bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rules for retinotectal terminal arborizations in the goldfish optic tectum: A whole‐mount study
Authors: Stuermer Claudia A. O. 
Published: January 2005

AbstractRetinal axons were labeled in the retina and optic nerve with horseradish peroxidase and traced in tectal whole‐mounts. The typical network formed by retinal fibers in the five retinorecipient layers of tectum is illustrated in camera lucida drawings. Three size classes of terminal arbors were identified in the Stratum fibrosum et griseum superficiale (SFGS)–ca. 34 × 52, ca. 103 × 150, and ca. 158 × 274 μm. Terminal arbors are flattened and occupy three sublayers of SFGS.Passing an HRP‐coated needle through the optic nerve labeled ganglion cells in retina and axons and terminal arbors in tectum. Terminal arbors of axons that originated in retinal annuli lay in distinct annular regions in SFGS, with old generations from central retina lying central to younger generations from peripheral retina. The tectal annuli were concentric with one another and agreed with the retinotopic map as it had been described before.The youngest terminal arbors from peripheral retina were next to the path of their fascicle along the tectal periphery, connected to their fascicle by short, centrally directed extrafascicular axons. The oldest terminal arbors from central retina were caudally displaced from their rostral fascicle of entrance, at the end of long, caudally directed extrafascicular axons. Terminal arbors from intermediate retina occupied intermediate positions in the tectum. Rostrally, they arose from centrocaudally directed extrafascicular axons but caudally from axons of various orientations. Terminal arbors arising from those extrafascicular axons exhibited different orientations and shapes depending on their tectal position.The spatial order of intratectal paths and terminal arbor sites, and the variability of terminal arbor orientation and shape, are consistent with an earlier model on shifting retinotectal terminals (Easter and Stuermer, '84).
Cortical and thalamic afferent connections of the insular and adjacent cortex of the cat
Authors: Guldin W. O. , Markowitsch H. J. 
Published: January 2005

AbstractThe thalamo‐cortical and cortico‐cortical afferents of the cat's insular cortex were investigated with the retrograde horseradish peroxidase technique. The most prominent loci of thalamic labeling were the suprageniculate nucleus and parts of the posterolateral nucleus. Injections into the anterior part of the insular cortex also resulted in labeled cells in the ventromedial posterior nucleus and in the intralaminar nuclei, while injections into posterior parts revealed projections from the medial and dorsal parts of the medial geniculate nucleus. Only the anterior and most ventral parts of the insular cortex overlying the anterior rhinal sulcus were connected with the mediodorsal nucleus of the thalamus. All injections into the gyrus sylvius anterior showed a specific pattern of cortical afferents: With the exception of the labeling in the prefrontal cortex and the inferotemporal region, the labeled cells were very narrowly restricted to the presylvian, the suprasylvian, and the splenial sulcus.The thalamic neurons projecting to the cortex were generally organized in a bandlike pattern which crossed nuclear borders. The majority of the cortico‐cortical connections originated from sulcal areas next to the prefrontal, parietal, and cingulate cortex, that is, next to so‐called association cortices.In the light of the present results the role of the insular cortex as a multifunctional association area is discussed, as well as its relation to other cortical centers.
Nonintralaminar thalamostriatal projections in the gray squirrel (Sciurus carolinensis) and tree shrew (Tupaia glis)
Authors: Lin Chia‐Sheng , May Paul J. , Hall William C. 
Published: January 2005

AbstractIn mammals, the corpus striatum receives prominent projections from the neocortex and from the intralaminar nuclei of the dorsal thalamus. The present study provides evidence based on anterograde degeneration and axonal transport that the corpus striatum also receives input from two nonintralaminar thalamic nuclei, the pulvinar and the medial geniculate body. Each of these nuclei projects to a separate region of the corpus striatum. Moreover, the same regions of the corpus striatum that receive projections from the pulvinar and medial geniculate body also receive projections from the cortical targets of these nuclei.
The serotonin and norepinephrine innervation of primary visual cortex in the cynomolgus monkey (Macaca fascicularis)
Authors: Kosofsky Barry E. , Molliver Mark E. , Morrison John H. , Foote Stephen L. 
Published: January 2005

AbstractThe morphology and laminar distribution of norepinephrine (NE) and serotonin (5‐hydroxytryptamine, 5‐HT) axons in the primary visual cortex of cynomolgus monkeys (Macaca fascicularis) have been analyzed by immunocytochemistry with antibodies directed against dopamine‐beta‐hydroxylase (DBH) and against 5‐HT. The NE and 5‐HT innervation of primary visual cortex (area 17) in the monkey exhibit highly differentiated laminar patterns. Both of these monoamine axonal systems form tangentially continuous laminar bands that differ in density, morphology, and predominant orientation of constituent fibers. Serotonin axons, present in all cortical layers, form two especially prominent, dense bands of arborizing fibers; one extending from midlayer III through IVC‐alpha and the other from VA through VI. NE axons within cynomolgus visual cortex are markedly less dense than 5‐HT axons, and laminar differences in NE density are less prominent. NE axons form two broad bands of moderate density extending through deep and superficial cortical layers, separated by layer IVC, which is conspicuously poor in NE fibers. The laminar complementarity of 5‐HT and NE innervation that is a notable feature of the squirrel monkey visual cortex is not present in cynomolgus monkey; in this Old World monkey NE and 5‐HT axons show considerable overlap such that the same cortical layers appear to be innervated by both neurotransmitters. By virtue of their laminar distribution, 5‐HT and NE axons may each have a selective influence on the intrinsic circuitry of primate cerebral cortex, and, for 5‐HT in particular, the specific cellular targets of this influence are likely to differ in New and Old World monkeys.
Ultrastructure of transganglionic degeneration in brain stem trigeminal nuclei during normal primary tooth exfoliation and permanent tooth eruption in the cat
Authors: Westrum L. E. , Johnson L. R. , Canfield R. C. 
Published: January 2005

AbstractElectron microscopy is used to study changes in the axons and terminals in the cat brain stem trigeminal nuclei, main sensory, and partes interpolaris and caudalis, during the process of natural tooth shedding. Areas previously showing light optical argyrophilic degeneration products and adjacent areas lacking this degeneration are included. Various types of alteration occur early during tooth loss, including increased presumed glycogen, increased cytoplasmic density, flocculence, lucency, and neurofilamentous hyperplasia. By the stage of maximum exfoliation, terminals and axons of marked density become prominent in areas showing argyrophilia, whereas nondense forms occur elsewhere. By late eruption ages, all forms of degenerated terminals and axons are rare, but phagocytes are heavily laden with similar forms of debris. The sequence of ultrastructural events is discussed in light of recent studies of transganglionic degeneration, their correlation with light microscopic findings, and the potential implications for central plasticity in this system.
Hearing loss in dogs after lesions of the brachium of the inferior colliculus and medial geniculate
Authors: Heffner Rickye S. , Heffner Henry E. 
Published: January 2005

AbstractSeven dogs were tested for their sensitivity to pure tones following lesions of the brachium of the inferior colliculus and medial geniculate body. Bilateral section of the brachium of the inferior colliculus consistently resulted in an average hearing loss of as much as 37 dB in the midrange of the animals' audiograms. Lesions of the medial geniculate appear to produce a similar hearing loss if the ventral division of the medial geniculate is completely destroyed.
Cerebellar efferents in the lizard Varanus exanthematicus. II. Projections of the cerebellar nuclei
Authors: Bangma G. C. , Donkelaar H. J. Ten , Dederen P. J. W. , de Boer‐Van Huizen R. 
Published: January 2005

AbstractThe projections of the cerebellar nuclei have been studied in the lizard Varanus exanthematicus with various experimental anatomical techniques. In anterograde degeneration experiments (lesions of the cerebellar peduncle) both ascending and decending contralateral projections were found. Ascending fibers which could be traced from the cerebellar commissure ventralward decussated at the level of the trochlear and oculomotor nuclei. These fibers coursed rostralward to the mesodiencephalic junction. With anterograde tracing techniques (3H‐leucine and HRP) this tract was found to terminate in the nucleus ruber and the interstitial nucleus of the fasciculus longitudinalis medialis. Moreover, retrograde tracer studies (HRP, “Fast Blue”) showed that this tract appeared to arise mainly in the lateral cerebellar nucleus. With both anterograde degeneration and tracing techniques (3H‐leucine and HRP) a bundle of fibers could be followed, which decussates in the basal part of the cerebellum and passes dorsally around the contralateral medial cerebellar nucleus to the lateral side of the brainstem. This contralaterally descending projection system was found, lateral to the vestibular nuclear complex, and as far caudally as the descending vestibular nucleus, to terminate on various vestibullar nuclei. Horseradish peroxidase studies showed that this contralaterally descending projection system originates mainly in the medial cerebellar nucleus, but ipsilaterally descending projections were also found. With the fluorescent double labeling technique (“Fast Blue” and “Nuclear Yellow”) the projections of the cerebellar nuclei described above were confirmed. Furthermore, double labeling revealed neurons in both cerebellar nuclei (especially the medial nucleus) that project to both the mesencephalon and the cervical spinal cord. The present results indicate that the efferent connections of the cerebellar nuclei in the lizard Varanus exanthematicus are organized as two main projections, an ascending projection comparable to the mammalian brachium conjunctivum arising in the lateral cerebellar nucleus, and a descending projection comparable to the mammalian hook bundle (fasciculus uncinatus), originating mainly in the medial cerebellar nucleus. Such projections are common for terrestrial vertebrates.
Electron microscopic analysis of the mesencephalic ventromedial tegmentum in the cat
Authors: Halliday Glenda M. , Törk Istvan 
Published: January 2005

AbstractWe have studied the normal ultrastructure of the ventral mesencephalic tegmentum (VMT) in the cat, particularly the morphology and distribution of presynaptic terminals and the types of synaptic junctions. The following subnuclei of the region were examined: n. linearis rostralis (LR), n. paranigralis (PN), and n. interfascicularis (IF). The qualitative and quantitative data revealed significant ultrastructural differences between these subnuclei. Each subnucleus had a characteristic dendritic structure. In LR the dendrites were nonspinous and cylindrical and had presynaptic terminals randomly distributed over their surface. In PN we observed varicose dendrites with spines; the presynaptic terminals formed clusters on the narrow segments of the dendrites and around the spines. Dendrodendritic synapses were also observed in this nucleus. In IF, there was an internal division regarding dendritic structure: in the rostral part of the nucleus there were cylindrical dendrites while in the caudal part irregularly shaped dendrites bearing long spines were found. In IF and LR some of the cylindrical dendrites were seen to be in direct contact with the basal lamina of blood vessels.Four types of presynaptic terminals were distinguished by the morphology of their vesicles, and the proportion of each type in the total terminal population was determined. On this basis the compositions of the presynaptic terminal population in the three subnuclei were found to be very similar. Most terminals contained clear, round vesicles (62.6%), or both clear and dense‐cored vesicles (35.1%). Few terminals were seen with dense‐cored vesicles only (1.4%) or with pleomorphic vesicles (0.9%). The majority of synapses in the VMT were found to have symmetrical densities. LR had twice as many asymmetrical synapses as the other two subnuclei. Eighty percent of the terminals formed synapses with dendrites, although axosomatic and axoaxonic synapses were also seen. The density of the terminals was significantly different for each subnucleus: 191/1,000 μm2 in IF, 120/1,000 μm2 in PN, and 81/1,000 μm2 in LR. These data indicate that while the subnuclei of the VMT receive morphologically similar afferents, each has a unique way of processing the information provided by them, through a different internal circuitry.
The morphology of growth cones of regenerating optic nerve axons
Authors: Scalia Frank , Matsumoto Dan E. 
Published: January 2005

AbstractThe morphology of growth cones of regenerating optic nerve axons was examined by light and electron microscopy in adult frogs (Rana pipiens), using a horseradish peroxidase (HRP) fiber‐filling method, during early and later phases of regeneration. Optic nerve regeneration was initiated unilaterally by crushing the optic nerve in mid‐orbit. Fiber filling was accomplished by severing the affected nerve closer to the eye 24–48 hrs. prior to sacrifice and applying HRP to the central stump. Regenerating axons and their growth cones were observed in the optic nerves, chiasma, tract, pretectal neuropil, and optic tectum. Growth cones of normal‐appearing axons varied in shape and size. Flattened, foliate growth cones similar to those commonly described in vitro were observed in the pretectal neuropil and optic tectum. Other growth cones having vermiform, lanceolate, spatulate, and bulbous forms were observed throughout the optic pathway at all stages examined, although the longer (up to 70 μm) wormlike structures appeared only in the optic tract during the early period of outgrowth. Nearly complete serial‐section reconstructions were obtained for two growth cones in the contralateral optic tectum at 8 wks. regeneration time. One was thinly flattened (to 30–50 nm in places) and extended broadly (8 μm in diameter) in contact with a nouronal perikaryon. The other formed a hood over the blind end of a severed, nonregenerating myelinated axon, which was normal‐appearing except at its end within the confines of the growth cone. Morphological variation among the growth cones is discussed in relation to other descriptive in vivo studies and views concerning growth cone motility.
Torpedo electromotor system development: Developmentally regulated neuronotrophic activities of electric organ tissue
Authors: Richardson Guy P. , Rinschen Bernadette , Fox Geoffrey Q. 
Published: January 2005

AbstractExplant cultures of electric lobe from 45–60 mm stage Torpedo embryos and both ganglionic and dissociated cell cultures prepared from 8‐day chick ciliary ganglia have been used to determine whether the electric organs of Torpedo marmorata contain developmentally regulated neuronotrophic activity. Electric lobe explants were evaluated by measuring their neurone density choline acetyltransferase (CAT), and low salt, Triton X‐100‐soluble protein contents. Addition of soluble extracts prepared from the electric organs of late stage embryos (8–105 mm) to standard medium results in the maintenance of nearly theoretical neurone densities in electric lobe explants during a 7‐day culture period. Soluble electric organ extracts from early embryonic stages (42–59 mm) do not increase neurone density relative to control cultures but cause an elevation in the CAT content of the explants over control values. On the basis of this analysis it is concluded (1) that late embryonic stage and adult electric organs contain neuronotrophic activity that allows electromotor neurones to survive in vitro and (2) that activity increases rapidly in the electric organs between the 59 and 72 mm stages of development at a time when rapid increases in postsynaptic membrane markers in the electric organs occur and when peripheral synaptogenesis begins. The activity of late stage embryonic electric organs is heat stable and lost on dialysis.Using ciliary ganglion explants and evaluating both the initial fibre outgrowth and the CAT content after 4 days in vitro, trophic activity is found to be maximal at early embryonic stages (45–55 mm) and to decline thereafter. It is shown that the decline in activity is not due to an increase in toxicity. Using established dissociated ganglionic cell survival assays the specific activity of neuronotrophic factors allowing survival is constant between the 45 and 73 mm stages in the electric organs and then rapidly declines, but activity per electric organ increases rapidly between the 45 and 73 mm stages and then remains at a constant level. The use of poly‐dl‐ornithine substrates coated with heart‐conditioned medium for the cell survival assay results in up to tenfold increases in the trophic titre of the electric organ extracts. The neuronotrophic activity supporting survival of ciliary motorneurones present in embryonic electric organs is heat labile and retained on dialysis. It is concluded that developing electric organs contain at least two neuronotrophic factors that have different properties and are differently regulated. Both factors may contribute during development to bringing naturally occurring electromotor neurone cell death to an end.
Distribution and morphology of callosal commissural neurons within the motor cortex of normal and reeler mice
Authors: Terashima Toshio , Inoue Kaoru , Inoue Yoshiro , Mikoshiba Katsuhiko , Tsukada Yasuzo 
Published: January 2005

AbstractRetrograde transport of horseradish peroxidase was used to examine the cells of origin, of the callosal commissural fibers (CC neurons) in the primary motor cortex of normal and reeler mice. Quantitative analysis of the intracortical, laminar distribution, and dendritic orientation of CC neurons was performed in conjunction with qualitative observation of their morphology. For comparison, similar quantitative data were obtained for the cells of origin of the corticospinal tract (CST) of normal and reeler mice from materials described previously by Terashima et al. ('83).In the normal mouse, CC neurons are distributed in a bilaminar pattern such that the largest number of cells are located in supragranular layers II and III and in infragranular layer V. The majority of CC neurons are normal (upright) pyramids, although a few in the upper zone of layer VI are inverted pyramidal cells. In the reeler mutant, CC neurons are found in all cortical layers, but two‐thirds are situated in the lower half of the cortex. On the basis of the cell shape and orientation of the apical dendrite, CC neurons of the reeler were classified into six morphological types: (1) typical pyramidal, (2) inverted pyramidal, (3) tumbled, (4) hook‐shaped, (5) polymorphic, and (6) simple. The apical dendrites of the CC neurons in all layers of the cortex of the reeler mouse are randomly oriented; no direct relationship between the intracortical position of the soma and orientation of the apical dendrite was found. In contrast, CST neurons in the reeler mutant are concentrated in the outer third of the cortex, and there is a relationship between the laminar distribution of these cells and the alignment of their dendrites with respect to the pial surface: the apical dendrites of CST neurons lie in superficial layers tend to be oriented obliquely, whereas those of CST neurons in the deeper of cortex most often are oriented vertically, i.e, toward the pial surface. Quantitative analysis revealed that the relative intracortical positions of CC and CST neurons are reversed in the reeler mutant although both populations exhibited greater laminar disposition, and as a consequence, there is more intermingling of the two cell groups in the reeler than in the normal mouse. Thus, the present study suggests that the normal cytoarchitectonics of the primary motor cortex are inverted in the reeler mutant mouse.
Early stages in the formation of the cerebellum in the frog
Authors: Uray Nándor J. 
Published: January 2005

AbstractThe formation of the cerebellum was studied during the first 6 months of the tadpole stage of the bullfrog by using standard histological methods and reconstructions from serial horizontal sections.Three major developmental phases were noted in the formation of the cerebellum. (1) During the first 5 weeks of development, the neuroepithelium proliferated and the dorsal metencephalic plates increased in size. (2) Starting in the sixth week, a patch of neuroepithelium began to differentiate and gave rise to a small population of Purkinje cells. In subsequent weeks, the area of differentiation continued to spread and a Purkinje cell layer became established along the dorsal margin of the cerebellar plate. (3) In the 12th week, the ventrolateral part of the cerebellar plate began to increase in size and generate two populations of small cells. The lateralmost part of the neuroepithelium in this area generated a group of cells that formed an external granular layer that was one cell deep. Cells of this external granular layer migrated inward into the primitive molecular layer, and by the 26th week only a remnant of an external granular layer remained in the cerebellum. The more medially situated part of the neuroepithelium gave rise to another population of small cells that formed a column, which appeared to be continuous with the Purkinje cells, but differed from them in size. It should be noted that full maturation of the cerebellum occurs during metamorphosis, which in this species remains some 2 years away.