bluuebunny/crossref_metadata_2025 huggingface dataset:
Glycine receptor immunoreactivity in the ventral cochlear nucleus of the guinea pig
Authors: Wenthold Robert J. , Parakkal Merianne H. , Oberdorfer Michael D. , Altschuler Richard A.
Published: January 2005

Glycine appears to be a major inhibitory neurotransmitter in the cochlear nucleus. In order to determine more precisely the distribution of glycinergic synapses, we have studied the immunocytochemical distribution of the glycine postsynaptic receptor. Two monoclonal antibodies were used, Gly Rec Ab 2, which recognizes the 48kD polypeptide and Gly Rec Ab 7, which primarily recognizes the 93kD subunit of the glycine receptor complex. At the light microscopic level, glycine receptor immunoreactivity was found throughout the ventral cochlear nucleus with a punctute distribution often found outlining large cell bodies. Indistinguishable patterns of staining were obtained with the two antibodies. Ultrastructural localization was done with Gly Rec Ab 7 because immunoreactivity remained after fixation with glutaraldehyde containing solutions. At the ultrustructural level, immunoreactivity was concentrated at postsynaptic sites on dendrites and cell bodies. In the anteroventral cochlear nucleus, neurons identified as spherical cells contained numerous inmunoreactive synapses on their cell bodies, whereas most immunoreactive synapses on stellate cells were on their proximal dendrites. In the posteroventral cochlear nucleus, neurons identified as octopus cells were immunoreactive on their cell bodies and proximal dendrites. In the granule cell layer, immunoreactivity was found only in the neuropile. Throughout the ventral cochlear nucleus, glycine receptor immunoreactivity was found postsynaptic to terminals containing flattened synaptic vesicles as well as those containing oval/pleomorphic synaptic vesicles.
Distribution of histamine in the cockroach brain and visual system: An immunocytochemical and biochemical study
Authors: Pirvola Ulla , Tuomisto Leena , Yamatodani Atsushi , Panula Pertti
Published: January 2005

The distribution of histamine‐immunoreactivity in the carbodiimide‐fixed brain and visual system of the cockroach was revealed immunocytochemically with an antiserum against histamine (HA). Histamine levels were measured with high‐pressure liquid chromatography. The results show a widespread distribution of histamine‐containing somata and fibers in the brain, particularly in the visual system. The most intense immunolabeling was seen in the retinal photoreceptors and in the first optic ganglion, the lamina, where the short visual fibers make synaptic connections with the monopolar neurons, which also displayed immunofluorescence. Immunoreactive long visual fibers traversed the lamina and outer chiasma, terminating in the distal medulla. Tracts of histamine‐immunopositive fibers appeared to link the optic ganglia to the protocerebrum. Prominent histamine‐containing neurons were situated in the lateral protocerebrum. Immunolabeled pathways consisting of large‐diameter fibers also were seen in the cockroach brain. The central parts of the brain, including the central body, were reached by thick immunoreactive fibers that gave rise to intensely fluorescent varicose processes there. In the mushroom bodies, immunoreactivity was limited to the calyces. The protocerebral bridge was nonreactive. Immunofluorescence was seen also in the antennal lobes, but not in the antennal nerves. The biochemical measurements correlated well with the immunocytochemical data. The retinas and optic lobes, measured together, contained remarkably large amounts of histamine. These results reinforce the hypothesis presented by Hardie ('87) and Elias and Evans ('83) that histamine functions as a neurotransmitter in the photoreceptors of some, if not all, insect species.
Development of neurons in the ectostriatum of normal and monocularly deprived zebra finches: A quantitative Golgi study
Authors: Herrmann Kathrin , Bischof Hans‐Joachim
Published: January 2005

The postnatal development of the main neuron type in the ectostriatum, the telencephalic station of the tectofugal pathway, was followed in normally reared and monocularly deprived zebra finches by using the Golgi method. Three parameters were investigated: dendritic field radius, branching index, and spine density. The results show that all three exhibit the same developmental trend—namely, an increase from day 5 until day 20, followed by a subsequent reduction until adulthood (> 100 days). Monocular deprivation from birth until day 20, 40, or at least 100 does not seem to interfere with the development of the dendritic field radius or branching index. Clear changes in spine density result from depriving the birds for at least 40 days. In these birds, neurons in the deprived hemisphere bear significantly fewer spines than those in the nondeprived hemisphere, which is mainly due to a lack of normally occurring spine reduction in the nondeprived hemisphere rather than to spine reduction in the deprived hemisphere.
Migration of schwann cells and axons into developing chick forelimb muscles following removal of either the neural tube or the neural crest
Authors: Noakes Peter G. , Bennett Max R. , Stratford Jacqueline
Published: January 2005

A study has been made of the effects of neural crest and neural tube removal at the brachial level on the migration of Schwann cells and axons into the flexor digitorum profundus (fdp) and flexor carpi ulnaris (fcu) muscles of the avian forelimb. The identification of Schwann cells was based on the assumption that antibody HNK‐1 uniquely labels these cells at the growing end of limb nerves. Myotubes and nerves were identified by using antibodies to myosin and to neurofilament protein, respectively. The removal of neural crest cells at stage 13 gave a complete Schwann cell‐free embryo at the brachial level. Motor axons only grew to the base of the forelimb, forming a rudimentary plexus by stage 27, and failed to penetrate the limb. Removal of the neural tube at stage 13 did not prevent sensory axons from forming a plexus at the base of the limb; these axons subsequently developed into the brachialis longus inferior (bli n) and superior (bls n) nerves. By stage 27 the bli n had branched into the interosseus nerve (in n) and the medial‐ulnar nerve (m‐u n) trunks. However, unlike the result in control embryos, no nerves were detected amongst the developing fdp and fcu muscles, thus indicating that sensory axons do not grow into the muscles in the absence of motor axons. In contrast, Schwann cells were observed amongst the myotubes at the level of the in n and m‐u nerve trunks. The present observations show that motor axons do not enter the limb bud and innervate limb muscles in the absence of Schwann cells. Furthermore, in the absence of motor axons (neural‐tube‐removed embryos) sensory axons still enter the limb (behind migrating Schwann cells) but fail to innervate developing muscles even though Schwann cells are present among the developing myotubes.
Projections of submucosal neurons to the myenteric plexus of the guinea pig intestine: In vitro tracing of microcircuits by retrograde and anterograde transport
Authors: Kirchgessner A. L. , Gershon M. D.
Published: January 2005

The enteric nervous system (ENS) can mediate reflex activity without input from the brain or spinal cord. The ENS thus contains intrinsic primary afferent neurons that link mucosal sensory receptors with motor neurons in the myenteric plexus. The intrinsic primary afferent neurons of the gut have not yet been identified. Although the submucosal plexus is known to innervate the mucosa, where enteric sensory receptors are located, no submucosal to myenteric projections have previously been found. In order to detemine whether such projections exist, the submucosal plexus was examined following the microinjection of a retrograde tracer (Fluoro‐Gold or 4‐acetoamido, 4′‐isothiocyanostilbene‐2,2′‐disulphonic acid [SITS]) into single myenteric ganglia. In addition, the myenteric plexus was studied following the iontophoretic injection of an anterograde tracer (Phaseolus vulgaris leucoagglutinin; [PHA‐L]) into single submucosal ganglia. Ganglia were visualized by use of differential interference contrast optics and were injected from the beveled tip of a glass micropipette; 2.5–3.0 hours were allotted for retrograde and 20–24 hours (under culture conditions) for anterograde transport. In the myenteric plexus, a small number of the neurons of each injected ganglion were fluorescent and additional neurons in distant myenteric ganglia (predominantly orad) were also retrogradely labeled. About five to six submucosal neurons deep to but not directly underneath the injected myenteric ganglion were labeled by Fluoro‐Gold or SITS and only rarely was there more than one labeled neuron in a submucosal ganglion. When control injections of Fluoro‐Gold were placed into the muscle instead of a ganglion, some myenteric neurons near the injection site became labeled indicating an innervation of the circular muscle by myenteric neurons; however, there was no labeling of neurons in the submucosal plexus. Similarly, if connections between the myenteric and submucosal plexuses were severed before injecting Fluoro‐Gold, no submucosal neurons were labeled. Following injection of PHA‐L into a single submucosal ganglion, small‐diameter axons were labeled in ∼︁2 myenteric ganglia as well as in several distant submucosal ganglia (mainly anal and circumferential to the injection site). Additional labeled fibers traveled with blood vessels or surrounded mucosal crypts. It is concluded that submucosal neurons project to the myenteric plexus as well as to the mucosa and to one another. These observations are consistent with the hypothesis that at least some intrinsic enteric primary afferent neurons reside in the submucosal plexus.
Cholinergic innervation of canine thalamostriatal projection neurons: An ultrastructural study combining choline acetyltransferase immunocytochemistry and WGA‐HRP retrograde labeling
Authors: Isaacson Lori G. , Tanaka Duke
Published: January 2005

Choline acetyltransferase (ChAT) immunocytochemistry and lectin‐conjugated horseradish peroxidase (WGA‐HRP) histochemistry were combined at the electron microscopic level to examine the morphology of cholinergic terminals in the canine centrum medianum—parafascicular complex (CM‐Pf) and to localize cholinergic terminals making synaptic contact with retrogradely labeled CM‐Pf thalamostriatal projection neurons. Following WGA‐HRP injections into the caudate nucleus, CM‐Pf neurons were heavily labeled with WGA‐HRP reaction product. Examination with the electron microscope revealed retrogradely labeled neurons characterized by a large nucleus with deep infoldings of the nuclear envelope. ChAT‐positive terminals were observed arising from small‐diameter nonmyelinated axonal profiles. These terminals varied in size from 0.5 to 1.4 μm in long diameter. The smaller terminals (0.5–0.7 μm) were seen most frequently and established symmetrical or slightly asymmetrical synaptic contacts with small dendritic profiles. The larger ChAT‐positive terminals (1.0–1.4 μm) were less frequently observed, contained several mitochondria and small clusters of pleomorphic vesicles, and contacted large dendritic shafts and cell somata. Some of the postsynaptic targets of both smaller and larger ChAT‐positive terminals were identified as belonging to retrogradely HRP‐labeled thalamostriatal neurons.

These observations indicate that at least some thalamostriatal neurons within the CM‐Pf complex are innervated by cholinergic terminals which probably arise from ChAT‐positive cell bodies located within the pontomesencephalic tegmentum, particularly within the nucleus tegmenti pedunculopontinus and the laterodorsal tegmental nucleus. These findings provide evidence for direct influence by cholinergic brainstem nuclei over activities of thalamostriatal neurons.
Sequential development of connections between striate and extrastriate visual cortical areas in the rat
Authors: Coogan Thomas A. , Burkhalter Andreas
Published: January 2005

In these experiments we have asked whether the projection from the rat's primary visual cortex, area 17, to the extrastriate visual cortical area 18a is formed in a sequence and whether that sequence resembles the pattern of inside‐out cortical neurogenesis. For this purpose fluorescent retrograde tracers were injected into area 18a at different postnatal ages (P1, P5, adult). Animals survived until 3–4 weeks of age, after migration is complete and neurons have arrived at their final laminar location. In the ipsilateral cortex, P1 injections retrogradely labeled cells in layers 5 and 6 of area 17. Labeling after P5 injections extended into more superfical layers and included the bottom of layer 2/3 and layers 4–6. After P5, more labeled cells were found at the top of layer 2/3, producing the adult laminar pattern, where the projection originates predominantly from layer 2/3. A similar sequence of laminar labeling was observed in the transcallosal connection of area 18a. This sequence of labeling, deep layers before superficial, resembles the pattern in which cortical neurons are born and indicates that axons arrive at their cortical targets in the order the cells were generated.
Distribution of substance P and vasoactive intestinal polypeptide neurons in the chicken spinal cord, with notes on their postnatal development
Authors: Du Fu , Dubois Paul
Published: January 2005

The distribution of substance P (SP) and vasoactive intestinal polypeptide (VIP) was investigated by immunohistochemistry in the adult chicken spinal cord. By using colchicine treatment, populations of neurons containing either SP or VIP was observed in several regions of the spinal cord. SP neurons were found dorsal to the central canal (CC) and in lamina IV throughout the cord. However, at the thoracic level, numerous relatively larger SP perikarya were located ventral to the CC and aligned on either side of the midline. The distribution of SP fibers is very similar to that reported previously in mammals: they were mostly observed in laminae I and II, in Lissauer's tract, in the dorsolateral funiculus, and dorsal to the CC. In addition, two dense plexuses of SP fibers were noticed in lamina IV. VIP neurons were located mainly in lamina I, in the nucleus of the dorsolateral funiculus, and in the lateral portion of the neck of the dorsal horn throughout the spinal cord. At the thoracic level, many also were located lateral to the CC. Occasionally, single VIP neurons also were encountered dorsal to the CC, in laminae II–IV, and in the intermediate zone. VIP fibers were observed in similar numbers at all spinal levels, occurring mainly in laminae II (probably I) and III, dorsal to the CC, and in the intermediate zone. In addition, examination of the developing chick spinal cords showed similar results as in adult chickens.
Distribution of muscarinic receptor subtypes within architectonic subregions of the primate cerebral cortex
Authors: Mash Deborah C. , White W. Frost , Mesulam M.‐Marsel
Published: January 2005

The regional distributions of muscarinic receptor subtypes (M1 and M2) in the macaque brain were investigated by in vitro receptor autoradiography. Putative muscarinic receptor subtypes were distinguished by their differential affinities for pirenzepine and carbachol in competition with [3H]‐quinuclidinyl benzilate. Autoradiographic visualization of muscarinic receptor subtypes demonstrated marked regional and laminar variations that respected architectonic boundaries.

The M1 receptor subtype was widely distributed throughout most cortical areas and was most intense over the superficial layers. Almost all limbic and paralimbic regions including the amygdala, hippocampus, orbitofrontal, temporopolar, parahippocampal, cingulate, and parolfactory areas displayed peak densities of the M1 receptor subtype. The M2 receptor subtype was selectively elevated in the primary sensory areas of all five sensory modalities, including the visual (area 17, V1), auditory (A1), and somatosensory (3b,S1) koniocortices, the anterior olfactory nucleus, and the gustatory area. The primary motor area also displayed a relative peak of M2 receptor subtype labeling.

In the hippocampal formation, M1, M2, and nicotine receptors were distributed differentially, with each subdivision having a specific complement of cholinergic receptor subtype. The M1 receptor subtype was prevalent in the dentate gyrus, the CA4‐CA3 region, and the CA1 ammonic sector. The M2 receptor subtype was concentrated in the CA2 sector, the subiculum, the rhinal cortices, and the parasubiculum. Putative neural nicotinic receptors, tagged with L‐[3H]‐nicotine, were most concentrated within the presubiculum.
Direct projection of the corticospinal tract to the superficial laminae of the spinal cord in the rat
Authors: Casale Eugene J. , Light Alan R. , Rustioni Aldo
Published: January 2005

The anterograde transport of both wheat germ agglutinin conjugated to horseradish peroxidase and the kidney bean lectin Phaseolus vulgaris leucoagglutinin was utilized to investigate the projection of primary sensorimotor corticospinal tract axons to the superficial laminae of the spinal dorsal horn in the rat. Both methods yielded qualitatively similar patterns of connectivity. Corticospinal tract axons were found to terminate within all laminae on the side contralateral to the injection site. Labeling was most dense within laminae III and IV and medial portions of laminae I, II, and V in the cervical and lumbar enlargements. Labeling in the ventral horn, though present, was relatively less dense. P. vulgaris leucoagglutinin—labeled axons within laminae I and II exhibited boutons en passant and terminaux; many of these axons also terminated or were collaterals of axons that terminated in deeper dorsal horn laminae. Results are discussed with reference to the somatotopic organization of the spinal cord and to a possible role for the cortex in the modulation of nociception within the spinal cord.
Brainstem branches from olivocochlear axons in cats and rodents
Authors: Brown M. C. , Liberman M. C. , Benson T. E. , Ryugo D. K.
Published: January 2005

Horseradish peroxidase was used to label axons of olivocochlear (OC) neurons by intracellular injections in cats and extracellular injections in rodents. These axons arise from cell bodies in the superior olivary complex and project to the cochlea. En route to the cochlea, the thick axons (> 0.7 μm diam.) of medial olivocochlear (MOC) neurons formed collaterals that terminated in the ventral cochlear nucleus, the interstitial nucleus of the vestibular nerve (in cats), and the inferior vestibular nucleus (in rodents). The thin axons (< 0.7 μm diam.), presumed to arise from lateral olivocochlear (LOC) neurons, did not branch near the CN. Within the CN, the MOC collaterals tended to ramify in and near regions with high densities of granule cells, regions also associated with the terminals of type II afferent axons (Brown et al.: J. Comp. Neurol. 278:581–590, '88). These results suggest that those fibers associated peripherally with outer hair cells (MOC efferents and type II afferents) are associated centrally with regions containing granule cells, whereas those fibers associated with inner hair cells peripherally (LOC efferents and type I afferents) are not.
Neuroanatomical studies of the nigrotectal projection in the cat
Authors: Harting J. K. , Huerta M. F. , Hashikawa T. , Weber J. T. , van Lieshout D. P.
Published: January 2005

We have used retrograde and anterograde transport methods to analyze then nigrotectal projection in the cat. This projection arises from both pars reticulata (SNr) and pars lateralis (SNl) and distributes to all cellular laminae of the superior colliculus. This extensive nigrotectal innervation is not a simple, single circuit. Rather it appears to consist of several parallel channels, with each taking origin from a particular zone of the substantia nigra and terminating within specific collicular laminae and/or sublaminae. For instance, only neurons within the SNl project to the stratum griseum superficiale; such neurons also project diffusely to all other tectal laminae. Cells in the most lateral portion of the SNr project to a horizontal, patchy tier in the interface region between the stratum opticum and the stratum griseum intermediale (SGI). Finally, more medially placed neurons within the SNr project to a horizontal patchy tier within the middle of the SGI and to a wedge‐shaped locus in the stratum griseum profundum.

Our findings provide an anatomical substrate for electrophysiological data (Karabelas and Moschovakis: J. Comp. Neurol. 239:309–329, '85) showing a widespread distribution of nigrorecipient tectal neurons in the cat.
Auditory forebrain organization of an australian marsupial, the northern native cat (Dasyurus hallucatus)
Authors: Kudo Motoi , Aitkin Lindsay M. , Nelson John E.
Published: January 2005

Structures and connections of auditory forebrain regions of the Northern native cat, a member of one of the most primitive families among Australian marsupials, have been examined anatomically by using anterograde and retrograde tracing techniques with wheat germ agglutinin‐conjugated horseradish peroxidase (WGA‐HRP) after defining the acoustically responsive neocortical area physiologically.

The structure of the medial geniculate body (MG) was similar to that described in other species. The results obtained from a case with a WGA‐HRP injection into the MG showed that the MG strongly projects to the lateral amygdaloid nucleus (LAmy) and the putamen as well as the auditory neocortex (ACx). Results obtained from other cases with WGA‐HRP injections into the physiologically defined ACx show also that the ACx is connected not only with the ipsilateral MG and the contralateral ACx but also with the LAmy both bilaterally and reciprocally. The regions within the LAmy in which the MG‐LAmy projection fibers terminate largely overlap with those in which the ACx‐LAmy fibers terminate and the LAmy‐ACx pathway originates.

The connectional relationships revealed in the present study‐that the LAmy receives auditory information from the MG and reciprocates auditory information with the ACx bilaterally‐strongly suggest that, in some primitive mammals with small neocortical areas, a specific portion of noncortical telencephalon functions as an auditory center and occupies a relatively large volume of space in the forebrain. It is possible that the auditory sector of noncortical telencephalon in some primitive mammals such as the American Didelphidae and the Australian Dasyuridae is homologous with part of the auditory sector of the dorsal ventricular ridge (DVR) in reptiles and birds and also may have functions shared with the auditory primary and association neocortex in advanced mammals such as the domestic cat and the monkey (Kudo et al., '86a).
GABA‐like immunoreactivity in the cat retina: Electron microscopy
Authors: Chun M. H. , Wässle H.
Published: January 2005

The synaptic organization of the cat retina was studied with antibodies against the GABA‐GA (glutaraldehyde)‐BSA (bovine serum albumin) complex. The postembedding technique combined with immunogold labelling ensured ultrastructural preservation and made identification of synapses possible. The most common putative GABA‐ergic synapses in the inner plexiform layer were amacrine‐to‐bipolar‐cell synapses followed by amacrine‐to‐ganglion‐cell and amacrine‐to‐amacrine‐cell synapses. GABA‐immunoreactive amacrine cells received most of their synaptic input from bipolar cells followed by other amacrine cells. Synapses between two labelled amacrine cells were common. Rod bipolar cells were the predominant input source and also the preferred output target of GABA‐labelled amacrine cells. OFF‐ and ON‐ganglion cells received putative GABA‐ergic synapses at their dendrites in laminas a and b, respectively, and also at their somata.

In the outer plexiform layer, synapses of interplexiform cells onto bipolar cell dendrites expressed GABA‐like immunoreactivity. In both the cone pedicles and the rod spherules, GABA‐like immunoreactivity was observed in horizontal cell processes.
Zonal organization of climbing fiber projections to the uvula in the cat
Authors: Kanda Ken‐Ichi , Sato Yu , Ikarashi Katsumi , Kawasaki Tadashi
Published: January 2005

Climbing fiber projections from the inferior olive to the uvula of the cerebellum were studied in the cat by using retrograde axonal transport of horseradish peroxidase. Following large and small injections into various parts of the uvula, the distribution of labeled cells in the inferior olive was investigated. The findings indicate six longitudinal zones extending throughout the dorsal and ventral uvula: the caudal part of the nucleus beta projects to a most medially located zone (caudal beta zone) with a width of about 0.4 mm; the rostral part of the nucleus beta projects to a zone located at about 0.6 mm from the midline (rostral beta zone); the caudal part of the medial accessory olive (MAO) projects to a zone (caudal MAO zone) located lateral to the rostral beta zone; the dorsomedial cell column projects to a zone (dorsomedial cell column zone) located in the intermediate part of the uvula at about 1.2 mm from the lateral edge of the uvula; the ventral lamella of the principal olive (PO) projects to a zone (ventral lamella of PO zone) about 0.7 mm from the lateral edge of the uvula; finally, the rostral part of the MAO projects to the most lateral zone (rostral MAO zone). These conclusions are in general agreement with those of earlier studies and also provide a more detailed zonal configuration of climbing fiber projections to the uvula.
Differential mossy fiber projections to the dorsal and ventral uvula in the cat
Authors: Sato Yu , Kanda Ken‐Ichi , Ikarashi Katsumi , Kawasaki Tadashi
Published: January 2005

The brainstem afferents to the uvula were studied by using retrograde axonal transport of horseradish peroxidase in the cat. Findings indicate differential afferent projections to the ventral and dorsal uvula. Major sources projecting to the ventral uvula include the caudal parts of the medial and inferior vestibular nuclei, the x‐ and f‐groups of the vestibular nuclei, the dorsal and central parts of the superior vestibular nucleus, the rostral dorsomedial part of the paramedian nucleus of the pontine nuclei, the caudal part of the prepositus hypoglossal nucleus, and the infratrigeminal nucleus. Labeled cells in the vestibular nuclei were 74.7% of the total number of labeled cells in cat 40. On the other hand, the major sources projecting to the dorsal uvula are the peduncular, paramedian, and lateral nuclei of the pontine nuclei at the rostral and intermediate levels. Labeled cells in the pontine nuclei comprised 82.1% of the total number of labeled cells in cat 1. Findings also indicate that the lateral part of the ventral uvula receives input mainly from the pontine nuclei, whereas the medial part of the ventral uvula receives input mainly from the vestibular nuclei. Mediolateral differences were not found for the dorsal uvula. These mossy fiber zones are mediolaterally wide, with a dorsoventral partition in the uvula, in contrast to the climbing fiber zones, which are narrow (about 0.4 mm) and extend longitudinally throughout the uvula.

There are quantitative differences in afferent sources to the ventral uvula and flocculus, both of which belong to the vestibulocerebellum. The largest afferent sources for the ventral uvula are the vestibular nerve and nuclei, whereas the largest sources for the flocculus are the reticular formation and raphe nuclei. These quantitative differences may have an important role for differential functions between the ventral uvula and flocculus. It has been suggested that the ventral uvula controls the velocity storage integrator of the vestibuloocular and optokinetic reflexes, whereas the flocculus is responsible for rapid changes of eye velocity in these reflexes.
Number of neurons in individual laminae of areas 3B, 4γ, and 6aα of the cat cerebral cortex: A comparison with major visual areas
Authors: Beaulieu Clermont , Colonnier Marc
Published: January 2005

The number of neurons per mm3 of tissue (number per volume) and the number under 1 mm2 of cortical surface (number per column) have been estimated for each lamina of seven cytoarchitectural areas of the cat cortex by using a method of size frequency distribution. The areas studied consisted of four visual areas (the binocular and monocular portions of area 17: 17B and 17M; area 18; and the posteromedial lateral suprasylvian area: PMLS), a somatosensory area (3B), and two motor areas (4γ and 6aα).

For both series of measurements, significant differences could be demonstrated among the seven areas studied (one‐way ANOVA; P < .001). The number of neurons per volume in the binocular and monocular regions of area 17 (≈︁ 49,000/mm3) is 85% greater than that of each of the other regions (≈︁ 27,000) with a P < .01 on an a posteriori Tukey test, but there are no significant differences between the latter areas. The number of neurons per column is greater in the binocular portion of area 17 (78,000 under 1 mm2 of cortical surface) than in any other area (P < .01). Other sensory areas (17M, 18, PMLS, and 3B) have fewer neurons per column (P < .01) and the numbers do not vary significantly between these regions (range from 56,100 to 61,900). Areas 4γ and 6aα have still fewer neurons ( ≈︁ 44,000; P < .01, except P < .05 when compared to PMLS). Thus, the seven areas studied fall under three different categories. Motor areas have the smallest number of neurons per column, sensory areas have more, and the greatest number is found in the binocular region of area 17. It appears that these differences are principally (but not exclusively) due to variations in the number of neurons in layer IV: These variations are largely responsible for the differences that we have found between the binocular portion of area 17 and other sensory areas as well as between the binocular portion of area 17 and other sensory areas as well as between the latter and motor areas. We thus cannot confirm the view of Rockel et al. (Brain 103:221–244, ';80) that there is a basic uniformity of the number of neurons per unit of cortical surface in different cortical areas of the cat.
Comparative distribution of three opioid systems in the lower brainstem of the monkey (Macaca fuscata)
Authors: Ibuki Takae , Okamura Hitoshi , Miyazaki Masao , Yanaihara Noboru , Zimmerman Earl A. , Ibata Yasuhiko
Published: January 2005

The regional distribution of the three opioid peptide neuronal systems‐proopiomelanocortin (POMC), proenkephalin A, and proenkephalin B‐was investigated in the lower brainstem of Japanese monkeys (Macaca fuscata) by immunocytochemical techniques. Antiserum to β‐endorphin/β‐lipotropin, [Met]‐enkephalin‐Arg6‐Gly7‐Leu8, and human leumorphin were used to identify the POMC and the proenkephalin A and B systems, respectively. POMC‐related immunoreactive material was not found in the neuronal perikarya in the lower brainstem; reactive fibers and apparent terminals were distributed in the substantia nigra, lemniscus lateralis, midbrain central gray, the nucleus raphes, nucleus parabrachialis lateralis, ventral area of the spinal trigeminal nerve, nucleus tractus solitarii, and in the reticular formation throughout the lower brainstem. Proenkephalin A‐related immunoreactive neuronal perikarya were detected in the central gray, reticular formation, nucleus raphes, trapezoid body, nucleus parabrachialis lateralis and medialis, nucleus spinalis nervi trigemini, nucleus dorsalis nervi vagi, and in the nucleus tractus solitarii. Densely packed immunoreactive fibers were widely distributed in the substantia nigra, nucleus interpeduncularis, nucleus raphes, superior colliculus, periaqueductal central gray, nucleus parabrachialis lateralis and medialis, locus coeruleus, trapezoid body, nuclei cochleares, nucleus spinalis nervi trigemini, tractus spinalis nervi trigemini, nucleus tractus solitarii, nucleus dorsalis nervi vagi, nucleus gracilis, nucleus cuneatus, nucleus cuneatus accessorius, and in the reticular formation throughout the lower brainstem. Neuronal perikarya containing immunoreactive material related to proenkephalin B were found in the periaqueductal central gray, nucleus parabrachialis lateralis and medialis, nucleus tractus solitarii, and nucleus spinalis nervi trigemini. In addition, immunoreactive fibers were detected in the ventral tegmental area, substantia nigra, nucleus parabrachialis lateralis and medialis, nucleus vestibularis lateralis and medialis, and in some areas of the reticular formation. These anatomical findings demonstrate that these three opioid peptide neuronal systems are widely but uniquely distributed in the lower brainstem of the monkey.
Sensory pathways and motoneurons of the proboscis reflex in the suboesophageal ganglion of the honey bee
Authors: Rehder Vincent
Published: January 2005

A morphological description is given for the motoneurons underlying the proboscis extension reflex in the honey bee (Apis mellifera). Sensory neurons from the mandibles and labium were examined and their projection areas were related to those of the motoneurons. Motoneurons are located in the ventral part of the suboesophageal ganglion, have their somata in the hemiganglion ipsilateral to the filled nerve, and send prominent branches through identified ventral commissures into the contralateral hemiganglion. Motoneurons to the same muscle have parallel‐running projections into the contralateral hemiganglion, often parallel‐running neurites, and show vast areas of dendritic overlap. Arborizations of motoneurons are not restricted to their neuromere of origin but invade adjacent neuromeres, resulting in regions of dendritic overlap of motoneurons to different muscles. Sensory fibers from the mouthparts terminate in medio‐ and mediolateral parts of the suboesophageal ganglion, where their arborizations overlap with projections from motoneurons. A few sensory fibers descend in ventral parts of the cervical connective. Although sensory neurons from the mandible are restricted to the ipsilateral hemiganglion, those of the labium also show contralateral branches. These observations are discussed in the context of the suboesophageal ganglion as a ganglion composed of the embryonic fusion of three single neuromeres.
Postembryonic development of serotoninlike immunoreactivity in the central nervous system of the snail, lymnaea stagnalis
Authors: Croll Roger P. , Chiasson Bernard J.
Published: January 2005

Posthatching growth in the pond snail Lymnaea stagnalis involves approximately a 20‐fold increase in the linear dimensions of the ganglia composing the central nervous system. Developmental change within the population of neurons exhibiting serotoninlike immunoreactivity (SLIR) was examined in order to explain this growth in cellular terms. The study indicates that at least two factors contribute to the growth of the nervous system. First, SLIR cells approximately double in number from the 200–250 cells in hatchlings to the complement found in animals approaching sexual maturity. Much of this increase in cell number occurred within identifiable discrete clusters of neurons with different clusters adding cells at different rates and at different times. The number of SLIR cells also increased in more diffuse populations, particularly along the medial aspects of the paired pedal and the right parietal ganglion. No identified cells were added postembryonically. In addition to the increases in neuron numbers, posthatching development in Lymnaea also involves the growth of individual cells. All cells examined showed continuous somatic growth during posthatching development, but different identified cells and different cell clusters were characterized by different rates of relative growth. Together, the results highlight the complexity of postembryonic development in the snail by indicating the temporal and spatial specificity for both cell addition and cell growth within the nervous system.
Forms and measures of adult and developing human corpus callosum: Is there sexual dimorphism?
Authors: Clarke Stephanie , Kraftsik Rudolf , van der Loos Hendrik , Innocenti Giorgio M.
Published: January 2005

The sexual dimorphism of the human corpus callosum (CC) is currently controversial, possibly because of difficulties in morphometric analysis. We have reinvestigated the issue by using morphometric techniques specially designed to yield objective measurements of CC size and shape. The development of the CC was studied with similar techniques in order to investigate whether its final shape and size might be influenced by axonal elimination, as could be expected from previous animal studies.

We have measured the CCs of 32 men and 26 women; 27 male and 19 female CCs were from brain tissue, the others were from magnetic resonance imaging graphs. Women tended to have (1) a smaller cross‐sectional callosal area (CCA); (2) a larger fraction of CCA in the posterior fifth of the CC; (3) more slender CCs; and (4) more bulbous splenia. These differences could not be detected by simple inspection but were demonstrated by measurement and statistical analysis. However, CCA was correlated with the other sexually dimorphic parameters, and the sex‐related differences in the latter became nonsignificant when variations in CCA were factored out or when male and female populations with similar CCA were compared.

In addition, we analyzed CCs of 16 male and 16 female fetuses and of 13 male and 15 female infants and children. This sample ranged in age between 20 weeks of gestation and 14 years but covered in detail the period up to 14 months after birth. CCA increased throughout the latter period but decreased slightly between about 33 weeks of gestation and the beginning of the second postnatal mouth. This decrease coincided with thinning of the CC and a marked increase in bulbosity of the splenium. No sexual dimorphism could be demonstrated until the beginning of the postnatal period. In the age group between birth (at term) and the 14th month, CCA was, as in the adult, larger in males. Unlike in the adults, the CC was longer in males and the bulbosity index was the same in the two sexes. Axonal elimination may play a role in the perinatal pause in CCA growth and in the concomitant changes in callosal shape.
Efferent projections from limbic cortex of the temporal pole to the magnocellular medial dorsal nucleus in the rhesus monkey
Authors: Gower E. C.
Published: January 2005

The efferent projection from the rostral cortices of the temporal lobe to the magnocellular division of the medial dorsal nucleus (MDmc) was studied in the rhesus monkey (Macaca mulatta). The temporal pole region contains four architectonically defined cortical divisions. Medially, the allocortex of the temporal limb of the pyriform cortex is annexed to the temporal lobe neocortices at the limen insulae. Two transitional neocortices, the periallocortical and proisocortical divisions, are situated subjacent to the pyriform area. They make up the largest part of the temporal tip and separate the pyriform cortex from the architecturally more progressive isocortical divisions of the pole found laterally at the rostral ends of the superior and inferior temporal gyri. Neuroanatomical tracers were injected into each of the major divisions of the temporal pole cortex, and the injection site locations were characterized cytoarchitectonically as well as geographically. Injections of tritiated amino acids into pyriform allocortex or into the transitional neocortical fields revealed an efferent projection to the magnocellular medial dorsal nucleus. The terminal field was characterized by a mosaic type of organization and contained discrete zones of axonal termination in which bursts of coarse label surrounded neuronal perikarya and their proximal dendrites. A similar projection was also observed when horseradish peroxidase was injected into the transitional cortices. However, perikarya participating in the terminal clusters were not retrogradely labeled. Intracortical injections restricted to lateral polar isocortex did not result in either anterograde or retrograde transport of label to MDmc. These findings demonstrate a nonreciprocal, corticofugal pathway to MDmc that originates in the phylogenetically older districts of the temporal pole. The conduction of limbic sensory information directly from temporal neocortex to the medial thalamus may play a fundamental role in human and primate memory.
Laminar and segregated distribution of immunoreactivities for some neuropeptides and adenosine deaminase in the superior colliculus of the rat
Authors: Miguel‐Hidalgo Jose‐Javier , Senba Emiko , Matsutani Shinji , Takatsuji Koichi , Tohyama Masaya , Fukui Hiroyuki
Published: January 2005

The distribution and morphology of adenosine deaminase, substance P, leucine‐enkephalin, corticotropin‐releasing factor, and calcitonin gene‐related peptidelike immunoreactive cells and fibers throughout the superior colliculus of the rat were examined by means of the unlabelled‐antibody peroxidase‐antiperoxidase method. Adenosine deaminase immunoreactive cells were found in the stratum opticum and lower stratum griseum superficiale; substance P immunoreactive cells were localized to the upper stratum griseum superficiale, and calcitonin gene‐related peptide immunolabelled neurons were situated in deeper strata. Substance P, leucine‐enkephalin, and calcitonin gene‐related peptide immunoreactive fibers were distributed similarly in their lamination and in their patchlike organization. Corticotropin‐releasing factor immunoreactive fibers were observed evenly throughout all the strata and were fewer in the stratum griseum superficiale.

These findings suggest that, as in afferent modules and segregated efferents of the mammalian superior colliculus, the cells and fibers containing neuroactive substances and neuroactive substance‐related enzymes also show a segregated and laminar distribution.
Endbulbs of held and spherical bushy cells in cats: Morphological correlates with physiological properties
Authors: Sento Seishiro , Ryugo David K.
Published: January 2005

Single auditory nerve fibers of type I spiral ganglion cells in cats were electrophysiologically characterized by recording with micropipettes inserted into the axon and then labeled by intracellular injections of horseradish peroxidase (HRP) through the same pipettes. This method for staining and studying single neurons allowed us to describe structure‐function relationships for labeled endbulbs of Held and the somata of their postsynaptic spherical bushy cells. The silhouette areas of terminal endbulbs and the corresponding somata of spherical bushy cells were determined by planimetry from drawings made with a light microscope and drawing tube. On the presynaptic side, endbulb area is related to fiber characteristic frequency (CF, the frequency to which a fiber is most sensitive) such that the largest endbulbs arise from fibers having CFs between 1 and 4 kHz; smaller endbulbs can arise from fibers of any CF. Endbulb area is not correlated with fiber spontaneous discharge rate (SR). Dividing the endbulb's silhouette area by its silhouette perimeter, however, yields a “form factor” that is a reliable indicator of fiber SR: Endbulbs from fibers of low‐medium SR (≤18 spikes/second) have form factor values less than 0.52, whereas endbulbs of high SR fibers (>18 spikes/second) have values greater than 0.52. This form factor should therefore be predictive of SR groupings in auditory fibers for which physiological data are not available.

On the postsynaptic side, the somata of spherical bushy cells receiving endbulbs from low‐medium SR fibers are on average smaller than those receiving endbulbs from high SR fibers. In contrast, the nuclei of the spherical bushy cells are the same size regardless of presynaptic fiber SR. Some of the effects of low‐medium SR fibers on their postsynaptic targets, when compared to those of high SR fibers, appear to be mimicked by effects of experimentally induced deprivation.
Distribution of neuropeptidelike immunoreactivities in the guinea pig olfactory bulb
Authors: Matsutani Shinji , Senba Emiko , Tohyama Masaya
Published: January 2005

The distribution of neuropeptidelike immunoreactivities in the adult guinea pig olfactory bulb was studied immunohistochemically with antiseraraised against neurotensin (NT), substance P (SP), methionine‐enkephalin‐Arg6‐Gly7‐Leu8 (ENK), somatostatin (SOM), neuropeptide Y (NPY), and cholecystokinin‐8 (CCK).

In the main olfactory bulb, NT‐like immunoreactive (NT‐IR) neurons were found among periglomerular cells. In addition, a few periglomerular cells showed ENK‐like immunoreactivity. Granule cells displaying SP‐ or ENK‐like immunoreactivities and short axon cells with SOM‐ or NPY‐like immunoreactivities were observed in the deeper half of the granule cell layer. SOM‐IR short axon cells were also seen in the external plexiform layer. Dense NT‐ or NPY‐IR fibers were distributed in superficial lamina of the granule cell layer, and sparse SP‐ or CCK‐IR fibers were found in the glomerular layer.

In the accessory olfactory bulb, some mitral, periglomerular, and granule cells showed NT‐like immunoreactivity. SP‐ or ENK‐IR granule cells were also observed.

These results are discussed in relation to laminar organization of the olfactory bulb. The most characteristic features of peptide distribution in guinea pigs, as compared with that of rats in previous studies, were the relative abundance of NT‐IR structures and the lack of SP‐and CCK‐IR juxtaglomerular and tufted cells.
Hormonal control of neuron number in sexually dimorphic spinal nuclei of the rat: I. Testosterone‐regulated death in the dorsolateral nucleus
Authors: Sengelaub D. R. , Arnold A. P.
Published: January 2005

Adult male rats have substantially more motoneurons than do females in two motor nuclei in the lumbar spinal cord: the spinal nucleus of the bulbocavernosus (SNB) and the dorsolateral nucleus (DLN). Previous studies of the development of the SNB revealed that the sex difference in SNB motoneuron number is established through a differential motoneuron death which is under the control of androgens. In this study the development of the sexually dimorphic DLN was examined to test the hypothesis that early androgen action also determines the sex difference in DLN motoneuron number by regulating normally occurring motoneuron death. Because SNB motoneurons may migrate from the DLN, quantitative examination of DLN development was necessary in order to understand more completely the cellular mechanisms contributing to the establishment of dimorphic motoneuron number.

At 5 days before birth, the number of motoneurons in the DLN is significantly higher than in adulthood in both sexes, and no sex difference is present. There is a decrease in motoneuron numbers prenatally in both sexes, which is consistent with the emigration of presumptive SNB motoneurons. Motoneuron number declines differentially through the first week of postnatal life and by postnatal day 10 motoneuron numbers are in the adult range and the sex difference is fully expressed. Females lose significantly more DLN motoneurons than males through a differential death as revealed by the higher incidence of degenerating cell profiles. Females treated with testosterone propionate have a male‐typical motoneuron loss and incidence of degenerating cells. These results indicate that steroid hormones establish the sex difference in DLN motoneuron number by regulating normally occurring cell death.