bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ascending auditory afferents to the nuclei of the lateral leminscus
Authors: Glendenning K. K. , Brusno‐Bechtold J. K. , Thompson G. C. , Masterton R. B. 
Published: January 2005

AbstractAfferents from the hindbrain auditory system to the nuclei of the lateral lemniscus were analyzed by the use of orthograde and retrograde axontracing techniques. Three divisions of the nuclei of the lateral lemniscus, a dorsal, an intermediate, and a ventral division are discussed. The dorsal nucleus of the lateral lemniscus is a recipient of afferents from cells located mainly in the superior olivary complex and the contralateral dorsal nucleus of the lateral lemniscus. It receives direct afferents from only a few cells in the cochlear nuclei. In sharp contrast, the ventral nucleus of the lateral lemniscus is the recipient of afferents from many cells in the contralateral ventral cochlear nucleus and from only a few cells in the superior olivary complex. Further, it receives no afferents from cells in the contralateral nuclei of the lateral lemniscus. The intermediate nucleus of the lateral lemniscus receives afferents from some cells in the cochlear nucleus and the superior olivary complex. It is unique among the three nuclei of the lateral lemniscus in that it receives a substantial projection from the medial nucleus of the trapezoid body.
Fine structure of myelinated mechanical nociceptor endings in cat hairy skin
Authors: Kruger L. , Perl E. R. , Sedivec M. J. 
Published: January 2005

AbstractHigh‐threshold mechanoreceptors (mechanical nociceptors) with myelinated axons were electrophysiologically identified in hairy skin of the cat as described by Burgess and Perl ('67). Such elements possess receptive fields consisting of a number of punctate areas from which maximal firing can be elicited by intense (skin‐damaging) mechanical stimuli. The spots of the receptive field are separated from each other by unresponsive regions, i.e., by skin areas from which responses cannot be evoked by stimuli effective at the spots.Fine steel pins were inserted to bracket closely a number of the spotlike responsive areas for each of several units. After aldehyde perfusion of the animal, osmification of the tissue and embedding in plastic, the marked skin zones were examined in semithin and ultrathin sections at the light and electron microscopic level. Near each delineated area, a thinly myelnated axon was fond that could be traced to the papillary layer where it loses its myelin sheath. Unmyelinated axons accompanied by thin Schwann cell processes were then traced and found to penetrate the epidermal basal lamina in one of the papillae.At the epidermal penetration site, the axons contained both clear round, and large, dense core vesicles; at this level, the surrounding Schwann cell cytoplasm exhibited numerous pinocytotic vesicles. The zone of pentration may constitute the receptive apparatus. Some of these axons have been traced within the basal epidermal layer where they become surrounded by keratinocytes, lose their Schwann sheath, and apparently terminate. This overall morphological pattern was consistently present in the demarked areas of focal responsiveness, and was rare in the surrounding skin; this and its difference from other cutaneous neural endings suggest that the intraepidermal axon‐Schwann cell complex constitutes the receptive structure for myelinated mechanical nociceptors. It is suggested that such complexes are the sense organs responsible for initiating the sensation of pricking pain produced by localized mechanical injury of the skin.
The laminar distribution and ultrastructure of fibers projecting from three thalamic nuclei to the somatic sensory‐motor cortex of the opossum
Authors: Donoghue John P. , Ebner Ford F. 
Published: January 2005

AbstractThe projections of the ventrobasal complex (VB), the ventrolateral complex (VL), and the central intralaminar nucleus (CIN) to the somatic sensory‐motor (SSM) cortex of the Virginia opossum were studied with light and electron microscopic autoradiographic methods. VB, VL, and CIN have overlapping projections to SSM cortex and each one also projects to an additional cortical area. Unit responses to somatic sensory stimulation and the areal and laminar distribution of axons in cortex is different for VB, VL, and CIN, but the axons from each form similar round asymmetrical synapses, predominantly with dendritic spines.As in other mammals, VB units in the opossum have discrete, contralateral cutaneous receptive fields. VB projects somatotopically to SSM cortex and also projects to the second somatic sensory representation. Within the cortex, VB axons terminate densely in layer IV and the adjacent part of layer III. A few axons also terminate in the outermost part of layer I and the upper part of layer VI. Most VB axon terminate upon dendritic spines (86.6%), but they also contact dendritic shafts (10%) and neuronal cell bodies (3%).Neurons in VL have no reliable response to somatic stimulation under our recording conditions. VL projects to the SSM cortex and to the posterior parietal area. Throughout this entire projection field VL fibers terminate in layers I, III, and IV most densely, and sparsely in the other cortical layers. The density of termination in the mid‐cortical laminae is quite sparse compared to VB, but the projection to layer I is considerably greater. Nearly all (93%) of VL axons contact dendritic spines, the remainder (7%) end dendritic shafts.CIN is a thalamic target of ascending medial lemniscal, cerebellar, spinal, and reticular formation axons. Neurons in CIN respond to stimulation restricted to a particular body part, but typically responses may be evoked from larger areas and at longer latencies than neurons in VB that are related to the same body part. CIN neurons require a firm tap or electrical stimulation within their receptive field to elicit a response in the anesthetized preparation. CIN axons terminate throughout the entire parietal cortex, but unlike VB and VL, CIN fibers end almost exclusively in the outer part of layer I. Approximately 21% of CIN fibers contact dendritic shafts in layer I, which is twice the percentage of shafts contacted by VL or VB axons. All of the other CIN synapses are formed with dendritic spines.These experiments demonstrate three different pathways to SSM cortex. The results suggest that each projection has a unique role in controlling the patterns of activity of neurons within the SSM cortex.
Olfactory bulb projections to the parahippocampal area of the rat
Authors: Kosel Keith C. , Van Hoesen Gary W. , West James R. 
Published: January 2005

AbstractRecent evidence suggests that the main olfactory bulb projects caudally beyond the prepiriform cortex and the cortical amygdaloid nuclei to the region of the piriform lobe called the parahippocampal area. Included within this area is the entorhinal cortex, which is composed of six major subdivisions. Since question remain as to which of these subdivisions receives centripetal fibers from the bulb, we reexamined these projections using autoradiography and HRP histochemistry and correlated the sites of termination with the cytoarchitecture of the entorhinal cortex.The results indicate that olfactory bulb axons reach all parts of the parahippocampal area, including the cortex which forms the medial and lateral banks of the amygdaloid sulcus (area TR), and both subdivisions of the laterally located entorhinal cortex (28L' and 28L). Also, label is observed over the more medially located fields of the entorhinal cortex, including the cortex posterior to the cortical amygdaloid nucleus (28M'), as well as the ventrolateral parts of medial entorhinal cortex (28M). In addition, evidence of label occurs over the full extent of the trasition zone (28i) which separates areas 28L and 28M. These results suggest that the olfactory bulb has a more extensive projection to the parahippocampal area in the rat than previously thought, and may provide at least some input to all of the parahippocampal areas which project to the hippocampal formation.
Pontocerebellar projections to the pyramis and copula pyramidis in the rat: Evidence for a mediolateral topography
Authors: Eisenman Leonard M. 
Published: January 2005

AbstractIn this study, using the horseradish peroxidase (HRP) retrograde tracing technique, the pontocerebellar projection to the pyramis and copula pyramidis in the rat has been analyzed in a series of experiments which had been performed to study the olivocerebellar projection (Eisenman, '81). Microinjections of HRP were made in different mediolateral positions along the width of the pyramis and copula pyramidis. Injections situated within the pyramis but in different loci resulted in the retrograde labeling of primarily two bilateral (much heavier contralaterally) groups of pontine cells: a medial and a ventrolateral group, both situated in the caudal pontine nuclei. With injections in the intermediate region, i.e., the border between the pyramis and copula pyramidis, a different pattern of labeled cells is seen. In these cases the intermediate part of the caudal pontine nuclei contains labeled cells. Injections placed in the lateral parts of the copula pyramidis resulted in still another pattern of retrograde labeling. Injections in this region resulted in the presence of labeled cells in four pontine areas, three caudal groups, and one group in the rostral pontine nuclei. Two of the caudal groups overlap with, but extend more rostrally than, the regions containing labeled cells after pyramis injections. These data suggest the presence in the pyramis and copula pyramidis of three parasagittal zones of differing widths, each of which receives a mainly differential projection from the pontine nuclei.
Time of cell origin and cell death in the avian dorsal motor nucleus of the vagus
Authors: Wright Linda L. 
Published: January 2005

AbstractCessation of cell proliferation and cell death were studied in the dorsal motor nucleus of the vagus of the chick embryo, hatchling, and adult. Most of the cells comprising the nucleus (94%) complete their final DNA synthesis on days 2 and 3 of incubation. There is a caudo‐rostral gradient in the cessation of proliferation, with the caudalmost cells withdrawing from the cell cycle slightly in advance of the middle and rostral cells. Cell death in the dorsal motor nucleus results in a 21% loss of cells between days 8 and 12, and 37% loss by hatching. A caudo‐rostral gradient was also present with respect to cell death, with more delayed and gradual cell loss occurring in the rostral region. The timing and spatial pattern of cell death may be related to the asynchronous innervation of the several targets of the nucleus.
Light‐microscopic immunocytochemical localization of tyrosine hydroxylase in prenatal rat brain. II. Late ontogeny
Authors: Specht Linda A. , Pickel Virginia M. , Joh Tong H. , Reis Donald J. 
Published: January 2005

AbstractThe immunocytochemical localization of tyrosine hydroxylase is examined at embryonic (E) days 18 and 21 in rat brain in order to determine changes in the distribution and cytology of neurons showing immunoreactivity for the enzyme during late prenatal developmnt. As compared with earlier stages of development, the distribution and morphology of the tyrosine hydroxylasecontaining neurons at E18 and E21 more closely resemble catecholaminergic neurons in the adult brain. The changes occuring from the early to the late prenatal stages of development appear to be the result of an increase in number of cells and continued aggregation and migration of the labeled neurons.The major differences in the distribution of labeled perikarya between E18 and E21 are in the olfactory bulb and cerebral cortex. In the olfactory bulb, tyrosine hydroxylase‐containing neurons are not detected until E21. In contrast in the cerebral cortex, a few neurons are transiently labeled for the enzyme at E18, but are not detected at E21 and have not been reported in the adult brain.The most striking change in the tyrosine‐hydroxylase labeled structures in the late prenatal period is the increase in detectable immunoreactivity in bundles of axons and in terminal aborizations. The orderly appearance of tyrosine hydroxylase‐labeled axons in the neostriatum and cortex are discussed in relation to the formation of these two contrasting regions innervated by catecholaminergic neurons.
An ultrastructural examination of early ventral root formation in amphibia
Authors: Nordlander Ruth H. , Singer Jon F. , Beck Ruth , Singer Marcus 
Published: January 2005

AbstractThe morphology of early interactions between neural tube and myotome in the amphibian embryo and tail regenerate was examined using the electron microscope. Two types of contacts were observed. At the most primitive level where the myotome was yet unsegmented, multiple adhesive‐type contacts linked neural tube and myotome. In newly segmented areas early ventral roots were recognizable as small bundles of one to five axons extending the short distance to the myotome. There was only one bundle per segment and in addition to axons, each bundle always contained one or more primitive glial cell processes which accompanied axons as they left the cord. At points of root exit primitive glial processes appeared to funnel axons into the root. The cytoarchitecture of the cord and the new roots suggested that the primitive glia may play a role in pathfinding for motor axons as they leave the cord and extend toward their targets.
Organization of thalamic afferents to anterior dorsal ventricular ridge in turtles. II. Properties of the rotundo‐dorsal map
Authors: Balaban Carey D. , Ulinski Philip S. 
Published: January 2005

AbstractThis study describes some properties of the map of nucleus rotundus onto dorsal area of anterior dorsal ventricular ridge (ADVR) in emydid turtles by correlating results of anterograde and retrograde tracing experiments with observations from Golgi‐ and myelin‐stained brains. An earlier paper (Balaban and Ulinski, '81) demonstrated that this projection is restricted to zone 4 of dorsal area of ADVR. This paper indicates that the rotundal pathway is organized such that longitudinally aligned groups of neurons in nucleus rotundus project to longitudinal regions in zone 4 of dorsal area. The projection field spans the dorsoventral (or concentric) dimension of zone 4 at each transverse level. Comparisons of experimental and Golgi preparations suggest that each rotundal neuron projects, via collaterals, to the entire rostrocaudal extent of rotundorecipient zone 4. Individual terminal branches span the dorsoventral dimension of zone 4 and are confined within both sagittal and transvere planes. Lesion experiments suggest that collaterals of a single rotundal axon are also distributed over at least one‐third to one‐half of the superficial‐deep dimension of zone 4. This is also reflected in the observation that neurons from disjoint dorsal, dorsolateral and medial rotundal loci project to overlapping, concentric regions of dorsal area. Both this prominent concentric component of terminal branches and the extensive overlap of projections of neurons at distinct rotundal loci preclude the possibility of a topographic representation of either dorsoventral or mediolateral rotundal axes in zone 4 of dorsal area.
The central cholinergic system studied by choline acetyltransferase immunohistochemistry in the cat
Authors: Kimura H. , McGeer P. L. , Peng J. H. , McGeer E. G. 
Published: January 2005

AbstractAn atlas of the distribution of cholinergic cell bodies, fibers, and terminals, as well as cholinoceptive cells, in the central nervous system of the cat (excluding the cerebellum) is presented from results obtained in immunohistochemical work on choline acetyltransferase. Cholinergic cell bodies are observed in more than forty areas, and cholinoceptive cells in sixty discrete areas of brain sections from the spinal cord to the olfactory bulb. The atlas is presented in seventy cross‐sectional drawings of cat brain extending from the olfactory bulb to the upper cervical spinal cord.
Transplantation of embryonic occipital cortex to the brain of newborn rats: A golgi study of mature and developing transplants
Authors: Jaeger C. B. , Lund R. D. 
Published: January 2005

AbstractSegments of the occipital cortex were taken from rat embryos (E16–E19) and transplanted to the cerebral cortex or the tectal region ofa new‐born rat host. With the aid of Golgi impregnation techniques, neuron morphology was studied in cortical transplants which had survived for 1 week or more in the host brain. In mature transplants (> 4 weeks) three main groups of neurons, termed groups I–III, were identified. Group II neurons resembled pyramidal neurons of the intact cerebral cortex. No preferential orientation of either soma or dendrites of group I neurons was observed in the transplants, and some group I neurons was observed in the transplants, and some group I neurons had curved spical dendrites. Group II neurons had predominantly stellate form and their dendrites were densely covered with spines. Paucity or absence ofdendritic spines characterized group III neurons which exhibited various dendritic topologies.Different neuron types were also recognized in immature transplants growing for 1 and 2 weeks in the host brain. The sequence of dendritic maturation of transplanted cortical neurons is similar to that seen in intact cortex, although the stage reached related more to the actual age of the transplant than to that of the host. Thus, group I neurons in the 1‐week‐old transplants taken from E16 embryos had not attained the same complexity of branching as pyramidal neurons in the surrounding host cortex, but rather resembled slightly younger cells more like those found in the cerebral cortex of the newborn rat.These results show, therefore, that at least the basic cell classes identified in intact visual cortex can also be recognized in the cortical transplants. This will provide a foundation for studies defining which cells project to the host brain and which are involved in particular intrinsic connections.
Identification of early neurons in the brainstem and spinal cord. II. An autoradiographic study in the mouse
Authors: McConnell Jo Ann 
Published: January 2005

AbstractEarly neurogenesis was studied in two series of mouse embryos with tritiated thymidine (3H‐Tdr) autoradiography to determine (1) the time of origin and (2) the identity of the first postmitotic neurons. Time of origin was studied in embryos cumulatively labeled on the 9th–11th day of gestation (E8, E9, or E10, since the day of finding the vaginal plug is EO) and terminated after one cell cycle (8 hours). Autoradiographs were examined for unlabeled neurons, those which had undergone final DNA synthesis and which were usually also postmitotic. A 16‐somite embryo, cumulatively labeled from the 6‐somite stage, demonstrated 234 such cells in both alar and basal plates from the caudal diencephalon to the cervical spinal cord. Some of these young neurons, therefore, arose prior to neural tube closure, which begins at the 7‐somite stage. Data from other embryos in this series suggests that the first neurons arise at the 1–2 somite stage.Early arising neurons were identified in embryos pulse labeled with 3H‐Tdr during E8–11 and killed after postnatal day (P) 30, when neuronal types could be determined. Autoradiographs were examined for heavily labeled cells, those in final DNA synthesis at the time of treatment. Heavily labeled cells in the youngest mouse in this series (injected at E8½; ca. 8‐somite stage) were primarily small‐to medium‐sized neurons of the brainstem reticular formation, but also some small neurons of the superior olivary nucleus and large primary sensory neurons of the mesencephalic nucleus of the trigeminal nerve. The earliest neurons in the spinal cord appeared early on E9, were medium sized, and were located in the ventral horn and the intermediate zone.Comparisons between the results of this study and those of McConnell and Sechrist ('80) in the chick suggest that the youngest stages of neurogenesis are similar. The first chick nerve cells arise just before formation of the first somites; a slightly later time is indicated in the mouse. Reticular neurons are the earliestarising cells in the chick and make up the majority of the population in each of the youngest chick and mouse stages obtained. Motor and sensory neurons do not begin to originate in large numbers until later, during E3 in the chick and E9 in the mouse.
Astrocyte cell lineage. I. Astrocyte progenitor cells in mouse neopallium
Authors: Juurlink B. H. J. , Fedoroff S. , Hall C. , Nathaniel E. J. H. 
Published: January 2005

AbstractThe astrocyte cell lineage during postnatal development of the neopallium of Swiss mice was studied, using a colony culture assay method in which dissociated neopallial cells form discrete colonies in culture.It was found that immature epithelial‐like cells that form type A colonies in culture come primarily from the subventricular zone but also from other regions of the neopallium. In culture, cells oftype A colonies form type C colonies consisting of cells, which although still epithelial like, differ morphologically from the type A colony‐forming cells. In the presence of dibutyryl cyclic adenosine monophosphate (dBcAMP) the type C colonies form cells rich in glial fibrillary acidic protein (GFAP) and stainable with Cajal's gold chloride sublimate, a stain specific for astrocytes. Therefore, it is proposed that type A colony‐forming cells are astrocyte progenitor cells resembling the “pale” cells found in the subventricular zone (Blakemore and Jolly, '72), the “largeglioblasts” (Sturrock, '76) and the free subependymal cells (Privat, '70; Paterson et al., '73) in the corpus callosum.The sequence of the lineage, i.e., cells forming type A colonies give rise to cells forming type C colonies which eventually differentiate into astrocytes, takes place in situ as well as in culture. As postnatal development of the neopallium progresses the number of colony‐forming cells decreases in the subventricular zone and in other parts of the neopallium. The astrocyte progenitor cells migrate from the subventricular zone to other parts of the neopallium and progress through the lineage of differentiation in all regions of the neopallium.