bluuebunny/crossref_metadata_2025_split huggingface dataset:
Localization of aspartate‐like immunoreactivity in the retina of the turtle (Pseudemys scripta)
Authors: Yaqub Asma , Eldred William D. 
Published: January 2005

AbstractAspartate has been reported to be a putative excitatory neurotransmitter in the retina, but little detailed information is available concerning its anatomical distribution. We used an antiserum directed against an aspartate‐albumin conjugate to analyze the anatomy, dendritic stratification, and regional distribution of cell types with aspartate‐like immunoreactivity in the turtle retina. The results showed dramatic differences in immunoreactivity in the peripheral versus the central retina. Strong aspartate‐like immunoreactivity was shown in the peripheral retina, with many well‐labeled processes in the inner plexiform layer. Many bipolar, horizontal, amacrine, and ganglion cells, some photoreceptors, and some unidentified cells were strongly immunoreactive in the peripheral retina. In contrast, although the central retina showed well‐labeled horizontal cells, there was only light labeling in the inner plexiform layer with weakly immunoreactive amacrine and ganglion cells and no labeled bipolar cells. There were several strongly immunoreactive efferent nerve fibers which left the optic nerve head and arborized extensively in the retina. At the electron microscopic level, electron‐dense reaction product was associated with synaptic vesicles at bipolar and amacrine cell synapses in the inner plexiform layer. These results suggest that aspartate may be involved in many diverse synaptic interactions in both the outer plexiform layer and the inner plexiform layer of the turtle retina.
Lysosomal activity in developing cat alpha‐motor axons under normal conditions and during retrograde axonal transport of horseradish peroxidase
Authors: Gatzinsky Kliment P. , Berthold Claes‐Henric , Fabricius Christian 
Published: January 2005

AbstractThe occurrence of acid phosphatase (AcPase)‐positive bodies, i.e., lysosomes, in lumbosacral alpha‐motor axons of kittens, 0–16 weeks of age, was analyzed by light and electron cytochemical methods under normal conditions and after intramuscular injection of horseradish peroxidase (HRP). Axonal lysosomes wore rare early postnatally. In 3‐week‐old animals, a few AcPase‐positive bodies appeared in the axoplasm at some nodes of Ranvier in the peripheral nervous system (PNS) and internodally in the intrafunicular motor axon parts within the central nervous system (CNS). From 6 weeks postnatally, a nodal concentration of AcPase‐positive bodies was also noted in the CNS. The number of AcPase‐positive bodies continued to increase gradually in the course of neuronal maturation. In 16‐week‐old animals, axonal AcPase activity was still at considerably lower levels than at adult stages. At all ages, acid hydrolase‐containing organelles were most commonly found at ventral root nodes. After injection of HRP in the medial gastrocnemius muscle, accumulations of AcPase‐positive bodies were seen in the axoplasm at some PNS nodes of the HRP‐injected sides of kittens aged 8, 12, and 16 weeks. Incubation for demonstration of both HRP and AcPase activity showed that some organelles at HRP‐transporting nodes contained both types of reaction product. The nodal AcPase activity in the intrafunicular, CNS parts of alpha‐motor axons of the HRP‐exposed sides did not differ from that of the contralateral, uninjected sides.In view of our previous observations in alpha‐motor neurons of adult cats in which a lysosome‐mediated degradation of axonally transported materials may take place at PNS nodes of Ranvier, the present study illuminates possible differences in the ability to interfere with axonal transport between developing and mature neurons. The infrequent presence of lysosomes in developing alpha‐motor axons and the implied disability of their nodal regions to interfere with axonally transported constituents in a way similar to that seen in adult animals may be of significance in that trophic and chemical signals can pass unhindered between the periphery and perikaryon. However, this could also have negative consequences for the vulnerable immature neuron in that various materials retrieved at the axon terminals outside the CNS are permitted a more‐or‐less free access to the perikaryon.
N‐acetylaspartylglutamate immunoreactivity in neurons of the monkey's visual pathway
Authors: Tieman Suzannah Bliss , Neale Joseph H. , Tieman David G. 
Published: January 2005

AbstractThe acidic dipeptide N‐acetylaspartylglutamate (NAAG) was identified immunohistochemically within neurons of the visual pathways of two adult macaque monkeys which had undergone midsagittal sectioning of the optic chiasm 6 or 9 years earlier. In both temporal and nasal retinae, amacrine cells, including some displaced amacrine cells, expressed NAAG immunoreactivity. In temporal but not nasal retina, retinal ganglion cells were stained, as were their dendrites in‐the inner plexiform layer, and their axons in the optic nerve fiber layer. In nasal retina, the ganglion cells had degenerated because they were axotomized by the optic chiasm section. In the target regions of the retinal ganglion cells, the superior colliculus and the lateral geniculate nucleus (LGN), both neuropil and cell bodies were stained. In LGN, staining was confined to layers 2, 3, and 5, that is, to the layers innervated by the intact ipsilateral pathway. Immunoreactivity was also seen in the cells of layers 2, 3A, 4B, 5, and 6 of area 17 and layers 3 and 5 of area 18. The neuropil was stained in all layers of area 17, but more heavily in layers 1, 2, 4B, the bottom of 4Cβ, 5B, and 6B. Within 4C the staining was patchy; in tangential sections there were alternating bands of light and dark label which matched the ocular dominance bands demonstrated by cytochrome oxidase histochemistry in adjacent sections. This banding pattern is consistent with the presence of NAAG in geniculocortical terminals of the intact ipsilateral pathway and the absence of such terminals for the contralateral pathway, which had undergone transneuronal degeneration due to the optic chiasm sectioning. Overall, our results for monkey are very similar to those in cat and suggest that NAAG or a structurally related molecule may have a prominent role in the communication of visual signals at retinal, thalamic, and cortical levels.
Diverse thalamic projections to the prefrontal cortex in the rhesus monkey
Authors: Barbas H. , Henion T. H. Haswell , Dermon C. R. 
Published: January 2005

AbstractWe studied the sources of thalamic projections to prefrontal areas of nine rhesus monkeys with the aid of retrograde tracers (horseradish peroxidase or fluorescent dyes). Our goal was to determine the proportion of labeled neurons contributing to this projection system by the mediodorsal (MD) nucleus compared to those distributed in other thalamic nuclei, and to investigate the relationship of thalamic projections to specific architectonic areas of the prefrontal cortex. We selected areas for study within both the basoventral (areas 11, 12, and ventral 46) and the mediodorsal (areas 32, 14, 46, and 8) prefrontal sectors. This choice was based on our previous studies, which indicate differences in cortical projections to these two distinct architectonic sectors (Barbas, '88; Barbas and Pandya, '89). In addition, for each sector we included areas with different architectonic profiles, which is also relevant to the connectional patterns of the prefrontal cortices.The results showed that MD included a clear majority (over 80%) of all thalamic neurons directed to some prefrontal cortices (areas 11, 46, and 8); it contributed just over half to some others (areas 12 and 32), and less than a third to area 14. Clusters of neurons directed to basoventral and mediodorsal prefrontal areas were largely segregated within MD: the former were found ventrally, the latter dorsally. However, the most striking findings establish a relationship between thalamic origin and laminar definition of the prefrontal target areas. Most thalamic neurons directed to lateral prefrontal cortices, which are characterized by a high degree of laminar definition (areas 46 and 8), originated in the parvicellular and multiform subdivisions of MD, and only a few were found in other nuclei. In contrast, orbital and medial cortices, which have a low degree of laminar differentiation, were targeted by the magnocellular subdivision of MD and by numerous other limbic thalamic nuclei, including the midline and the anterior. Thus topographic specificity in the origin of thalamic projections increased as the laminar definition of the target area increased. Moreover, the rostrocaudal distribution of labeled neurons in MD and the medial pulvinar also differed depending on the degree of the laminar definition of the prefrontal target areas. The rostral parts of MD and the medial pulvinar projected to the eulaminate lateral prefrontal cortices, whereas their caudal parts projected to orbital and medial limbic cortices. Selective destruction of caudal MD is known to disrupt mnemonic processes in both humans and monkeys, suggesting that this thalamic‐limbic prefrontal loop may constitute an important pathway for memory.
Reorganization of organotypic cultures of mouse cerebellum exposed to cytosine arabinoside: A timed ultrastructural study
Authors: Seil Fredrick J. , Herndon Robert M. , Tiekotter Kenneth L. , Blank Nathan K. 
Published: January 2005

AbstractThis study was designed to examine the sequential changes in the developing granuloprival cerebellar culture. In this model of anomalous cerebellar development, organotypic cultures derived from newborn Swiss‐Webster mice were exposed to the DNA synthesis inhibitor, cytosine arabinoside, at explantation and were fixed for electron microscopic examination on successive days in vitro. Similar developmental stages were compared in control explants. Granule cell destruction began early, and was widespread by 2 days in vitro, when oligodendrocyte destruction also began in treated cultures. A few granule cells survived, but no recognizable oligodendrocytes remained by 7 days in vitro, at a time when myelin was initially evident in control explants. Purkinje cell recurrent axon collateral sprouting began at 3 days in vitro in cultures exposed to cytosine arabinoside, and the sprouted terminals initially synapsed with Purkinje cell somata, somatic spines and dendritic shafts. Synapses with Purkinje cell dendritic spines developed later, at approximately the same time as parallel fiber‐Purkinje cell dendritic spine synapses formed in control cultures. Astrocytic ensheathment of control Purkinje cells was well underway by 6 days in vitro and Purkinje cell somata were relatively rounded and almost completely ensheathed by 9 days in vitro. Glial ensheathment did not occur in cytosine arabinoside treated cultures, and Purkinje cell somata were scalloped at 7 days in vitro by excess impinging recurrent axon collateral terminals, and never developed the smooth contours characteristic of control Purkinje cells. Purkinje cell somatic spines persisted in treated explants, and reduction of excess extracellular space was delayed until 12 days in vitro, when most‐of the developmental changes had been completed. The earlier development of synapses by excess recurrent axon collateral terminals with Purkinje cell somata, somatic spines and dendritic shafts, followed by the later development of heterotypical synapses with dendritic spines, in parallel with synapse formation by normal presynaptic elements, suggests that the sequence of development of synapses is a function of the maturational state of the postsynaptic components.
Morphological taxonomy of the neurons of the primate striatum
Authors: Yelnik Jérôme , Francis Chantal , Percheron Gérard , Tandéa Dominique 
Published: January 2005

AbstractA quantitative taxonomy of primate striatal neurons was elaborated on the basis of the morphology of Golgi‐impregnated neurons. Dendritic arborizations were reconstructed from serial sections and digitized in three dimensions by means of a video computer system. Topological, metrical, and geometrical parameters were measured for each neuron. Groups of neurons were isolated by using uni‐ and multidimensional statistical tests. A neuronal species was defined as a group of neurons characterized, quantitatively by a series of nonredundant parameters, differing statistically from other groups, and appearing as a separate cluster in principal component analysis. Four neuronal species were isolated: (1) the spiny neuronal species (96% of striatal neurons) characterized by spine‐free proximal dendrites (up to 31 μm) and spine‐laden distal dendrites, which are more numerous, shorter, and less spiny in the human than in the monkey, (2) the leptodendritic neuronal species (2%) characterized by a small number of long, thick, smooth, and sparsely ramified dendrites, (3) the spidery neuronal species (1%) characterized by very thick dendritic stems and a large number of varicose recurrent distal processes, and (4) the microneuronal species (1%) characterized by numerous short, thin, and beaded axonlike processes. All striatal neurons give off a local axonal arborization.The size and shape of cell bodies were analyzed quantitatively in Golgi material and in materials treated for Nissl‐staining, immunohistochemical demonstration of parvalbumin and histochemical demonstration of acetylcholinesterase. Only three types were distinguishable: small, round cell bodies corresponding to either spiny neurons or microneurons, medium‐size elongated cell bodies, which were parvalbumin‐immunoreactive and corresponded to leptodendritic neurons, and large round cell bodies, which were acetylcholinesterase‐positive and corresponded to spidery neurons. Thorough analysis of previously elaborated classifications revealed that spidery neurons do not exist in rats and cats and that large cholinergic neurons in these species correspond to leptodendritic neurons. From this, it can be assumed that the dendritic domain of striatal cholinergic neurons is considerably smaller in primates than in other species.Computer simulations based on both the frequency of each neuronal species and their three‐dimensional dendritic morphology revealed that the striatum consists of two intertwined dendritic lattices: a fine‐grain lattice (300–600 μm) formed by the dendritic arborizations of spiny, spidery, and microneurons, and a large‐grain lattice (1,200 μm) formed by the dendritic arborizations of leptodendritic neurons. This suggests that cortical information can be processed in the striatum through two different systems: a fine‐grain system that would conserve the precision of the cortical input, and a large‐grain system that would blur it.
Segmental differentiation in the leech central nervous system: Proposed segmental homologs of the heart accessory neurons
Authors: Stewart R. R. , Gao W.‐Q. , Macagno E. R. 
Published: January 2005

AbstractAs part of an on‐going study of segmental differentiation in the central nervous system (CNS) of the leech Hirudo medicinalis, a search was made for putative segmental homologs of the heart accessory (HA) neurons, which exist exclusively as a bilateral pair in the ganglia of the fifth and sixth body segments. As it is not yet feasible to obtain adequate cell lineage information in H. medicinalis potential homologs of the HA neurons were determined using morphological, immunohistochemical, and electrophysiological criteria. Among cells in other body ganglia with somata in the same locations as HA neurons, a pair was found having extensive morphological and physiological similarities to HA neurons. These we have called HA‐like (HAL) neurons.Adult HA and HAL neurons have closely related patterns of primary branching, in terms of shape, intraganglionic pathways taken, and extraganglionic projections. The number, location, and relative thickness of branches are also similar among these cells. In embryos 10 to 11 days old, HA and HAL neurons have virtually identical branching patterns, with primary and secondary branches of nearly uniform caliber. Differences in branch thickness develop gradually; by embryonic day 20, they resemble those found in adult neurons. Two features found to differ between HA and HAL neurons were the cell body diameter (larger for the HA cells) and the expression of antigens recognized by the monoclonal antibody Laz1‐1 (absent at a detectable level in the HA neurons). At a physiological level, the HA and HAL neurons showed action potentials of similar size and shape, as well as inhibitory synaptic inputs from a common source, the heart interneurons (HN).The observations presented here suggest that there is a common developmental origin for the HA and HAL neurons, and hence that their fates are positionally determined by as yet unknown factors.
Adrenal steroids regulate postnatal development of the rat dentate gyrus: I. Effects of glucocorticoids on cell death
Authors: Gould Elizabeth , Woolley Catherine S. , McEwen Bruce S. 
Published: January 2005

AbstractThe rat dentate gyrus undergoes a period of naturally occurring cell death during the first postnatal week. In the adult rat, removal of circulating adrenal steroids by adrenalectomy is followed by massive death in the granule cell layer, thus raising the possibility that developmental cell death results from low levels of these hormones. Interestingly, the first two postnatal weeks of life in the rat, termed the stress hyporesponsive period, are characterized by very low levels of adrenal steroids. In order to determine whether low levels of adrenal steroids enable developmental cell death to occur in the dentate gyrus, we examined the density of pyknotic and healthy cells in the dentate gyrus of rat pups which received one of the following treatments: (1) injections of the endogenous rat glucocorticoid corticosterone during the first postnatal week, or (2) adrenalectomy at the time when glucocorticoid levels normally rise. Quantitative analysis of the density of pyknotic cells in the granule cell layers revealed significant decreases with corticosterone treatment by the end of the first postnatal week. In these same brains, treatment with corticosterone resulted in a substantial increase in the density of pyknotic cells in the hilus. Adrenalectomy resulted in a significant increase in the density of pyknotic cells in the granule cell layer as well as in the hilus. Despite the dramatic alterations in the density of pyknotic cells with both increases and decreases in glucocorticoid levels, the density of healthy cells remained the same. These observations suggest that glucocorticoids regulate several processes, possibly including neurogenesis and migration, in addition to cell death.
Differential regulation of the low‐affinity nerve growth factor receptor during postnatal development of the rat brain
Authors: Koh Sookyong , Higgins Gerald A. 
Published: January 2005

AbstractWe studied the temporal and spatial localization of the low‐affinity nerve growth factor receptor (LNGF‐R) during the early postnatal period in rat brain in order to understand better the relationship between nerve growth factor (NGF)‐like responsiveness and the development of specific central neuronal populations. Four different developmental patterns of LNGF‐R mRNA hybridization were found in this study. First, some neurons contain high levels of LNGF‐R mRNA from postnatal time points into adulthood, as exemplified by neurons of the cholinergic basal forebrain and mesencephalic trigeminal nucleus. Second, several cell groups exhibit robust hybridization during the early postnatal period but contain much reduced levels of LNGF‐R mRNA in the adult brain. These include striatal neurons, Purkinje cells of the cerebellum, and several medullary nuclei. A third group of cells produces the LNGF‐R transiently during development, including cranial nerve nuclei of the brainstem, the periolivary nuclei complex, the reticular formation, and the deep cerebellar nuclei. Finally, cell populations which may exist only transiently during central nervous system (CNS) development, such as subplate neurons of the cerebral cortex, appear to express the LNGF‐R during only a brief period. These results show that the LNGF‐R gene is differentially regulated in a cell type‐specific manner during development, and suggests that diverse neuronal populations require only transient growth factor sensitivity, while others exhibit NGF‐like responsitivity into maturity.
Distribution of hippocampal CA1 and subicular efferents in the prefrontal cortex of the rat studied by means of anterograde transport of Phaseolus vulgaris‐leucoagglutinin
Authors: Jay Thérèse M. , Witter Menno P. 
Published: January 2005

AbstractProjections of the hippocampal formation to the prefrontal cortex were visualized in the rat by means of the anterograde tracer Phaseolus vulgaris‐leucoagglutinin. These projections distribute only to the prelimbic and the medial orbital cortices and arise exclusively from restricted portions of field CA1 of the Ammon's horn and the subiculum. The most dorsal portion of CA1 does not contribute fibers to this projection. In the subiculum, its origin is restricted to the proximal half, i.e., the portion that directly borders field CA1. Fibers from field CA1 and the subiculum have comparable distribution patterns in the prelimbic and medial orbital cortices. The density and distribution in the prefrontal cortex of the projections from the proximal portion of the subiculum depends on the location of the injections along the dorsoventral axis of the hippocampal formation: the intermediate portion of the subiculum projects more densely and diffusely than its dorsal and ventral portions.In the prelimbic cortex, labeled fibers are present in all layers, showing marked morphological differences in deep versus superficial layers. In layers V and VI, most of the fibers are vertically oriented, while in layers II and III they are short and oriented towards the pial surface. Although no clear differences in terminal distribution were observed along the rostrocaudal extent of the prelimbic cortex, its dorsal and ventral portions show different innervation patterns. In the ventral portion of the prelimbic cortex, varicose fibers and terminal arborizations were present in all cortical layers, deep (V and VI) as well as superficial (II and III). In its dorsal part, the innervation was less dense and mostly present in the deep layers (V and VI). The fiber and terminal distribution in the medial orbital cortex was diffuse in all layers with a slight preference for layers deep to layer II.