bluuebunny/crossref_metadata_2025_split huggingface dataset:
Extrinsic determinants of retinal ganglion cell development in primates
Authors: Leventhal Audie G. , Ault Steven J. , Vitek Damgmar J. , Shou Tiande 
Published: January 2005

AbstractAs in all mammals studied to date, primate retina contains morphologically distinct classes of retinal ganglion cells (Polyak: The Retina. Chicago: University of Chicago Press, '41; Boycott and Dowling: Philos. Trans. R. Soc. Lond. [Biol.] 225:109–184, '69; Leventhal et al.: Science 213:1139–1142, '81; Perry et al.: Neuroscience 12:1101–1123, '84; Rodieck et al.: J. Comp. Neurol. 233:115–132, '85; Rodieck: In H.D. Steklis and J. Erwin (eds): Comparative Primate Biology, Volume 4: Neurosciences. New York: Alan R. Liss, Inc., pp. 203–278, '88). We have now studied the morphologies, central projections, and retinal distributions of the major morphological classes of ganglion cells in the normal adult monkey, the newborn monkey, and the adult monkey in which restricted regions of retina were depleted of ganglion cells at birth as a result of small lesions made around the perimeter of the optic disc. Both old‐world (Macaca fascicularis) and new‐world (Saimiri sciureus) monkeys were studied.Our results indicate that, at birth, the major morphological classes of monkey retinal ganglion cells are recognizable; cells in central regions are close to adult size whereas cells in peripheral regions are much smaller than in the adult. As in the adult (Stone et al.: J. Comp. Neurol. 150:333–348, '73), in newborn monkeys there is a very sharp division between ipsilaterally and contralaterally projecting retinal ganglion cells (nasotemporal division). Consistent with earlier work (Hendrickson and Kupfer: Invest. Ophthalmol. 15:746–756, '76) we find that the foveal pit in the neonate is immature and contains many more ganglion cells than in the adult.In the adult monkey in which the density of retinal ganglion cells in the central retina was reduced experimentally at birth, the fovea appeared immature, and an abnormally large number of retinal ganglion cells were distributed throughout the foveal pit. The cell bodies and dendritic fields of ganglion cells that developed within cell‐poor regions of the central retina were nearly ten times larger than normal. In peripheral regions the effects were smaller. The dendrites of the abnormally large foveal cells on the borders of cell‐poor zones were directed normally toward the foveal pit. They did not extend preferentially into the cell‐poor region as do the abnormally large cells on the borders of experimentally induced cell‐poor regions of cat central retina (Leventhal et al.: J. Neurosci. 8:1485–1499, '88) or, as we found here, in paracentral regions of primate retina.It is hypothesized that (1) competition for afferents as well as direct interactions among neighboring ganglion cells in the immature retina may contribute to the development of the structure of primate retinal ganglion cells, (2) other factors are also likely to be involved, and (3) foveal development can only proceed normally if the central retina contains an extremely high concentration of retinal ganglion cells.
Deprived somatosensory‐motor experience in stumptailed monkey neocortex: Dendritic spine density and dendritic branching of layer IIIB pyramidal cells
Authors: Bryan Guy K. , Riesen Austin H. 
Published: January 2005

AbstractInfant macaque monkeys (Macaca arctoides) were individually raised to age 6 months in large clear cubes built into one wall of a control colony that allowed them visual access to it but not tactile contact. The two deprivation conditions (Cond 2 and Cond 3) were equal both in physical size and with respect to partial social isolation. They differed in the degree of somatosensory‐motor opportunity available during development in that the Cond 2 chamber was empty, whereas Cond 3 contained ladders, a trapeze, and play objects. Four monkeys from each of these conditions were compared with four colony‐reared (Cond CR) monkeys. Neuroanatomical changes were evaluated by using light microscopy in Golgi‐Cox‐stained neocortex. Dendritic spines on the apical shafts of layer IIIB pyramidal cells were counted in primary motor (MI), somatosensory (SI), and visual (area 17, V1) cortical regions. Layer IIIB pyramidal neurons with somas of medium size were selected from each cortical region and the density of apical dendritic spines determined. The basilar dendritic branches of these same neurons were traced, and the dendritic branching complexity was assessed in order to compare the sensitivity of the dendritic spine and branching measures consequent to deprived rearing. The number of apical dendritic spines was significantly reduced in Cond 2 when compared with either Cond 3 or Cond CR (which did not differ from each other). This occurred in both MI and SI cortex, but not in the visual cortex, the region used as a control for a global brain effect. Branching complexity measured on the same pyramidal neurons was reduced only in MI cortex of Cond 2. These results show spine density, a more direct measure of neuronal connectivity, to be the more sensitive measure of early environmental deprivation. Also, the enriched environment provided by Cond 3 relative to Cond 2 offset the effect of partial social isolation such that both morphometric measures had values comparable to Cond CR monkeys.
Morphological substrate for eyelid movements: Innervation and structure of primate levator palpebrae superioris and orbicularis oculi muscles
Authors: Porter John D. , Burns Leigh Ann , May Paul J. 
Published: January 2005

AbstractThe levator palpebrae superioris and orbicularis oculi are antagonistic muscles that function during movements of the eyelid. The levator also functions in conjunction with superior and inferior rectus muscles in coordinated eye/lid movements. The present study examined the innervation and morphology of these muscles in Cynomolgous monkeys (Macaca fascicularis) in order to provide a better understanding of the anatomical substrate for lid movements. Motoneurons innervating the levator and orbicularis muscles were identified and localized by retrograde transport of WGA/HRP and HRP. Retrogradely labelled levator motoneurons were distributed bilaterally throughout the caudal central division of the oculomotor nucleus. A few labelled cells were also present within the contralateral superior rectus division, possibly because of the spread of tracer at the injection site. The possibility that individual motoneurons collateralize to innervate the levator muscle bilaterally was tested by using double retrograde labelling techniques. Doubly labelled levator motoneurons could not be detected by suing a combination of tracers (HRP and Fast Blue). Motoneurons innervating the upper lid portion of the orbicularis oculi muscle were distributed within the dorsal subdivision of the ipsilateral facial motor nucleus, with a few neurons in the corresponding locus of the contralateral facial nucleus. Species differences in levator motoneuron distribution, particularly distinctions in lateral‐eyed versus frontal‐eyed mammals, are discussed in relation to the neural control of lid movements.The levator palpebrae superioris contains three of the same ultrastructurally defined types of singly innervated muscle fiber found in the global layer of other extraocular muscles and an additional, unique slow‐twitch fiber type. Moreover, the multiply innervated fiber types so characteristic of the other extraocular muscles are conspicuously absent from levator muscles. Unlike the rectus and oblique extraocular muscles, the levator lacks a layered distribution of fiber types. The morphological profiles of levator muscle fiber types are such that they generally do not respect traditional fiber classification schemes, but are consistent with a role for the levator in sustained elevation of the lid.The orbicularis oculi muscle, by contrast, exhibited three distinct fiber types that resembled categories of skeletal muscle twitch fibers. One slow‐twitch and two fast‐twitch fiber types were noted. On the basis of oxidative enzyme profiles and mitochrondrial content, the majority of orbicularis oculi fibers would be fatigue‐prone, an assessment consistent with their rapid onset/offset of action in blinks. Morphological differences between the levator palpebrae superioris and orbicularis oculi muscles reflect not only their dis‐tinct functional roles in blinking and other lid movements, but also their diverse embryological origins.
Effects of iontophoresis of noradrenaline and stimulation of the periaqueductal gray on single‐unit activity in the rat superficial dorsal horn
Authors: Millar Julian , Williams Graham V. 
Published: January 2005

AbstractRecordings were made with a new form of low‐noise carbon fibre microelectrode from 75 units in the superficial laminae of the lumbar dorsal horn of the anaesthetized rat. The response of each unit to adequate stimulation of its peripheral receptive field, to noradrenaline (NA) applied iontophoretically, and to electrical stimulation of the periaqueductal gray (PAG) was investigated. Only units that could be excited by iontophoresis of glutamate (10–100 nA) were analyzed. Recording sites in the spinal cord and stimulation sites in the brainstem were identified histologically at the end of each experiment.Forty‐six units with low‐threshold receptive fields and small spike amplitudes were found, mainly located in laminae II and III. Both stimulation of the PAG and NA iontophoresis excited the majority (32/46) of these units. The rest were unaffected. Eight high‐threshold (HT) units were located in the region of lamina I. Twenty‐one wide‐dynamic‐range (WDR) units were found mainly in deeper laminae. Both WDR and HT units were inhibited by NA and PAG stimulation. This inhibition affected both glutamate‐evoked activity and responses to nociceptive stimuli.We suggest that the small LT units are inhibitory interneurones of the substantia gelatinosa (SG), which act on the WDR and HT units to produce nociceptive‐specific inhibition. The inhibition can be modality‐specific without necessarily being presynaptic because of the laminar arrangement of the dorsal horn. The PAG could thus exert its known antinociceptive effects at least partly via descending noradrenergic axons that excite these SG cells.
Cellular localization of substance P‐ and neurokinin A‐encoding preprotachykinin mRna in the female rat brain
Authors: Harlan Richard E. , Garcia Meredith M. , Krause James E. 
Published: January 2005

AbstractTo determine the locations of neurons in the rat brain expressing substance P and neurokinin A mRNA, we performed in situ hybridization with a radiolabeled cRNA probe that was complementary to α‐, β‐, and γ‐preprotachykinin mRNA. Several types of controls indicated specificity of the labeling. Brain regions containing many labeled neurons include the anterior olfactory nucleus, layer II of the olfactory tubercle, the islands of Calleja, the nucleus accumbens, the caudate‐putamen, portions of the amygdala and hypothalamus, the medial habenular nucleus, nuclei of the pontine tegmentum, several raphe nuclei, several portions of the reticular formation, and the nucleus of the solitary tract. Less frequent labeled neurons were also found in many other regions of the brain. These results extend many previous immunocytochemical studies of the locations of neurons containing immunoreactive substance P, neurokinin A, and neuropeptide K.
Computer‐assisted three‐dimensional reconstructions of [14C]‐2‐deoxy‐D‐glucose metabolism in cat lumbosacral spinal cord following cutaneous stimulation of the hindfoot
Authors: Crockett D. P. , Smith W. K. , Proshansky E. , Kauer J. S. , Stewart W. B. , Woodward D. J. , Schlusselberg D. S. , Egger M. D. 
Published: January 2005

AbstractWe report on computer‐assisted three‐dimensional reconstruction of spinal cord activity associated with stimulation of the plantar cushion (PC) as revealed by [14C]‐2‐deoxy‐D‐glucose (2‐DG) serial autoradiographs. Moderate PC stimulation in cats elicits a reflex phasic plantar flexion of the toes.Four cats were chornically spinalized at about T6 under barbiturate anesthesia. Four to 11 days later, the cats were injected (i.v.) with 2‐DG (100 μCi/kg) and the PC was electrically stimulated with needle electrodes at 2–5 times threshold for eliciting a reflex. Following stimulation, the spinal cord was processed for autoradiography. Subsequently, autoradiographs, representing approximately 8–18 mm from spinal segments L6–;S1, were digitized for computer analysis and 3‐D reconstruction.Several strategies of analysis were employed: (1) Three‐dimensional volume images were color‐coded to represent different levels of functional activity. (2) On the reconstructed volumes, “virtual” sections were made in the horizontal, sagittal, and transverse planes to view regions of 2‐DG activity. (3) In addition, we were able to sample different regions within the grey and white matter semi‐quantitatively (i.e., pixel intensity) from section to section to reveal differences between ipsi‐ and contralateral activity, as well as possible variation between sections.These analyses revealed 2‐DG activity associated with moderate PC stimulation, not only in the ipsilateral dorsal horn as we had previously demonstrated, but also in both the ipsilateral and contralateral ventral horns, as well as in the intermediate grey matter. The use of novel computer analysis techniques—combined with an unanesthetized preparation—enabled us to demonstrate that the increased metabolic activity in the lumbosacral spinal cord associated with PC stimulation was much more extensive than had heretofore been observed.
Organization of cholinergic synapses in the cat's dorsal lateral geniculate and perigeniculate nuclei
Authors: Raczkowski Denis , Fitzpatrick David 
Published: January 2005

AbstractIn the preceding article, we showed that cholinergic fibers originating from the brainstem reticular formation provide a dense innervation of the lateral geniculate nucleus. In this report we describe the ultrastructure of these fibers and their relations with other elements in the neuropil of the lateral geniculate nucleus. Cholinergic fibers were labeled with an antibody to choline acetyltransferase (ChAT), the synthesizing enzyme for acetylcholine (ACh). In the A‐laminae of the lateral geniculate nucleus, ChAT + profiles are small and contain tightly packed, mostly round vesicles. Some end in encapsulated synaptic zones where they form asymmetrical synaptic contacts with processes of both projection cells and interneurons. Others form synapses upon the shafts of dendrites. Of the four classical types of vesicle‐containing profiles identified by Guillery (Z. Zellforsch: Mikrosk. 96: 1–38, '69; Vision Res. [Suppl.] 3: 211–227, '71), ChAT + profiles most closely resemble RSD profiles (Round vesicles, Small profile, Dark mitochondria). However, as a population, ChAT + profiles can be distinguished from the unlabeled population of RSD profiles because they are larger in size, contain more mitochondria, and make synapses with smaller postsynaptic membrane specializations. Each of these differences is statistically significant and together they indicate that ChAT + profiles are a distinct morphological type of synaptic profile. ChAT + profiles in the perigeniculate nucleus resemble those found in the lateral geniculate nucleus; they also make synapses with obvious postsynaptic thickenings.
Ontogeny of catecholaminergic and cholinergic cell distributions in the cat's retina
Authors: Mitrofanis John , Maslim Juliani , Stone Jonathan 
Published: January 2005

AbstractThe development of catecholaminergic and cholinergic neurones in the cat's retina has been examined with antibodies against their respective ratelimiting enzymes, tyrosine hydroxylase (TH) and choline acetyl transferase (ChAT). ChAT‐immunoreactive (IR) cells were first detected at E (embryonic day) 56 with somata in the ganglion cell layer (GCL) or in the inner cytoblast layer (CBL). At P (postnatal day) 1, two faint bands of ChAT‐IR fibres were evident in an inner and outer strata of the inner plexiform layer (IPL) and by P26, the bands were similar to those in the adult. TH immunoreactivity was first detected at E59 in either darkly labelled somata in the inner CBL with processes extending toward the IPL or in lightly labelled somata also located in CBL but with no processes. At P1, most TH‐IR cells had prominently labelled dendrites and, by P8, most of the features of the adult cells were evident.Soma size gradients among TH‐IR cells were first detected at P8, with cells in temporal retina being larger than those in nasal retina or at the area centralis. The smaller sizes of cells at the area centralis emerged after P26. The smaller sizes of ChAT‐IR somata at the area centralis, by contrast, emerged between P8 and P26.The number of both TH‐IR and ChAT‐IR cells declined from the time they first appeared till adulthood. The decline was smaller among ChAT‐IR cells (24%) than among TH‐IR cells (68%). In distribution, the differential expansion of the retina appeared to be largely responsible for generating the final adult distribution of ChAT‐IR cells. However, during late postnatal development (P26 to adulthood), the density of ChAT‐IR cells in the periphery declined more than that of the ganglion cells, suggesting that some ChAT‐IR cells may die in the periphery during this time. Prior to P26, the changes in the distribution of TH‐IR cells were inconsistent with the pattern of retinal expansion. It is suggested that during this period, regional cell loss and cell addition may account for the changes in distribution of TH‐IR cells. Later in development (P26 to adulthood), the changes in the density of TH‐IR cells closely conformed to the differential expansion of the retina.
Monoclonal antibody markers for amphibian oligodendrocytes and neurons
Authors: Steen P. , Kalghatgi L. , Constantine‐Paton M. 
Published: January 2005

AbstractFew immunocytochemical probes have been developed for cold‐blooded vertebrates, thus hampering analyses of cellular processes in these species. Those developed from mammalian and avian tissue often fail either to react or to show similar specificities in poikilotherms. Therefore, we have begun raising monoclonal antibodies (mabs) in mice against frog and tadpole brain tissue. The following analyses of two of these mabs suggest that these antibodies represent specific probes for frog axons and oligodendrocytes.Mab Olig recognizes all the myelinated axon tracts of the mature frog brain and spinal cord, as well as the tracts of the developing tadpole CNS once they have become myelinated. Axons cut in cross section show characteristic o‐shaped staining around individual axons when processed with this antibody. Particularly easy to visualize in the tadpole are immunoreactive cell bodies and processes, seen in continuity with the myelin sheath. Occasionally, in this developing tissue, cells with highly branched processes characteristic of immature oligodendrocytes are observed. No other cells or processes within the brain or spinal cord react with this antibody.Mab Linc stains numerous filaments in all axonal projections. Occasionally, a thin rim of filamentous staining is observed in cell somata, but many regions rich in neuronal somata or dendrites are unreactive to this antibody. This in vivo staining pattern suggests that the Linc antigen is differentially distributed within neurons and exhibits a high concentration in axons.Linc immunoreactivity is robust in the processes of a subpopulation of dissociated tectal cells in culture. These Linc‐positive cells are characterized as neurons on morphological criteria. Also, intense Linc immunoreactivity is present in the bundles of retinal axons that extend from retinal explants. Olig immunoreactivity, however, has not been detected in tectal cultures or retinal explants.Improved staining following Triton X‐100 treatment of tissue sections suggests that neither of the mabs recognizes lipid antigens and that both are probably localized within the cell cytoplasm. Only the Linc mab reacts on Western blots of denatured brain protein. Linc consistently recognizes two Triton X‐100‐insoluble proteins with apparent molecular weights of 56 and 58 kD.The epitopes recognized by the Olig and Linc mabs have been surveyed in terms of their resistance to optic nerve crush and their consequent value in studies requiring such procedures. Possible homologies to known cell‐type‐specific molecules are discussed.
Structure‐Function relationships in rat brainstem subnucleus interpolaris: VII. Primary afferent central terminal arbors in adults subjected to infraorbital nerve section at birth
Authors: Renehan William E. , Rhoades Robert W. , Jacquin Mark F. 
Published: January 2005

AbstractPrior studies in this series have clarified the normal organization of subnucleus interpolaris and the response of higher‐order neurons to neonatal deafferentation. The present report describes the response of individual rat trigeminal primary afferents to transection of the infraorbital (IO) nerve on the day of birth. Physiologically characterized afferents in adult animals were labeled by intraaxonal injection of horseradish peroxidase (HRP). Qualitative and quantitative examination of the interpolaris collaterals of 62 recovered neurons revealed: (1) an increase in the transverse area of vibrissa afferent terminal arbors, (2) a decrease in the number of boutons per collateral of vibrissa afferents, (3) a decrease in the bouton density of both vibrissa and guard hair primary afferents, (4) a decrease in the circularity of guard hair afferent arbors, (5) an increase in the number of collaterals given off by nociceptive fibers, and (6) abnormal primary afferent topography. The data support the hypothesis that vibrissa afferents respond to neonatal axotomy by central arbor expansion, but not by sprouting. Arbor expansion provides a morphological substrate for the abnormal histochemical staining patterns seen in animals subjected to IO damage in the early postnatal period.
Quantitative analysis of cone photoreceptor–horizontal cell connectivity patterns in the retina of a cyprinid fish: Electron microscopy of functionally identified and HRP‐labelled horizontal cells
Authors: Downing J. E. G. , Djamgoz M. B. A. 
Published: January 2005

AbstractHorizontal cells generating photopic luminosity and biphasic/chromaticity‐type S‐potentials were identified and intracellularly labelled with horseradish peroxidase in the retina of the roach. The synaptic connectivity patterns of the horizontal cell dendrites within pedicles of different spectral types of cone were then quantitatively studied by electron microscopy. Luminositytype responses were generated by H1‐like horizontal cells contacting similar numbers of red‐ and green‐sensitive cones and very few blue‐sensitive cones. Most dendritic contacts were lateral to synaptic ribbons. Central contacts with ribbons were made almost exclusively within red‐sensitive cone pedicles. Biphasic/chromaticity‐type S‐potentials were generated by H2‐like horizontal cells. The dendrites of the latter contacted green‐ and blue‐sensitive cones, both at central and lateral sites at synaptic ribbons. An attempt was made to correlate cone ribbon connectivity patterns and spectral characteristics of the horizontal cells according to several hypotheses, some proposed in earlier studies.