bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cone synapses with Golgi‐stained bipolar cells that are morphologically similar to a center‐hyperpolarizing and a center‐depolarizing bipolar cell type in the turtle retina
Authors: Kolb Helga , Wang Hou Hua , Jones Jill 
Published: January 2005

AbstractTwo types of Golgi‐stained bipolar cells have been examined by light and electron microscopy to determine the ultrastructure of their synapses with photoreceptors and the spectral type of photoreceptor with which they connect in the retina of the turtle (Pseudemys scripta elegans). We have chosen bipolar cells that correspond in morphology to a center‐hyperpolarizing type (H‐bipolar) and a center‐depolarizing type (D‐bipolar) shown in Marchiafava and Weiler's paper (Proc. R. Soc. B 208:103‐113, '80).The latter authors recorded intracellular responses and marked their cells with the fluorescent dye Procion yellow, so that we have a clear picture of their morphology. These bipolars have been called B4 and B6, respectively, according to our recent classification scheme of Golgi‐stained cells. Serial section electron microscopy of two B4 bipolars shows that they made wide‐cleft, striated basal junctions with red and green cone pedicles. They connected to six or seven different cone pedicles. The three B6 bipolar cells studied made narrow‐cleft, semi‐invaginating basal junctions with cone pedicles. The dendrites of B6 bipolars did not become central elements at ribbon synapses ‐although they invaginated toward the synaptic ribbon. Serial section electron microscopy indicated that B6 bipolars contacted three to five cone pedicles also of a red or green cone type. We suggest that in the case of these two varieties of bipolar cell in turtle retina, sign‐conserving synapses with cones are wide‐cleft basal junctions while sign‐inverting synapses are narrow‐cleft, semi‐invaginating in morphology.
Changing role of forebrain astrocytes during development, regenerative failure, and induced regeneration upon transplantation
Authors: Smith George M. , Miller Robert H. , Silver Jerry 
Published: January 2005

AbstractWhen the cerebral midline is lesioned in the embryo or neonate, the would‐be callosal axons form neuromas. We have shown that an untreated Millipore implant inserted between the neuromas in young acallosal animals can support the migration of immature astrocytes that, in turn, support the de novo growth of commissural axons between the hemispheres. Since callosal neuromas persist into adulthood, we asked whether a critical period exists after which reactive glia no longer promote axon growth. We found that a critical period does exist and have documented a variety of changes in reactive gliosis that, in part, may lead to the axon growth‐refractory state.In acallosal mouse postnates given untreated implants on or prior to day 8, glial fibrillary acidic protein (GFAP)+, stellate‐shaped astrocytes migrated and attached to the implant by inserting foot processes into the pores of the filter. This form of gliotic response established an axon growth‐promoting substratum within 24–48 hours after implantation. During this critical stage there was no evidence of scar formation or necrosis at or around the implant surface. However, when acallosal mice were implanted on or later than postnatal day 14, extensive tissue degeneration occurred, and a mixed population of astrocytes and fibroblasts invaded the surface of the filter, producing a dense scar. Reactive cells within the scar did not promote axonal outgrowth.To determine whether glia from neonates can influence the host environment and/or induce axonal regeneration in acallosal animals after the critical period, we harvested immature astrocytes on Millipore from critical‐period mouse forebrains and transplanted the glia‐coated prostheses into the brains of post‐critical‐period acallosal animals. Such transplants reduced glial scarring in the host, inhibited extensive bleeding and secondary necrosis, and promoted axonal regeneration.Our studies suggest (1) that when controlled with a prosthesis, gliosis during the critical period is a beneficial process that can promote the reconstruction of malformed axon pathways; (2) that in older animals a variety of changes‐in reactive glia and the extracellular matrix may work together to hinder axon regeneration after the critical period; and (3) that axonal regeneration in the postcritical CNS may be stimulated by reintroducing an immature glial environment at the lesion site.
Competion and the dynamics of axon arbor growth in the cricket
Authors: Murphey R. K. 
Published: January 2005

AbstractThe growth of an identifiled axonal arborization in the cricket cercal sensory sytem was studied under conditions that vary the number of neighboring axonal arborizations. The cell stuided is one of a samll number of neurons that arborize bilaterally and is called the X‐neuron. Normally the axonal arborization of X is distributed roughly symmertrically about the midlen. Seven days after the birth of this neuron, as soon after its birth as it can be stained, the axonal arbor is more than half the normal size and it exhibits the normal degree of bilaterality. During the remaining 50 days of postermbryonic development, the arbor grows to its adult size, maintaning the bilateral distribution.The relationship between the growth of this axonal arbor and the presence of absence of its neighbors was studied by the removal of one of the sensory appendages. The removal of a those neighbours near one half of the X‐neuron's arbor and causes a dramatic shift in the bilateral distribution of X's axonal processes; after treatment nearly all of the vaicosities were found in the deafferented region (Figs. 2, 6). Thus, neuron X responds to the loss of some to its neighbors by removing synaptic material from the area with normal neighbors and inserting additonal material in the region with fewer neighbors.This effect is age dependent. Removal of neighbors early in life, during the initial period of synaptogenesis, causes a very rapid chang, while similar treatment later in life causes a much slower response (Fig. 7). Thus the flexilbility of the neuron is correlated with its growth rate; it is very flexible during its early, rapid growth phase and less flexible when the growth rate slows later in life.This continuing flexibility of the axonal arbor could also be demonstrated by allowing the amputated cercus to regenerate (Figs. 8, 9). Under these conditons the growth of X's arbor returned toward the normal bilateral distribution. However, regenration of the neighboring arbors never restored the arbor to complete normality because a bias in the structure had already been imposed. In effect, regeneration arrested the chage but could not resverse it.In breief, an identified sensory neuron's growth has been demonstrated to depend in part on the presence or absence of neighbors. This dependence extends throughout the life of the animal and fits the defination of a competitive interation.
Development of reticulospinal neurons of the zebrafish. II. Early axonal outgrowth and cell body position
Authors: Mendelson Bruce 
Published: January 2005

AbstractThe sequence of axonal outgrowth and the early cell body positions of identifiable types of reticulospinal (RS) neurons of the zebrafish (Brachydanio rerio) were determined in order to learn if differences in neuronal characterstics among specific cell types correlate with differences in the times at which the cells develop. The time of axonal outgrowth and the location of the cells in the developing embryo were determined by filling RS neurons retrogradely with horseradish peroxidase from their growing axons over a series of developmental stages.Hindbrain cells developed in two distinct waves separated by about 10 hours. In the first wave, axons initiating growth at nearly the same time and from nearly the some location in the hindbrain diverged in their choice of an ipsilateral or contralateral pathway into the spinal cord. Individual types of RS neurons grew axons into the rostral spinal cord in a similar temporal sequence to that of their birthdays although the lag time between birthday and time of axonal outgrowth was variable (RS neuronal birthdays were reported in the previous paper, Mendelson: J. Comp. Neurol., 251:160–171 1986). All RS somata were initially observed along the ventral surface of the brain and were subsequently displaced dorsally. The displacement could be passive, due to growth of the ventral hindbrain, and could explain the previously observed dorsoventral differences in RS neuronal time of origin.
NADPH diaphorase histochemistry in the macaque striate cortex
Authors: Sandell Julie H. 
Published: January 2005

AbstractThe distribution of the enzyme dihydronicotinamide adenine dinucleotide phosphate (NADPH) diaphorase was examined in the striate cortex of the rhesus monkey. The pattern of activity in the neuropil matched that of cytochrome oxidase in adjacent sections and the enzymes were similarly modulated by monocular deprivation. Scattered individual cells were also intensely positive for NADPH diaphorase. Labelled cells were most common in the white matter and layers 2 and 3; they were least common inlayers 4 and 5. Diaphorase cells were morphologically diverse, but no pyramidal or spiny cells were labelled. Labelled cells often had multiple varicose processes, which extended laterally for over 1 mm. Although the function of this enzyme is unknown, the morphology and distribution of the diaphorasepositive cells resembles published reports of cortical cells containing somatostatin, avian pancreatic polypeptide, and neuropeptide Y‐like immunoreactivity, and NADPH diaphorase is colocalized with these substances in the rodent striatum (S.R. Vincent, O. Johansson, T. Hökfelt, L. Skirboll, R.P. Elde, L. Terenius, J. Kimmel, and M. Goldstein, J. Comp. Neurol. 217:252–263, '83).
Connections of the parahippocampal cortex in the cat. II. Subcortical afferents
Authors: Room Peter , Groenewegen Henk J. 
Published: January 2005

AbstractThe organization of subcortical inputs to the parahippocampal cortex, which in the present study in the cat is considered to comprise the entorhinal and perirhinal cortices, was studied by using retrograde and anterograde tracing techniques. The results of the retrograde tracer horseradish peroxidase (HRP), HRP conjugated with wheat germ agglutinine (WGA‐HRP), Fast Blue (FB) or Nuclear Yellow (NY) injections indicate that the entorhinal and perirhinal cortices receive inputs from the magnocellular basal forebrain and from distinct portions of the amygdaloid complex, the claustrum, and the thalamus. The two cortices are further projected upon by fibers from the supramamillary region of the hypothalamus, the ventral tegmental area of the mesencephalon, the dorsal raphe nucleus, the nucleus centralis superior, and the locus coeruleus. The entorhinal cortex, in addition, receives projections from the medial septum. As regards the projections from the amygdaloid complex, it was observed that the entorhinal cortex receives its heaviest input from the basolateral amygdaloid nucleus, whereas the perirhinal cortex receives a strong projection from the lateral nucleus and a weaker projection from the basomedial nucleus of the amygdala. Of the thalamic nuclei that project to the parahippocampal cortex, the nucleus reuniens is only connected with the entorhinal cortex, while fibers from the medial geniculate nucleus and the lateral posterior nucleus terminate in the perirhinal cortex. Injections of tritiated amino acid (3H‐leucine) were placed in the medial septum, the dorsal and ventral claustrum, the basolateral and basomedial amygdaloid nuclei, and the nucleus reuniens of the thalamus. The results of these experiments demonstrate that, with the exception of the claustrum, these subcortical areas project mainly to the superficial layers I‐III and the lamina dissecans of the parahippocampal cortex, and to a lesser degree to the deep layers V and VI.
Histaminergic neurons in the rat brain: Correlative immunocytochemistry, golgi impregnation, and electron microscopy
Authors: Wouterlood F. G. , Sauren Y. M. H. F. , Steinbusch H. W. M. 
Published: January 2005

AbstractHistamine‐containing neurons were visualized in Vibratome‐sections of rat brain with the indirect peroxidase‐antiperoxidase immunocytochemical method of Sternberger (Immunocytochemistry, 2nd edition, New York: John Wiley and Sons, pp.1–354, '79) by utilizing a primary antibody directed against L‐histidine decarboxylase (HDC). Cell bodies of HDC‐immunoreactive neurons are located exclusively in the posterior hypothalamus: tuberal magnocellular nucleus (TM), caudal magnocellular nucleus (CM), and post‐mammillary magnocellular nucleus (PCM). With the light microscope, all the HDC‐immunoreactive neurons in CM and PCM and the majority of the HDC‐immunoreactive neurons in TM appear to be large neurons, with a short, thick dendrite emerging from each pole of the long axis of the oval perikaryon and one or more, thinner, nonpolar primary dendrites.In the electron microscope, it can be seen that the immunoreaction product is diffusely dispersed in the cytoplasm. The ultrastructural features of all investigated (70) HDC‐immunoreactive neurons in the three nuclei, independent of their light microscopic characteristics, are remarkably similar: large, unindented, pale nucleus; a high proportion of cytoplasm to nucleus (with the exception of the medium‐sized HDC‐immunoreactive neurons in TM); large, perinuclear array of Golgi apparatus; numerous mitochondria; endoplasmic reticulum fragmented into numerous small cisterns; thick initial portions of the primary dendritic trunks; few axosomatic synaptic contacts.Twenty‐one Golgi‐Kopsch‐impregnated neurons taken from CM, PCM, and TM were embedded in epoxy resin, serially sectioned, and investigated in the electron microscope. The ultrastructural characteristics typical of HDC‐immunoreactive neurons were observed in all three nuclei in neurons with large cell bodies tapering into two thick, sparsely spinous primary dendrites that subsequently dichotomize into very long (up to 100 μm), nontapering, aspinous secondary dendrites. In sections taken from the posterior hypothalamic area of rats prepared in a conventional way for electron microscopy, distinct populations of large cells can be observed in TM, CM, and PCM displaying the same set of ultrastructural characteristics as the HDC‐immunoreactive neurons.
Observations on the cerebellum of normal‐reeler mutant mouse chimera
Authors: Terashima Toshio , Inoue Kaoru , Inoue Yoshiro , Yokoyama Minesuke , Mikoshiba Katsuhiko 
Published: January 2005

AbstractThe normal‐reeler chimera mouse (+/+ ↔ rl/rl) provides an experimental system in which an analysis of the migration of immature neurons in the cerebellum can be accomplished. In the present study, five chimera mice were produced from embryos of the wild‐type control (C57Bl/6N) and the reeler mutant mouse (BALB/c) by the aggregation technique. The isozyme pattern of glucosephosphate isomerase (GPI) revealed that the brain tissue in the chimera contained both isozymes of the BALB/c (reeler) and C57Bl/6N (normal) strains, implying that internal mosaicism of the cerebellum truly existed. We found no abnormality in the cerebellum of the chimera mouse: the neuronal and glial subpopulations revealed no difference from those of the control. Such normalization of the cerebellum in the chimera suggests that the disturbance of neuronal migration in the reeler is attributable to an abnormal cell‐to‐cell interaction between migrating young neurons and the radial glial cells.
Cortical connections of the somatosensory fields of the lateral sulcus of macaques: Evidence for a corticolimbic pathway for touch
Authors: Friedman David P. , Murray Elisabeth A. , O'Neill J. Blanche , Mishkin Mortimer 
Published: January 2005

AbstractThe ipsilateral corticocortical connections of the somatosensory fields of the lateral sulcus of macaques were examined with both anterograde and retrograde axonal transport methods. In most cases, the field of interest was identified prior to the injection of the tracer substance by recording neuronal responses to somatic stimulation.The results show that the second somatosensory area (S2) is reciprocally connected with the retroinsular area (Ri), area 7b, and the granular (Ig) and dysgranular (Id) insular fields. Ri is also reciprocally connected with Ig. Previously reported connections were confirmed between S2 and areas 3a, 3b, 1, and 2 and between area 5 and both area 7 and Ri. Moreover, the portions of Ig and Id that receive somatic inputs were shown to project to the amygdaloid complex. Id projects, in addition, to the perirhinal cortex, which supplies input to the hippocampal formation.The corticocortical projections were found to have two distinct laminar patterns of termination. One is characterized by heavy terminations in layers IV and IIIb and the other by heavy terminations in layer I, but no terminations in layers IV and IIIb. These two patterns were typically found to be reciprocally related.The results suggest that somatosensory information is processed by a series of cortical fields, including areas 3a, 3b, 1, 2, 5, 7b, S2, Ig, and Id. These fields have access to the amygdaloid complex and the hippocampal formation. Thus, a ventrally directed tactile processing pathway can be followed from S1 to the temporal lobe limbic structures via relays in S2 and the insula; this corticolimbic pathway may subserve tactile learning and memory.
Successive waves of differentiation of cutaneous afferents in rat mystacial skin
Authors: Munger Bryce L. , Rice Frank L. 
Published: January 2005

AbstractThe present study has traced the sequence of maturation of sensory receptors in the mystacial pad of postnatal rats. At birth the follicle‐sinus complexes (F‐SC) are well innervated by deep vibrissal nerves although the number of axons entering the sinus is less than that in the adult. The innervation of the F‐SC by the conus or superficial vibrissal nerves derived from skin nerves that form the superficial dermal nerve plexus is limited to the Merkel rete ridge collar at birth, and the innervation to the inner conical body is conspicuously absent. The inner conical body innervation begins to appear 3–4 days after birth and rapidly matures over the week. By 3 weeks of age the F‐SCs have a mature sensory innervation. At birth small guard hairs are present in the intervibrissal pelage and are associated with scant axons of the superficial dermal nerve plexus, but no mature sensory terminals are present. The sensory innervation of the intervening pelage begins to differentiate during the second week and mature piloneural complexes can be recognized by 3 weeks of age. Innervation to vellus hairs is still developing at 3–4 weeks of age. These maturational changes in peripheral sensory innervation correlate with gradual changes in the structure of barrels in the first somatosensory cortex (SI). Sequential waves of differentiation of sensory receptors appear to be a general feature of neural development.
Pattern in the laminar origin of corticocortical connections
Authors: Barbas H. 
Published: January 2005

AbstractThe laminar origin of cortical projections to the frontal cortex was studied in 17 adult rhesus monkeys with the use of the retrograde transport of horseradish peroxidase (HRP). The frontal regions injected with HRP extended from the posterior periarcuate region to the frontal pole. The architectonic boundaries of areas containing HRP‐labeled neurons were determined from matched sections stained for the visualization of cell bodies, myelin, or acetylcholinesterase. The results showed that the laminar origin of both nearby and distant corticocortical projections was correlated with the architectonic differentiation of the regions giving rise to the projecting afferent fibers. Frontally directed projections from limbic cortices, which show a redimentary laminar organization, emanated mainly from deep layers. On the other hand, projections from increasingly more differentiated cortices arose progressively from the upper (or superagranular) layers. This pattern was observed for projections originating along the axis of architectonic differentiation of the visual, somatosensory, auditory, motor, and preforntal cortical systems. Thus, as the cortical architecture within each system changes from limbic areas toward the primary cortices, the origin of frontally directed projections shifts from predominantly infragranular to predominantly superagranular layers.
Morphology and distribution of neurons in the retinal ganglion cell layer of the adult tammar wallaby—Macropus eugenii
Authors: Wong R. O. L. , Wye‐Dvorak J. , Henry G. H. 
Published: January 2005

AbstractThe morphology of the ganglion cell layer of the adult tammar wallaby has been examined from Nissl‐stained retinal flatmounts. From this material, neurons have been classed as ganglion cells or displaced amacrine cells according to the disposition of Nissl substance. A further subdivision of ganglion cells into a separate group of alphalike cells was assisted by determining the range of soma sizes in neurofibrillar‐stained flatmounts, a method which, in the cat, has revealed the presence of alpha cells. Isodensity contour maps prepared from the Nissl‐stained flatmounts show a well‐developed visual streak and an area centralis in the total neuronal population. A similar pattern was also found in the ganglion cells, thus confirming Tancred's (J. Comp. Neurol. 196:585–603, '81) finding, and, as well, in the alphalike ganglion cells and the displaced amacrine cells. The relative proportions of ganglion cells to displaced amacrines (GC:DA) were evaluated from isodensity profiles drawn along and vertical to the visual streak for the two cell types and also from maps showing the variation in the GC:DA ratio throughout the retina. A comparison with results published for other species shows that the visual streak development in the tammar wallaby is consistent with the expectations of the “terrain” theory and that, in its relative proportion of displaced amacrines, the tammar closely resembles the rabbit but contrasts sharply with the cat, which has half as many ganglion cells and three times as many displaced amacrines as the other two species.
Fasciculation in the early mouse trigeminal nerve is not ordered in relation to the emerging pattern of whisker follicles
Authors: Davies Alun M. , Lumsden Andrew G. S. 
Published: January 2005

AbstractDetailed reconstructions of lengths of the embryonic mouse maxillary nerve were made from serial light and electron microscope sections to determine whether there is any correspondence between the arrangement of fasciculi in the developing nerve and the emerging pattern of whisker follicles on the snout. There was neither correspondence nor obvious pattern in the arrangement of fasciculi at either E11, when trigeminal nerve fibers first contact the presumptive whisker pad, or at E12, when the pattern of developing whisker follicles becomes apparent. Fasciculi merged and branched to form an intricate plexus. Furthermore, the ratio of the number of nerve fibers in one fasciculus to the number in another prior to their merger differed significantly from the ratio of fiber numbers in the two fasciculi after their separation, which indicates that nerve fibers are freely exchanged between fasciculi. Our findings suggest that the somatotopic representation of the whisker follicle pattern in the brainstem does not develop by nerve fiber growth augmenting an initially ordered pattern of fasciculi.