bluuebunny/crossref_metadata_2025_split huggingface dataset:
Organization of HRP‐labeled trigeminal mandibular, primary afferent neurons in the rat
Authors: Jacquin Mark F. , Semba Kazue , Egger M. David , Rhoades Robert W. 
Published: May 2005

AbstractHorseradish peroxidase (HRP) applied to the transected mandibular division of the trigeminal (V) ganglion was transported anterogradely to pri‐mary afferent terminal zones in the dorsal and dorsomedial trigeminal brain‐stem nuclear complex (TBNC). Primary V afferents of ganglionic origin were also visible in the ipsilateral cerebellar cortex (crus I and II, paraflocculus) and the dentate, cuneate, solitary, supratrigeminal, and dorsal motor vagal nuclei, parvicellular reticular formation, area postrema and C1–C6 dorsal horn, laminae I–V. Contralateral subnucleus caudalis and C1–C2 dorsal horn were also innervated by primary afferents which crossed in the spinal gray to terminate medially, primarily in laminae I, II, and V. Almost all of these projections were also labeled in various combinations when HRP was applied to individual sensory branches of the mandibular nerve: lingual, infe‐rior alveolar, mylohyoid, and auriculotemporal. Transganglionic transport of HRP in the latter four cases revealed strong evidence for mtradivisional somatotopy among the four branches in both the ganglion and TBNC. Cell bodies innervating posterior and/or lateral portions of the head and face (i.e., auriculotemporal and mylohyoid) were found with greater frequency in dor‐sal mandibular ganglion regions, while somata supplying more rostral oral‐perioral regions (i.e., lingual and inferior alveolar) were predominant ventrally. Components of the mandibular projection to the TBNC were organized topographically in at least some portion of all of its three dimen‐sions. Subnuclear preferences were not clear‐cut; all four nerves innervated at least some portion of principalis, oralis, interpolaris, and caudalis, save for mylohyoid, which did not project to caudalis. Lingual fibers were most prominent in principalis and oralis, occupied medial portions of the mandib‐ular projection to the TBNC, and descended only to rostral caudalis, most notably laminae I‐III. Inferior alveolar afferents were ubiquitous in the mandibular component of the TBNC and C1–C2, save for its far lateral bor‐der. Mylohyoid terminals were sparse, most prominent in interpolaris, and occupied only dorsolateral TBNC regions and laminae III and IV of C1–C3. The auriculotemporal innervation of the mandibular TBNC was heaviest in interpolaris and was restricted to mostly ventrolateral regions. Its primary focus, however, was laminae III and IV of C1–C4. The clinical implications of this topographical organization are discussed, particularly with respect to the rostrocaudal intradivisional lamination in caudalis and the cervical dorsal horn.
The embryonic development of the cortical plate in reptiles: A comparative study in Emys orbicularis and Lacerta agilis
Authors: Goffinet A. M. 
Published: May 2005

AbstractFrom the earliest stage of its ontogenesis, the mammalian cerebral cor‐tex displays a remarkable cytoarchitectonic organization, with its neurons oriented radially within the cortical plate (CP).It is not known whether this radial organization of cortical neurons is characteristic of every cerebral cortex or whether it reflects a progressive phylogenetic acquisition. In order to study this question, the embryonic de‐velopment of the cortex has been examined in reptiles, where it is the most primitive. Two species, Emys orbicularis and Lacerta agilis, representative of the two principal reptilian orders (chelonians and squamates), have been studied with histological methods, Golgi impregnation, and electron micros‐copy. Very similar patterns of cell proliferation, migration, maturation, and synaptogenesis have been observed. However, important species differences are present in the cellular organization of the cortical plate. Whereas in Emys the structure of the cortical plate is rudimentary, in Lacerta it appears well developed and quite reminiscent of its mammalian counterpart. Prelimi‐nary comparisons with embryological preparations of Sphenodon and Croco‐dilus niloticus show that the organization of the cortical plate displays significant variations among the different reptilian groups.The present results suggest that the radial organization of cortical neu‐rons is not an all or nothing phenomenon but has been acquired indepen‐dently and is thus acase of homoplasy, probably due to convergence (North‐cutt, 1981). Several possible implications of these findings are discussed and a working hypothesis based on the role of radial glial cells in the formation of cytoarchitectonic patterns (Rakic, 1980) is presented.
Collaterals of spinothalamic cells in the rat
Authors: Kevetter Gold Aanne , Willis William D. 
Published: May 2005

AbstractSpinothalamic (STT) cells were investigated in the rat to determine the distribution of subpopulations with terminals in both the lateral and medial thalamus, the thalamus bilaterally, or the thalamus and the medullary retic‐ular formation. Two or more retrogradely transported substances (fluores‐cent dyes, and/or horseradish peroxidase) were injected in each animal. Three combinations of injections were most commonly used: (1) injections of the medullary reticular formation and thalamus, (2) separate injections into each side of the thalamus, and (3) separate injections into the medial and lat‐eral thalamus. The distribution of single labeled cells after each injection was compared with previously published results for rats. The distribution of cells which contained both tracers, double‐labeled (DL) cells, was the focus of this study. An average of 15% of STT cells and 8% of spinoreticular cells projected to both the reticular formation and thalamus. However, only a small component of STT cells (less than 2%) projected bilaterally into the thalamus. Most DL cells were found in upper cervical segments. The laminar distributions of all three groups of DL neurons were similar. These cells were most often located in the reticulated part of lamina V and the intermediate zone, lamina VII. STT cells that had terminals in both the medial and lateral thalamus and STT cells with collaterals in the reticular formation were con‐centrated on the side contralateral to their terminals. These DL neurons pro‐vide an anatomical substrate for noxious stimuli to activate the reticular for‐mation and thalamus and/or specific sensory and intralaminar thalamus simultaneously.
Dendritic distribution of splenius motoneurons in the cat: Comparison of motoneurons innervating different regions of the muscle
Authors: Keirstead S. A. , Rose P. K. 
Published: May 2005

AbstractThe distribution and dendritic organization of splenius motoneurons innervating extrafusal muscle fibers in different regions of the muscle were examined by electrophysiological and intracellular HRP staining techniques. Motoneurons innervating the regions of the splenius muscle supplied by the C2, C3, and C4 peripheral nerves were arranged in three nonoverlapping sub‐nuclei. Reconstructions of the dendritic trees of splenius motoneurons in these three subnuclei showed that there were no major differences in their dendritic distributions. Instead, the dendritic distribution followed a single pattern which was composed of five major dendritic projections. These included a dorsolateral projection to the lateral part of lamina VIII, a lateral projection into the spinal accessory nucleus and beyond the gray‐white border, ventral and ventrolateral dendrites in the lateral half of the ventromedial nucleus and the surrounding white matter, medial dendrites which projected both dorsally and ventrally, and finally a conspicuous collection of dendrites which projected rostrally and caudally from the cell body.These results indicate that the dendritic distributions of splenius motoneurons are not related to the segmental position of the motoneuron or the zone of the muscle innervated by the motoneuron. However, a comparison of the dendritic distribution of splenius motoneurons to the dendritic distribution of biventer cervicis‐complexus motoneurons indicated that there are major differences in the form of their dendritic trees even though dendrites from both sets of motoneurons share the same territory. As a consequence, although these motoneurons may receive the same connections, the effect of these connections on the excitability of the motoneurons may differ.
Distribution of dendrites of mitral, displaced mitral, tufted, and granule cells in the rabbit olfactory bulb
Authors: Mori Kensaku , Kishi Kiyoshi , Ojima Hisayuki 
Published: May 2005

AbstractTo determine the dendritic fields, mitral, displaced mitral, middle tufted, and granule cells in the rabbit olfactory bulb were stained by intracellular injection of HRP. The secondary dendrites of mitral cells were distributed mostly in the inner half of the external plexiform layer (EPL). Those of displaced mitral cells extended mainly into the middle and superficial sublayers in the EPL. The secondary dendrites of middle tufted cells weredistributed mostly in the superficial portion of the EPL.Mitral cells extended their secondary dendrites in virtually all directions within a plane tangential to the mitral cell layer (MCL) and thus had a disklike projection field with a radius of about 850 μm. Displaced mitral cells had similar dendritic projection fields in the tangential plane but with somewhat distorted shapes. The secondary dendrites of middle tuftedcells had a tendency to extend in particular directions.From the projection pattern of the gemmules on the peripheral processes, granule cells were classified into three types. Type I granule cells had gemmules both in the superficial and in the deep sublayers of the EPL. The peripheral processes of Type II granule cells were confined to the deep half of the EPL. The gemmules of Type III granule cells were distributed in the superficial half of the EPL.The differing dendritic ramification among mitral, displaced mitral, and middle tufted cells suggests the separation of the dendrodendritic synaptic interactions with granule cells in different sublayers in the EPL. It also suggests a functional separation of the sublayers of the EPL.
Postnatal changes in retinal ganglion cell and optic axon populations in the pigmented rat
Authors: Perry V. H. , Henderson Z. , Linden R. 
Published: May 2005

AbstractThe number of ganglion cells in the retina of the postnatal rat has been examined. We estimated both the number of axons in the optic nerve and the number of cells which can be retrogradely labelled with horseradish peroxidase from injections into the brain. In the retina of the newborn rat there are at least twice as many ganglion cells as in the adult rat. By retrograde labelling of the ganglion cells and following transection of their axons 24‐48 hrs later we can find no evidence that ganglion cells withdraw their axon without degeneration of the parent cell body. We have found that the excess ganglion cells are lost over the first ten postnatal days and during this period we observe pyknotic nuclei in the ganglion cell layer. From our estimates of the total number of neurones in the ganglion cell layer and the number of ganglion cells found at different ages we conclude that themigration of amacrine cells into the ganglion cell layer occurs in the first five postnatal days.
Transient cholinesterase staining in the mediodorsal nucleus of the thalamus and its connections in the developing human and monkey brain
Authors: Kostovic Ivica , Goldman‐Rakic Patricia S. 
Published: May 2005

AbstractThe histochemical and morphological maturation of the mediodorsal nucleus (MD) and its connections were compared in human and rhesus monkey using acetylthiocholine iodide and Nissl methods. Histochemical analysis in fetuses, neonates, and adults of both primate species revealed that MD passes through three major stages of cholinesterase (ChE) reactivity. In Stage I (up to about 16 fetal weeks in man; 9 fetal weeks in monkey), ChE staining gradually increases in the MD nucleus and is intense in axons directed toward the frontal lobe through the internal and external capsules. In Stage II (about 16‐28 fetal weeks in man; about 9‐14 weeks in monkey), ChE staining in MD reaches peak intensity so that reaction product in the neurons and neuropil blackens the entire nucleus in both species. In favorable planes of section, ChE‐positive fibers appear to connect MD and the basal forebrain both of which stain intensely. ChE‐positive fibers can also be traced from the lateral margins of MD to the subplate zone beneath the developing frontal cortical plate where they continue to accumulate before later invading the cortex with heaviest concentration in presumptive layers 3 and 5. In Stage III (after 28 weeks of gestation to 6 postnatal months in man; from about 14 fetal weeks until 2 postnatal months in monkey), except for scattered positive cells, ChE staining gradually disappears in MD and the formerly dense laminar pattern in the cortex begins to lighten. The dramatic but transient increase in ChE staining in MD during fetal development as well as the sequentially related changes in its projections indicate that this early appearing enzyme may play a role in the development of the frontal lobe by influencing the differentiation of thalamoprefrontal connections.
Structure of the piriform cortex of the opossum. III. Ultrastructural characterization of synaptic terminals of association and olfactory bulb afferent fibers
Authors: Haberly Lewis , Behan Mary 
Published: May 2005

AbstractTerminals of olfactory bulb afferent (OB) and association (ASSN) fiberswithin the piriform cortex were characterized ultrastructurally. Identification was by electron microscopic (EM) autoradiography following injections of tritiated amino acids into the olfactory bulb and anterior piriform cortex. The results show that terminals of both fiber systems contain round vesicles and make asymmetrical synaptic contacts predominantly onto dendriticspines. Profiles with pleomorphic vesicles do not appear to be labeled from either site. Since there is strong evidence that both fiber systems generate excitatory postsynaptic potentials (EPSPs) in pyramidal cells, these results provide additional examples in the mammalian CNS of terminals with round vesicles and asymmetrical contacts that mediate an excitatory effect.Percentage density analysis and quantitative study of a large number of heavily labeled terminals revealed that while OB and ASSN terminals are similar in terms of vesicle shape and contact type, they differ in many morphological details including pre‐and postsynaptic profile size, the packing density and distribution of synaptic vesicles, synaptic contact shape, and the presence of overlying neuroglial lamellae. However, large variations in appearance of different terminals of the same type are also present so that a small percentage of OB and ASSN terminals are indistinguishable morphologically in the absence of label.An important finding of the quantitative analysis is that spines contacted by lateral olfactory tract (LOT) terminals appear to be of two types based on a bimodal distribution in size and differences in morphology, while spines contacted by ASSN terminals appear to be of a single type. Comparison of these data with results from Golgi analysis indicates that ASSN terminals predominantly contact pyramidal cell spines while OB terminals contact both pyramidal and semilunar cell spines.Quantitative analysis of synaptic vesicles revealed that histograms of vesicle size for OB and ASSN terminals are virtually identical in shape, but peaks are slightly displaced (ASSN vesicles are 5% larger; significant with P < .002).An analysis of the laminar distribution of OB and ASSN synaptic terminals revealed that while moat OB terminals are segregated in layer Ia and most ASSN terminals in layer Ib, occasional OB terminals are observed up to approximately 50 μm deep to the Ia‐Ib boundary and occasional ASSN terminals up to approximately 50 μm superficial to this boundary.
Developmental alterations in sensory neuroanatomy of the Caenorhabditis elegans dauer larva
Authors: Albert Patrice S. , Riddle Donald L. 
Published: May 2005

AbstractThe anterior sensory ultrastructure of the C. elegans dauer larva was examined in several specimens and compared with that of the second‐stage (L2) larva, which immediately precedes the dauer stage. In some instances comparisons were made with L3, postdauer L4, and adult stages. Whereas sensory structures in different nondauer stages closely resemble each other, the dauer larva differs in certain chemosensory and mechanosensory organs, including the inner labial sensilla, amphids, and deirids. The relative positions of the afferent tips of the two types of inner labial neurons are reversed in the dauer stage compared to the L2 and postdauer L4 stages. Inner labial neuron 1 rather than neuron 2 is more anterior in each of the six sensilla, and neuron 1 has an enlarged tip. The neuron 2 cilia are only one‐third as long as those in the L2. Amphidial neurons c., d, g, and i and the amphidial sheath cell are altered in shape or position in the dauer stage. Neurons g and i are displaced posteriorly within the dauer amphidial channel. Neuron d has significantly more microvillar projections than do the d cells in L2, L3, or postdauer L4 larvae. Winglike processes of dauer neuron cform a 200°–240° are in transverse section, including extensive overlap of the two cells. The arc in an L2 seldom spans more than 100°, and overlap does not occur. While L2 larvae possess two separate bilateral amphidial sheath cells, the left and right sheath cells are often continuous in the dauer larva. Deirid sensory dendrites exhibit a dauer‐specific structure and orientation. The tip of each neuron is attached to the body wall cuticle by a substructure not observed in L2 or postdauer L4 stages, and the neurons are oriented parallel to the longitudinal axis of the dauer larva. The deirid sensory terminals are oriented perpendicular to the cuticle in other stages. Reversible alterations in neural structure are discussed in the context of dauer‐specific behavior.
The development and postnatal organization of primary afferent projections to the rat thoracic spinal cord
Authors: Smith Carolyn L. 
Published: May 2005

AbstractPrimary afferent projections to the thoracic spinal cord in fetal and postnatal rats were labelled by applying horseradish peroxidase (HRP) to the central stumps of cut peripheral nerves. Diaminobenzidine (DAB) and tetramethyl benzidine (TMB) histochemical processing procedures were used to reveal the HRP reaction product.In postnatal rats, individual muscle nerves were labelled to reveal the organization of muscle afferent projections to the motor nuclei. The terminals of muscle afferents were distributed widely across the dendritic arbors of motoneurons supplying the same muscles. No spatial segregation of the terminations of different populations of muscle afferents was discernable.Afferents supplying different regions of the skin were labelled by applying HRP to the dorsal and ventral primary rami of the spinal nerves. Afferents in the dorsal rami projected to lateral portions of both the ipsilateral and contralateral dorsal horns while afferents in the ventral rami projected to the medial portions of both dorsal horns. The projections of the dorsal rami were shifted caudally relative to those of the ventral rami. This relationship reflects the fact that the regions of skin innervated by the dorsal rami are displaced caudally relative to those innervated by the corresponding ventral rami.In fetuses, dorsal rami were labelled alone or in combination with ventral rami. These experiments disclosed the time course of development of the projections to different laminae of the spinal gray matter and revealed that afferents in the two primary rami project to appropriate regions in the ipsilateral and contralateral dorsal horns from the very outset.
Computer‐assisted analyses of barrel neuron axons and their putative synaptic contacts
Authors: Harris Roger M. , Woolsey Thomas A. 
Published: May 2005

AbstractThe “barrels” in layer IVof rodent SmI neocortex receive inputs from individual whiskers on the contralateral face. Previous analyses of neuronal morphology in mouse and rat barrel cortex, as revealed by Golgi impregnations, have focused on the dendritic patterns of the stellate cells. The cells can be classified into two groups: Class I cells with spiny dendrites and Class i I cells with smooth, beaded dendrites. These classes can be subdivided further according to somal position and spatial distribution of dendrites with respect to barrel cytoarchitectonic boundaries. In the present study the axons of these cells were examined and the locations of close appositions to dendrites of other impregnated neurons were mapped. All data are taken from Golgi‐Cox preparations, cut parallel to layer IV at 140 μm, counter‐stained with Nissl to reveal the barrels, and measured with a computer‐microscope. Axons which had extensive branching within the section (present on 10% of all impregnated cells) were chosen for measurement.The analysis of the axons revealed: (1) Class I axons are thin and directed to the white matter with recurrent collaterals in the barrels, while Class II axons are thick, frequently beaded, and directed toward the pia before cascading down into the barrels; (2) in layer IV, the axons of both cell classes tend to be as restricted to a barrel as the dendrites of the same cell are (i.e., most axons are confined to one barrel); (3) within layer IV, the Class II cell axons have a total length about three times that of Class I cell axons, and about four times as many branch points.The analysis of the appositions of these axons to impregnated dendrites of other cells revealed: (1) A maj ority of “contacts” tended to be made by terminal branches of the axonal trees. (2) For the Class I neurons, a greater number of appositions occur near the distal ends of complete dendritic segments. As measured from the “contacted” cell soma, appositions are more or less uniformly distributed along dendritic trees. (3) No striking patterns are found, such as an obvious propensity for axons of one cell type to prefer or avoid another cell type.These results show that the axons of barrel cells of each class are as consistent and distinctive as their dendritic trees. Specifically, the cells in each class can be distinguished by their axonal patterns on purely numerical bases. The new computer programs which were developed to systematically search for sites of apposition between axons and dendrites ‐a necessary prerequisite for the existence of synaptic contacts‐greatly facilitated the collection of these data: The data may be of value for defining “probable” sites of interaction between particular cell types. In particular, these light microscopic observations of the distribution of appositions along dendritic segments are similar in some ways to White and Rock's ('80, '81) electron microscopic mapping of synapses on single‐barrel neurons.