bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrastructure and synaptic contacts of enkephalinergic amacrine cells in the retina of turtle (Pseudemys scripta)
Authors: Eldred William D. , Karten Harvey J. 
Published: January 2005

AbstractBistratified amacrine cells of the turtle retina containing enkephalin‐like immunoreactivity were examined with the electron microscope with the aid of peroxidase immunocytochemical techniques. Our goal was to determine the nature and the location of the synaptic contacts of these cells and the intracellular localization of the immunoreactivity. There was a diffuse reaction product throughout the cytoplasm which coated the surfaces of all the organelles and a dense reaction product which filled the core of some large cytoplasmic vesicles (130 nm in dia.). These labeled amacrine cells received conventional synaptic contacts from other unlabeled amacrine cells and ribbon synaptic contacts from unlabeled bipolar cells, in both the proximal and distal inner plexiform layer. These enkephalin‐positive amacrine cells made conventional synaptic contacts containing unlabeled synaptic vesicles (60 nm in dia.), with ganglion cells in the proximal inner plexiform layer and with bipolar cells in the distal inner plexiform layer. These results suggest that enkephalin‐like material coexists with another neurotransmitter within these neurons and that these amacrine cells are able to integrate information from both amacrine cells and bipolar cells and provide synaptic input to bipolar cells, ganglion cells, and possibly other amacrine cells.
Studies of innervation patterns in grafted chick wings
Authors: Neset Monica , Muniak Charles , Edwards Charles 
Published: January 2005

AbstractThe pattern of innervation of 12 day embryonic chick wings was studied by morphological and electrophysiological techniques. Several types of chick wing grafts were performed to investigate the rules governing nerve pattern formation: whether the motor neurons actively seek out and connect with specific muscles or are passively guided and whether cell death plays any role in pattern formation. In each type of graft the outgrowing neurons were confronted with extra targets distal to the elbow. Two grafts replicated lower arm parts in series (proximodistal graft) or in parallel (forearm and hand replicated, in the same pattern of asymmetry in a split limb graft); a third produced a mirror image limb. The flexor carpi ulnaris muscle (F.C.U.) was studied in these limbs.The innervation of the most distal f.c.u. muscle in proximodistal grafted limbs varied with the extent of host f.c.u. muscle present. The f.c.u. muscles in the split limb graft were always innervated. In both limb grafts the f.c.u. muscles were innervated by the appropriate neurons, as determined by retrograde HRP technique and electrophysiological recordings. This strongly suggests that the motor neurons are able to seek out and connect with their appropriate muscle. Results of the mirror image limb graft suggest that other factors may be involved.In addition, motor neuron cell counts were performed. From this one can infer that the normally occurring pattern of cell death was not affected by the grafts. Cell death is therefore excluded as a major factor in nerve pattern formation.
Anatomical evidence for medial pulvinar connections with the posterior cingulate cortex, the retrosplenial area, and the posterior parahippocampal gyrus in monkeys
Authors: Baleydier C. , Mauguiere F. 
Published: January 2005

AbstractReciprocal connections between the medial pulvinar and the limbic neocortex in monkeys were demonstrated by means of tritiated amino acid injections in the medial pulvinar and the cingulate cortex, and HRP injections in the medial pulvinar. It appears that the medial nucleus of the pulvinar sends projection fibres to the posterior cingulate gyrus (area 23), the retrosplenial area, and the posterior parahippocampal gyrus (areas TH and TF). The labeled terminals were concentrated in two bands, one in the deeper part of layer III and in layer IV, and the other in layer I. These projections were observed to be reciprocal, and the cortical afferent fibers to the medial pulvinar were found to originate from the deep layers of the cortex.The medial nucleus of the pulvinar was already known to be connected with the prefrontal cortex and with the inferior parietal lobule. Since this nucleus is now demonstrated to be connected with the posterior limbic neocortex, it is envisaged as being the thalamic counterpart of a cortical triad (prefrontal, parietal, and limbic) involved in modulating directed attention.
Regeneration of lumbar dorsal root axons into the spinal cord of adult frogs (rana pipiens), an HRP study
Authors: Liuzzi Francis J. , Lasek Raymond J. 
Published: January 2005

AbstractLumbar dorsal roots of adult frogs were crushed or cut and reanastomosed. Following survival times of up to 75 days, the regenerating dorsal roots were recut and anterogradely injury‐filled with horseradish peroxidase. This revealed that in the adult frog, regenerating axons re‐enter the spinal cord. Comparison of the distribution of these axons with that of normal, dorsal root axons showed that there is a partial restoration of the segmental distribution in the gray matter. However, the long ascending sensory tract of the dorsal funiculus was not restored, The dorsal funiculus was markedly gliotic and had relatively few labelled, regenerated axons. The labelled axons that were seen in the dorsal funiculus either extended longitudinally for a distance just beneath the pia, apparently in association with the glia limitans, or traversed the region to enter the dorsal gray matter. Most of the large and small diameter axons that entered the gray matter did so by passing through the region of the dorsolateral fasciculus. Within the gray matter, small diameter, regenerated axons arborized in the region of the dorsal terminal field, a region that has been shown in the normal frog to receive cutaneous afferents only. Many large diameter axons, presumably muscle afferents, arborized in the ventral terminal field, a region shown in the normal frog to receive muscle afferents exclusively. However, many of these large diameter axons had arborizations that extended to both terminal fields, thus suggesting that some abberant connections are made during dorsal root regeneration in the adult frog.
Rat medulla oblongata. I. Cytoarchitectonic considerations
Authors: Kalia Madhu , Fuxe Kjell 
Published: January 2005

AbstractThe goal of thin study was to define the detailed cytoarchitecture of the medulla oblongata of the rat in order to accurately localize immunocytochemically distinct populations of neurons in this region. The cytoarchitectonic features of this region of the rat brain stem were examined in 40 μm thick serial sections of celloidin embedded brains blocked in the Horsley‐Clarke stereotaxic plane. These sections were stained with cresyl violet and examined at a number of different magnifications with a variety of different intensities of staining to demonstrate particular features of the cells in this region. High magnification photomicrographs of this material revealed characteristic features of the various populations of cells.The results illustrate that the cytoarchitecture of the medulla oblongata of the rat changes remarkably within very short distances in the rostrocaudal direction. These changes indicate the need to study the anatomy and immunocytochemistry of this region in detailed serial sections. The ventral reticular formation of the rat medulla is cytoarchitectonically complex. Nuclear groups such as the lateral reticular nucleus (LRt) contain a number of cytoarchitectonically distinct subnuclei, as does the dorsally located nucleus of the tractus solitarious (nTS) (Kalia and Sullivan, '82). These nuclei occupy a considerable length of the medulla and terminate abruptly at the pontomedullary boundary. A number of other cytoarchitectonic features of the medulla were examined and the detailed characteristics were defined.
Development of the human retina: Patterns of cell distribution and redistribution in the ganglion cell layer
Authors: Provis Jan M. , Van Driel Diana , Billson Frank A. , Russell Peter 
Published: January 2005

AbstractNeurogenesis in the ventricular layer and the development of cell topography in the ganglion cell layer have been studied in whole‐mounts of human fetal retinae. At the end of the embryonic period mitotic figures were seen over the entire outer surface of the retina. By about 14 weeks gestation mitosis had ceased in central retina and differentiation of photoreceptor nuclei was evident within a well‐defined area which constituted about 2% of total retina area. This area was approximately centered on the site of the putative fovea, identified by the exclusive development of cone nuclei at that location. The area of retina in which mitosis had ceased increased as gestation progressed. By mid‐gestation mitosis in the ventricular layer occupied about 77% of the outer surface of the retina and by about 30 weeks gestation mitosis in the ventricular layer had ceased. Cell density distributions in the ganglion cell layer were nonuniform at all stages studied (14–40 weeks). Densities were highest at about 17 weeks gestation, and by mid‐gestation the adult pattern of cell topography was present with maps showing elevated cell densities in posterior retina and along the horizontal meridian. Cell densities generally declined throughout the remainder of the gestation period, except in the posterior retina, where densities in the perifoveal ganglion cell layer remained high during the second half of gestation. There is a rapid decline in cell density in the foveal ganglion cell layer toward the end of gestation, and it is suggested that the persistence of high densities in the perifoveal region may be related to migration of cells away from the developing fovea. The total population of cells in the ganglion cell layer was highest (2.2–2.5 million cells) between about weeks 18 and 30 of gestation. After this the cell population declined rapidly to 1.5–1.7 million cells. It is suggested that naturally occurring neuronal death is largely responsible for this decline.
The ultrastructural localization of enkephalin and substance P immunoreactivities in the nucleus tractus solitarii of the cat
Authors: Maley Bruce E. 
Published: January 2005

AbstractIn the medial and commissural subdivisions of the nucleus tractus solitarii enkephalin and substance P immunoreactivities were localized within synaptic terminals, unmyelinated axons, and neuronal cell bodies. Both enkephalin and substance P immunoreactivities were contained within synaptic terminals which had a mixture of small clear vesicles and dense core vesicles. The presence of dense core vesicles within both the enkephalin‐and substance P‐immunoreactive terminals was a consistent feature, although they were not associated with the actual synaptic junction. While enkephalin‐ and substance P‐immunoreactive terminals shared a similar morphology, their respective distributions along the dendritic tree were quite distinct. Enkephalin‐immunoreactive terminals contacted mainly the cell body and proximal portions of the dendritic tree. In contrast, substance P‐immunoreactive terminals synapsed predominantly with spines and shafts of small to medium‐sized dendrites. Few substance P‐immunoreactive terminals contacted proximal dendrites and they were never presynaptic to the neuronal cell body. This apparent segregation of synaptic terminals on neurons suggests that enkephalin synapses have a more pronounced effect than substance P terminals.
Cortical projections of the dorsolateral visual area in owl monkeys: The prestriate relay to inferior temporal cortex
Authors: Weller R. E. , Kaas J. H. 
Published: January 2005

AbstractThe dorsolateral visual area (DL) is one of a number of visual areas that have been defined by electrophysiological mapping procedures and cortical architecture in the extrastriate cortex of owl monkeys. The projections of DL were determined by the intra‐axonal transport of 3H‐proline, 3H‐aceytl‐wheat germ agglutinin, and horseradish peroxidase after cortical injections. The major ipsilateral projection of DL defined a new subdivision of the visual cortex in owl monkeys, the caudal inferior temporal cortex. Single injections in DL sometimes produced label in two separate regions in the caudal inferior temporal cortex, suggesting that functional subdivisions exist in this projection zone. Other targets of DL included the region of the frontal eye fields, the dorsomedial visual area, the dorsointermediate visual area (DI), a region of the cortex rostral to DI which we call the temporoparietal cortex, and possibly the ventral (V) and posterior parietal areas. A major feedback projection of DL was to V‐II. Projections from DL to V‐II and the dorsomedial visual area were roughly retinotopic. Projections from DL to the contralateral cerebral hemisphere were to DL and the inferior temporal cortex. Overall, the results support the concept that a major relay of visual information proceeds from V‐I to V‐II to DL and then to the inferior temporal cortex. In addition, similarities in connection patterns of DL in owl monkeys and V4 in macaque monkeys suggest that DL and much or all of V4 are homologous.
Direct cortical projections to the parabrachial nucleus in the cat
Authors: Yasui Yukihiko , Itoh Kazuo , Takada Masahiko , Mitani Akira , Kaneko Takeshi , Mizuno Noboru 
Published: January 2005

AbstractDirect projections from the cerebral cortex to the parabrachial nucleus in the cat were examined by the horseradish peroxidase (HRP)method. When HRP was injected into the parabrachial nucleus, retrogradely labeled neuronal cell bodies were seen, bilaterally with an ipsilateral predominance, mainly in the orbital gyrus, the lateral bank of the presylvian sulcus, and a restricted region in the infralimbic cortex on the medial surface of the frontal lobe (stereotaxic coordinates; Fr: 22, L: 1, H: ‐1); all labeled neurons were in deep pyramidal cell layer.After injecting HRP conjugated to wheat germ agglutinin (WGA‐HRP) into the cortical regions where retrogradely labeled neurons were found after injecting HRP into the parabrachial nucleus, anterogradely labeled cortical fibers were traced to the parabrachial nucleus. Corticoparabrachial fibers originating from the orbital gyrus and the lateral bank of the presylvian sulcus ran ipsilaterally through the internal capsule and the cerebral peduncle down to the lower brainstem, whereas those from the infralimbic cortex coursed down ipsilaterally through the medial forebrain bundle. These cortical fibers to the parabrachial nucleus were distributed bilaterally with an ipsilateral predominance. Cortical fiber terminals in the parabrachial nucleus were topographically arranged: Corticoparabrachial fibers from the lateral bank of the presylvian sulcus ended most massively in the dorsal part of the lateral parabrachial nucleus. Corticoparabrachial fibers from the orbital gyrus ended most heavily in the medial parabrachial nucleus and less heavily in the lateral parabrachial nucleus. Corticoparabrachial fibers from the infralimbic cortex ended mostly in the parabrachial regions surrounding the brachium conjunctivum.
The neuronal composition of area 17 of rat visual cortex. II. The nonpyramidal cells
Authors: Peters Alan , Kara Daniel A. 
Published: January 2005

AbstractIn the preceding article the characteristics of the various types of pyramidal cells present in area 17 of rat visual cortex were described (Peters and Kara, '85). In the present article the nonpyramidal cell population of this cortex is considered. It is known from Golgi preparations that in layers II–VIa there are bipolar cells, smooth or sparsely spinous multipolar and bitufted cells with either unmyelinated local plexus or myelinated axons, and chandelier cells. Each of these cell types has been previously examined in Golgi‐electron microscopic preparations. The question now being asked is whether the information about the characteristics of these different types of nonpyramidal cells derived from the Golgi‐electron microscopic studies can be used to identify the cell bodies of nonpyramidal cells in tissue prepared for conventional electron microscopy. If this can be done then the neuronal composition of area 17 can be determined.It has been found that the cell bodies of bipolar cells can be readily identified because they are elongate and have nuclei with a vertical infolding and few axosomatic synapses, which are of both the symmetric and asymmetric varieties. Evidence is presented to show that there are two types of bipolar cells, small ones and large ones, the large ones being distinguished by their well‐developed endoplasmic reticulum in which the cisternae are arranged parallel to the cell surface. Bipolar cells account for 6% of the neuronal profiles in layer II/III, 3% in layer IV, 5% in layer V, and 2% in layer VIa.The cell bodies of other types of nonpyramidal cells in layers II–VIa cannot be distinguished from each other in thin sections, because recognition of the different cell types depends upon the characteristics and distribution of their dendrites and axons. However, it is evident that in this group of neurons there are some with small cell bodies and others with large cell bodies, and in both size groups there are varieties of neurons which can be recognized from the characteristics of their perikaryal cytoplasm. All of these neurons have both symmetric and asymmetric axosomatic synapses. The greatest number of these nonpyramidal cells which are not bipolar in form is found within layer II/III, where they account for 7% of all neuronal profiles. These neurons comprise 4% of all neuronal profiles in layer IV, 6% in layer V, and 2% in layer VIa.Layers I and VIb contain only nonpyramidal cells, but these are different from the ones in layers II–VIa.Overall, bipolar cells account for 4% of the neuronal profiles encountered in layers II–VIa, and the other nonpyramidal cells account for 6% of the neuronal population. Consequently, in these layers 90% of the neurons are pyramidal cells. These results are considered in relation to analyses of the neuronal population of rat area 17 carried out by previous authors, and in the context of information about the disposition and frequency of nonpyramidal cells derived from the use of antibodies to potential neurotransmitters.
Degeneration of thalamic neurons in “Purkinje cell degeneration” mutant mice. I. Distribution of neuron loss
Authors: O'Gorman Stephen , Sidman Richard L. 
Published: January 2005

AbstractThe Purkinje cell degeneration (pcd)mutation of the mouse is an autosomal recessive allele which previous studies have shown to be the cause of rapid degeneration of nearly all cerebellar Purkinje cells between 18 and 30 postnatal days of age (P18–P30), and slowly developing, progressive losses of retinal photoreceptor cells and mitral cells of the olfactory bulb. Through examination of serial frozen sections alternately stained for Nissl substance and for degenerating neuronal processes, we have found that discrete populations of thalamic neurons degenerate rapidly between P50 and P60. Severely affected nuclei, in which a majority of neurons degenerate, include the central division of the mediodorsal nucleus, the ventral medial geniculate, posterior, posterior ventromedial, and submedial nuclei, and those portions of the ventrolateral and posteromedial nuclei which immediately surround the medial division of the ventrobasal complex. More subtle cell losses occur during the same time period in restricted portions of the lateral ventrobasal, dorsal lateral geniculate, and lateral posterior nuclei, but even at P180 these nuclei are not markedly atrophic.No common denominator among target cell populations has been established. The pcd allele affects a diverse assortment of specific relay nuclei; degeneration has not been recognized in thalamic nuclei characterized primarily or exclusively by subcortical projections or by cortical projections directed relatively selectively to superficial or deep cortical laminae. The neuronal degenerations in the thalamus are not precipitated by prior or concurrent degeneration of cortical targets or afferent sources, though striking transneuronal changes, including cell death, do develop following thalamic neuronal degeneration in this mutant. No previously described murine mutant phenotype includes the rapid degeneration of highly restricted neuronal populations beginning at these relatively advanced ages.
A Golgi study of the human neostriatum: Neurons and afferent fibers
Authors: Graveland Gerda A. , Williams Roger S. , Difiglia Marian 
Published: January 2005

AbstractThe neostriatum of 20 adult humans was examined in Golgi‐Kopsch and rapid Golgi preparations. At least five types of neurons and four types of afferent fibers are described. Neurons of medium size with spine‐rich dendrites (spiny type I) are the most frequent type. These cells exhibit a greater morphological diversity than those previously studied in the monkey. Also, quantitative data show that, compared to the monkey, spiny type I neurons in man have a greater somal size and dendritic field radius. Although the types of spines are similar, the mean density and radial distribution of spines along dendrites differ in the two species. Morphologic features of the axon, which is usually long with extensive collateral branches, suggest that more than one process from the axon may be efferent. Medium to large neurons with sparsely spined dendrites (spiny‐type II) differ from type I neurons in having a poorer branching and greater radial spread of their dendrites and a lower density of spines. They also differ from spiny type I neurons in their distribution and relative proportion of various spine types. The axon of the spiny type II neuron is long and has collaterals which are poorly arborized in comparison to those of spiny type I cells. Aspiny neurons are of medium (aspiny type I) and large (aspiny type II) size. They have varicose, curved dendrites and a short axon which arborizes mostly within the dendritic field. A group of smaller neurons with more variable dendritic morphology is also seen. Observations suggest that in the human brain the proportion of medium‐sized aspiny neurons and small neurons may be greater than in other species.
Serotoninlike immunoreactivity in the cestode Hymenolepis diminuta
Authors: Webb Rodney A. , Mizukawa K. 
Published: January 2005

AbstractSerotoninlike immunoreactivity in the cestode Hymenolepis diminuta was studied at the light microscope level by using an antibody specific to serotonin. The rostellum, the cerebral ganglia and commissure, and the strobila contained numerous process‐free, unipolar and multipolar serotoninlike immunoreactive cells. The suckers contained a plexus of branching immunoreactive fibers. In the strobila the multipolar cell bodies were situated laterodorsal and lateroventral to the longitudinal nerve cords, from which neurites were directed to the contralateral and ipsilateral nerve cord to form up to three transverse commissures per proglottid. Secondary varicose branches passed anteriorly, posteriorly, and obliquely along the proglottids at the level of the deep longitudinal muscles. Other varicose multibranching neurites passed centrifugally from the primary and secondary neurites, forming vertebratelike en passant or terminal varicosities on the deep longitudinal muscles with bulbous or spinose terminals at the level of the superficial longitudinal muscles, or in the cortical parenchyma, Serotoninlike immunoreactivity was seen on the external seminal vesicle, the sphincter and cirrus sac, and the proximal portion of the vagina. Varicose terminals were concentrated at the sphincter. The close association of serotoninlike immunoreactive terminals and varicosities with the longitudinal muscles gives credence to the concept that serotoinin functions as a neuromuscular transmitter or modulator in the platyhelminths.