bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tracing of two‐neuron pathways in the olfactory system by the aid of transneuronal degeneration: Projections to the amygdaloid body and hippocampal formation
Authors: Carlsen Jørn , de Olmos Jose , Heimer Lennart 
Published: January 2005

AbstractFollowing an olfactory bulb lesion in guinea pig (2 to 3 days), neuronal degeneration occurs in several olfactory‐bulb‐related areas, primarily in the piriform cortex. The degenerating neurons, which are argyrophilic, are also found in the posterolateral cortical amygdaloid nucleus and the ventrolateral entorhinal cortex. It is suggested that the neurons degenerate because of a transneuronal effect due to a sudden loss of afferent input from the the olfactory bulb, although a retrograde effect acting in concert with transneuronal factors cannot be excluded.Terminal degeneration can be identified in several areas outside the olfactory bulb projection area, and is interpreted as degeneration in the axons of the degenerating cortical neurons. Such terminal degeneration, which is best seen 3 to 4 days postoperatively, has been identified in part of the basolateral amygdaloid complex, in the basomedial amygdaloid nucleus, and in the temporal parts of the fascia dentata of the hippocampal formation. Terminal degeneration has also been observed in the deep layers of the anterior olfactory nucleus, the olfactory tubercle, the nucleus of the lateral olfactory tract, and the anterior amygdaloid area. All these projections, apparently, represent the second link in two‐neuron pathways, where mitral or tufted cells in the olfactory bulb make up the first neuron. This interpretation was confirmed in control experiments in which areas of argyrophilic neurons coincided with the location of retrogradely labeled neurons following injection of flurorescent substances into several of the abovementioned areas of terminal degeneration.
Effect of morphine on 3H‐Thymidine incorporation in the subependyma of the rat: An autoradiographic study
Authors: Miller Clara R. Dodge , O'steen W. Keith , Deadwyler Sam A. 
Published: January 2005

AbstractFollowing morphine treatment, an autoradiographic study investigated the uptake of 3H‐thymidine by the subependymal cells in the rat brain. 3H‐thymidine was administered subcutaneously to adult, male Sprague‐Daw‐ley rats 30 minutes after saline or morphine (10 mg/kg) injection. The animals were sacrified 1 hour after 3H‐thymidine administration. In some experiments the opioid antagonist, naloxone, was given alone 45 minutes before 3H‐thymidine or 15 minutes before morphine treatment. Three areas of the subependyma were evaluated in terms of the percentage labeled cells and number of grains per nucleus, and a dorsal‐to‐ventral gradiant was described. Morphine treatment significantly increased the number of 3H‐thymidine labeled subependymal cells and number of grains/nucleus within labeled cells. Examination of the distribution of grains/nucleus showed that morphine‐treated animals had significantly more cells labeled with 30 or more grains than did saline‐injected controls. Prior administration of naloxone blocked the increased 3H‐thymidine uptake in morphine‐treated animals but had no significant influence on cell proliferation when administered alone. The data are discussed in terms of morphine's possible dual influence on mechanisms which enhance cell transition from G to S phase and/or which accelerate DNA synthesis once these cells have entered the S phase of cell replication.
Indirect visual cortical input to the deep layers of the hamster's superior colliculus via the basal ganglia
Authors: Rhoades Robert W. , Kuo David C. , Polcer Jeffrey D. , Fish Stephen E. , Voneida Theodore J. 
Published: January 2005

AbstractAnterograde and retrograde tracing techniques were employed to delineate the organization of a visual cortical input to the deep layers of the hamster's superior colliculus which may be mediated by links in the striatum and substantia nigra.Autoradiographic experiments showed that areas 17, 18a, and the cortex medial to area 17 (areas 18b and 29) all projected to the dorsocaudal part of the ipsilateral striatum. This projection was organized so that the rostrocaudal axis of the visual cortex was represented along the anteroposterior axis of the striatum. Large posterior neocortical injections which included all of these areas also revealed a weak, crossed corticostriatal pathway. Such injections also demonstrated clear discontinuities in the terminal distribution of the visual corticostriatal projection, similar to those which have been noted after injections of tracers into the motor and premotor cortices.Retrograde tracing experiments showed that the cells of origin of the visual cortical projections to the striatum were medium‐sized pyramidal neurons located primarily in the upper portion of lamina V.Anterograde transport of [3H]‐leucine and HRP showed that the portion of the striatum heavily innervated by the visual cortex projected to the part of substantia nigra, pars reticulata immediately adjacent to the cerebral peduncle. Injections in the rostral striatum labeled more medial portions of this nucleus. The cells of origin of the striatonigral pathway measured between 13 and 20 μm in diameter and they were located primarily in the dorsal and lateral parts of the striatum.Anterograde tracing after substantia nigra, pars reticulata injections revealed a projection to both superior colliculi. The uncrossed pathway terminated primarily as a series of patches throughout the mediolateral and rostrocaudal extents of the lower stratum griseum intermediale and stratum album intermedium. Labeling was also visible in the lateral portion of the stratum griseum profundum. The crossed nigrotectal pathway terminated primarily in the rostrolateral stratum griseum profundum. The cells of origin of the nigrocollicular pathway were fusiform or multipolar cells and were located primarily adjacent to the cerebral peduncle throughout the rostral half of the substantia nigra, pars reticulata.
A physiological and morphological study of the horizontal cell types of the rabbit retina
Authors: Bloomfield Stewart A. , Miller Robert F. 
Published: January 2005

AbstractA perfused, isolated retina‐eyecup preparation of the rabbit was utilized to correlate the physiology and morphology of horizontal cells. Neurons were physiologically characterized by intracellular recording techniques and subsequently stained with intracellular iontophoretically injected horseradish peroxidase for morphological identification. Three types of rabbit horizontal cell recordings have been differentiated, based on variations in response waveform, amplitude‐intensity properties, and area summation characteristics. These three types have been unequivocally associated with the axonless A‐type horizontal cells and the somatic and axon terminal endings (each displaying its own distinct physiology) of B‐type horizontal cells first described in studies using Golgi‐impregnation techniques (Fisher and Boycott, 1974). In addition, the sizes of A‐type horizontal cells were found to be directly related to their retinal eccentricities from the optic disk. However, a unique subclass of A‐type cells has been discovered (elongated or Ae type) which displayed the largest dendritic field of any cells studied here, yet had the smallest eccentricities—within 1.4 mm of the optic disk. Moreover, elongated A‐type cells exhibited long asymmetrical dendritic fields which were oriented parallel with the visual streak. The unique asymmetry and orientation of these cells suggests that they may have orientation‐biased receptive field properties. Physiological evidence for an orientation‐biased horizontal cell is presented in support of this notion.
Anatomy of the isolated area dentata grown in the rat anterior eye chamber
Authors: Goldowitz Dan , Seiger Åke , Olson Lars 
Published: January 2005

AbstractWe used the intraocular transplantation technique to test the developmental potential of isolated, fetal area dentata, and to help define the determinants of such critical aspects of brain development as cell arrangements, dendritic arborization, axon growth, synaptogenesis, and connectional specificity. Fetal hippocampal formations were removed from embryos of 19 to 20 days of embryonic age. A region, termed area dentata, was dissected from the hippocampal formation. This region included the anlage of the dentate gyrus, the hilus, and the medial regio inferior. Areae dentatae were transplanted into the anterior eye chamber of isogenic, adult rats. The growth and vascularization of area dentata transplants were monitored over the first 2 months in oculo. From 2 to 7 months after transplantation host animals were killed and the area dentata transplants were examined with a variety of histological techniques. The cytoarchitectonics of a great majority of the transplants were highly reminiscent of area dentata in situ. A typical morphogenetic outcome included tightly packed, continuous, C‐shaped sheets of granule cells with mossy fibers which made contact with the proximal dendrites of a segregated group of dispersed hilar cells and a loosely packed layer of pyramidal cells. The axons of pyramidal and hilar cells, in turn, provided the major innervation of the granule cell dendrites. The granule cell dendritic spine density was nearly normal, and synapses were common in the granule cell neuropil. Very little innervation of the transplant was found to originate from the axons of the ciliary or trigeminal ganglia which innervate the host iris and enter the transplant. Sympathetic fibers from the host iris innervate the transplant in a reproducible and organotypic fashion although the degree of innervation is less than the in situ noradrenergic innervation of area dentata. Few Timm‐positive fibers of the transplant were found to leave the transplant and enter the host iris. Area dentata transplants had several features which were different from their in situ counterparts. These differences included less expansive granule cell dendrites, extensive presence of fibrous astrocytes, pyramidal cells with reduced kainic acid sensitivity, hypervascularized neuropil, and transformation of peripheral adrenergic fiber morphology to one of central characteristics.Thus, pieces of isolated area dentata display a great self‐developing capacity, in terms of cellular and afferent organization, both of which follow “rules” present in situ. A powerful capacity for intrinsic and appropriate innervation of area dentata is apparent in the face of a total lack of normal extrinsic afferents and an availability of extrinsic but inappropriate sources of innervation. This initial description of isolated area dentata organization in oculo is meant to lay the groundwork for experimental investigations into the regulatory mechanisms governing morphogenesis and afferent organization.
Cytoarchitecture of the central amygdaloid nucleus of the rat
Authors: McDonald Alexander J. 
Published: January 2005

AbstractSince recent studies indicate that distinct neuropeptides and projections are associated with discrete portions of the central amygdaloid nucleus (CN), a detailed investigation of the cytoarchitecture of CN should contribute to an understanding of its organization. Qualitative and quantitative analyses of the rat CN using Nissl, Klüver‐Barrera, and Golgi techniques suggests that it consists of four subdivisions. The medial subdivision (CM), which is closely associated with the stria terminalis, is narrow caudally but enlarges near the rostral pole of CN. Most neurons in CM have long dendrites that branch sparingly and have a moderate number of dendritic spines. A smaller number of CM neurons have thick dendrites with virtually no spines. Lateral to CM is the lateral subdivision (CL) which appears round in coronal sections. Neurons of CL have a very dense covering of dendritic spines and resemble medium‐size spiny neurons of the striatum. Area X of Hall contains spiny neurons similar to those of CL and spine‐sparse neurons that resemble medium‐size spine‐sparse cells of the striatum. Since area X encapsulates the lateral aspect of CL, it is termed the lateral capsular subdivision (CLC) of CN. The lateral capsular subdivision enlarges rostrally and is divided into dorsal and ventral portions by a laminar extension of the putamen. Near the rostral pole of CN a small region of tightly packed, intensely stained neurons is interposed between CL and CM. Golgi preparations reveal that this intermediate subdivision (CI) of CN contains neurons similar to those of CM. The lateral subdivision, CLC, and CM correspond, in part, to subdivisions recognized in previous Nissl studies. The intermediate subdivision has not been recognized as a distinct subdivision in previous investigations. This is the first Golgi study to recognize differences in neuronal morphology in particular subdivisions of the rat CN. The correlation of Nissl and Golgi preparations has permitted a more accurate determination of the boundaries and total extent of each subdivision than the use of Nissl techniques alone.
Neuronal addition and retinal expansion during growth of the crucian carp eye
Authors: Kock Jan‐Henrik 
Published: January 2005

AbstractUsing standard paraffin technique the addition of new cells in crucian carp retinas was examined. Between eye diameters 4.4 and 10.0 mm the number of ganglion cells increases from 103,000 to 205,000, INL cells from 1.5 to 3 million, cones from 250,000 to 900,000, and rods from 2 to 9 million. Concomitantly retinal area increases fivefold and the cell densities decrease by 37% for the cones, 57% for th e INL cells, and 58% for the ganglion cells, while the rod density remains stable.In relation to the rods the cell ratios at different retinal loci undergo marked changes during growth. The contributions to retinal growth by addition of new neurons and by expansion of the retina have been determined for the different retinal layers. The layer of rods grows exclusively by addition of new rod mosaic. In the cone layer 81% of growth is due to addition of new cone mosaic. In the inner nuclear layer (INL) 56% of growth is due to addition of new cells and in the ganglion cell layer 52% is due to cell addition. In each case retinal expansion accounts for the remainder of increase in retinal area.On morphological grounds six cone types can be found in the crucian carp retina. Their ratios are constant during retinal growth and at different retinal loci.
A quantitative study of the reinnervation of the goldfish optic tectum following optic nerve crush
Authors: Murray Marion , Edwards Michael A. 
Published: January 2005

AbstractStereological and quantitative morphometric methods were used to study changes in the stratum fibrosum et griseum superficialis (SFGS), the major retinal target, in optic tectum of goldfish, during regeneration of the optic nerve. Orthograde transport of HRP by optic axons was used to characterize the retinal projection in SFGS. Profiles of HRP‐labeled optic terminals contained round vesicles, contacted small dendrites, and were distributed uniformly throughout the area of SFGS sampled; labeling density estimates indicate that at least 37% of the total terminal population in SFGS is retinal in origin. Partial denervation of the tectum by optic nerve crush is accompanied by a loss of 40% of the total terminal population in SFGS and by a marked decrease of SFGS thickness. Entry of massive numbers of regenerating optic axons into SFGS begins about 3 weeks postoperatively, about the time that some visual function recovers and produces a marked increase in SFGS thickness which persists for several months postoperatively. The area occupied by regenerating axons and the number of terminals in the tectum only approach preoperative levels 3 months postoperatively. The recovery of normal synaptic number is therefore delayed several months beyond the time of entry of regenerative axonal sprouts. The results indicate that return of synaptic number to normal is temporally associated with the reduction of the excess number of regenerating optic axons and that both these processes are prolonged.
Dopaminergic neurons in the human retina
Authors: Frederick Jeanne M. , Rayborn Mary E. , Laties Alan M. , Lam Dominic M. K. , Hollyfield Joe G. 
Published: January 2005

AbstractThe utilization of dopamine in the adult human retina was examined by using high‐affinity uptake, localization, synthesis, and release as neurotransmitter‐specific physiological probes. Autoradiographic and histochemical studies have shown that dopamine‐accumulating and dopamine‐containing cells of the human retina belong to a population of neurons whose somata are located in the proximal regions of the inner nuclear layer. Some of these are amacrine cells which are pre‐and postsynaptic to other amacrine cells exclusively in the inner plexiform layer. However, evidence is presented which indicates the existence of interplexiform dopaminergic neurons which send processes to both plexiform layers of the retina. These neurons contain a high concentration of dopamine, take up 3H‐dopamine by a high‐affinity mechanism, and release endogenous or accumulated dopamine by a Ca2+‐dependent mechanism upon depolarization with high extracellular K+. An endogenous level of about 20 pmoles dopamine per mg protein was measured in freshly isolated retina using high‐pressure liquid chromatography with electrochemical detection. These results demonstrate that mechanisms for dopaminergic neurotransmission are present in the human retina.
Organization and development of brain stem auditory nuclei in the chick: Ontogeny of postsynaptic responses
Authors: Jackson Hunter , Hackett John T. , Rubel Edwin W. 
Published: January 2005

AbstractThe onset of responsiveness to eighth nerve stimulation was examined in n. magnocellularis and n. laminaris, (second‐ and third‐order neurons) of the chick brainstem auditory system. Extracellular microelectrode mapping techniques were used to examine postsynaptic responses in in vitro brainstem preparations. Two specific questions were addressed. First, what is the earliest time at which postsynaptic action potentials can be evoked in n. magnocellularis and n. laminaris by eighth nerve stimulation? Second, does responsiveness to eighth nerve stimulation develop along a spatial gradient in n. magnocellularis and, if so, how does this gradient compare with other developmental events observed in the chick auditory system?Postsynaptic responses in n. magnocellularis were first recorded at 11 days of incubation. Nucleus laminaris responses to direct stimulation of n. magnocellularis were also first recorded at 11 days, although n. laminaris responses to eighth nerve stimulation were not seen until 12 days of incubation.A gradient of response development within n. magnocellularis was indicated by mapping of responsive sites on days 11–13. At 11 days, responses to eighth nerve stimulation were restricted to the most anteromedial portion of n. magnocellularis. Between 11 and 13 days, cells in increasingly more posterolateral portions of n. magnocellularis became responsive. This is anteromedial‐to‐posterolateral gradient in n. magnocellularis is correlated with the basal‐to‐apical gradient of morphogenesis observed in the basilar papilla and morphogenetic gradients previously observed in n. magnocellularis and n. laminaris.
Projections of the dorsal lateral geniculate and lateral posterior nuclei to visual cortex in the rabbit
Authors: Towns Lex C. , Burton S. L. , Kimberly C. J. , Fetterman M. R. 
Published: January 2005

AbstractThe origin and terminations of thalamic inputs to the striate cortex and the occipital cortex of the rabbit were studied using both anterograde autoradiographic techniques and retrograde transport of horseradish peroxidase (HRP). After injections of [3H]‐leucine into the dorsal lateral geniculate nucleus (DLGN) the transport of radiolabeled material was demonstrated in separate loci in both the striate and the occipital cortex. In both these cortical areas, the principal site of geniculocortical termination was in lamina IV with some diminished input spreading into laminae II‐III and a light termination in layer I overlying the lamina IV termination. Layer VI of striate cortex received a substantial projection from DLGN while infragranular laminae of occipital cortex received a similar although lighter and more diffuse projection. The lateral posterior nucleus (LPN) was similarly demonstrated to project to both striate and occipital cortices, the projection terminating principally in lamina IV of occipital cortex, lamina V of striate cortex, and layer I over a large, continuous area of the posterior pole of the cortex. Moreover, a projection from LPN to the retrosplenial cortex medial to the striate area was consistently seen.The autoradiographic demonstration of a projection from DLGN and LPN to both striate cortex and occipital cortex was corroborated by the retrograde studies. Following the injection of HRP into either the striate or occipital cortex, columns of retrogradely filled somata were identified in both the DLGN and LPN. The location of the column of labeled neurons within each nucleus varied predictably with the location of the injection in either the striate or the occipital cortex.
The morphology of corticofugal axons to the dorsal lateral geniculate nucleus in the cat
Authors: Robson J. A. 
Published: January 2005

AbstractThe structural features of corticogeniculate axons were studied in adult cats after labeling them with horseradish peroxidase (HRP). Injections of HRP into the optic radiations near the dorsal lateral geniculate nucleus result in Golgi‐like filling of both geniculate relay neurons and corticogeniculate axons. In the present material at least two main types of axons could be defined. The most common type is called the type I axon because it so closely resembles the type I axons described by Guillery (1966, 1967) in Golgi preparations. These fine axons have smooth surfaces and consistent fiber diameter. Most terminal swellings are at the ends of short collateral branches and these swellings form asymmetric synaptic contacts onto small and medium‐sized dendrites. Type I axons typically innervate more than one lamina as well as interlaminar zones and they clearly arise from the cerebral cortex. The second type of axon is called the beaded axon because of its numerous swellings, en passant. These swellings frequently are larger than those on type I axons and they differ from previously described corticogeniculate axon terminals in their ultrastructural features. That is, their synaptic contacts appear symmetrical and they form axosomatic contacts. Because of these differences, the possibility that beaded axons are of subcortical origin, particularly from the perigeniculate nucleus, is discussed.When type I axons and geniculate relay neurons are filled in the same region of the nucleus it is possible to identify probable sites of synaptic contactby using the light microscope. Such analyses indicate thatcorticogenic‐ulate axons synapse directly onto relay cells, primarily on peripheral dendritic branches. Further, it appears that single axons contact many geniculate neurons and that single neurons are contacted by many axons.