bluuebunny/crossref_metadata_2025_split huggingface dataset:
Axons of the dorsal division of the medial geniculate body of the cat: A study with the rapid Golgi method
Authors: Winner Jeffery A. , Morest D. Kent 
Published: January 2005

AbstractThe arrangement of eight groups of axons afferent to the nuclei of the dorsal division of the medial geniculate body is described in rapid Golgi impregnations from young cats. Three kinds of axons travel predominantly in the brachium of the inferior colliculus and enter the medial geniculate body ventromedially: group I, thin axons resembling ivy tendrils ending along dendrites; group II, thicker axons with a sinuous course and few branches group IV, coarse thick axons with grumous collaterals and massive peridendritic terminals near principal cells and interneurons. Three kinds of axons enter from the parabrachial region and pass laterally group III, very thin axons with many collaterals forming dense terminal nests; group V, runcinate axons with sparse, thin collaterals; group VI, either medium‐sized (group VIa) or thin (group VIb) smooth axons, perhaps corticofugal, and ending near principal neuron dendrites; group VII, thick axons, entering from the auditory radiation, with large, grapelike terminal arbors and group VIII, thin and forming peridendritic festoons on principal cells after entering from the brachium of the superior colliculus.There appears to be some, though not complete, segregation of axons in the dorsal division nuclei. Thus axons of groups I, III, IV, and VI are found in each nucleus, although group VI axons are conspicuous in the superficial dorsal nucleus, and group IV endings are much more elaborate in the dorsal and deep dorsal nuclei than in the superficial dorsal nucleus. Each axon type has a specific pattern of terminal branches, which contributes to the texture of the neuropil in each nucleus. Golgi type II axons accentuate these textural differences. Thus each nucleus has a specific pattern of neuropil by virtue of the relative proportions of the different groups of axons ending there and the density and architecture of the axonal plexus. For example, both the dorsal nucleus and the deep dorsal nucleus receive the same groups of afferent axons, but the axonal plexus is more diffusely and evenly distributed in the dorsal nucleus, whereas the neuropil of the deep dorsal nucleus is highlighted by aggregates of grumous endings, more irregularities in the distribution of the axonal plexus, and many more fibers of passage.The extrinsic axons in the dorsal division come from the inferior and superior colliculi, the lateral tegmental system of the midbrain, and the cerebral cortex. Since there is variation in the density and diversity of input in the various parts of the dorsal division, as well as differences in the intrinsic organization of nuclei, there might also be functional distinctions between subdivisions. This hypothesis is supported by the existence in each nucleus of cell types unique to it, different patterns of cortical projections to and from each nucleus, and dissimilar midbrain inputs. The synaptic organization of the dorsal division suggests a functional heterogeneity in this part of the medial geniculate body.
Growth and death of cells of the mesencephalic fifth nucleus in Rana pipiens larvae
Authors: Kollros Jerry J. 
Published: January 2005

AbstractPositions, numbers, and nuclear sizes of mesencephalic fifth nucleus M‐V) cells were determined in Rana pipiens lervae in stages XIII through the end of metamorphosis at stage XXV, in a few just postmetamorphic juveniles, and in adults. M‐V cells are found throughout the tectum, with the greatest concentrations just anterior to each optic ventricle, and along the medioanterior aspect of each ventricle. Some cells lie below these levels, ventricle; a very few cells occur in the anterior medullary velum and in the adjacent anterior cerebellum. Up to 879 M‐V cells were seen in single animals in stages XIV–XVIII, with mean values near 650 cells. Pyknotic M‐V cells appear in all stages from XVII through XXV, and possibly in the youngest juveniles. Peak rates of cell loss occur at stage XXI, some 4–5 days after the forelimbs have emerged. Mean postmetamorphic cell numbers are about 350, suggesting an average M‐V cells loss of 300 per animal. Nuclear cross‐sectional areas are 72 m̈m2 at stage XIII, slightly above the size of such cells in hypophysectomized tadpoles. Nuclear growth is progressive to 102–111 m̈m2 at stages XXI–XXV. Adult sizes increase to a mean of 121 m̈m2. Hypophysectomized animals display pyknotic cells only after the tadpoles have been strongly stimulated by thyroid hormone, as demonstrated by significant growth of the legs and of the M‐V cells themselves.
The morphology of two groups of spiking local interneurons in the metathoracic ganglion of the locust
Authors: Siegler M. V. S. , Burrows M. 
Published: January 2005

AbstractTwo bilaterally symmetrical groups of spiking local interneurons are described in a segmental ganglion of the locust. Interneurons in both groups are excited by specific sets of sensory receptors on one leg. The cell bodies of the anterior‐lateral group lie amongst approximately 40 small cell bodies at the anterior of the ganglion, close to the lateral edge of an anterior connective. Interneurons in this group have primary neuritis in Ventral Commisure I (VCI), and dorsoventral processes in the Oblique Tract, which divide the extensive neuropilar branches into distinct ventral and dorsal regions. Cell bodies of the midline group lie amongst a group of approximately 100 small cell bodies near the ventral midline. Interneurons in this group have primary neuritis in Ventral Commisure II (VCII), and dorsoventral processes in the Perpendicular Tract, which divide the neuropilar branches into dorsal and ventral regions. The ventral branches of interneurons in both groups are numerous and of uniform texture, whereas the dorsal branches are sparse and varicose. The ventral branches project to the same ventral areas of neuropil as the afferent from some hairs on the hind leg. The dorsal branches of midline interneuron and the branches of leg motor neuron that it affects project to the same dorsal area of neuropil. Some midline interneurons receive direct inputs from leg hair afferent and make direct connections with leg motor neurons.
Demonstration of a sexual dimorphism in the distribution of serotonin‐immunoreactive fibers in the medial preoptic nucleus of the rat
Authors: Simerly R. B. , Swanson L. W. , Gorski R. A. 
Published: January 2005

AbstractThe distribution of serotonergic fibers in the medial preoptic nucleus (MPN) and adjacent areas was evaluated with an indirect immunohistochemical method in the normal adult male and female albino rat. Sections through the MPN were processed for immunofluorescence with an antiserum directed toward serotonin and were counterstained with the fluorescent Nissl stain ethidium bromide. The distribution of serotonin‐immunoreactive fibers in the MPN was correlated with cytoarchitectonic features of the nucleus. On the basis of the results, we have subdivided the MPN into three parts: a medial cell‐dense part (MPNm), a lateral cell‐sparse part (MPN1), and a central very cell‐dense part (MPNc) that is embedded in the medial part. The MPNc corresponds to the sexually dimorphic nucleus of the preoptic area identified by Gorski et al. (′80). A marked sexual dimorphism was found in the relative size of each part of the MPN. In the male, the volumes of the cell‐dense MPNm and MPNc appear to be notably larger, while in the female more than half of the nucleus is occupied by the cell‐sparse lateral part. The MPN as a whole appears to be slightly larger in the male. Each subdivision contains a characteristic pattern of serotonin‐immunoreactive fibers. In each sex, the MPN is surrounded by a low to medium density of serotonin‐stained fibers, while the MPN1 is filled with a dense plexus of varicose immunoreactive fibers. In contrast, the MPNm contains a low density of stained fibers, and the MPNc is virtually devoid of serotonin‐stained fibers. Since both the MPNm and the MPNc are larger in the male, a correspondingly larger region of very low serotonin‐stained fiber density is found in the male. It appears then that the MPN is a sexually dimorphic complex composed of at least three cytoarchitectonically distinct subdivisions, each of which contains a characteristic density of serotonin‐immunoreactive fibers.
Light and electron microscopic evidence for a direct corticospinal projection to superficial laminae of the dorsal horn in cats and monkeys
Authors: Cheema S. S. , Rustioni A. , Whitsel B. L. 
Published: January 2005

AbstractThe anterograde transport of horseradish peroxidase (HRP) and wheat germ agglutin conjugated to horseradish peroxidase (WGA‐HRP) was employed in cats and monkeys to investigate, at both the light and electron microscopical levels, the contribution of the corticospinal tract (CST) to the superficial laminae of the dorsal horn.At the light microscopic level, this approach not only confirmed the previously documented pattern of CST termination, but also revealed a sparse projection to laminae VIII and IX of the cat and a prominent projection to the most superficial parts of the brachial dorsal horn, i.e., laminae I and II. Discrete injections involving particular cytoarchitectonic areas (4, 3a, 3b, and 1–2) of monkeys showed that the superficial laminae receive their corticofugal inputs primarily from areas 3b, 1, and 2.Electron microscopic observations were made on CST fibers and boutons which were labelled, after histochemical processing, with the reaction product of anterogradely transported WGA‐HRP. The labelled fibers in the superficial laminae were small (± 0.5 μm), and boutons established mainly axodendritic contacts, contained mostly clear, spherical, or pleomorphic vesicles, but sometimes also displayed dense core vesicles. These boutons were primarily in lamina I and outer lamina II, but not in inner lamina II.The possible role of n direct monosynaptic pathway from the cerebral cortex to the superficial laminae of the dorsal horn is discussed in relation to the previous reports that laminae I and II play a significant role in nociception.
Serotoninergic terminals: Ultrastructure and synaptic interaction with catecholamine‐containing neurons in the medial nuclei of the solitary tracts
Authors: Pickel Virginia M. , Joh Tong H. , Chan June , Beaudet Alain 
Published: January 2005

AbstractThe ultrastructural morphology of serotoninergic terminals and their synaptic relation with catecholaminergic neurons were examined in the medial nuclei of the solitary tracts (m‐NTS) using combined autoradiographic and immunocytochemical methods. Adult rats were pretreated with a monoamine oxidase inhibitor and subjected to a 2‐hour intraventricular infusion of 50 nM tritiated 5‐hydroxytryptamine (3H‐5HT). At the termination of the infusion, the brains were fixed by aortic arch perfusion with a mixture of 4% paraformaldehyde and 0.5% glutaraldehyde. Coronal Vibratome sections through the NTS and more rostral raphe nuclei were immunocytochemically labeled with specific antiserum to serotonin or tyrosine hydroxylase and then processed for autoradiography. By light microscopy, concentrations of reduced silver grains indicating uptake of 3H‐5HT usually paralleled the localization of peroxidase immunoreactivity for serotonin in neuronal perikarya of the rostral raphe nuclei and in varicosities in the brainstem. The 3H‐5HT‐containing varicosities were found throughout the medial and commissural portions of the NTS, where they were frequently associated with processes showing immunoreactivity for the catecholamine‐synthesizing enzyme tyrosine hydroxylase. Ultrastructural examination of the m‐NTS revealed that the silver grains for 3H‐5HT were accumulated over axon terminals. The 5HT‐labeled terminals contained a heterogeneous population of vesicles and formed both symmetric and asymmetric synapses with dendrites. The recipient dendrites were either unlabeled or showed immunoreactivity for tyrosine hydroxylase. These findings support a direct serotoninergic modulation of catecholaminergic neurons within the rat m‐NTS.
A study of the reciprocal connections between the septum and the entorhinal area using anterograde and retrograde axonal transport methods in the rat brain
Authors: Alonso Angel , Köhler Christer 
Published: January 2005

AbstractThe reciprocal connections between the septum and the entorhinal area (EA) was studied in the rat brain using antero‐ and retrograde axonal transport methods. After injections of large volumes (2 × 100 nl) of horseradish peroxidase (HRP) conjugated to wheat‐germ agglutinin (WGA) into the medial septum (MS) and the diagonal band of Broca (dbB), anterogradely transported HRP‐WGA was found primarily in layers II and IV of the medial and lateral EA. Injections of HRP‐WGA (50–100 nl) or fluorescent dyes (50–100 nl) into different parts of the retrohippocampal region resulted in labeling, by retrograde axonal transport, of cells in the MS and dbB, both ipsi‐ and contralateral to the injected hemisphere. The labeled cells were either small (long axis of soma: 10–15 μm), round, and oval, or medium (15–25 μm) to large (25–35 μm) of fusiform or multipolar shape. By using the method of retrograde fluorescent double labeling, the septal afferents to the EA were found to give off collaterals to other parts of the hippocampal region. A much smaller number of septal cells appeared to send bilateral projections to the EA of both hemispheres. Studies employing retrograde transport of HRP in combination with acetylcholinesterase (AChE) histochemistry on the same tissue section showed that, while a large number of cells projecting to the EA contain AChE, many projecting cells are devoid of AChE reaction products. These findings suggest that the septo‐entorhinal projection consists of a cholinergic as well as a noncholinergic component.The entorhinal efferents to the septum were studied after injections of HRP‐WGA into different parts of the retrohippocampal region. Labeled fibers could be traced through the fimbria to their terminal fields in the intermediate parts of the lateral septal nucleus and to the most lateral aspect of the vertical limb of the dbB. The cells giving rise to this projection were situated in layer IV of the medial and layers II through V of the lateral EA. Taken together, the present findings demonstrate a close anatomical relationship between the septum and the entorhinal area, in addition to the better known connections between the septum and the Ammon's horn.
Somatotopy within the medullary electrosensory nucleus of the little skate, Raja erinacea
Authors: Bodznick David , Schmidt Anne W. 
Published: January 2005

AbstractThe dorsal octavolateral nucleus is the primary electrosensory nucleus in the elasmobranch medulla. We have studied the topographic organization of electrosensory afferent projections within the dorsal nucleus of the little skate, Raja erinacea, by anatomical (HRP) and physiological experiments.The electrosensory organs (ampullae of Lorenzini) in skates are located in four groups on each side of the body, and each group is innervated by a separate ramus of the anterior lateral line nerve (ALLN). Transganglionic transport of HRP in individual rami demonstrated that electroreceptor afferents in each ramus project to a separate, nonoverlapping division of the central zone of the ipsilateral dorsal nucleus. These divisions, which are distinct areas separated by compact cell plates, are somatopically arranged. The volume of each division of the dorsal nucleus that is related to a single ramus is proportional to the number of ampullae innervated by the ramus, but not to the body surface area on which the receptors are distributed. Nearly one‐half of the nucleus is devoted to electrosensory inputs from the buccal and superficial ophthalmic ampullae concentrated in a small area on the ventral surface of the head rostral to the mouth. Multiple and single unit recordings demonstrated that adjacent cells in the nucleus have similar receptive fields on the body surface and revealed a detailed point‐to‐point somatotopy within the nucleus. With threshold stimuli most single units have ipsilateral receptive fields made up by excitatory inputs from 2–5 ampullary organs.The somatotopy within the mechanosensory medial nucleus, also revealed by the HRP fills of individual ALLN rami, appears less rigid than that in the dorsal nucleus, as extensive overlap is present in the terminal fields of separate ALLN rami.
Temporal pattern of HRP spread from an iontophoretic deposit site and description of a new HRP‐gel implant method
Authors: Fahrbach Susan E. , Morrell Joan I. , Pfaff Donald W. 
Published: January 2005

AbstractIn the course of examining afferents to ventromedial hypothalamic (VMH) neurons using horseradish peroxidase (HRP), we needed to know how close to an iontophoretic deposit site neurons could be proved to be retrogradely labeled. In evaluating cells near but clearly outside HRP deposit sites visualized after a 24‐hour survival period, for example, neurons which had been filled with HRP by somal or dendritic uptake could not be treated as retrogradely labeled and thus would not add to studies of intrahypothalamic connections.Rats were given standardized iontophoretic applications of HRP into VMH (continuous positive current 0.25 μamp for 1 minute) and sacrificed after 5 or 15 minutes, 1, 4, 8, 12, or 24 hours in order to examine the pattern of HRP spread. The chromogen was tetramethylbenzidine. The volume of the application site visualized at 24 hours was less than 10% of maximum site size, which occurred at 1 hour. Since the cells located within the maximal spread boundary are candidates for nonretrograde labeling, HRP data on local connections obtained even from small iontophoretic deposits must be evaluated in the light of the demonstrated expansion and subsequent contraction of the application site. These results may also hold implications for the precision with which distant connections can be examined using the HRP retrograde method, as sites that appear discrete when visualized after 24‐hour survival may have overlapped at shorter times post‐iontophoresis.Incorporation of retrograde tracers into polyacrylamide gels provides an effective alternative to pressure injection or iontophoresis of aqueous tracer solutions. We describe a method for filling micropipettes with HRP‐polyacrylamide gel. The pipettes are then implanted into brain sites to provide a confined pool of HRP. With postimplantation survival of 24 hour or longer, this method produces sites comparable in size to iontophoretic sites examined at 24 hours and results in improved retrograde labeling. Some results obtained with this method concerning the afferent connections of the dorsomedial hypothalamus are described.
Acetylcholinesterase‐immunoreactive axonal network in monkey visual cortex
Authors: Hedreen John C. , Uhl George R. , Bacon Sarah J. , Fambrough Douglas M. , Price Donald L. 
Published: January 2005

AbstractImmunocytochemistry with antibodies to human erythrocyte acetylcholinesterase (AChE) was used to demonstrate axons containing this enzyme in the visual cortex (area 17) of macaques. AChE‐positive fibers were most dense in layers I, IIIB, IV, and VIB of Hassler and Wagner (I, IVA, IVC, and VIB of Brodmann) with three strata of more sparsely distributed fibers (layers II‐IIIA, IIIC, and V‐VIA of Hassler and Wagner [II‐III, IVB, and V‐VIA of Brodmann]). Layer I contained the most dense plexus of AChE‐positive axons, oriented horizontally. Horizontally oriented axons were also located in layers IIIB, IIIC, IV, and V of Hassler and Wagner (IVA, IVB, IVC, and V of Brodmann). Layer VIB contained axons of variable orientation, apparently afferent to cortex. Moderately stained neuronal perikarya were occasionally encountered in layer VIB and superficial white matter, but no intensely stained neurons were seen.
Neurohemal contact in the internal zone of the rabbit median eminence
Authors: Page Robert B. , Dovey‐Hartman Barbara J. 
Published: January 2005

AbstractThe concept of neurosecretion as the mechanism by which neural control of adenohypophyseal function is accomplished was based on the observation that long capillary loops penetrate deeply into the supra‐opticohypophyseal tract as it passes through the median eminence internal zone. However, neural contact upon these capillary loops has not been demonstrated in the mammalian median eminence. The present transmission electron microscopic investigation of the rabbit median eminence demonstrates neurohemal contact in the median eminence internal zone. Axons containing small lucent vesicles 53.3 ± 3.28 nm in diameter (mean ± SEM) or small lucent and large granular vesicles with a mean diameter of 122.4 (±3.28 nm) in their terminals make neurohemal contact with capillary loops in the internal zone and form a cuff about them. These terminals resemble terminals found in the external zone. Intravenous injection of the false neurotransmitter 5‐hydroxydopamine (5‐OH‐DA) renders small lucent vesicles granular in both the external and internal zone. The effect of 5‐OH‐DA injecting is abolished by concurrent reserpine administration. Whereas large granular vesicles in many terminals become lucent after reserpine administration, in others they remained electron dense. Viewed in the light of previous studies our findings suggest that the internal plexus arises from the external plexus and invaginates the neuropil carrying connective tissue and parvicellular axon terminals of aminergic and peptidergic systems from the external zone into the internal zone, that some elements making neurohemal contact with long capillary loops are terminals of the noradrenergic reticular infundibular tract arising outside the hypothalamus in the brainstem, and that long capillary loops form a system of repeating microvascular modules which markedly increase the surface available for neurohemal contact.