to morphological diversity among astrocytes. Recent studies have indicated that subsets of astrocytes are involved in glial‐axonal interactions critical to both development and reinnervation of the rat olfactory bulb. Here, we have characterized the morphologies and distribution of astrocytes within anatomically and functionally distinct layers of the adult main olfactory bulb (MOB).

Using a known immunohistochemical marker for astrocytes, glial fibrillary acidic protein (GFAP), and the classic gold sublimate method, we identified six astrocyte subtypes based on their morphology and distribution: (1) unipolar, (2) irregular, (3) wedge‐shape, (4) circular, (5) semicircular, and (6) elongate. Unipolar, irregular and wedge‐shape astrocytes have not been previously described in the CNS. The unipolar and irregular types are located exclusively in the olfactory nerve layer. Wedge‐shape astrocytes are unique to, and are the major subtype in, the glomerular layer. These three morphologically unique astrocyte subtypes may correspond to olfactory nerve layer (ONL) and glomerular layer (GL) astrocytes, which express molecules that regulate axonal growth or synaptogenesis during development and/or regeneration of the olfactory nerve.

In the glomerular layer, astrocytes are highly organized with respect to the glomeruli. Individual astrocytes are loyal to a single glomerulus. In the external plexiform layer, astrocytes are spaced relatively uniformly. In the granule cell layer, astrocytes appear to compartmentalize granule cell aggregates, recently shown to be coupled by tight junctions. The distribution and patterns of astrocyte processes and the density of GFAP immunoreactivity are distinctive for each of the layers of the olfactory bulb. The spacing of astrocytes and the organization of their processes may be important to compartmentalization of neuronal functions. High levels of GFAP immunoreactivity correlated with layers of high neuronal plasticity.

The morphological diversity and differential distribution of astrocytes in the olfactory bulb reported here support growing evidence for functional diversity of astrocytes and important interactions among specific astrocyte and neuron subtypes. It is reasonable to hypothesize, therefore, that as for neurons, morphologically distinctive astrocyte subtypes may correspond to functionally specific classes. © 1993 Wiley‐Liss, Inc.
The diencephalon of the pacific herring, Clupea harengus: Cytoarchitectonic analysis
Authors: Butler Ann B. , Northcutt R. Glenn
Published: January 2005

The cytoarchitecture of nuclei in the preoptic area, ventral thalamus, dorsal thalamus, epithalamus, hypothalamus, posterior tuberculum, synencephalon, and pretectum and the accessory optic nuclei was analyzed in the clupeomorph teleost, Clupea harengus. Plesiomorphic (evolutionarily primitive) and apomorphic (evolutionarily derived) features of nuclei were identified by cladistic analysis. Plesiomorphic features include the cytoarchitectonic organization of most of the preoptic nuclei, the somewhat scattered cells of nucleus ventrolateralis, the compact, oval shape of nucleus intermedius, the presence of dorsoventrally oriented laminae in the central posterior nucleus, and most features of the hypothalamic nuclei. Also plesiomorphic are the presence of a thick, prominent paraventricular organ, a nucleus of the paraventricular organ, a nucleus tuberis posterior, and a preglomerular complex in which the boundaries between multiple nuclei are relatively difficult to distinguish. Additionally, the cytoarchitecture of the three synencephalic nuclei present in Clupea, the presence of small cells in nucleus pretectalis superficialis pars parvicellularis and of larger, scattered cells in nucleus pretectalis superficialis pars magnocellularis, the presence of large cells in the dorsal accessory optic nucleus that form a rostrocaudally oriented column, and the feature of a small, cell‐sparse ventral accessory optic nucleus are plesiomorphic. Apomorphic features include the presence of a single, large, circular lamina that surrounds a central neuropil in all but the most caudal part of nucleus anterior, a lack of bilateral asymmetry in the habenular nuclei, the relatively small size of the periventricular nucleus of the posterior tuberculum, the presence of two, distinguishable caudomedial nuclei in the posterior tuberculum, elongation and folding of the neuropil of nucleus pretectalis superficialis pars parvicellularis, and the relatively large size of nucleus pretectalis superficialis pars magnocellularis and the posterior pretectal nucleus. © 1993 Wiley‐Liss, Inc.
Off‐alpha and OFF‐beta ganglion cells in cat retina: II. Neural circuitry as revealed by electron microscopy of HRP stains
Authors: Kolb Helga , Nelson Ralph
Published: January 2005

An OFF‐center alpha and an OFF‐center beta ganglion cell in cat retina, which had been recorded from and intracellularly stained with horseradish peroxidase (HRP) were examined by serial section electron microscopy. We counted synapses and identified presynaptic neurons to the HRP‐stained cells in 20 μm radial slices through the centers of their dendritic trees. Presynaptic amacrine and bipolar cells were identified on cytological criteria known from previous studies.

The OFF‐beta cell with a 62 μm dendritic arbor, restricted to S1 and S2 (sublamina a) of the inner plexiform layer (IPL), received 38% bipolar and 62% amacrine cell synapses. The bipolar input was from both cb1 and cb2 cone bipolar types. Input from three distinct amacrine cell types occurred upon the dendrites, namely from: (1) AII amacrine lobular appendages, (2) large pale amacrine profiles (possibly A2 or A3 cells), and (3) small, dark amacrine types (possibly A8 cells). Large pale amacrine profiles (possibly A13) were found on the cell body and apical dendrite in sublamina b of the IPL. In addition, several amacrine profiles synapsed directly on the sides and base of the cell body in the ganglion cell layer. We estimate that the complete dendritic tree of this beta cell received about 1,000 synapses contributed by 12–14 bipolar cells, 7–10 AII amacrines and 28–41 other amacrine cells.

The OFF‐alpha cell had a dendritic tree size of 680 × 920 μm. A 250 μm length of two major dendrites stratifying narrowly in S2 of the IPL was reconstructed. Amacrine cells provided most of the synaptic input (80%). This input came from: (1) AII amacrine lobular appendages, (2) amacrines exhibiting large, pale synaptic profiles (possibly A2 or A3 cells), (3) pale amacrines with large mitochondria and a few neurotubules (unknown type), and (4) densely neurotubule‐filled amacrine profiles (possibly A19 cells). A large pale amacrine cell type (possibly A13) provided synaptic input to the cell body as a serial synaptic intermediary with rod bipolar cells. Cone bipolar synapses were from only one type of cone bipolar, the cb2 type and formed 20% of the total synaptic input. We estimate that a minimum of 142 bipolar cells, 256 AII amacrine cells and 1,011 other amacrine cells, altogether providing 6,000–10,000 synapses, converged on the dendritic tree of this OFF‐alpha cell. © 1993 Wiley‐Liss, Inc.
Goldfish bipolar cells and axon terminal patterns: A Golgi study
Authors: Sherry David M. , Yazulla Stephen
Published: January 2005

The morphology and axon terminal arrangement of Golgi stained goldfish bipolar cells were examined to understand better the organization of bipolar cells in the inner plexiform layer (IPL) of the retina. Fifteen morphological bipolar cell types were identified, representing two major cell classes: mixed input cells that receive input from rod and cone photoreceptors, and cone bipolar cells that receive input from cones only. Mixed input bipolar cells comprised six types, including two new types, characterized by large somas and terminals. The terminals of mixed input bipolar cells terminated strictly within sublamina a or b of the IPL. Cone bipolar cells comprised nine subtypes, including seven new types, characterized by small somas and from one to four small terminal bulbs along the length of the axon, each having a characteristic termination depth in the IPL. The cone bipolar cell system had a complex multilaminar organization of terminals in the IPL, but maintained a high degree of anatomical symmetry about sublamina a and b. Cone bipolar cells could be divided into three groups: cells terminating within sublamina a and having an anatomically symmetrical counterpart terminating in sublamina b; cells with anatomically similar terminals in both sublamina a and b; and cells having no anatomically symmetrical counterpart or having anatomically dissimilar terminals in sublamina a and b. Based on bipolar cell terminal arrangement, we suggest that each bipolar cell type probably has a unique set of synaptic targets in the IPL, and that several bipolar cell types may be involved in functionally equivalent circuits at more than one level in the IPL. © 1993 Wiley‐Liss, Inc.
Codistribution of GABA‐ with acetylcholine‐synthesizing neurons in the basal forebrain of the rat
Authors: Gritti Ivana , Mainville Lynda , Jones Barbara E.
Published: January 2005

In recent years, GABAergic neurons have been identified in the basal forebrain where cholinergic cortically projecting neurons are located and known to be important in mechanisms of cortical activation. In the present study in the rat, the relationship of the GABA‐synthesizing neurons to the acetylcholine‐synthesizing neurons was examined by application of a sequential double staining immunohistochemical procedure involving the peroxidase‐antiperoxidase technique for glutamic acid decarboxylase (GAD) and choline acetyltransferase (ChAT). In these double and adjacent single immunostained series of sections, the GAD+ and ChAT+ cells were mapped, counted and measured with the aid of a computerized image analysis system.

Through the entire basal forebrain, there was no evidence for colocalization of GAD and ChAT in the same neurons. Instead, a large population of GAD‐immunoreactive neurons is codistributed with ChAT‐immunoreactive neurons and outnumbers them by a factor of two: approximately 39,000 GAD+ cells to 18,000 ChAT+ cells. Although the GAD+ and ChAT+ neurons lie intermingled within fascicles of the major longitudinal and transverse forebrain fiber systems in subregions of the basal forebrain, the GAD+ cells are more highly concentrated within different sectors of the pathways and regions than the ChAT+ cells. Although GAD+ neurons resemble ChAT+ neurons in certain regions, both being bi‐ or multipolar and, on average, medium‐sized cells, the GAD+ neurons are, in the majority (51%), small‐sized cells ( < 15 μm in length) and as a population significantly smaller than the ChAT+ neurons. These results suggest that many GABAergic neurons may represent interneurons in the basal forebrain and potentially exert an inhibitory influence on adjacent cortically projecting cholinergic neurons. Medium‐ to large GAD+ cells, which resemble similar ChAT+ cells, are also present and represent the majority of the GAD+ cells in the nucleus of the diagonal band of Broca, magnocellular preoptic nucleus, and olfactory tubercle, but represent the minority in the anterior and posterior substantia innominata and globus pallidus. Given their prominent size, such GABAergic cells may also exert an inhibitory influence outside the basal forebrain as projection neurons and potentially in parallel with cholinergic neurons, to certain regions of the cerebral cortex. Accordingly, GABAergic cells may be considered as constituents of the magnocellular basal nucleus and potentially important elements within the ventral extrathalamic relay from the brainstem reticular formation to the cerebral cortex. © 1993 Wiley‐Liss, Inc.
Ultrastructural morphology, synaptic relationships, and CGRP immunoreactivity of physiologically identified c‐fiber terminals in the monkey spinal cord
Authors: Alvarez Francisco J. , Kavookjian Anahid M. , Light Alan R.
Published: January 2005

The spinal cord terminations of two electrophysiologically identified single C‐fibers (one identified as a C‐nociceptor) were intraaxonally labeled with horseradish peroxidase and analyzed with both light and electron microscopy. Serial section ultrastructural analysis and postembedding immunocytochemical techniques for calcitonin gene‐related peptide (CGRP), substance P (SP), and GABA were used to study the synaptology, and neuropeptide content.

All C‐terminal synapses were in laminae I and II. The terminals sampled (n = 73) from these two C‐fibers rarely established glomerular synaptic complexes, but rather, simple terminals, usually measuring 1–4 μm in length and 1–3 μm in diameter. They most often established 1 or 2 (range 1 to 5) quite large asymmetric axodendritic synaptic contacts. Postsynaptic structures included dendritic spines and shafts with and without vesicles. C‐terminals were filled with small round synaptic vesicles (45–60 nm) and also contained variable numbers of large dense‐core vesicles (LDCVs, 80–110 nm). LDCVs inside identified C‐terminals frequently displayed CGRP immunoreactivity. We were unable to detect SP immunoreactivity inside our sample of C‐fiber LDCVs. C‐terminals were never found postsynaptic to other profiles.

Thus, the C‐fiber terminals sampled in this study have simple synaptology, do not receive presynaptic control and contain CGRP immunoreactivity. They differ greatly from the terminals of Aδ nociceptors studied previously by our group that had glomerular endings, often received presynaptic input and did not contain CGRP immunoreactivity. This suggests the existence of different processing mechanisms, at the level of the first synapse, for nociceptive inputs arriving to lamina I and II through different types of primary afferents. © 1993 Wiley‐Liss, Inc.
Deafferentation‐induced terminal field expansion of myelinated saphenous afferents in the adult rat dorsal horn and the nucleus gracilis following pronase injection of the sciatic nerve
Authors: Lamotte Carole C. , Kapadia Shanta E.
Published: January 2005

We have previously demonstrated sprouting of small diameter saphenous afferents, labelled with wheat germ agglutinin conjugated with horseradish peroxidase (WGA‐HRP) and (HRP), into the sciatic territory of the adult rat superficial dorsal horn follwing destruction of sciatic afferents by injection of the sciatic nerve with pronase (a combination of proteolytic enzymes). In the present experiments, we examined the response of myelinated saphenous axons, which terminate in lamina I and the deep dorsal horn (laminae III–V) under the same conditions, with the tracer B subunit of cholera toxin conjugated to HRP (B‐HRP) which specifically labels myelinated primary afferents when injected into a peripheral somatic nerve. We also examined changes in the nucleus gracilis, another site of sciatic degeneration and a target of saphenous afferents. Four months after injection of the pronase, the area of label determined by measurement of the width of the saphenous territory in lamina III was expanded by 24% on the pronase side. Since there was also expansion throughout the deep dorsal horn, the area measured by tracing the labelled region in transverse sections was actually twice that of the control side, and the intensity of labelling within the traced area increased by 18%. There was no change in grey matter area due to the lesion. The traced area of labelling in the nuleus gracilis increased by 40%, and increased in intensity by 17%. The substantia gelatinosa is not normally supplied by B‐HRP‐labelled afferents, and there was no expansion of these sprouted saphenous afferents into the gelationosa. These results indicate that myelinated afferents can sprout as vigorously in lamina I and the deep dorsal horn as the small diameter afferents do in the substantia gelatinosa; that there is no invasion of the substantia gelatinosa by the myelinated afferents at least as long as the small diameter afferents also have the opportunity to sprout; and that primary afferents have the potential to sprout at more than one site of termination, i.e., both the dorsal horn and the dorsal column nuclei.
Dorsal motor nucleus of the vagus nerve: A cyto‐ and chemoarchitectonic study in the human
Authors: Huang Xu‐Feng , Törk Istvan , Paxinos George
Published: January 2005

In order to investigate the topography and subdivisions of the human dorsal motor nucleus of the vagus nerve (10), studies were conducted using cyto‐ and chemoarchitectonic (acetylcholinesterase and substance P‐like immunoreactivity) and computer reconstruction techniques.

The six brainstems examined were obtained within 17 hours postmortem from adults with no known neurological disorders. Serial sections cut in transverse, sagittal, and coronal planes were stained with cresyl violet, or tested for acetylcholinesterase or substance P. The neurons of the 10 (16,826 ± 967) displayed cyto‐ and chemoarchitectonic heterogeneity and could be classified into six types. Types I–V consist of presumed vagal motor neurons (13,802 ± 844), while the remaining type (Type VI) consisted of presumed interneurons (3,024 ± 769). The 10 was subdivided into nine subnuclei grouped regionally into rostral, intermediate, and caudal divisions on the basis of neuronal morphology, cell density, and differential AChE and substance P reactivities. The rostral division contains the dorsorostral (DoR) and the ventrorostral (VeR) subnuclei; the intermediate division contains the rostrointermediate (RoI), dorsointermediate (DoI), centrointermediate (CeI), ventrointermediate (VeI), and caudointermediate (CaI) subnuclei; the caudal division (Ca) is not subdivided. Morphologically, small round or oval cells populate the VeR and VeI. Medium‐sized oval cells occur in the DoR, CeI, and Ca, while medium‐sized fusiform and multipolar cells are the main features of CaI. Large triangular cells appear mainly in DoI. Glial cells show the highest predilection for CeI, lowest densities in DoI and medial fringe subnucleus (MeF), and intermediate densities in the remaining six subnuclei. VeI showed the strongest AChE reactivity. Although the cell bodies of VeR and DoI are AChE positive, the neuropil (background) is weakly stained. Densely distributed fine granular substance P‐like immunoreactivity occurs throughout the entire nucleus, while the intermediate and caudal divisions contain substance P‐like‐immunoreactive neurons. Three‐dimensional computer reconstructions afforded an appreciation of the distinctiveness of the intermediate division (a division that contains the majority of cells) and the caudal division, which displays the lowest density of presumed vagal motoneurons. It is possible that the subnuclei identified herein form functional units innervating specific organs.
Adrenalectomy‐induced granule cell degeneration in the rat hippocampal dentate gyrus: Characterization of an in vivo model of controlled neuronal death
Authors: Sloviter Robert S. , Sollas Anne L. , Dean Evelyn , Neubort Simon
Published: January 2005

The recent discovery that adrenalectomy results in hippocampal granule cell loss suggested that this phenomenon might be useful as a model of selective, experimentally controlled neuronal death possibly relevant to neurodegenerative disorders. This study was designed to provide a detailed qualitative anatomical description of the phenomenon and to determine whether adrenalectomy‐induced dentate granule cell degeneration constitutes a reliable model of selective neuronal death. Silver impregnation staining revealed that granule cell degeneration begins immediately after adrenalectomy and continues for months in both sexes, in young and older adults, and in all strains tested. In one group of 77 adrenalectomized rats, 82% exhibited silver‐impregnated granule cells. This phenomenon is extraordinarily selective in that no neurons other than dentate granule cells degenerated after adrenalectomy. There was considerable variability among animals in the number of cells degenerating at a given time‐point or in the degree of ultimate cell loss. In the most extreme cases, virtually complete granule cell loss was present throughout approximately 80% of the dentate gyrus. Nissl staining revealed that degenerating granule cells exhibited coalescing of nuclear chromatin into multiple nuclear bodies and pyknosis without accompanying glial swelling. This morphology is distinct from the necrosis caused by other neurotoxic insults and is the subject of the ultrastructural companion paper identifying this type of cell death as apoptosis. Taken together, these results indicate that adrenalectomy reliably initiates an immediate, highly selective, and longcontinuing process of hippocampal granule cell degeneration that exhibits morphological features characteristic of apoptosis, rather than necrosis. The possibility that this apoptotic cell death involves a biochemical cascade relevant to programmed cell death and/or neurodegenerative diseases suggests that this model may be valuable for studies of neuronal death and its prevention. Some practical guidelines for use of this model are described.
Electron microscopic analysis of adrenalectomy‐induced hippocampal granule cell degeneration in the rat: Apoptosis in the adult central nervous system
Authors: Sloviter Robert S. , Dean Evelyn , Neubort Simon
Published: January 2005

As described in the preceding paper, adrenalectomy triggers hippocampal granule cell degeneration that begins within days after adrenalectomy, continues for months, and is the only apparent cell death anywhere within the brain. At the light microscopic level, granule cell degeneration is characterized by coalescing of nuclear chromatin into numerous spherical bodies. Since the morphology at the light microscopic level resembled the nuclear morphology characteristic of “apoptosis” rather than “necrosis”, we undertook this ultrastructural study to determine if adrenalectomy induces the morphological features characteristic of apoptosis. Electron microscopy revealed coalescing of nuclear chromatin, compaction of cytoplasm, and the budding‐off of cytoplasmic bodies that were engulfed by glia. Mitochondria, the Golgi apparatus, and rough endoplasmic reticulum appeared relatively normal early in the process of granule cell degeneration when nuclear changes were prominent. Presynaptic terminals innervating degenerating granule cells appeared normal. Electron‐dense degeneration of granule cell axon terminals in association with normal postsynaptic elements of CA3 pyramidal cells highlighted the extraordinary selectivity of adrenalectomy‐induced granule cell death. Ten weeks after adrenalectomy, astrocytes were filled with abnormally abundant glial fibrils and neuronal debris. This “apoptotic” morphology produced by adrenalectomy was clearly distinct from the “necrotic” granule cell morphology produced by intrahippocampal injection of the neurotoxin volkensin. These results indicate that, in a manner possibly analogous to castrationinduced prostate cell death, loss of adrenal hormone triggers a process in dentate granule cells that causes the morphological changes characteristic of “apoptosis.”. Thus, adrenal steroids may be obligatory growth factors for dentate granule cells and their loss may initiate a selective process in the mature brain that is unique or that may normally occur only in the developing brain.
Organum vasculosum laminae terminalis (OVLT) in rabbit and rat: Topographic studies
Authors: Yamaguchi Kazuhito , Morimoto Akio , Murakami Naotoshi
Published: January 2005

The microcirculation and fine structure of the rabbit and rat organum vasculosum laminae terminalis (OVLT) were examined by light microscopy and scanning and transmission electron microscopy. In both animals, the microcirculation is composed of a superficial and a deep vascular bed but the system is more complex and extensive in the rabbit. This was particularly true of the deep vascular bed. In the rabbit, the deep bed is composed of fenestrated capillaries, which are arranged in glomerular tufts surrounded by very wide perivascular spaces (PVS). In contrast, the deep vascular bed of the rat OVLT usually consists of only one or two small vessels. These are either fenestrated and surrounded by a PVS or lined by continuous endothelium with only a few fenestrae and without a dilated PVS. A corresponding difference was seen in the contours of the ventricular surface. It is much more irregular in the rabbit than in the rat and numerous bulges reflect the underlying vascular tufts and pockets of PVS in the rabbit. Supraependymal cells are present in both species and two sizes of them occur in the rabbit.

The results demonstrate that the microcirculation of the OVLT is more elaborate and more highly developed in the rabbit than in the rat. We suggest that this might result in a different neurohemal microenvironment and, ultimately, in functional differences.
Neurons in rat hippocampus that synthesize nitric oxide
Authors: Valtschanoff Juli G. , Weinberg Richard J. , Kharazia Viktor N. , Nakane Masaki , Schmidt Harald H. H. W.
Published: January 2005

We studied the distribution and light‐ and electron‐microscopic morphology of neurons in the hippocampal formation containing nitric oxide synthase (NOS), and thus likely to release nitric oxide, a freely diffusible neuromediator implicated in long‐term potentiation. Only a small fraction of hippocampal neurons contained NOS or its marker, NADPH diaphorase. Most of the positive neurons were in the pyramidal layer of the subiculum, stratum radiatum of Ammon's horn, and subgranular zone of the dentate gyrus. Positive neurons were also conspicuous in the molecular layer of the dentate gyrus and in the pyramidal layer of CA3, sparse in the pyramidal layer of CA2 and CA1, and almost absent from presubiculum and parasubiculum. Numerous positive fibers were seen, especially in stratum radiatum and stratum lacunosum‐moleculare of Ammon's horn. Double staining experiments demonstrated that nearly all NADPH diaphorase‐positive neurons in the hippocampus also contained γ‐aminobutyric acid.

On the basis of their morphology, distribution, and inhibitory neurotransmitter content, most NOS‐positive cells in the hippocampus are probably local circuit neurons. These data suggest that nitric oxide in CA1 may function as a paracrine agent, rather than a spatially precise messenger, in long‐term potentiation. © 1993 Wiley‐Liss, Inc.
Distribution of acetylcholinesterase in the hippocampal region of the mouse. III. The area dentata
Authors: Slomianka L. , Geneser F. A.
Published: January 2005

The distribution of acetylcholinesterase (AChE) was examined in the area dentata of the adult mouse (Mus musculus domesticus). A distinctly stratified distribution of the enzyme was observed and was compared in detail with cytoarchitectural fields and layers. In the stratum moleculare, bands of relatively high AChE activity were seen immediately beneath the pia, at the borders between the outer, middle, and deep portions of the stratum moleculare, and superficial to the granule cell layer. AChE activity was low in the intervening parts of the stratum moleculare. In contrast to the rat, three sublaminae could be discerned in the hilus of the mouse at most septotemporal levels: a limiting subzone, a hilar plexiform layer, and a deep hilar cell mass. Deep to the granule cell layer, AChE activity was high in the limiting subzone and, septally, in the hilar plexiform layer. The deep hilar cell mass stained lightly towards the septal pole of the region but darker at more temporal levels. Numerous AChE‐stained cells were seen in the hilus, with the exception of the most temporal levels. A comparative analysis of the AChE pattern of the area dentata reveals that (1) AChE‐intense supra‐ and infragranular bands are found in all mammals, whereas (2) considerable differences between various strains of mice and between species are seen in the stratum moleculare. The functional significance of the AChE pattern is discussed in relation to species differences and connectivity and also with respect to possible activities of the enzyme other than hydrolysis of ACh, which may be involved in growth‐related functions and in the plastic and degenerative processes observed in Alzheimer's disease. © 1993 Wiley‐Liss, Inc.
Comparative localization of mRNAs encoding two forms of glutamic acid decarboxylase with nonradioactive in situ hybridization methods
Authors: Esclapez Monique , Tillakaratne Niranjala J. K. , Tobin Allan J. , Houser Carolyn R.
Published: January 2005

Nonradioactive in situ hybridization methods with digoxigenin‐labeled cRNA probes were used to localize two glutamic acid decarboxylase (GAD) mRNAs in rat brain. These mRNAs encode two forms of GAD that both synthesize GABA but differ in a number of characteristics including their molecular size (65 and 67 kDa). For each GAD mRNA, discrete neuronal labeling with high cellular resolution and low background staining was obtained in most populations of known GABA neurons. In addition, the current method revealed differences in the intensity of labeling among neurons for each GAD mRNA, suggesting that the relative concentrations of each GAD mRNA may be higher in some groups of GABA neurons than in others.

Most major classes of GABA neurons were labeled for each GAD mRNA. In some groups of GABA neurons, the labeling for the two mRNAs was virtually identical, as in the reticular nucleus of the thalamus. In other groups of neurons, although there was substantial labeling for each GAD mRNA, labeling for one of the mRNAs was noticeably stronger than for the other. In most brain regions, such as the cerebellar cortex, labeling for GAD67 mRNA was stronger than for GAD65 mRNA, but there were a few brain regions in which labeling for GAD65 mRNA was more pronounced, and these included some regions of the hypothalamus. Finally, some groups of GABA neurons were predominantly labeled for one of the GAD mRNAs and showed little or no detectable labeling for the other GAD mRNA, as, for example, in neurons of the tuberomammillary nucleus of the hypothalamus where labeling for GAD67 mRNA was very strong but no labeling for GAD65 mRNA was evident. The findings suggest that most classes of GABA neurons in the central nervous system (CNS) contain mRNAs for at least two forms of GAD, and thus, have dual enzyme systems for the synthesis of GABA. Higher levels of one or the other GAD mRNA in certain groups of GABA neurons may be related to differences in the functional properties of these neurons and their means of regulating GABA synthesis. © 1993 Wiley‐Liss, Inc.
Spinal and facial innervation of the skin in the gadid fish Ciliata mustela (Teleostei)
Authors: Kotrschal Kurt , Whitear Mary , Finger Thomas E.
Published: January 2005

The pattern of innervation of the skin of the rockling Ciliata mustela was investigated to sort out spinal from facial nerve innervation of cutaneous chemosensory and mechanosensory systems. This fish has a variety of appendages with different functional sensory specializations, i.e., the chin barbel, pelvic fin, anterior dorsal fin, and dorsal trunk skin. The carbocyanine dye, diI, was applied to nerve stumps in dissected aldehyde‐fixed tissue. In the case of the chin barbel, the dye was applied to both the trigeminal and facial nerve components. In the other cases, the dye was applied either selectively to the spinal nerves, to the facial nerves, or to both components. In the chin barbel, diI labeled nerve fibers associated with taste buds (TBs) and solitary chemosensory cells (SCCs) as well as relatively blunt free nerve endings, which closely approach the epidermal surface. In the pelvic fin, anterior dorsal fin, and dorsal trunk skin, taste buds, solitary chemosensory cells, and their innervation were labeled only after diI was applied to the facial nerve stumps. Application of diI to spinal nerves labeled delicate, free nerve endings and nerve fibers associated with small cells deep in the epidermis with features characteristic of Merkel cells. Transmission electron microscopy supports these results; after denervation of the facial component of the anterior dorsal fin, synaptic contacts with Merkel cells remained intact, whereas the synapses with the SCCs vanished. © 1993 Wiley‐Liss, Inc.
Tyrosine hydroxylase neurons in the male hamster chemosensory pathway contain androgen receptors and are influenced by gonadal hormones
Authors: Asmus Stephen E. , Newman Sarah Winans
Published: January 2005

Chemosensory and hormonal signals, both of which are essential for mating in the male Syrian hamster, are relayed through a distinct forebrain circuit. Immunocytochemistry for tyrosine hydroxylase, a catecholamine biosynthetic enzyme, previously revealed immunoreactive neurons in the anterior and posterior medial amygdaloid nucleus, one of the nuclei within this pathway. In addition, dopamine‐immunoreactive neurons were located in the posterior, but not hte anterior, medial amygdala. In the present study, tyrosine hydroxylase‐immunostained neurons were also observed in other areas of the chemosensory pathway, including the posteromedial bed nucleus of the stria terminalis and the posterior, lateral part of the medial preoptic area, while dopamine immunostaining was only seen in the posteromedial bed nucleus of the stria terminalis. The colocalization of tyrosine hydroxylase and androgen receptors was examined in these four tyrosine hydroxylase cell groups by a double immunoperoxidase technique. The percentage of tyrosine hydroxylase‐immunolabeled neurons that were also androgen receptor‐immunoreactive was highest in the posterior medial amygdaloid nucleus (74%) and the bed nucleus of the stria terminalis (79%). Fewer tyrosine hydroxylase‐immunostained neurons in the anterior medial amygdala (33%) and the medial preoptic area (4%) contained androgen receptors. Surprisingly, castration resulted in a significant decrease in the number of tyrosine hydroxylase‐immunoreactive neurons only in the anterior medial amygdaloid nucleus, and this effect was transient. Six weeks after castratio, the anterior medial amygdala contained 61% fewer tyrosine hydroxylase‐immunolabeled neurons, but 12 weeks after gonadectomy, immunostaining returned to intact values. The number of immunostained neurons in testosterone‐replaced, castrated hamsters was not significantly different from that of intact or castrated animals at any time. The results of this study indicate that a substantial number of tyrosine hydroxylase‐immunostained neurons in the chemosensory pathway are influenced by androgens; the majority of these neurons in the posterior medial amygdala and the posteromedial bed nucleus of the stria terminalis produce androgen receptors, and tyrosine hydroxylase immunoreactivity is altered by castration in the anterior medial amygdala. © 1993 Wiley‐Liss, Inc.
Somatotopic and laminar organization of fos‐like immunoreactivity in the medullary and upper cervical dorsal horn induced by noxious facial stimulation in the rat
Authors: Strassman Andrew M. , Vos Bart P.
Published: January 2005

The distribution of fos‐like‐immunoreactivity (fos‐LI) in the medullary and upper cervical dorsal horn was examined following noxious facial stimulation, in order to evaluate the use of fos as a marker for neuronal activation in trigeminal nociceptive pathways. Control animals that received urethane anesthesia and no facial stimulation showed substantial bilateral labeling in the trigeminal complex that was restricted to one rostrocaudal level, at the transition between the medullary dorsal horn (nucleus caudalis) and nucleus interpolaris. Noxious mechanical stimulation (pinch) of different facial sites produced labeling in the ipsilateral dorsal horn whose distribution varied predictably with the rostrocaudal and dorsoventral position of the facial stimulation site, such that rostral facial sites were represented rostrally in the dorsal horn and dorsal sites were represented ventrolaterally. The cornea was exceptional among the facial stimulation sites in that it had a specific representation at two distinct rostrocaudal levels, in C1 and the interpolaris‐caudalis transition region; the position of the rostral peak was somatotopically inappropriate, based on the representation of other facial sites. The proportion of labelling in laminae III–IV relative to laminae I–II was higher with noxious mechanical stimulation than with noxious thermal (55°C) or chemical (subcutaneous injection of capsaicin) stimulation. The proportion of labelling in laminae III–IV produced by electrical stimulation of the infraobital nerve was no greater than that produced by pinch.

The results suggest that fos‐LI mapping can be a useful method for the investigation of somatotopy but is subject to serious limitations when used for the investigation of laminar organzation. The results also suggest that the interpolaris‐caudalis transition region may have properties that are distinct from those of the rest of the trigeminal complex, possibly related to an involvement in autonomic function. © 1993 Wiley‐Liss, Inc.
The octavolateral systems in the stingray, Dasyatis sabina. I. Primary projections of the octaval and lateral line nerves
Authors: Puzdrowski Richard L. , Leonard Robert B.
Published: January 2005

The central projections of the electrosensory, mechanosensory, and octaval nerves of the Atlantic stingray were examined by transganglionic transport of horseradish peroxidase. Particular attention was paid to the relation of the projections to cell plates C1 and C2, and to a newly described cell plate, C3.

The electroreceptors in the stingray are found in three groups on the dorsal and ventral sides of the body. The electroreceptors are represented topographically on the ipsilateral dorsal nucleus. Those of the rostral part of the head and pectoral fins are represented on the rostroventral part of the nucleus, and those on the caudal part of the head and the pectoral fin on the dorsocaudal part of the nucleus.

Mechanosensory lateral line afferents terminate within the ipsilateral intermediate and caudal nuclei, and the lateral granular mass of the vestibulocerebellum. Anterior lateral line afferents also project to the magnocellular octaval nucleus. A topographic representation of the mechanosensory lateral line periphery is present on the intermediate and caudal nuclei. Mechanoreceptors on the trunk are represented laterally and those on the head medially. The terminal field of the anterior lateral line afferents on the intermediate nucleus surrounds cell plates C1 and C2. The anterior lateral line afferents also project to the medial part of the lateral granular mass, whereas the posterior lateral line afferents project to the lateral portion. Sparse projections of anterior lateral line afferents to the periventricular octaval nucleus were also observed.

The octaval nerve afferents terminate largely within the octaval column. Octaval nerve projections were also observed to the reticular formation, the periventricular octaval nucleus, the deep cerebellar nucleus, the vestibulocerebellum, particularly the lower lip and medial granular mass, and the intermediate nucleus. A sparse projection to cell plate C3 was found.

The relation between cell plates C1 and C2 and the anterior lateral line afferents suggests that these cell plates are related to processing lateral line information. While the relationship between cell plate C3 and the octaval afferents is not strong, the sparse octaval projection C3 receives suggests that it is relaying octaval information. © 1993 Wiley‐Liss, Inc.
Development of the rat septohippocampal projection: Tracing with DiI and electron microscopy of identified growth cones
Authors: Linke Rüdiger , Frotscher Michael
Published: January 2005

The factors determining the development of specific fiber tracts in the central nervous system as well as the interactions of growth cones with the surrounding micromilieu are largely unknown. Here we investigated the ontogenetic development of the septohippocampal projection in the rat with the lipophilic carbocyanine dye DiI which is transported anterogradely and retrogradely in neurons and can be applied to fixed embryonic tissue. Photoconversion of anterogradely labeled fibers allowed us to study individual growth cones by electron microscopy.

The first axons originating from the septal complex were found in the hippocampus as early as on embryonic day (ED) 19, reaching the fimbrial pole of the hippocampus on ED 18. However, on ED 17 we consistently found retrogradely labeled cells in the hippocampus, indicating that the development of the hippocamposeptal projection precedes that of the septohippocampal projection. On ED 19, the majority of the axons directed toward the hippocampal formation passed the hippocampus and grew further into the subicular complex and entorhinal cortex. These axons gave off collaterals that invaded the hippocampus proper. A fairly adult pattern of the septohippocampal projection was reached on postnatal day 10, although many growth cones were still found. A comparative analysis of individual growth cones found in the fimbria and the hippocampus proper revealed no striking differences in their morphology. Electron microscopic analysis showed that growth cones in the fimbria were mainly contacted by other axons, whereas growth cones in the hippocampus had contact with all available elements. This may indicate that growing septohippocampal fibers are guided by axons of the earlier formed hippocamposeptal projection. In the hippocampus proper, other cues, probably derived from the target itself, may guide the septhippocampal axons to their appropriate target cells. © 1993 Wiley‐Liss, Inc.
Innervation of the amygdaloid complex by catecholaminergic cell groups of the ventrolateral medulla
Authors: Roder Stefanie , Ciriello John
Published: January 2005

The projections to the amygdaloid complex (AMG), originating in the catecholaminergic cell groups of the ventrolateral medulla (VLM), were studied in the rat by using either the retrograde tracer fluorogold (FG) or the anterograde tracer Phaseolus vulgaris leucoagglutinin (PHA‐L) in combination with tyrosine hydroxylase (TH) and/or phenylethanolamine‐N‐methyltransferase (PNMT) immunohistochemistry. In the first series of experiments, injections of FG were made into regions of the central nucleus of the amygdala (ACe) where dense TH and PNMT immunoreactivity was previously observed, and then sections of the brainstem were processed for TH and PNMT immunoreactivity. FG retrogradely labelled neuronal cell bodies were observed throughout the rostrocaudal extent of VLM, bilaterally, with a contralateral predominance. Approximately 44% of the FG labelled cell bodies in VLM were also immunoreactive to the catecholamine biosynthetic enzymes TH and/or PNMT. Most of these catecholaminergic neurons were part of the A1 noradrenergic cell group in the caudal VLM and to a lesser extent part of the C1 adrenergic cell group in the rostral VLM.

In the second series of experiments, PHA‐L was iontophoresed into VLM at different rostrocaudal levels where in the previous series of experiments FG retrogradely labelled cell bodies were observed Transverse sections of the forebrain and brainstem were then processed for the demonstration of PHA‐L and either TH or PNMT immunoreactivity in cell bodies, axons, and presumptive axon terminals. PHA‐L injection sites within either the caudal or rostral VLM resulted in labelled axons and terminal bouton‐like swellings primarily in the contralateral AMG and to a lesser extent in the ipsilateral AMG. The ACe was observed to receive the greatest innervation from either VLM site. Additionally, PHA‐L labelled fibers and presumptive terminal boutons were observed within the intercalated, medial, basomedial, and basolateral nuclei of the AMG. Most of the PHA‐L labelled fibers and presumptive terminal boutons in the AMG after a caudal VLM (A1 region) injection also displayed TH immunoreactivity, whereas after a PHA‐L injection into the rostral VLM (C1 region) all of the labelled axons and axon terminals in the AMG also were immunoreactive to PNMT. These data demonstrate that catecholaminergic neurons in A1 and C1 regions of VLM innervate the AMG and suggest that these VLM neurons may be involved in relaying afferent information directly to the AMG which influences the activity of AMG neurons controlling autonomic, endocrine, and behavioural functions. © 1993 Wiley‐Liss, Inc.