bluuebunny/crossref_metadata_2025_split huggingface dataset:
The organization of the lateral thalamus of the hooded rat
Authors: Takahashi Terry 
Published: January 2005

AbstractAnalysis of cytoarchitecture and connectivity showed that the lateral thalamus of the hooded rat is composed of eight nuclei. An examination of the cytoarchitecture permitted the identification of seven cellular fields: nucleus suprageniculatus (sg), nucleus lateralis posterior pars caudomedialis (lpcm), nucleus lateralis posterior pars lateralis (lpl), nucleus lateralis posterior pars rostromedialis (lprm), intramedullary area (ima), nucleus lateralis dorsale pars ventrolateralis (ldvl), and nucleus lateralis dorsale pars dorsomedialis (lddm). An analysis of the connectivity showed that lpl is further divisible into a rostral (lplr) and a caudal (lplc) sector, bringing the total number of nuclei to eight. Nucleus suprageniculatus, the most caudal element of the lateral thalamus, is composed of medium to large, fusiform, and multipolar neurons. It contains a terminal field of the projection of the superficial layers of the ipsilateral superior colliculus. Nucleus lpcm, found rostrolateral to sg, is loosely packed with large multipolar neurons. A terminal field of the superficial layers of the superior colliculus of both sides fits precisely within its cytoarchitectural boundaries. Nucleus lpl, a long cellular territory found lateral to lpcm, extends from the caudal pole of the dorsal lateral geniculate nucleus to the caudal pole of ldvl and contains round cells which are smaller and more densely packed than those of lpcm. Its caudal portion (lplc) contains another terminal field of the ipsilateral superior colliculus while its rostral portion (lplr) contains a terminal field of the projection of Area 17. Area 18 also projects to lplr, whereas Area 18a projects to both lplr and lplc. The intramedullary area, which occupies the fibrous zone between lpl and the dorsal lateral geniculate nucleus, contains round and fusiform neurons and is innervated by Area 18a. Nucleus lprm, situated medial to lpl, is characterized by round neurons which are frequently found in clusters. It is innervated by Areas 17, 18, and 18a. Nucleus ldvl is evenly packed with moderately large, polygonal cells and contains the complete terminal fields of both Areas 17 and 18. It also receives inputs from Area 18a. Finally, lddm, tightly packed with small, round cells and lying medial to ldvl, receives inputs from Area 4.
Afferent influences on brain stem auditory nuclei of the chicken: Changes in succinate dehydrogenase activity following cochlea removal
Authors: Durham Dianne , Rubel Edwin W. 
Published: January 2005

AbstractWe have examined one of the metabolic consequences of unilateral cochlea (basilar papilla) removal in the chick brain stem auditory system. We assessed changes in succinate dehydrogenase (SDH), a mitochondrial enzyme involved in energy metabolism, in neurons of second‐order n. magnocellularis (NM) and third‐order n. laminaris (NL). Chickens undergoing surgery at 10 days of age were perfused 4 hours to 35 days postlesion. Chickens 6 or 66 weeks of age at cochlea removal were examined 1 or 8 days after surgery. In all groups, cryostat sections were prepared for SDH histochemistry or Nissl staining.In normal chickens, NM cell bodies and NL neuropil contain SDH reaction product. In young birds, the density of SDH reaction product in NM shows a rapid biphasic response to cochlea removal. From 8 to 60 hours postlesion, density increases ipsilateral to cochlea removal; for survival times of 3–35 days, SDH density decreases in ipsilateral NM. In NL, no changes were observed until 3 days after cochlea removal. Then we observed a long‐lasting decrease in density of SDH reaction product in the neuropil regions receiving input from the deafferented NM. All of these changes are age‐dependent in that they were observed only following cochlea removal on or before 6 weeks of age.
An electron microscopic study of terminals of rapidly adapting mechanoreceptive afferent fibers in the cat spinal cord
Authors: Semba K. , Masarachia P. , Malamed S. , Jacquin M. , Harris S. , Yang G. , Egger M. D. 
Published: January 2005

AbstractThe intra‐axonal horseradish peroxidase technique was used to examine the central terminals of 7 Aβ primary afferent fibers from rapidly adapting (RA) mechanoreceptors in the glabrous skin of the cat's hindpaw.At the light microscopic level, labelled collaterals were seen to bear occasional boutonlike swellings, mostly (75–82%) of the en passant type. These swellings were distributed more or less uniformly from lamina III to a dorsal part of lamina VI in the dorsal horn, over a maximum longitudinal extent of about 4 mm.At the electron microscopic level, we observed that labelled boutons of RA afferent fibers were 1.0 to 3.3 μm in longest sectional dimension, and contained clear, round synaptic vesicles. They frequently formed asymmetric axospinous and axodendritic synapses and commonly appeared to receive contacts from unlabelled structures containing flattened or pleomorphic vesicles plus occasional large dense‐cored vesicles. The examination of synaptic connectivity over the entire surface of individual boutons indicated that RA afferent boutons each made contacts with an average of one spine and one dendrite and, in addition, appeared to be postsynaptic to an average of two unlabelled vesicle‐containing structures. This synaptic organization was, in general, more complex than that we had seen previously in Pacinian corpuscle (PC) and slowly adapting (SA) type I mechanoreceptive afferent fibers.Our findings indicate that RA, SA, and PC afferent terminals, while displaying some differential synaptic organizations, have many morphological and synaptological characteristics in common. These afferent terminals, in turn, seem to be generally distinguishable from the terminals of muscle spindle Ia afferents or unmyelinated primary afferents.
(3H) glycine‐accumulating neurons of the human retina
Authors: Marc Robert E. , Liu Wei‐Ley S. 
Published: January 2005

AbstractIsolated human retinas were incubated in physiological saline containing micromolar (3H) glycine. The types, distributions, and synaptologies of glycine‐accumulating neurons were determined by light and electron microscope autoradiography. Two types of amacrine cells were discriminated on the bases of number of processes descending into the inner plexiform layer, density of label in light‐microscope autoradiographs, size, and synaptic features: (1) Gly1 amacrine cells have moderate labeling, several oblique dendrites arising from the soma, and electron lucent synaptic terminals containing large presynaptic specializations, and (2) Gly2 amacrine cells have dense labeling, a single proximal dendrite, and moderately electron‐dense terminals with small presynaptic specializations. Gly1 amacrine cells constitute ∼ 15% and Gly2 amacrine cells ∼ 38% of all cells in the amacrine cell layer. The laminar distribution of label in the inner plexiform layer was measured by scanning microdensitometry, which provided a format for categorizing types of synaptic contacts. Many features of glycine‐accumulating amacrine cell contacts were similar to those of cat AII/Gly2 amacrine cells: a diffuse yet bisublaminar distribution of label, concentration of synaptic output in sublamina a, rod bipolar cell input in sublamina b and gap junctions in mid‐inner plexiform layer involving labeled cells. The evidence seems to indicate that human Gly2 amacrine cells and cat AII/Gly2 amacrine cells are homologous cell types. Finally, some cone bipolar cells were labeled with (3H) glycine.
Regulation of neuron numbers in Xenopus laevis: Effects of hormonal manipulation altering size at metamorphosis
Authors: Sperry David G. , Grobstein Paul 
Published: January 2005

AbstractXenopus laevis tadpoles reared in a 0.01% solution of 6‐n‐propyl‐2‐thiouracil (PTU) are blocked in their development at larval stage 54 out continue to increase in size. When released from the effects of PTU they metamorphose into frogs of sizes significantly larger than those of their untreated siblings. Using this size difference to examine the hypothesis that neuron numbers are matched to the size of their postsynaptic targets during neuronal cell death, we measured the following on stage 66 frogs metamorphosing from PTU‐treated and untreated tadpoles: lumbar lateral motor column (L‐LMC) motoneuron number and mean nuclear cross‐sectional area; thoracic and lumbar dorsal root ganglion (DRG) cell number and mean nuclear cross‐sectional area; and muscle fiber number in two representative thigh muscles. A few measurements of neuron number and cell size were also made on untreated and PTU‐treated stage 54 tadpoles.The most striking correlations observed were not between peripheral size and neuron numbers but between peripheral size and neuron size. Motoneuron numbers were not increased in the PTU‐treated animals, perhaps because the increase in peripheral size involved an increase in muscle fiber diameter rather than an increase in muscle fiber number. Thoracic DRG cell number, but not the sum of thoracic and lumbar DRG cell numbers, was increased. In general, our findings do not support the hypothesis that neuron numbers are matched to peripheral size by a process regulating the amount of cell death that occurs during metamorphic stages in Xenopus laevis.
Neuronal death and synapse elimination in the olivocerebellar system. I. Cell counts in the inferior olive of developing rats
Authors: Delhaye‐Bouchaud Nicole , Geoffroy Brigitte , Mariani Jean 
Published: January 2005

AbstractA transient multiple innervation of cerebellar Purkinje cells by climbing fibers has been described during postnatal development of the rat. The aim of the present study was to determine if the regression of redundant synapses is related to the loss of presynaptic cells in the inferior olivary nucleus (ION), which is the sole source of climbing fibers in rodents. To this end, the population size of the ION was evaluated by counting healthy cells of the four main subnuclei in rats from birth to adulthood. The cell population at birth was found to be very similar to that of the adult animal (27,655 versus 28,385), but a loss of 25% of the cells occurred in the first five days, presumably through their death since degenerating cells were observed over the same period. Although cell loss was found throughout the whole nucleus, it was more pronounced in the medial accessory olive. A subsequent apparent increase of the cell population was observed so that the adult value was again reached at 15 days. The evolution of the ION population is then characterized by a period of moderate cell death which takes place before the peak of polyneuronal innervation of Purkinje cells by olivary axons is attained. This strongly suggests that the removal of the redundant synaptic contacts established by climbing fibers onto Purkinje cells during development is caused by a progressive reduction of the branching of olivary axons rather than by degeneration of the presynaptic cells.
Ascending somatosensory projections to the medial accessory portion of the inferior olive: A retrograde study in cats
Authors: Molinari Helen H. 
Published: January 2005

AbstractThe cells in the dorsal column nuclei, lumbosacral spinal cord, lateral cervical nucleus, and nucleus z that project to the medial accessory portion of the inferior olive of cats were identified with retrograde tracing techniques. Injections of wheat germ agglutinin complexed to horseradish peroxidase were made in the caudal portion of the medial accessory olive, either (1) involving no portion of the dorsal accessory olive or (2) involving in addition the caudal tip of the dorsal accessory olive. The tissue was processed with tetramethyl benzidine. The locations of all relay neurons were compared with those of dorsal accessory olive projection neurons, as described in a previous study (Molinari, 1984a).Localized populations of neurons gave rise to most of the projection to the medial accessory olive. These neurons were found in the peripheral portions of the dorsal column nuclei caudal to the obex and in the ventromedial ventral horn of the entire lumbosacral enlargement. Few projection neurons were found in the lateral cervical nucleus and none in the nucleus z.Neurons in the peripheral dorsal column nuclei and ventromedial ventral horn were labeled by injections in either the medial or dorsal accessory olives. Following medial accessory olive injections, however, they constituted the only labeled somatosensory neurons, while following dorsal accessory olive injections they represented only a small fraction of the labeled neurons. Based on their locations, it is proposed that these neurons might be the source for both the medial and dorsal accessory olives of information signalling movement of the proximal limb. Such a proposal is consistent with functional descriptions of the medial and dorsal accessory olives and the cerebellar anterior lobe.
Parasol and midget ganglion cells of the human retina
Authors: Rodieck R. W. , Binmoeller K. F. , Dineen J. 
Published: January 2005

AbstractGolgi‐impregnated ganglion cells were studied in two flat‐mounted human retinas. A number of different morphologic forms were observed, and those showing a thickly branching dendritic field with terminals that stratified within a narrow zone of the inner plexiform layer were selected for further investigation. When the dendritic field diameter of these cells was plotted against distance from the fovea, the scatter diagram showed two distinct clusters. At any given eccentricity, there was no overlap between the cell group with large dendritic fields and the group with small dendritic fields. Those with the larger dendritic fields also tended to have larger somas and thicker axons than the group with the smaller dendritic fields.The dendritic fields of both groups tended to be elongated, and the orientation and degree of this elongation were quantified by determining the best‐fitting ellipse for each dendritic field. The degree of elongation was independent of eccentricity. The orientation of the dendritic field (major axis of the ellipse) of a cell did not appear to be independent of its position on the retina. To test whether the major axes tended to be directed toward any particular point on the retina, the positions of the cells on the retinal flat mount were transformed to relative positions on the retinal hemisphere, and the orientations of the dendritic fields were expressed in a spherical coordinate system for this hemisphere. A search was made for the position on the hemisphere which minimized the mean square deviation of the orientations from this point. The group with the large dendritic fields showed a significant tendency to be radially oriented toward a specific location on the retinal hemisphere, and that location lay within a few degrees of the fovea. Leventhal and Schall ('83) have reported a similar finding for ganglion cells of the cat retina. For the group with small dendritic fields, the retinal location that minimized the mean square deviation was also near the fovea; however, the set of orientations showed no greater tendency for mutual alignment than did a randomized set.The cell group with the large dendritic fields appears to correspond to Dogiel's (1891) type II cells, to Polyak's ('41) parasol cells, to the A cells of the monkey retina described by Leventhal et al. ('81), observed following HRP injection to the magnocellular layer of the LGN, and to the Pα cells of the monkey retina, observed by Perry and Cowey ('81), following HRP uptake by cut axons of the optic nerve.The cell group with the smaller dendritic fields appears to correspond to Dogiel's type III cells, to Polyak's midget ganglion cells, and in the monkey retina to the B cells of Leventhal et al., observed following HRP injection to the parvocellular laminae of the monkey LGN, and to the Pβ cells of Perry and Cowey.
Heterogeneous properties of segmentally homologous interneurons in the ventral nerve cord of locusts
Authors: Pearson K. G. , Boyan G. S. , Bastiani M. , Goodman C. S. 
Published: January 2005

AbstractThe G, B1, and B2 neurons are three prominent interneurons located in adjacent segmental ganglia in the central nervous system of locusts. Previous studies on the adult nervous system have shown that each of these cells has its own distinctive morphology and responsiveness to auditory input. Previous studies on the embryonic nervous system have described the lineage and development of one of these cells, the G neuron, in the mesothoracic (T2) segment. In this paper it is shown that the G, B1, and B2 neurons are segmental homologues in that they arise from equivalent lineages during embryogenesis in the T2, T3, and A1 segments, respectively. Each cell arises (along with its identified sibling neuron) from the division of the second ganglion mother cell of neuroblast 7–4. The segment‐specific morphology of the G homologues was determined in the T3 and A1 segments between 60–70% of embryonic development, and their identity was established as the adult B1 and B2 neurons by comparing the distinctive cell‐specific features of their morphology between embryo and adult. Although all three neurons display striking morphological differences, they all share certain structural features in common, including the location of their primary axons and neurites in specific tracts in the neuropil.By recording intracellularly from the main neurites of the G, B1, and B2 neurons, clear differences were found in the synaptic inputs each of the neurons receives and the synaptic outputs each makes. For example, G and B2, but not B1, receive direct monosynaptic input from the descending contralateral movement detector (DCMD) interneurons and from auditory afferents; B1, but not B2, connects directly to G; and B2, but not B1 or G, connects directly to flight motoneurons. The main conclusion from these observations is that lineally equivalent neurons in different segments can develop similar primary structures but quite different secondary morphologies and synaptic connections. How these segment‐specific differences arise during embryogenesis remains unknown.
Morphology and laminar distribution of electrophysiologically identified cells in the pigeon's optic tectum: An intracellular study
Authors: Hardy Olivier , Leresche Nathalie , Jassik‐Gerschenfeld Dora 
Published: January 2005

AbstractThe responses of 65 cells to electrical stimulation of the contralateral optic nerve were intracellularly recorded in the pigeon optic tectum by using micropipettes filled with a solution of horseradish peroxidase. Nineteen of them were successfully labeled. Microscopic examination of the filled cells shows that our sample includes six pyramidal, ten ganglion, two stellate, and one, bipolar horizontal cells. Thus, pyramidal and ganglion neurons constitute the most numerous types of cells in our sample. Pyramidal cells were located in layer II but mostly in its non‐retinorecipient part, and they had restricted ascending dendritic trees oriented orthogonal to the tectal lamination. Ganglion cells were located in layer in with one exception, which was in sublayer IIi. These cells had non‐oriented dendritic trees which ramify over considerable distances. Terminal dendritic branches from a number of pyramidal and ganglion cells extended superficially well within the region of optic fibers termination. In our study, ganglion cells constituted the efferent tectal elements. Pyramidal cells responded to optic nerve stimulation with a pure EPSP, with an EPSP‐IPSP sequence, or with a pure IPSP. Ganglion cells always exhibited an IPSP either alone or preceded by an EPSP. Stellate and bipolar cells responded with a pure EPSP. The study of the laminar distribution of labeled and non‐labeled cells shows from surface to depth, a gradual increase in the number of cells responding with an EPSP‐IPSP or with a pure IPSP and a gradual decrease in the number of those exhibiting a pure EPSP. The analysis of the sensitivity of EPSPs and IPSPs to high frequency optic nerve stimulation shows that (1) monosynaptic as well as polysynaptic EPSPs can be recorded from cells in the non‐retinorecipient tectal region, (2) a number of ganglion and pyramidal cells receive a direct retinal excitatory input as their dendrites pass through the region of optic endings, (3) most IPSPs are polysynaptic, (4) some cells located in the retinorecipient region may receive direct retinal inhibitory connections.
Somatostatin (SRIF)‐like immunoreactivity in subcortical and cortical visual centers of the rat
Authors: Laemle Lois K. , Feldman Susan C. 
Published: January 2005

AbstractThe distribution of neuronal elements containing immunoreactive somatostatin (I‐SRIF) in the rat central visual pathway was examined by light‐microscopic immunocytochemistry. These studies were concerned with the location and morphology of neurons and innervated cells and the distribution of fiber and terminal plexuses in the primary visual cortex (area 17), visual association areas 18 and 18a, the superior colliculus, the lateral geniculate nucleus, and the pretectum.In the superior colliculus, I‐SRIF‐containing fibers and perikarya were distributed predominantly in the superficial, or visual, layers; these elements were moderately dense and occupied the entire mediolateral extent of these layers. In the intermediate and deep layers, immunoreactive neurons were widely scattered, and fibers were located mainly in the medial third. Immunoreactive cell populations in the superior colliculus included small bipolar neurons with fusiform perikarya and multipolar neurons with round to ovoid perikarya. In the pretectum, the peptide was demonstrable in large and small multipolar neurons of the nucleus of the optic tract and in the posterior and olivary pretectal nuclei. I‐SRIF‐containing neurons were also present in the nucleus of the posterior commissure, the nucleus of Edinger‐Westphal, and the ventral division of the lateral geniculate nucleus. In the visual cortex, the peptide was present in all layers and in a variety of morphologically defined cell populations, including some which are presumed excitatory (pyramidal and bipolar cells) and others which are presumed inhibitory (bitufted and stellate cells).Our data suggest that somatostatin is involved in visual and visuomotor reflex pathways and in the horizontal optokinetic nystagmus reflex pathway. These results provide a foundation for further studies to evaluate the role of this peptide in visual processes.
Cochlear nerve of the alligator lizard
Authors: Mulroy Michael J. , Oblak Thomas G. 
Published: January 2005

AbstractThe innervation of the auditory organ of the alligator lizard is described. Patterns of distribution of the nerve fibers were studied at the light microscopic level with the horseradish peroxidase technique, and the types of synaptic contacts with hair cells were studied at the transmission electron microscopic level with standard techniques. The innervation of the two regions of the basilar papilla differs in the following ways. In the apical region, some fibers send branches along the length of the basilar papilla, and both afferent (non‐vesiculated) and efferent (vesiculated) nerve endings are present. In the basal region, all fibers terminate in the immediate area where they enter the papilla without sending branches along the length of the papilla; efferent endings are lacking, and nerve fibers are of a smaller average diameter. The punctate nature of the innervation of hair cells in the basal region is consistent with the hypothesis that the systematic organization according to frequency sensitivity observed in electrophysiological recordings from basal nerve fibers may be related to the length of the stereocilia on the hair cells with which the nerve synapses.