bluuebunny/crossref_metadata_2025_split huggingface dataset:
Auditory neurons expand their terminal arbors throughout life and orient toward the site of postembryonic hair cell production in the macula neglecta in elasmobranchs
Authors: Corwin Jeffrey T. 
Published: May 2005

AbstractThe population of sensory hair cells in the macula neglecta auditory epithelium in skates increases from 500 to more than 3,000 postembryonically, but during the same time period the number of neurons innervating the epithelium changes by a much smaller amount, if at all. Morphometric analyses of the peripheral terminal arbors of these neurons demonstrate that the arbors expand in area through intussusceptive growth, so that each neuron contacts more hair cells as the epithelium grows by appositional addition of new hair cells at its outer edge. The synaptic contacts that these neurons make with hair cells may not be permanent. Many of the neurons that innervate the growing macula appear to shift their terminal arbors, breaking synaptic contacts with older hair cells in the center of the sensory epithelium as they branch to form new contacts with younger hair cells that are located in the periphery of the epithelium. Over 80% of the terminal branches of these auditory neurons are directed toward the outer edge of the macula, the site where new hair cells are produced. This suggests that the growth cones of these continually growing neurons are guided to newly produced hair cells by an active attraction mechanism.
Connections of area 2 of somatosensory cortex with the anterior pulvinar and subdivisions of the ventroposterior complex in macaque monkeys
Authors: Pons T. P. , Kaas J. H. 
Published: May 2005

AbstractThe principal goal of the present study was to determine the thalamic connections of area 2 of postcentral somatosensory cortex of monkeys. The placement of injections of anatomical tracers (horseradish peroxidase, wheat germ agglutinin, or 3H‐proline) was guided by extensive microelectrode maps of cortex in the region of the injection site. These maps identified the body parts represented in the cortex included in the injection site, and provided information about the physiological boundaries of area 2, which was related later to the cortical architecture. Most injections were placed in the representation of the hand in area 2, which was highly responsive to cutaneous stimuli and could be mapped in detail. Injections were also placed in other parts of area 2, area 1, or area 5, and some injections involved more than one area.As other investigators have determined, regions of retrograde and anterograde thalamic label overlapped, demonstrating that connections with cortex are reciprocal. Injections completely confined to area 2 consistently produced label in two locations: the anterior pulvinar (Pa) and a dorsal capping zone of the ventroposterior complex that we term the ventroposterior superior nucleus (VPS). Single restricted injection sites resulted in one region of label in VPS, and multiple foci of label in Pa. In some cases where the injection was confined to the representation of the hand in area 2, label was also found more ventrally in the ventroposterior complex in ventroposterior nucleus proper (VP). Thus, area 2 receives input from Pa, VPS, and, at least in some locations and individuals, VP. Injections of tracers into area 1 confirmed previous findings that area 1 is densely interconnected with VP. In addition, there appear to be sparse connections with VPS. There was no evidence of connections with Pa. Evidence from injection sites that extended from area 2 into areas 5 and 7, and from injection sites in area 5, indicates that the lateral posterior nucleus (LP) projects to rostral areas 5 and 7.The results support the conclusion that area 2 is a functionally distinct subdivision of somatosensory cortex, and indicate that area 2 has thalamic connections that are characteristic of both “sensory” (VP and VPS) and “association” (Pa) cortical fields.
Substantia nigra transplants into denervated striatum of the rat: Ultrastructure of graft and host interconnections
Authors: Mahalik Thomas J. , Finger Thomas E. , Stromberg Ingrid , Olson Lars 
Published: May 2005

AbstractA number of recent experiments suggest that grafted dopaminergic neurons provide functional input to a host caudoputamen which previously had been deprived of its dopaminergic input. The purpose of the present study was to determine whether tyrosine hydroxylase immunoreactive processes which originate in the graft participate in morphologically identifiable synapses in the host neuropil.Prior to transplantation, adult Sprague‐Dawley rats received unilateral injections of 6‐hydroxydopamine into the medial forebrain bundle. Animals were screened for the success of striatal denervation by a test of apomorphine‐induced rotation. Transplants of fetal substantia nigra then were placed into cavities in the caudoputamen. After a 6–8 month survival period, animals were perfused and prepared for tyrosine hydroxylase immunocytochemistry. No evidence of sprouting of the host catecholoaminergic system was observed, even after long survival times.Both pre‐ and postsynaptic immunoreactive elements were clearly present in the host caudoputamen. Immunoreactive axons made synaptic contact with unlabeled dendrites; immunoreactive dendrites were postsynaptic to unlabeled axon terminals. The present results suggest that both host‐to‐graft and graft‐to‐host synapses are present in the host caudoputamen.
Segmental distribution of peptide‐ and 5HT‐like immunoreactivity in nerve terminals and fibers of the thoracolumbar sympathetic nuclei of the cat
Authors: Krukoff Teresa L. , Ciriello John , Calaresu Franco R. 
Published: May 2005

AbstractThe distribution of leucine‐enkephalin, methionine enkephalin, neurotensin, somatostatin, substance P, oxytocin, vasopressin, neurophysin II, and serotonin in nerve terminals and fibers of sympathetic autonomic areas of the thoracolumbar (T‐L) spinal cord was studied immunohistochemically in cats. Densities of these immunoreactive terminals and fibers were estimated in the intermediolateral nucleus pars principalis (IMLp) and pars funicularis (IMLf), the nucleus intercalatus (IC), and the central autonomic area (CA). Results for leucine‐ and methionine‐enkephalin‐like immunoreactivity (ENK) were similar and immunoreactivity for vasopressin was not observed.The greatest numbers of terminals and fibers in the IMLp region contained ENK, neurotensin‐(NT), and serotonin‐like immunoreactivity (5HT); terminals and fibers containing substance P‐(SP) and neurophysin II‐like immunoreactivity (NP2) were intermediate in number, and those containing somatostatin‐(SS) and oxytocin‐like immunoreactivity (OXY) were generally sparse. In the IC and CA, terminals and fibers containing ENK and NT were dense, those containing SP were moderate, and those containing OXY, NP2, and 5HT were sparsely represented. In the IMLp, where the largest proportion of sympathetic preganglionic neurons (SPN) is found, the greatest concentration of terminals and fibers containing ENK was found in segments T1–T8; for NT these segments were T1–T5 and T11–L1, for SP–C8–T2 and T11–L1, for NP2–T4–T7 and L2 to L3, and for 5HT–T1–T5. Terminals and fibers containing SS and OXY were present in segments C8–T10 and segments C8, T2–T8, T13, and L2 to L3, respectively. These results indicate that while ENK, NT, SP, NP2, and 5HT fibers and terminals are widely distributed throughout the T‐L cord, they may influence to a greater degree the SPN in segments where they are present in greater numbers. As SS and OXY were not found at all levels of the IMLp, their functions may be more organ specific.
Distribution and immunoreactivity of glia in the retina of the rabbit
Authors: Schnitzer Jutta 
Published: May 2005

AbstractGlial markers, namely antibodies to glial fibrillary acidic protein (GFAP), vimentin, galactocerebroside (GC), and 08 antigen, were used to study the occurrence and location of neuroglial cells in adult rabbit retinae. Müllerian glia were vimentin‐positive, lacked detectable amounts of GFAP, and were found in all parts of the rabbit retina. The neuronal A‐type horizontal cells were labeled by vimentin antibody only in the superior retina and at the medullary rays but not in the inferior retina. They lacked GFAP in all regions. Astroglia showing GFAP and vimentin immunoreactivity were absent from most of the superior and inferior retina, being found only in the myelinated area of the ganglion cell axon bundles, the medullary rays. Thus the rabbit retina differs from the retinae of all mammals studied to date by this restriction of astroglia to just one area. The medullary rays, which are known to be myelinated, were labeled by the antibodies to GC and 08 antigen.Boycott and Hopkins ('84) found, using whole‐mounted rabbit retinae stained by the reduced silver method of Richardson, that all neurons in the ganglion cell layer of the rabbit retina have a cilium, while cells that have only a diplosome are either neuroglia or microglia. By using this criterion as a basis to differentiate between neurons and glia, the absence of neuroglia from the nerve fiber layer outside the medullary rays was confirmed in the same silver‐stained material. Thus, the data obtained from immunocytochemistry and conventional silver staining agree closely. It has been concluded that, at least in the adult, significant lengths of ganglion cell axons extend without astroglial sheaths.
The organization of the neonatal rat's brainstem trigeminal complex and its role in the formation of central trigeminal patterns
Authors: Bates Carolyn A. , Killackey Herbert P. 
Published: May 2005

AbstractThe present study delimits the relationship of primary trigeminal afferents to their targets, the brainstem trigeminal nuclei of the neonatal rat. Previously, the brainstem trigeminal complex of the rat has been subdivided on the basis of either cytoarchitectonics or patterns of succinic dehydrogenase activity into the principal sensory nucleus and the three subnuclei of the spinal trigeminal nucleus, oralis, interpolaris, and caudalis. In this paper, we demonstrate that each of these subdivisions can also be identified by its pattern of primary trigeminal afferents. In addition, we demonstrate that the terminations of these afferents are distributed in a punctate fashion which correlates with vibrissae‐related patterns of histochemical staining. Further, vibrissae removal in the neonatal rat at any age studied results in a corresponding deafferentation of both the principal sensory nucleus and all subnuclei of the spinal trigeminal nucleus. This same procedure has a graded, age‐dependent effect on the vibrissae‐related pattern of cytochrome oxidase staining in somatosensory cortex. On this basis, we conclude that vibrissae‐related pattern formation in the central trigeminal system can be best understood in terms of a single “sensitive” period for the entire system. We hypothesize that this is the period during which an interaction normally occurs between primary trigeminal afferents and target neurons of the principal sensory nucleus.
Golgi and Nissl studies of the visual cortex of the bottlenose dolphin
Authors: Garey L. J. , Winkelmann E. , Brauer K. 
Published: May 2005

AbstractNissl, Golgi and fibre preparations were made of the cerebral cortex of the lateral gyrus of the bottlenose dolphin (Tursiops truncatus)in the region where visual evoked potentials have been reported (Sokolov et al., '72; Ladygina et al., '78). In the adult the visual cortex is relatively thin (average about 1,300 μm) for so large a brain (fixed brain weight for a typical adult in our series was 1,330 g). Layers I, III, and VI are wide and represent three‐quarters of the total cortical thickness. Layer I contains few cell bodies, while III and VI have a variety of pyramidal and nonpyramidal neurons. Layers II and V are narrow and contain striking palisades of darkly staining pyramidal cells that are particularly large in layer V. No clearly demarcated layer IV is present in the adult dolphin visual cortex. Many of the neurons identified with the Golgi technique are typical of pyramids in other mammals, with a single apical dendrite and a bouquet of basal dendrites, mostly highly spiny. Others are unusual in having bifurcated or oblique apical dendrites. Typical large and small spiny and nonspiny stellates are also found, mainly in layers III and VI. In addition various forms of spindle‐shaped, bipolar and multipolar neurons are found in most layers.An 18‐day‐old brain shows signs of immaturity in its visual cortex. It is thinner (970 μm) and on average its neurons are smaller, paler, and more densely packed. Especially the pyramids of layer V are much smaller than in the adult. Also, a distinct “granular” band occurs between layers III and V and seems to be a rudimentary layer IV. At 3 years of age most of the adult features have developed, but layer IV is still detectable.No striking differences were observed in cell and fibre architecture between the cortex of the lateral gyrus and that of the so‐called “calcarine” area that has also been considered as “visual.”We conclude that, although different in many respects from other mammalian visual cortices, that of the dolphin is apparently well developed and differentiated.
Morphology, central projections, and dendritic field orientation of retinal ganglion cells in the ferret
Authors: Vitek Dagmar J. , Schall Jeffrey D. , Leventhal Audie G. 
Published: May 2005

AbstractRetinal ganglion cells were studied in pigmented ferrets that received small electrophoretic injections of horseradish peroxidase (HRP) into the dorsal lateral geniculate nucleus (LGNd) or optic tract. Ferret retina contains a number of types of retinal ganglion cells of which the relative cell body sizes, dendritic field structures, and central projections correspond closely to those of retinal ganglion cell types in the cat. Ferret retina contains about the same proportion of alphalike cells, a lower proportion of betalike cells, and thus a high proportion of other types of ganglion cells than cat retina. Ferret retina has a visual streak and somewhat weaker area centralis than cat retina. Changes in ganglion cell morphology associated with eccentricity are less pronounced in the ferret than in the cat. The adult ferret retina is about 12.5 mm in diameter, and the nasotemporal division is about 2.7 mm from the temporal margin. Interestingly, virtually all alpha cells in the pigmented ferrets studied projected contralaterally. Studies of infant ferrets indicate that 4 days after birth (P4) the area of ferret retina is 25% that of the adult. The neonatal ferret retina contains numerous small, densely packed cells in the presumptive ganglion cell layer. At P4 these cells appear to be uniformly distributed across the retina. The area centralis and visual streak are not obvious as late as 8 days after birth.
Catecholaminergic innervation of the septal area in man: Immunocytochemical study using TH and DBH antibodies
Authors: Gaspar P. , Berger B. , Alvarez C. , Vigny A. , Henry J. P. 
Published: May 2005

AbstractThe catecholaminergic innervation of the human septal area and closely related structures has been visualized by using tyrosine hydroxylase (TH) and dopamine‐β‐hydroxylase (DBH) as immunocytochemical markers. TH‐like immunoreactivity with no corresponding DBH labelling was considered to be indicative of dopaminergic fibers.Catecholaminergic innervation offered the following similarities to that of rodents: (1) moderate innervation in the medial septal division, with predominant DBH immunolabelling; (2) dense dopaminergic innervation in the lateral septal nuclei, organized in a laminar pattern; (3) presence of dopaminergic pericellular arrangements in the dorsal septum and bed n. of the stria terminalis; (4) clustering of dopaminergic terminals in n. accumbens associated with a medioventral zone of DBH‐like immunoreactive fibers; (5) close overlap between dopaminergic fields and acetylcholinesterase‐reactive zones in both the lateral septum and the n. of the stria terminalis.Differences with the catecholaminergic septal innervation of rodents consisted of (1) general caudal extension of the dopaminergic fields, possibly accounted for by the vertical stretching and caudal displacement of the septal nuclei in man; (2) complementary lateromedial. topography of dopaminergic and DBH‐immunoreactive inputs in the n. of the stria terminalis as opposed to their dorsoventral organization in rodents; (3) presence of TH‐immunolabelled cell group in the anterior olfactory nucleus and parolfactory cortex, which seems specific for primates.Precise topographical mapping of the catecholaminergic structures in this central region of the limbic forebrain seems to be a prerequisite for accurate tissue sampling in the biochemical investigations of pathological cases and should help in the interpretation of aminergic dysfunction in a variety of human diseases.
Cerebellar external granule cells are attached to the basal lamina from the onset of migration up to the end of their proliferative activity
Authors: Hausmann Beate , Sievers Jobst 
Published: May 2005

AbstractThe development of cerebellar external granule cells in rats was studied from the time of demarcation of the cerebellar anlage on embryonal day 12 up to the time of their disappearance on postnatal day 20. Two types of cells were found. The first was orientated tangentially to the cerebellar surface and was characterized by a persistent contact to the basal lamina via an external process, with a lamellopodial tip and a cytoskeleton characteristic for migratory cells, and a retracting internal process featuring a single cilium. This cell type was the first to appear on embryonal day 14 in the caudolateral angle of the cerebellar anlage and, later, spread, over the whole cerebellar surface. It disappeared after the external granular layer was completely expanded over the cerebellum. The second cell type appeared for the first time on embryonal day 16 in the caudal part of the cerebellar anlage and disappeared on postnatal day 20. It was orientated radially and also had contact with the basal lamina either with its cell body or with one or two short, radial processes, whose morphology differed from that of the external process of tangential cells by the absence of a lamellopodium and a prominent cytoskeleton. After postnatal day 17 contacts of external granule cells with the basal lamina decreased rapidly in length and number and were absent on postnatal day 20.We interpret these findings to indicate that tangential external granule cells are migrating before taking on a radial orientation characteristic for the mitotic cycle of proliferating external granule cells. In the light of increasing evidence implicating extracellular matrix in various developmental events of the nervous system we propose that the basal lamina of the cerebellum may be used as substrate and guidance structure by migrating external granule cells, and, furthermore, that the persistent contact with the basal lamina may mediate stimuli maintaining external granule cells in a proliferative state.
The trigemino‐olivary projection in the cat: Contributions of individual subnuclei
Authors: Huerta M. F. , Hashikawa T. , Gayoso M. J. , Harting J. K. 
Published: May 2005

AbstractAnterograde autoradiographic methods were used to determine the projection of the principal sensory trigeminal nucleus and of each of the three spinal trigeminal subnuclei to the inferior olivary complex in the cat. Our data reveal that the principal sensory trigeminal nucleus does not contribute to the trigemino‐olivary pathway. Each spinal trigeminal subnucleus has a unique contribution to this pathway: pays oralis projects sparsely to the border between the dorsal accessory and principal olives (DAO‐PO), pars interpolaris projects mostly to the rostral medial DAO, and pays caudalis projects mostly to the rostral medial part of the ventral leaf of PO and slightly to the caudal medial accessory olive. In the light of recent physiological and anatomical findings, our data indicate that information from each spinal trigeminal subnucleus reaches a different segment of the contralateral inferior olivary complex, which in turn distributes differentially to the cerebellar cortex.
Anatomical organization of primary visual cortex (area 17) in the ferret
Authors: Rockland Kathleen S. 
Published: May 2005

AbstractThe present report describes the intrinsic and extrinsic cortical connectivity of striate cortex (area 17) in the ferret. Injections of horseradish peroxidase demonstrate periodic intrinsic connections over an extent of 2.5–3.0 mm, mainly in the supragranular layers but also occurring secondarily in layer 5. These connections have a stripelike configuration, with a centerto‐center spacing of 0.5–0.7 mm. Their laminar distribution and stripelike configuration resemble the pattern in the cat (Gilbert and Wiesel,′83), another member of the carnivore family, but not that in monkeys. In both macaque and squirrel monkeys, these connections have a bilaminar distribution in layers 2–3 and 4B, and a more complicated latticelike geometry (Rockland and Lund,'83). Their interperiod spacing, of about 0.5 mm, however, is relatively constant across species. Extrinsic connections in the ferret link striate cortex with territories probably homologous to feline areas 18 and 19, and to the suprasylvian region. Callosal connections extend on the lateral surface about 1.5 mm into area 17 and 4.0 mm into area 18 beyond their common border. There are homotopical connections between striate cortices and heterotopical connections from at least areas 18 and 19 to contralateral area 17. In addition to gray matter connections, intracortical injections also result in labeled interstitial neurons in the subgriseal white matter. These occur both subjacent to an injection site in area 17, and below labeled foci in area 18 projecting back to area 17, as if interstitial neurons shared the connectivity of overlying layer 6.
Freeze‐fracture study of an invertebrate multiple‐contact synapse: The fly photoreceptor tetrad
Authors: Fröhlich A. 
Published: May 2005

AbstractBow‐shaped particle arrays on the P‐faces of the photoreceptor terminals R1–R6 in the lamina ganglionaris of the house fly represent the presynaptic sites of chemically mediated multiple‐contact synapses (Shaw and Stowe, '82, Saint Marie and Carlson, '82). A particle array consists of two polar patches of regularly arranged particles and a central patch of irregularly arranged ones. Corresponding to these P‐face arrays, the receptor E‐faces have lattices of pits opposite the polar patches, and pits and some particles at the center. The presynaptic particle array corresponds in its dimensions to the electron‐dense bar found in thin sections. The center‐to‐center spacing of the regularly arranged particles agrees with the spacing of striations found in the bar overlying the two polar elements of the postsynaptic tetrad. The elements in the two medial postsynaptic positions are hyperpolarizing monopolar cells Ll and L2, which show a strip of P‐face particles within an otherwise bare postsynaptic membrane enclosed by a ridge, and a bare Eface. Comparison with other invertebrate synapses reveals two types of organization of postsynaptic membranes. IMPs fracture with the postsynaptic P‐face in GABAergic and/or inhibitory synapses and with the E‐face in glutaminergic and/or excitatory synapses; the fly photoreceptor synapse thus fits in the former category.