bluuebunny/crossref_metadata_2025 huggingface dataset:
Distribution of corticotropin‐releasing factor in the cerebellum and precerebellar nuclei of the cat
Authors: Cummings Sharon L.
Published: January 2005

The present study analyzes the distribution of corticotropin‐releasing factor‐immunoreactive (CRF‐IR) fibers and neuronal cell bodies within the cerebellum and brainstem, respectively, of the cat. Within the cerebellum, CRF is present in climbing fibers, mossy fibers, and a population of varicose fibers which traverses the lower molecular layer. CRF‐IR fibers are present throughout all lobules of the cat cerebellar cortex, though the density and immunostaining intensity of each fiber system vary. Bands of intensely immunoreactive climbing fibers are prominent within the vermis, intermediate cortex, and crus II. Bands of intensely immunoreactive mossy fiber terminals accompany the climbing fiber bands within the vermis. Collaterals of climbing and mossy fibers contribute to a beaded fiber plexus localized to the Purkinje cell layer. Varicose fibers containing CRF immunoreactivity are present in all deep cerebellar nuclei. CRF‐IR neuronal cell bodies are prominent within several brainstem nuclei known to project to the cerebellum: all divisions of the inferior olivary complex, the lateral reticular nucleus, paramedian reticular nucleus, gigantocellular reticular nucleus, raphe nuclei, perihypoglossal complex, medial and inferior vestibular nuclei and cell groups f and x, locus ceruleus, and nucleus subceruleus. This study confirms and extends a previous study of CRF distribution within cerebellar afferent systems of the cat (Cummings et al.: J. Neurosci. 8:543–554, '88) and compares this distribution with previous descriptions in other species. The ubiquitous distribution of CRF throughout the cat cerebellum suggests a primary role for this peptide in signal transduction.
Catecholamine‐containing neurons in the sheep brainstem and diencephalon: Immunohistochemical study with tyrosine hydroxylase (TH) and dopamine‐β‐hydroxylase (DBH) antibodies
Authors: Tillet Yves , Thibault Jean
Published: January 2005

The present study describes the distribution and morphological characteristics of neurons and nerve fibers containing the catecholamine‐synthesizing enzymes, tyrosine hydroxylase and dopamine‐β‐hydroxylase, in the sheep brainstem and diencephalon on the basis of immunohistochemical procedures. Neurons and fibers were considered to be dopaminergic if they showed antityrosine hydroxylase immunoreactivity, without corresponding anti‐dopamine‐β‐hydroxylase immunoreactivity. The structures labeled with both antisera were considered noradrenergic or adrenergic. The distribution of catecholaminergic neurons corresponds to that described by other authors with similar methods in the rat and in primates. The noradrenergic neurons belong to cell groups A1 to A7 and the dopaminergic neurons to cell groups A8 to A15. In almost all studied areas, the catecholaminergic innervation is similar to that observed in the other species. However, the central catecholaminergic systems of the sheep showed some specific characteristics: (1) groups A3 and A4, described in the rat, were not found, (2) group A14 contains fewer neurons than in the rat, (3) group A15 does not contain a dorsal but only a ventral portion, (4) there is a larger dispersion of neurons within each group, especially A6 and A7, than in rodents, and (5) there is a larger noradrenergic innervation of the catecholaminergic groups than in the other species.
Amygdaloid efferents through the stria terminalis in the rat give origin to zinc‐containing boutons
Authors: Pérez‐Clausell Jeús , Frederickson Christopher J. , Danscher Gorm
Published: January 2005

Many regions of the basal forebrain are innervated by zinc‐containing axonal boutons. In the present work, the lesion/degeneration method, coupled with histochemical staining for zinc‐containing boutons, was used to determine the origins and efferent pathways of these zinc‐containing projections to the basal forebrain.

Knife cuts of the stria terminalis or extensive electrolytic lesions of the amygdala resulted in the bleaching of the staining for zinc (Timm stain) and terminal degeneration (Fink‐Heimer method) ipsilaterally in the following areas: granule cell layer of the accessory olfactory bulb, shell of nucleus accumbens, bed nucleus of the stria terminalis, striohypothalamic nucleus, retrochiasmatic area, ventromedial hypothalamic nucleus (in the cell‐sparse shell), medial tuberal nucleus, terete hypothalamic nucleus, and ventral premammillary nucleus. Small lesions made with ibotenic acid in the posteromedial part of the amygdalohippocampal area caused bleaching of the stain for zinc in the accessory olfactory bulb, in the medial zone of the bed nucleus of the stria terminalis, and in the ventral premammillary nucleus. Lesions in either the ventral subiculum or the anterolateral part of the amygdalohippocampal area caused bleaching in the ventromedial hypothalamic nucleus. Lesions in the hippocampus or in the neocortex did not produce bleaching of the stain for zinc in the above‐mentioned terminal fields.

The present results agree with previous studies on amygdaloid efferents and suggest that neurons in the amygdalhippocampal area and, possibly, in the ventral subiculum give origin to zinc‐containing boutons.
Neuronal localisation of neuropeptide Y gene expression in rat brain
Authors: Morris Brian J.
Published: January 2005

The cellular location of Neuropeptide Y (NPY) synthesis in rat brain is identified by using in‐situ hybridisation histochemistry. The results show that NPY mRNA is widely distributed through the rat brain, although the levels of NPY mRNA are surprisingly low. There is a large degree of variation in the content of NPY mRNA in different regions. The highest cellular levels of NPY mRNA are found in the arcuate nucleus of the hypothalamus, in the cerebral cortex, and in the hilar region of the hippocampus. In general, the distribution of perikarya containing NPY mRNA corresponds to the reported distribution of perikarya containing NPY‐immunoreactivity. However, NPY mRNA was detected in the majority of the perikarya in the reticular nucleus of the thalamus, an area not previously known to contain NPY neurones. In many areas of the forebrain the distribution of NPY mRNA parallels that of somatostatin mRNA, supporting suggestions of their coexistence. The ability to detect NPY mRNA at the cellular level should be of considerable use in dynamic studies of the activity of NPY neurones.
Distribution of muscarinic acetylcholine receptors on processes of isolated retinal cells
Authors: Townes‐Anderson Ellen , Vogt Brent A.
Published: January 2005

Binding of propylbenzilylcholine mustard, a muscarinic acetylcholine receptor antagonist, to isolated retinal cells was examined with light microscopic autoradiography. Dissociation of the adult tiger salamander retina yielded identifiable rod, cone, horizontal, bipolar, amacrine/ganglion, and Müller cells. Preservation of fine structure was assessed with conventional electron microscopy. For all cell types, the plasmalemma was intact and free of adhering debris; in addition, presynaptic ribbon complexes were present in photoreceptor and bipolar axon terminals indicating that synaptic structures were retained. Specific binding to cell bodies and processes was analyzed separately by using morphometric and statistical techniques. The highest grain densities occurred on processes of amacrine/ganglion cells and axons and 2° and 3° dendrites of bipolar neurons. Bipolar cells, however, seemed to be a heterogeneous population because there was great variation in the density of binding sites on both their axons and distal dendrites. Intermediate levels of binding were found on bipolar 1° dendrites and horizontal cells. No specific binding was detected on Müller cells and most parts of photoreceptors. Comparisons between cells showed that grain densities were similar for bipolar axons and amacrine/ganglion cell processes but bipolar dendrites were richer in binding sites than horizontal cell dendrites. Thus, muscarinic receptors in the salamander retina are located on amacrine/ganglion, bipolar, and horizontal cells and primarily confined to the processes which compose the two synaptic layers. In the inner plexiform layer, muscarinic receptors reside on processes from all three inner retinal neurons; in the outer synaptic layer, receptors are only on second‐order cells and are more numerous along bipolar than horizontal cell dendrites.
Morphology of single primary vestibular afferents originating from the horizontal semicircular canal in the cat
Authors: Sato Fumi , Sasaki Hiroshi , Ishizuka Norio , Sasaki Sei‐Ichi , Mannen Hajime
Published: January 2005

The central projections of physiologically characterized vestibular nerve fibers originating from the horizontal semicircular canal were studied in the vestibular nuclei of adult cats after intracellular staining with horseradish peroxidase (HRP). First, primary nerve fibers were physiologically classified as regular or irregular types on the basis of the regularity of the spontaneous discharge pattern. Then, these two types of fibers were morphologically analyzed and compared following HRP intraaxonal injection. The two types of axons showed a basically similar trajectory in the four major vestibular nuclei. They bifurcated into an ascending and a descending branch in the ventrolateral part of the lateral vestibular nucleus (LVN). The ascending branch extended rostrally and gave off one or two collaterals in the superior vestibular nucleus (SVN), although some of the ascending branches further ran rostrally into the cerebellum. The collaterals, while running medially, gave rise to fine terminal branches with en passant boutons in the SVN, and further coursing caudally, they entered the rostral part of the medial vestibular nucleus (MVN). The descending branch, while running caudally in the lateral part of the LVN and the inferior vestibular nucleus (IVN), gave off several thick collaterals to the MVN and extensive terminals were present in the IVN and MVN. In each primary axon, about one‐third of the total terminal boutons were distributed in each of the SVN, the MVN, and the IVN. In contrast to this similarity of the overall axonal trajectory within the vestibular nuclei, both types of axons exhibited several marked differences in diameter and in the mode of terminal arborization. In almost every part of the ramification, the irregular‐type fibers were thicker than the regular‐type fibers. In the regular‐type axons, many small terminal boutons (mean size, 2.4 × 1.4 μm, N = 2,739) were located in close proximity (100–150 μm) to the parent collateral. In the irregular‐type axons, slightly larger terminal boutons (mean size, 3.0 × 1.7 μm, N = 1,287), were spread more widely (200–300 μm) around their collaterals. These clear morphological differences between the regular‐type and the irregular‐type terminal axons were consistently observed in any vestibular nucleus.
Parasagittal organization of the rat cerebellar cortex: Direct comparison of purkinje cell compartments and the organization of the spinocerebellar projection
Authors: Gravel Claude , Hawkes Richard
Published: January 2005

Retrograde and anterograde transport of tracers, electrophysiological recording, somatotopic mapping, and histochemical and immunological techniques have all revealed a parasagittal parcellation of the cerebellar cortex, including its efferent and many of its afferent connections. In order to establish whether the different compartments share a common organizational plan, a systematic comparative analysis of the patterns of parasagittal zonation in the cerebellar cortex of the rat has been undertaken, by using the parasagittal compartmentation of zebrin I+ and zebrin I‐Purkinje cells as revealed by monoclonal antibody Q113 as a reference frame. The distribution of mossy fiber terminals originating from the lower thoracic‐higher lumbar spinal cord was compared to the distribution of zebrin I bands. Three‐dimensional reconstructions from alternate frontal sections processed either for the anterograde transport of tracer or for zebrin I immunoreactivity reveal that the limits of the spinocerebellar terminal fields in the granular layer correlate well with the boundaries of some, but not all, zebrin I compartments in the molecular layer above. This leads to a subdivision of the zebrin I compartments into spinal receiving and spinal nonreceiving portions. In lobules II and VIII, the spinocerebellar terminal fields assume different positions relative to the zebrin I compartments in the ventral compared to the dorsal faces. Thus, each longitudinal compartment may be further divided transversely into subzones, each receiving a specific combination of mossy fiber afferents. The further subdivision of zebrin I compartments by mossy fiber terminal fields increases the resolution of the topography to such a point that anatomical compartment widths become compatible with the width of the microzones and the patches identified by electrophysiological methods.
Maturation of the corpus callosum of the rat: II. Influence of thyroid hormones on the number and maturation of axons
Authors: Gravel Claude , Sasseville Rachel , Hawkes Richard
Published: January 2005

Quantitative electron microscopy has been used to study the number of callosal axons in the corpus callosum of normal and hypothyroid rats during postnatal development. At birth, the normal corpus callosum contains 4.4 × 106 axons. This number increases to 11.4 × 106 by 5 days of age (P5) and then, in contrast to cats and primates, remains constant until at least P60, the oldest age examined. The number of axons in the corpus callosum of hypothyroid animals is not significantly different from the values observed in normal rats at all ages studied, although the callosal axons of hypothyroid rats remain structurally immature. As extensive elimination of callosal axons has been shown to occur in normal rats past P5, we conclude that new callosal processes grow through the corpus callosum past this age that compensate numerically for the loss. Moreover, as the number of callosally projecting neurons seems to be higher in hypothyroid rats than in normal controls, it seems that the constant axon number derives from more parent neurons, and thus that there are more axon collaterals per callosal neuron in a normal animal than in a hypothyroid one. Taken together, these data indicate that although hypothyroidism does not alter the total number of callosally projecting axons, it interferes with the normal processes that define or sculpt the projection fields, thereby leading to a numerically normal projection with abnormal topography.
Cells of origin of the spinohypothalamic tract in the rat
Authors: Burstein Rami , Cliffer Kenneth D. , Giesler Glenn J.
Published: January 2005

We recently demonstrated that large numbers of neurons in the spinal cord of rats project directly to the hypothalamus. In the present study, we used the retrograde tracer Fluoro‐Gold (FG) to examine this projection more completely. In the first series ofss studies, we attempted to label the entire population of spinal cord neurons that project to the hypothalamus. Injections that virtually filled the hypothalamus on one side without spreading into any other diencephalic area labeled a large number of neurons (estimated to be more than 9,000 in the case with the most neurons labeled) bilaterally at all levels of the spinal cord. Approximately 60° of the labeled neurons were contralateral to the injection. The greatest number of labeled neurons was found within the deep dorsal horn. Many were also found within the lateral spinal nucleus, the superficial dorsal horn, and the gray matter surrounding the central canal. A small number of labeled cells was located in the intermediate zone and ventral horn of the spinal gray matter. Labeled neurons were distributed bilaterally within the sacral parasympathetic nucleus and trigeminal nucleus caudalis.

Injections of FG restricted to the medial hypothalamus labeled neurons within the spinal cord in a distribution similar to that produced by injections that filled the hypothalamus. However, fewer neurons were labeled in the spinal cord (estimated to be more than 6,200) and trigeminal nucleus caudalis.

Injections of FG restricted to the lateral hypothalamus also labeled fewer neurons (approximately 3,300) than did injections that filled the hypothalamus. In these cases, also, the pattern of labeled neurons within the spinal cord was similar to that produced by injections within either medial or both medial and lateral hypothalamus. However, few neurons were labeled in the sacral parasympathetic nucleus following injections into the lateral hypothalamus.

These findings show the distribution of a large number of spinal cord neurons that project directly to medial or lateral hypothalamic regions that are involved in autonomic, neuroendocrine, and emotional responses to somatosensory stimulation, including painful stimuli.
Olivocerebellar fiber maturation in normal and lurcher mutant mice: Defective development in lurcher
Authors: Heckroth John A. , Goldowitz Dan , Eisenman Leonard M.
Published: January 2005

Olivocerebellar fiber maturation was examined in normal and lurcher mutant mice between postnatal day 5 (P5) and P15, using the anterograde transport of wheat germ agglutinin‐horseradish peroxidase (WGA‐HRP) from the inferior olive. Immunocytochemistry for the Purkinje cell marker PEP‐19 was used to demonstrate Purkinje cell development in the same material. In mutant and normal animals, a regional developmental variation is observed such that, when compared at a given age, cortex lining the vermal fissures appears developmentally advanced over cortex in the cerebellar hemispheres. In the primary fissure of the normal animals, the first recognizable Purkinje cell dendrites appear on P6, and the olivocerebellar fibers first enter the climbing stage of their development on P9. In lurcher animals Purkinje cell development proceeds on this schedule, but olivocerebellar fibers are never observed to enter the molecular layer. These afferents maintain dense perisomatic nests around Purkinje cells, even in P13‐15 lurchers. Examination of P14 lurchers by transmission electron microscopy indicates that the olivocerebellar fibers form synapses on Purkinje cell somatic spines and that the basket cell axons fail to form their typical perisomal nests around Purkinje cells. In addition, parallel fibers can be observed to synapse on dendritic spines on the Purkinje cell primary dendrites. We interpret these results as indicating a recognition defect between olivocerebellar fibers and Purkinje cell dendrites. An analysis of this defect in lurcher may reveal how the normal transformation of olivocerebellar fibers, from perisomal to dendritic terminals, is achieved.
Postnatal changes in the density and distribution of neurotensin‐like immunoreactive fibers in the mediodorsal nucleus of the thalamus in the rat
Authors: Ray James P. , Price Joseph L.
Published: January 2005

A previous report (Inagaki et al., Brain Res. 260:143‐146, '83) suggested that the peptide neurotensin is contained in neurons of the piriform cortex that project to the mediodorsal thalamic nucleus MD in young rats. To confirm this, we have studied the distribution of neurotensin‐like immunoreactive NTIR fibers in MD during development, using three antisera directed at different parts of the neurotensin molecule Emson et al., J. Neurochem. 38:992‐999, 82. In adult rats, NTIR fibers in MD are sparse. They are located mostly at the medial edge of MD and in the adjacent midline thalamic nuclei, with a few poorly stained NTIR fibers in the central part of MD. In contrast, during the first postnatal week, both the medial and central portions of MD stain heavily for neurotensin. The density of NTIR fibers in MD then progressively decreases until the density typical of adult rats is reached, at about 5 weeks. Changes in the distribution of NTIR fibers in MD also occur. In 7‐day‐old rats, the patches of NTIR fibers in the medial and central parts of MD are contiguous, but by 10 days a sparsely immunoreactive zone forms between them. With maturation, this zone enlarges as the density of neurotensin staining decreases, until the medial contingent of NTIR fibers reaches its adult position at the medial edge of MD.

From a comparison of the distribution of NTIR cells with that of cells that can be retrogradely labeled from MD or the midline thalamus, the probable source of the NTIR fibers to the central part of MD is in the deep layer of the piriform cortex, while the NTIR fibers to the medial edge of MD and the midline nuclei may arise from the preoptic region and the medial amygdala. In neonatal rats, neurons are found in the piriform cortex, the preoptic region, and the medial amygdala, which can be double‐labeled both for neurotensin and with a retrograde tracer injected into MD and the midline thalamus. Projections of the preoptic region to the thalamus have a distribution similar to that of the medial population of NTIR fibers, whereas the distribution of piriform cortical afferents in central MD matches the central patch of NTIR fibers.
Sensory properties and afferents of the N. dorsolateralis posterior thalami of the pigeon
Authors: Korzeniewska Ewa , Güntürkün Onur
Published: January 2005

According to previous studies, the avian n. dorsolateralis posterior thalami (DLP) receives visual and somatosensory afferents. While some authors (e. g., Gamlin and Cohen: J. Comp. Neurol. 250:296–310, '86) proposed a distinction between a visual caudal (DLPc) and a somatosensory rostral (DLPr) part, other authors (e. g., Wild: Brain Res. 412:205–223, '87) could not confirm such a differentiation. The aim of the present experiment was to study with physiological and anatomical methods the proposed parcellation of the DLP into various components dealing with different modalities.

The physiological properties of the DLP of the pigeon were analysed with extracellular single unit recordings. With the same approach, neurons of the n. dorsalis intermedius ventralis anterior (DIVA), a somatosensory relay nucleus in the dorsal thalamus, were also analysed. The afferents of the DLP were studied by using anatomical tract tracing techniques with retrograde and anterograde tracers. The sensory properties of DLP cells revealed that somatosensory, visual, and auditory modalities affect the neuronal firing frequency in this nucleus. All three modalities were present throughout the full caudorostral extent of the DLP. Cells recorded in DIVA responded nearly exclusively to somatosensory stimulation. Unlike the DLP, single units in DIVA generally had smaller receptive fields encompassing only one extremity.

The analysis of afferent connections of the DLP by using injections of retrograde and anterograde tracers (HRP, WGA‐HRP, Fast Blue, and Rhodamine‐β‐isothiocyanate) demonstrated extensive projections from the nuclei gracilis et cuneatus (GC) and more sparse projections from the nucleus tractus descendens trigemini (TTD), and the nucleus cuneatus externus (CE). Brainstem afferents of the DLP came from different vestibular nuclei, various areas of the brainstem reticular formation, and the optic tectum. Prosencephalic afferents originated in the n. posteroventralis thalami (PV), the n. ventromedialis posterior thalami (VMP), the n. dorsalis intermedius ventralis anterior (DIVA), and the nucleus reticularis superior pars dorsalis and ventralis (RSd and RSv). Telencephalic afferents of the DLP came from the hyperstriatum accessorium (HA) and a group of cells at the borderline between the hyperstriatum intercalatus superior (HIS) and the hyperstriatum dorsale (HD).

The somatosensory afferents of the DLP probably originate from the GC, TTD, and CE, whereas it is likely that the visual input is mediated by the optic tectum. The anatomical source for the acoustic input is unclear. The very long latencies of auditory DLP neurons make it likely that the acoustic input originates at least partly in the reticular formation. The sensory properties and the organization of afferents suggest a general similarity of the DLP to the n. ventromedialis thalami of teleosts and the posterior complex of nuclei of mammals.
Sources of neostriatal cholecystokinin in the cat
Authors: Adams Catherine E. , Fisher Robin S.
Published: January 2005

The objective of this study was to determine the sources of cholecystokinin within the neostriatum of the cat. Cholecystokinin‐immunoreactive cells and fibers were detected by means of the peroxidase antiperoxidase immunohistochemical technique. This method was combined with intrastriatal injections of the retrograde marker horseradish peroxidase conjugated with wheatgerm agglutinin to survey the possible afferent sources of cholecystokinin to the feline neostriatum. Intrinsic, apparently aspiny cholecystokinin‐immunoreactive neurons organized in a pericapsular pattern were found within both the caudate and putamen of the cat. In addition, both thalamostriatal and mesostriatal projections containing cholecystokinin were observed. These results indicate that cholecystokinin within the neostriatum of the cat arises from both intrinsic and extrinsic sites.
Numbers of neurons and glia in mature rat somatosensory cortex: Effects of prenatal exposure to ethanol
Authors: Miller Michael W. , Potempa Gregory
Published: January 2005

Stereological methods were used to examine the consequences of prenatal exposure to ethanol on the structure of area 3, primary somatosensory cortex, of the mature hooded rat. Pregnant rats were fed a liquid diet containing 6.7% (v/v) ethanol (Et), pairfed an isocaloric liquid control diet (Ct), or fed a diet of chow and water (Ch). Cresyl violet‐stained sections of 3‐month‐old pups were examined. The corrected mean size of the cell bodies of neurons in layers other than layer V was significantly smaller in the Ettreated rats; conversely, the mean somatic size of glia in each layer was significantly larger in the Ettreated rats. The laminar cell packing density for neurons and glia, however, was similar in rats from both treatment groups. The overall volume of area 3 and the volume of individual layers were about 33% smaller in Et‐treated rats than in the pair‐fed controls. Thus, the estimated total number of neurons in Et‐treated rats (1.79*106) was significantly fewer than in Chtreated rats (2.77*106) and in Ct‐treated rats (2.66*106). The total number of glia also was about 30% fewer in Et‐treated rats than in the controls. Not all layers were affected equivalently. The space occupied by the neuropil was significantly greater in Et‐treated rats, but only in layers II/III, IV, and VI; hence, the cell body/neuropil ratio in these layers was less in Et‐treated rats than in the controls. Therefore, microcephaly caused by prenatal exposure to ethanol results not only from a miniaturization of the brain, but also from a permanent abnormal organization of cerebral cortex.
Cortical projection patterns of the medial septum‐diagonal band complex
Authors: Gaykema Ronald P. A. , Luiten Paul G. M. , Nyakas Csaba , Traber Jörg
Published: January 2005

A detailed analysis of the cortical projections of the medial septum‐diagonal band (MS/DB) complex was carried out by means of anterograde transport of Phaseolus vulgaris leucoagglutinin (PHA‐L). The tracer was injected iontophoretically into cell groups of the medial septum (MS) and the vertical and horizontal limbs of the diagonal band of Broca (VDB and HDB), and sections were processed immunohistochemically for the intra‐axonally transported PHA‐L. The labeled efferents showed remarkable differences in regional distribution in the cortical mantle dependent on the position of the injection site in the MS/DB complex, revealing a topographic organization of the MS/DB‐cortical projection. In brief, the lateral and intermediate aspects of the HDB, also referred to as the magnocellular preoptic area, predominantly project to the olfactory nuclei and the lateral entorhinal cortex. The medial part of the HDB and adjacent caudal (angular) part of the VDB are characterized by widespread, abundant projections to medial mesolimbic, occipital, and lateral entorhinal cortices, olfactory bulb, and dorsal aspects of the subicular and hippocampal areas. Projections from the rostromedial part of the VDB and from the MS are preponderantly aimed at the entire hippocampal and retrohippocampal regions and to a lesser degree at the medial mesolimbic cortex. Furthermore, the MS projections are subject to a clear mediolateral topographic arrangement, such that the lateral MS predominantly projects to the ventral/temporal aspects of the subicular complex and hippocampus and to the medial portion of the entorhinal cortex, whereas more medially located cells in the MS innervate more septal/dorsal parts of the hippocampal and subicular areas and more lateral parts of the entorhinal cortex. PHA‐L filled axons have been observed to course through a number of pathways, i. e., the fimbria‐fornix system, supracallosal stria, olfactory peduncle, and lateral piriform route (the latter two mainly by the HDB and caudal VDB). Generally, labeled projections were distributed throughout all cortical layers, although clear patterns of lamination were present in several target areas. The richly branching fibers were abundantly provided with both “boutons en passant” and terminal boutons. Both distribution and morphology of the labeled basal forebrain efferents in the prefrontal, cingulate, and occipital cortices closely resemble the distribution and morphology of the cholinergic innervation as revealed by immunohistochemical demonstration of choline acetyltransferase. In contrast, the labeled projections to the olfactory, hippocampal, subicular, and entorhinal areas showed a heterogeneous morphology. Here, the distribution of only the thin varicose projections resembled the distribution of cholinergic fibers.
Innervation of a lizard auditory organ having gap junctions between most hair cells: A serial transmission electron microscopy study
Authors: Miller Malcolm R. , Beck Janet
Published: January 2005

Two apical unidirectional and 16 basal bidirectional papillar hair cells of the yucca night lizard, Xantusia vigilis, were serially sectioned for transmission electron microscopy (TEM) to determine the pattern of hair cell innervation. The 16 bidirectional hair cells (central group) were sectioned across the entire width of the papilla and consisted of four complete hair cells in each of the first three rows and the upper (or neural) half of the four hair cells in the fourth or last row. Both hair cell types were nonexclusively innervated, i.e., each afferent nerve fiber innervated two or more hair cells. The apical unidirectional hair cells were innervated by six or seven different afferent nerve fibers and five or six efferent fibers. The afferent nerve fibers made an average of 52.5 synapses/hair cell. In the central group of 16 bidirectional hair cells, 25 different afferent nerve fibers innervated an average of 4.5 hair cells. The average number of hair cells innervated by the eight afferent nerve fibers limited to the central group was 5.4. An unusual finding was the presence of gap junctions directly interconnecting more than half the hair cells in both papillar segments. In the bidirectional hair cell region, it was possible to count the number of gap junctions between 24 contiguous hair cells. The average number of gap junctions was four per hair cell, and all bidirectional hair cell were either directly or indirectly interconnected by gap junctions. The possible function of a nonexclusive type of hair cell innervation and the presence of large numbers of gap junctions are discussed.
Topographic organization of the ventral striatal efferent projections in the rhesus monkey: An anterograde tracing study
Authors: Haber S. N. , Lynd E. , Klein C. , Groenewegen H. J.
Published: January 2005

The ventral striatum is considered to be that portion of the striatum associated with the limbic system by virtue of its afferent connections from allocortical and mesolimbic areas as well as from the amygdala. The efferent projections from this striatal region in the primate were traced by using 3H aminoacids and Phaseolus vulgaris‐leucoagglutinin (PHA‐L). Particular attention was paid to the topographic organization of terminal fields in the globus pallidus and substantia nigra, the projections to non‐extrapyramidal areas, the relationship between projections from the nucleus accumbens and the other parts of the ventral striatum, and the comparison between ventral and dorsal striatal projections.

This study demonstrates that in monkeys a circumscribed region of the globus pallidus receives topographically organized efferent fibers from the ventral striatum. The ventral striatal fibers terminate in the ventral pallidum, the subcommissural part of the globus pallidus, the rostral pole of the external segment, and the rostromedial portion of the internal segment. The more central and caudal portions of the globus pallidus do not receive this input. This striatal output appears to remain segregated from the dorsal striatal efferent projections to pallidal structures.

Fibers from the ventral striatum projecting to the substantia nigra are not as confined to a specific region as those projecting to the globus pallidus. Although the densest terminal fields occur in the medial portion, numerous fibers also extend laterally to innervate the dorsal stratum of dopaminergic neurons of the substantia nigra and the retrorubral area. Furthermore, they project throughout the rostral‐caudal extent of the substantia nigra. Projections from the medial part of the ventral striatum reach the more caudally located pedunculopontine tegmental nucleus. Thus unlike the above described terminals in the globus pallidus, the ventral striatum project widely throughout the substantia nigra, a fact that indicates that they may contribute to the integration between limbic and other output systems of the striatum.

Finally, the ventral striatum projects to non‐extrapyramidal regions including the bed nucleus of the stria terminals, the nucleus basalis magnocellularis, the lateral hypothalamus, and the medial thalamus.
Immunolabelling by a newt retinal pigment epithelium antibody during retinal development and regeneration
Authors: Klein Lisa R. , MacLeish P. R. , Wiesel Torsten N.
Published: January 2005

The binding of RPE‐1, a mouse monoclonal antibody selective for newt retinal pigment epithelium, was followed in eyes undergoing embryonic developemnt and retinal regeneration. Using the indirect immunofluorescence technique on frozen sections, we observed bright and continuous labelling exclusively in the retinal pigment epithelium (RPE) of normal adult newts, but labelling became diminished near the ora serrata region and stopped abruptly at the ciliary margin. During development, labelling was not detected in the retinal pigment epithelium (RPE) until the formation of photoreceptor outer segments and was not observed in any other ocular tissue. There was no correlation between the appearance of pigment in retinal pigment epithelial cells and their labelling with the RPE‐1 antibody. Furthermore, albino salamander embryos showed the same pattern of labelling with RPE‐1 as that seen in age‐matched pigmented animals. During retinal regeneration, RPE cells were labelled less intensely, but heavy labelling was observed in the newly formed retinal cells. With time, labelling in regenerated retina receded, so that by the end of regeneration, labelling by RPE‐1 was once more restricted to the RPE cells. The identification of RPE‐1 as a marker for postmitotic retinal neurons about to undergo differentiation provides a promising approach for further studies of regeneration with the help of molecular tools.
Neuropeptides and catecholamines in efferent projections of the nuclei of the solitary tract in the rat
Authors: Riche D. , De Pommery J. , Menetrey D.
Published: January 2005

This study focuses on the involvment of catecholamines and nine different peptides in efferents of the nucleus of the solitary tract to the central nucleus of the amygdala, the bed nucleus of the stria terminalis, and different parabrachial and hypothalamic nuclei in the rat. A double‐labeling technique was used that combines a protein‐gold complex as the retrograde tracer with immunohistochemistry.

Catecholaminergic projection neurons were the most numerous type observed and projected mainly ipsilaterally to all targets studied. Most projections arose from areas overlying the dorsal motor nucleus, mainly the medial nucleus. Neurons synthesizing somatostatin, met‐enkephalin‐Arg‐Gly‐Leu, dynorphin B, neuropeptide Y, and neurotensin projected to all structures examined. Somatostatin and enkephalin immunoreactive projection cells were the most numerous. They were located in close proximity to each other, including all subnuclei immediately surrounding the solitary tract, bilaterally. Most dynorphin and neuropeptide Y immunoreactive projection cells were found rostral to that of enkephalinergic and somatostatinergic projections, and mainly in the ipsilateral medial nucleus. Neurotensinergic projections were sparse and from dorsal and dorsolateral nuclei.

Substance P and cholecystokinin contribute to parabrachial afferents. The location of substance P immunoreactive projection cells closely resembled that of enkephalinergic and somatostatinergic projections. Projecting cholecystokinin immunoreactive cells were observed in dorsolateral nucleus. Bombesin immunoreactive cells in dorsal nucleus projected to either the parabrachial or hypothalamic nuclei. No vasoactive intestinal polypeptide‐containing cells were detected.

Thus, most catecholaminergic and neuropeptidergic efferents originated from different populations of cells. It is proposed that catecholaminergic neurons constitute the bulk of solitary efferents and that they may contribute to autonomic neurotransmission. Peptidergic neurons mainly form other subgroups of projections and may play a role in modulating the physiological state of the target nuclei.
Distribution of locus coeruleus axons within the rat brainstem demonstrated by Phaseolus vulgaris leucoagglutinin anterograde tracing in combination with dopamine‐β‐hydroxylase immunofluorescence
Authors: Fritschy Jean‐Marc , Grzanna Reinhard
Published: January 2005

Projections of the locus coeruleus (LC) to the midbrain and hindbrain were analyzed by anterograde transport of the lectin Phaseolus vulgaris leucoagglutinin (PHA‐L). Following iontophoretic application of PHA‐L into the LC, the distribution of labeled axons was analyzed in sections processed for the immunoperoxidase method and in sections processed for double‐immuno‐fluorescence staining using antibodies to PHA‐L and to dopamine‐β‐hydroxylase. This combined staining approach proved to be necessary for the unequivocal identification of LC axons in the brainstem since all injections labeled many non‐noradrenergic axons whose distribution was different from that of LC fibers. The major new finding of the present study was the observation that large territories of the brainstem that receive a dense noradrenergic input are very sparsely innervated by the LC. Numerous labeled LC axons were observed in somatic afferent nuclei, tectum, pontine nuclei, interpeduncular nucleus, and inferior olivary complex. In contrast, very few labeled fibers were observed in autonomic and motor nuclei, and throughout the brainstem reticular formation, including raphe nuclei. Our data show that the distribution of LC axons in the brainstem is far less prominent than the projections of this nucleus to the forebrain and spinal cord. Our findings suggest that the dense NA projections to the core of the brainstem originate principally in non‐LC NA neurons. On the basis of the present anatomical findings, a prominent role of the LC in motor and integrative functions of the brainstem appears unlikely.
Cholera toxin B‐gold, a retrograde tracer that can be used in light and electron microscopic immunocytochemical studies
Authors: Llewellyn‐Smith I. J. , Minson J. B. , Wright A. P. , Hodgson A. J.
Published: January 2005

The purpose of this study was to test whether a new retrograde tracer, the B subunit of cholera toxin conjugated to colloidal gold particles (Ctb‐gold), was taken up and transported by neurons in the central nervous system of the rat. Retrograde transport of CTB‐gold was assessed from axon terminals, from damaged nerve fibers, and from axons of passage. For light microscopy, CTB‐gold was visualized by silver intensification; for electron microscopy, sections were silver‐intensified with or without subsequent gold toning.

Retrogradely transported CTB‐gold was detected in neurons after survival times of 12 hours to 42 days and appeared as black punctate deposits in perikarya and proximal dendrites at the light microscope level. Ultrastructurally, the deposits were usually associated with lysosomes.

Injections of CTB‐gold into the caudal ventrolateral medulla or into the lateral horn of the spinal cord gave small well‐defined injection sites and resulted in retrograde labelling in medullary neurons in the same locations as similarly placed injections of wheat germ agglutinin‐horseradish peroxidase. When injected into the superior cervical ganglion, CTB‐gold was transported to nerve cell bodies in the spinal cord, but application of CTB‐gold to the cut cervical sympathetic trunk did not label neurons in the spinal cord. Injection of CTB‐gold into the nodose ganglion retrogradely labelled neurons in the dorsal motor nucleus of the vagus and the nucleus ambiguus. CTB‐gold was not transported anterogradely from injections sites within the medulla.

Nerve fibers and cell bodies containing neuropeptides, monoamines, or neurotransmitter‐synthesizing enzymes were readily immunostained after silver intensification of retrogradely transported CTB‐gold. Immunoreactivity for neuropeptides and enzymes was also demonstrated ultrastructurally after silver intensification and gold toning.

These results show that CTB‐gold is retrogradely transported from nerve terminals and fibers of passage but not from damaged axons. CTB‐gold gives well‐localized injection sites and persists in neurons for weeks. Transported CTB‐gold is easily visualized and its detection is compatible with light and electron microscopic immunocytochemistry. These properties make CTB‐gold a valuable tool for studying the connectivity and neurochemistry of path ways in the central nervous system.
Galanin‐like immunoreactivity within the primate basal forebrain: Differential staining patterns between humans and monkeys
Authors: Kordower Jeffrey H. , Mufson Elliott J.
Published: January 2005

Galanin‐like immunoreactivity (GAL‐ir) was examined within the basal forebrain and adjacent regions of eight young adult New World monkeys (Cebus apella), one aged Old World monkey (Macaca mullata), and eight humans without clinical or pathological evidence of neurological disease. All monkeys demonstrated similar patterns of immunoreactive profiles characterized by a continuum of GAL‐in magnocellular neurons located within the medial septum, diagonal band nuclei, and nucleus basalis. Colocalization experiments revealed that most (>90%) of GAL‐ir basal forebrain neurons also expressed the receptor for nerve growth factor (NGFR), an excellent marker for primate cholinergic basal forebrain neurons. A few smaller parvicellular GAL‐ir neurons were also observed within the monkey basal forebrain. In contrast, identical cytochemical experiments revealed that virtually none of the magnocellular neurons within the basal forebrain of humans were GAL‐ir. Rather, a network of GAL‐containing fibers and terminal‐like profiles were observed encompassing the magnocellular cholinergic neurons in humans. This immunohistochemical species difference does not appear to be mediated by procedural or technical factors since human brains contained numerous GAL‐ir perikarya and fibers within adjacent regions including the bed nucleus of the stria terminalis and medial hypothalamus. These data demonstrate that there is a prominent phylogenetic transformation in primates with respect to the processing of GAL‐mediated information. This species difference potentially relates to the severe basal forebrain degeneration reported in human dementias and illustrates the possible need for a reevaluation of the use of monkeys as an animal model of human basal forebrain‐related cognitive dysfunction.
Dendritic morphology and development in the ferret medial superior olivary nucleus
Authors: Henkel Craig K. , Brunso‐bechtold Judy K.
Published: January 2005

Dendritic morphology and development in the medial superior olivary nucleus of the ferret were studied using the Golgi method. In the adult ferret most medial superior olivary neurons had disk‐shaped dendritic fields. These dendritic fields were oriented such that cells in a coronal plane of section appeared bipolar with major lateral and medial dendritic axes. In the horizontal plane the dendrites radiated about the soma. Dendrites of principal cells branched distally into tufts of numerous, tertiary processes that were beaded and thin. Peripheral cells in the fiber mantle encircling the nucleus were generally spindle‐shaped or tripolar and lacked the tufted dendrites of principal cells. The dendrites of these peripheral cells coursed parallel to the nucleus both dorsoventrally and rostrocaudally. Horizontally oriented dendrites were observed even at birth for some cells in the medial superior olivary nucleus and bipolar dendritic fields were typical of most cells by the end of the second postnatal week. Dendrites of immature cells varied in caliber and radiated in all directions from the soma. Around postnatal days 8‐10 transient appendages appeared on the soma and dendrites, first proximally and then more distally. These appendages persisted until the first postnatal month. Cell size and dendritic radius increased markedly during this same period. Postnatal days 28‐30 were marked by the first appearance of tufts of tertiary dendritic branches. The tendril‐like processes continued to increase in length until about the end of the second postnatal month.
Dendritic morphology of central auditory neurons correlates with their tonotopic position
Authors: Sanes Dan H. , Goldstein Nira A. , Ostad Masoud , Hillman Dean E.
Published: January 2005

We have investigated the morphology of dendritic arbors in a central auditory nucleus, the lateral superior olive, of the Mongolian gerbil. Morphometric observations were obtained directly from Golgi‐impregnated material by using a microcomputer‐based three‐dimensional data acquisition system. In particular, measurements were made to determine the dendritic arborization across each of three axes: the tonotopic axis, the rostrocaudal axis, and the isofrequency axis (i. e., perpendicular to the tonotopic axis). The tonotopic position of each cell was computed on the basis of a topographic map that has been constructed for the gerbil LSO (Sanes et al.: J. Comp. Neurol. 279:436‐444, 1989).

It was found that the span of a dendritic arbor along the tonotopic axis was directly correlated with the neuron's tonotopic position: Low frequency neurons had much broader arborizations than high frequency neurons. Moreover, the distribution of frequency bandwidths to which single LSO neurons responded showed a striking similarity to dendritic arborizations across the tonotopic axis. Lower frequency neurons responded to a larger number of octaves than higher frequency neurons.

There was no correlation between tonotopic position and dendritic arborization in the isofrequency or rostrocaudal axis. Nor was there any correlation between frequency and total dendritic length, number of primary dendrites, or soma area. However, there was a small but significant difference between the primary dendrite diameter of low and high frequency neurons. Low frequency neurons had significantly greater diameters. These results suggest that the frequency selectivity of central auditory neurons may employ, as one morphological substrate, the distance over which their dendrites arborize along the tonotopic axis.