bluuebunny/crossref_metadata_2025_split huggingface dataset:
The afferent connections of the main and the accessory olfactory bulb formations in the rat: An experimental HRP‐study
Authors: de Olmos Jose , Hardy Hay , Heimer Lennart 
Published: May 2005

AbstractThe afferent connections of the main and accessory olfactory bulbs in the rat were examined by injecting horseradish peroxidase (HRP) into one or the other of these structures either by microelectrophoresis or by hydraulic pressure. Alternate sections were stained with newly developed HRP‐procedures using either benzidine dihydrochloride (de Olmos and Heimer, '77) or tetramethyl‐benzidine.Eighteen to twenty‐four hours after unilateral HRP injections confined to the main olfactory bulb, a large number of HRP‐labeled perikaria appeared in the following telencephalic structures on the ipsilateral side: All portions of the anterior olfactory nucleus (AON) except its external part, the lateral transitional field (LT) between AON and the paleocortex, the whole extent of the primary olfactory cortex (POC); The medial forebrain bundle area deep to the olfactory tubercle, the nucleus of the horizontal limb of the diagonal band (NHDB) and the nucleus of the lateral olfactory tract (NLOT). A moderate to small number of labeled cells, furthermore, were seen in the dorsal (DT) and medial (MT) transition fields, the ventral praecommissural hippocampus (tt2), the ventral superficial part of the nucleus of the vertical limb of the diagonal band (NVDB), the sublenticular part of the substantia innominata (SI), the anterior amygdaloid area, the posterolateral cortical amygdaloid nucleus (C2) and the transition region (28 L') between the olfactory cortex and the lateral entorhinal area proper. On the contralateral side a large number of labeled cells were found in all parts of the AON, with especially heavy labeling in its external part. A moderate number of labeled cells could also be detected in the lateral transition field (LT) and the NLOT.In the diencephalon and the brain stem a moderate number of HRP‐labeled perikaria were observed in the dorsal, perifornical, and lateral hypothalamus, as well as in locus coeruleus and the dorsal and medial raphae nuclei.Following large HRP injections in the main olfactory bulb a moderate to small number of labeled cells were seen also in the posterior and premammillary hypothalamus and in field CA1 of the retrocommissural hippocampus on the ipsilateral side, as well as in POC on the contralateral side. It is possible, however, that the uptake of label took place in an undetected pool of HRP in the very rostral part of AON rather than in the olfactory bulb.HRP injections in the accessory olfactory bulb resulted in labeled neurons in the posterior ventro‐lateral part of the bed nucleus of the stria terminalis, the nucleus of the accessory olfactory tract, the rostrodorsal portions of the medial amygdaloid nucleus, and whole extent of the posteromedial cortical amygdaloid nucleus (C3) on the ipsilateral side. A few lightly labeled cells were seen also in the contralateral C3.
An autoradiographic study of the commissural and ipsilateral hippocampo‐dentate projections in the adult rat
Authors: Fricke R. , Cowan W. M. 
Published: May 2005

AbstractThe distribution of the associational and commissural afferents to the inner one‐fourth of the molecular layer of the dentate gyrus of the rat, has been studied autoradiographically following small injections of 3H‐proline into the hilar region of the dentate (from which both groups of afferents arise). Different patterns of axonal labeling are observed after injections into the temporal (i.e., caudal), middle, or septal (rostral) thirds of the hippocampus. Thus after temporal injections labeled commissural and associational afferents are found only in the caudal third of the dentate gyrus, and the grain densities observed on the two sides are markedly asymmetrical around the short, or transverse, axis of the dentate. On the other hand, injections into the middle third of the hippocampus lead to extensive labeling of the commissural and associational afferents throughout the rostral two‐thirds of the dentate gyrus, and their distribution, as judged by grain density estimates, is symmetrical on the two sides. Septal injections label fibers over the rostral half of the dentate, and again the labeling pattern of the two sides is asymmetrical (but in the reverse pattern from that seen after temporal injections).These distinctive patterns in the distribution of the two classes of afferents can generally be accounted for on the following assumptions: (1) the commissural and associational afferents share a common cytochemical specificity; (2) they compete with each other for the limited number of synaptic sites available upon the proximal portions of the granule cells; (3) the granule cells are generated along two distinct morphogenetic gradients: from the temporal to the septal pole of the dentate gyrus, and from the tip of its dorsal (or external) to the tip of its ventral (internal) blade; and (4) the first fibers to arrive monopolize the majority of the available synaptic sites, and those that reach their target field later, synapse predominantly upon the last‐formed granule cell dendrites. To this extent our findings are consonant with the “temporal hypothesis” first formulated by Gottlieb and Cowan ('72). However, to account for the restricted distribution of afferents from the temporal part of the hippocampus, it is necessary to further postulate that there is some degree of topographic (or region‐to‐region) specificity in the ipsilateral and contralateral hippocampodentate projections.
Categories of axons in mammalian rami communicantes, Part II
Authors: Coggeshall Richard E. , Galbraith Samuel L. 
Published: May 2005

AbstractThe Mammalian rami communicantes consist of preganglionic, postganglionic and sensory axons. The present study focusses on the number of sensory axons in the midthoracic rami communicantes in the cat. The conclusions are that the white rami contain approximately 250 myelinated and 200 unmyelinated sensory axons and the grey rami 4 to 5 myelinated and 20 to 25 unmyelinated sensory axons. A previous study determined the numbers of pre‐ and postganglionic fibers in these same rami. Thus the total number of axons in these rami are as follows: for the grey rami there are: (1) 3,000 to 5,000 unmyelinated postganglionic axons, (2) 25 myelinated postganglionic axons, (3) 20 to 25 unmyelinated sensory axons and; (4) 4 to 5 myelinated sensory axons; and for the white rami there are approximately: (1) 1,000 unmyelinated preganglionic axons, (2) 1,500 myelinated preganglionic axons, (3) 2,000 unmyelinated postganglionic axons, (4) 250 unmyelinated sensory axons and (5) 200 myelinated sensory axons. The implications of these findings are discussed.
The ultrastructure of the basilar papilla of the chick
Authors: Hirokawa Nobutaka 
Published: May 2005

AbstractThe basilar papilla of the chicken was studied by transmission and scanning electron microscopy. It is composed of two distinct types of hair cells, a tall hair cell (THC) and a short hair cell (SHC). Gradual transitions exist between these two forms. The THC occurs mainly in the anterior part of the neuroepithelium and is situated on the superior fibro‐cartilagenous plate, while the SHC dominates in the posterior part and is found on the free basilar membrane. The THC is a tall columnar cell with an elongated hexagonal apical surface. One kinocilium and 150 to 220 stereocilia protrude from the center of its surface. The THC makes synaptic contact with several large afferent nerve terminals and with small bouton‐shaped efferent terminals. The SHC is short and thick, having a much wider surface area than the THC. From the inferior part of the surface of the SHC 90 to 120 stereocilia protrude, whereas the kinocilium is lacking. The nucleus is located near the base of the cell. Small afferent nerve terminals and extremely large efferent nerve endings synapse with the SHC.
Morphological and electrophysiological characteristics of projection neurons in the nucleus interpositus of the cat cerebellum
Authors: McCrea R. A. , Bishop G. A. , Kitai S. T. 
Published: May 2005

AbstractThe populations of neurons in the nucleus interpositus (IP) of the cat cerebellum which project to the ventral lateral nucleus of the thalamus (VL), the red nucleus (RN), the nucleus reticularis tegmenti pontis (NRTP), the pontine nuclei (PN), the inferior olive (IO), and the cerebellar cortex were identified by intracellular and extracellular injections of HRP and studied electrophysiologically.When HRP was simultaneously injected into the VL, RN, and IO, over 95% of the neurons in the IP nuclei were labeled; indicating that there are few, if any, local circuit neurons. The vast majority (86%) of the larger IP neurons (soma length ≥ 20 μm) project rostrally to the RN and thalamus. These neurons typically have long, relatively spine free dendrites and axons which in a few cases gave rise to recurrent collaterals. Two intracellularly stained projection neurons which had exceptionally long spiny dendrites had axons which gave rise to nucleocortical collaterals in addition to several local collaterals. IP neurons projecting to the NRTP and PN were located primarily in the lateral aspect of the nucleus interpositus anterior. Electrophysiological experiments established that neurons projecting to the NRTP also project to the VL. The IP neurons projecting to the IO have small fusiform or multipolar somata, long thin dendrites, and receive excitatory inputs from the IO. At least 73% of the small neurons in the IP project to the IO, and some of these, in addition, project to the VL.There are at least three morphologically distinguishable populations of projection neurons in the IP, large VL projection neurons, small IO projection neurons, and neurons with nucleocortical collaterals. The projection of the IP to diverse regions of the brain is accomplished mainly by axon collateralization, but regional and morphological specialization also play a role in the organization of the output of the IP.
Organization of corticocortical connections in the parietal cortex of the rat
Authors: Akers Rebecca M. , Killackey Herbert P. 
Published: May 2005

AbstractAn analysis based on Nissl, anterograde degeneration, and sucinic dehydrogenase histochemical techniques reveals that there are two distinct regions of parietal cortex which are characterized by different cytoarchitectonic features and anatomical connections. The “granular” cortical zone possesses a well‐defined fourth layer composed of small, densely‐packed cells, receives dense projections from the ventral posterior nucleus of the thalamus, and is essentially free of callosal inputs. “Agranular” cortical areas which surround or lie embedded within the granular zone lack a well‐defined fourth layer, receive sparse projection from the ventral posterior nucleus, but send and receive extensive callosal projections. These findings suggest that thalamic and callosal projections to the parietal cortex maintain a pattern of areal segregation. The granular cortical zone, which apparently corresponds to SmI, projects ipsilaterally to motor cortex, SmII, and adjacent agranular areas. The superficial layers of the granular cortex also project heavily upon the underlying layer V. This intracortical projection is not organized in discrete clusters within the “barrel field” cortex. This suggests that the specialized organization of thalamic afferents and granule cells within the “barrel field” is not maintained in the intracortical circuitry of this region.
The hypothalamic magnocellular system of the rhesus monkey: An immunocytochemical study
Authors: Lobo Antunes J. , Zimmerman Earl A. 
Published: May 2005

AbstractThe hypothalamic magnocellular system of the adult female rhesus monkey is studied here, using immunoperoxidase technique and antisera to estrogen stimulated neurophysin (ESN), nicotine stimulated neurophysin (NSN), oxytocin (OT) and vasopressin (VP). These observations confirm and enlarge previous descriptions by others using Gomori techniques.It is apparent from this study that the magnocellular system spreads through a broader area than is generally accepted. A group of cells ventral to the head of the caudate nucleus and medial to the internal capsule is described.The general orientation of the nuclei and their tracts can only be appreciated when coronal, horizontal and sagittal sections are compared. Our observations suggest that the supraoptic nucleus is made up of a single group of cells that straddles the optic pathways, and is not divided in three segments, as it is generally described. It is also shown that the rostral extensions of the paraventricular and supraoptic nuclei merge above the optic chiasm.Cells containing ESN/OT and NSN/VP are evenly dispersed in the paraventricular nucleus but a topographical arrangement is present in the supraoptic nucleus.The magnocellular nuclei project to the organum vasculosum of the lamina terminalis, zona externa of the median eminence and pars nervosa of the pituitary gland. Reactive fibers were also seen within islets of cells from the pars in termedia located inside the pars nervosa.A globular structure containing small blood vessels surrounded by positive fibers was noticed protruding into the floor of the third ventricle, at the level of the median eminence.
Identified neurons in mouse smi cortex which are postsynaptic to thalamocortical axon terminals: A combined golgi‐electron microscopic and degeneration study
Authors: White Edward L. 
Published: May 2005

AbstractA recently developed Golgi‐electron microscopic technique (Fairén et al., '77) has been used to identify neurons in mouse SmI cortex which that thalamic axon terminals synapsed with dendrites of several distinct neuronal types whose cell bodies occurred either in layer III, IV or V. The procedures employed were as follows: electrolytic lesions were used to destroy the cortical projections of the nucleus ventralis posterior pars lateralis thalami (homologous to medial portion of ventrobasal complex) and the nucleus posterior thalami. These two thalamic nuclei project to the posteromedial barrel subfield (PMBSF) in mouse somatosensory cortex. Blocks of cortex containing the PMBSF were processed by the Golgi method, sectioned at 150 μm and examined with the light microscope. Neurons of interest were then selected for Golgi deimpregnation (Fairén et al., '77). Portions of these cells were serial thin sectioned and subsequently examined with the electron microscope to determine if they synapsed with degenerating axon terminals.Degenerating thalamocortical axon terminals synapsed at asymmetrical synaptic junctions with dendritic spines of pyramidal cells whose somata occurred in layers III and V, and with dendritic spines of spiny stellate cells with somata in layer IV. Only normal, symmetrical synapses occurred on the cell bodies of these neurons, and no degenerating axon terminals synapsed with the shafts of their dendrites. Two, unimpregnated, non‐spiny stellate cells whose somata occurred in layers IV and IV/V were partially reconstructed from serial thin sections. Many degenerating thalamocortical axon terminals synapsed with the dendrites and somata of these non‐spiny cells. In fact, for similar lengths of dendrite, the non‐spiny stellate cells made the most synapses with thalamocortical axon terminals, followed in order of decreasing frequency by the layer IV spiny stellate cells, the layer III pyramids and finally the layer V pyramids which received only few synapses from thalamocortical axon terminals.Direct evidence has been provided that at least six different types of neurons whose somata occur in several layers of the neocortex receive synapses from thalamocortically projecting neurons. It has been proposed that the cortex is organized such that thalamic input is processed sequentially by neurons of increasingly complex response properties beginning with cells in layer IV and proceeding to cells in other layers (Hubel and Wiesel, '62, '68). The results of this study now suggest that any such hierarchical processing of thalamic input must occur in conjunction with the parallel, and perhaps simultaneous, processing of thalamic input by neurons at several hierarchical levels. The evidence for, and some implications of, a newly proposed model of cortical organization which combines hierarchical and parallel processing are discussed.
Characterization of the monoaminergic innervation of immature rat neocortex: A histofluorescence analysis
Authors: Lidov H. G. W. , Molliver M. E. , Zecevic N. R. 
Published: May 2005

AbstractIn the neocortex of 6‐day‐old rat, abundant axon terminals which exhibit specific catecholamine fluorescence are found in all regions and throughout all cortical layers. The overall density of axons in 6‐day‐old cortex in similar to the density in the adult cortex. In immature cortex, there are two distinct fluorescent plexuses, both presumably noradrenergic, one in the molecular layer and another in the lower half of the cortex. The superficial plexus is composed primarily of horizontal fibers, and the deep plexus of a dense feltwork of obliquely oriented fibers suggestive of a terminal field. The cortical plate itself is traversed by a few vertical processes. Following lesions of the midbrain tegmentum no fluorescent axons are seen in cortex, providing evidence that the fluorescent axons in cortex arise from brain stem neurons. The deep and superficial plexuses can be differentially visualized depending on the histochemical techniques employed and on pharmacological treatment, such as loading with a monoamine congener. Both deep and superficial axons are shown to contain endogenous catecholamines but those fibers in the deep plexus are filled to far less than their maximum capacity. The pharmaco‐histochemical differences between axons in the two plexuses suggest that there may exist two distinct catecholaminergic projections to lateral neocortex. The demonstration of an extensive cortical monoamine innervation early in ontogeny supports the possibility that monoamine neurons play an important role in information processing and/or developmental interactions in the immature brain.
Localization of enkephalin‐like immunoreactivity to identified axonal and neuronal populations of the rat hippocampus
Authors: Gall Christine , Brecha Nicholas , Karten H. J. , Chang Kwen‐Jen 
Published: May 2005

AbstractThe distribution of enkephalin‐like immunoreactivity in the hippocampal formation of the rat was analyzed. Two specific projection systems are described. The first emerges from the hilus of the dentate gyrus and appears to terminate with notably large boutons on the proximal apical and, to a lesser extent, basal dendrites of hippocampal regio inferior pyramidal cells. This projection corresponds in source, position, and character to the hippocampal mossy fiber system. The second axonal population enters the temporal hippocampal formation from the medial wall of the subicular complex and follows the hippocampal fissure to occupy stratum lacunosum‐moleculare of the hippocampus proper and the distal third of the dentate gyrus molecular layer; this pattern corresponds to the distribution of afferent input from the lateral entorhinal cortex and/or perirhinal area. Lesions of the hilus or retrohippocampal area caused a selective depletion of immunoreactivity in the mossy fiber fields and molecular layers of the dentate gyrus, respectively. Enkephalin‐like immunoreactivity was found within the somata of three types of hippocampal neurons: (1) granule cells of the dentate gyrus, (2) occasional pyramidal shaped cells of field CA1 stratum pyramidale, and (3) varied scattered interneurons. Of this last group, two types of interneurons were consistently seen. The first occupy the border between stratum radiatum and stratum lacunosum‐moleculare and extend processes at right angles to the long axis of the pyramidal cell dendrites, whereas the second lie within stratum radiatum of field CA1 and extend processes in alignment with the long axis of the pyramidal cell dendrites. Cells containing enkephalin‐like immunoreacactivity were also observed in the subiculum and retrohippocampal region, most notably including layers II and III of the lateral entorhinal cortex‐perirhinal area—the probable source of extrinsic immunoreactive input to the hippocampal formation. Intraventricular colchicine treatment intensified the immunoreactive staining of some hippocampal neurons but did not reveal any cell types not seen to be labeled in untreated rats.
Sources of descending afferents to the inferior olive from the upper brain stem in the cat as revealed by the retrograde transport of horseradish peroxidase
Authors: Saint‐Cyr Jean A. , Courville Jacques 
Published: May 2005

AbstractThe retrograde transport of horseradish peroxidase (HRP) was employed in 35 cats to trace the sources of descending afferents to the inferior olivary nucleus. The majority of HRP‐labeled cells were located in the ipsilateral mesencephalon, from the rostral pole of the red nucleus to the caudomedial border of the thalamus. Among the heavily labeled nuclear groups were the parvocellular red nucleus, the interstitial nucleus of Cajal, the nucleus of Darkschewitsch, and the caudomedial extremity of the subparafascicular nucleus. Occasional cells were also labeled in the reticular formation lateral to the interstitial nucleus of Cajal, in the caudomedial parafascicular nucleus, in the nucleus of the fields of Forel, and in the centray gray. It was not possible to recognize a topographic distribution of the labeled cells corresponding to the loclization of the HRP deposits. Elsewhere in the midbrain, there were HRP‐labeled cells in the deep layers of the superior colliculus (IV and VI), predominantly on the side contralateral to the injection and in the nucleus of the optic tract, and in the anterior and posterior pretectal nuclei, ipsilaterally. These groups were best labeled after caudally located injections in the olive. Certain areas previously reported to project to the inferior olive were devoid of labeled cells; these included the basal ganglia, the rostral raphe nuclei, and the nucleus of Edinger‐Westphal. It appears that the mesecephalic nuclei bordering the central gray represent the major source of descending afferents to the olive.