bluuebunny/crossref_metadata_2025_split huggingface dataset:
Postnatal development of the ipsilateral corticospinal component in rat spinal cord: A light and electron microscopic anterograde HRP study
Authors: Joosten Elbert A. J. , Schuitman R. L. , Vermelis M. E. J. , Dederen P. J. W. C. 
Published: January 2005

AbstractMost developmental and regeneration studies using the corticospinal tract (CST) as a model are focussed on its major contralateral component in the ventralmost part of the dorsal funiculus. However, for a correct interpretation of the data in these and future studies, a complete anatomical description of the rat CST, including its ipsilateral uncrossed component, is a prerequisite. In this study we used anterograde horseradish‐peroxidase (HRP) tract‐tracing at the light and electron microscopic level to describe the development of the uncrossed ipsilateral CST component. In the far caudal portions of the medulla oblongata, most of the CST fibers decussate dorsally and medially to assume positions in the ventralmost part of the dorsal funiculus. However, a small number of labeled fibers continue uncrossed in a position just lateral to the ventral median fissure. Labeled ipsilateral CST fibers caudally extend into the ventral funiculus of the third thoracic segment at postnatal day 1 (P1), into the seventh thoracic segment at P3, and into the first lumbar segment at P5 and P7. After the first postnatal week labeled ipsilateral CST fibers gradually disappear from upper lumbar, lower‐, and mid‐thoracic spinal cord levels, respectively. From P14 through adulthood the ipsilateral CST projection can not be visualized below upper thoracic spinal cord levels. Quantitative analysis of the amount of label along the length of the outgrowing ipsilateral CST revealed a characteristic staggered pattern of outgrowth: a small number of fibers take the lead and additional fibers are successively added. The outgrowth of labeled ipsilateral CST fiber is mainly restricted to spinal cord white matter. Occasionally a few outgrowing fibers into the adjacent cervical spinal gray can be observed, however, only between P3 and P7. Electron microscopic observations at the cervical enlargement (fifth cervical segment) demonstrate that the first labeled ipsilateral CST fibers, at P1, are characterized by the presence of growth cone‐like enlargements at their distal endings. The process of myelination of labeled ipsilateral CST axons starts at about day P14. Although myelination seems to be largely completed at P28, labeled unmyelinated axons are still present in the adult ipsilateral CST component. © 1992 Wiley‐Liss, Inc.
Timing and duration of dihydrotestosterone treatment affect the development of motoneuron number and morphology in a sexually dimorphic rat spinal nucleus
Authors: Goldstein L. A. , Sengelaub D. R. 
Published: January 2005

AbstractThe spinal nucleus of the bulbocavernosus (SNB) is a sexually dimorphic motor nucleus in the rat lumbar spinal cord. SNB motoneurons and their perineal target muscles are present in adult males, but reduced or absent in adult females. This dimorphism is due to the presence of androgens during development. Perinatal treatment of females with testosterone (T), or a combination of dihydrotestosterone (DHT) and estrogen (E + D females) from embryonic (E) day 16 through postnatal (P) day 5, results in a masculine number of SNB motoneurons and the retention of the target muscles. Perinatal treatment with estrogen alone does not masculinize the SNB; prenatal treatment with DHT alone from E17–E22 results in a feminine number of SNB motoneurons and a significantly altered motoneuron morphology and connectivity. To determine if masculinization of the SNB involves the interaction of estrogen and DHT or results from a longer exposure to DHT alone, the number, morphology, and connectivity of SNB motoneurons in females treated with DHT both pre‐ and post‐natally (from E16–P5) were examined.At E22, DHTP (E16–P5) females have SNB motoneuron numbers identical to E+D and normal females, but far fewer than normal males, thus indicating that T is essential for prenatal masculinization. After E22, SNB motoneuron number declines precipitously in normal females but remains stable in DHTP (E16–P5) females and E+D females, which do not differ from normal males at P10. These results demonstrate that DHT can completely masculinize SNB motoneuron number without any synergistic actions with estrogen, and suggest that the development of SNB motoneuron number is strictly an androgen‐mediated event.In adulthood, horseradish peroxidase histochemistry reveals that the connectivity, dendritic length, and soma size of SNB motoneurons in DHTP (E17–P5) females are identical to those of normal males but differ significantly from those of DHTP (E17–E22) females. These data suggest that the altered connectivity in DHTP (E17–E22) females is not simply a hormone‐specific effect, but the result of a truncated hormone exposure. Thus, DHT can fully masculinize SNB morphology and connectivity if given during the appropriate period of development. It is suggested that while T may be required to masculinize the SNB prenatally, DHT may be involved in masculinizing postnatal aspects of SNB development. © 1992 Wiley‐Liss, Inc.
Course of the fiber pathways to pons from parasensory association areas in the rhesus monkey
Authors: Schmahmann Jeremy D. , Pandya Deepak N. 
Published: January 2005

AbstractThe course of the fiber pathways to pons from parasensory association areas in the rhesus monkey was investigated by injection of tritiated amino acids and the technique of autoradiography. Results confirm the projection to pons from parasensory association areas in the temporal, parietal, and occipital lobes and extend these observations to include the posterior parahippocampal gyrus. The findings reveal that the white matter of the posterior limb of the internal capsule above the midpoint of the lateral geniculate nucleus, and at the medical aspect of the lateral geniculate nucleus, comprise common regions through which these corticopontine fibers lead to the basis pontis. The fibers demonstrate a certain degree of topographic organization in the posterior limb of the capsule above the lateral geniculate nucleus and also in the cerebral peduncle. Taken together with previous observations concerning the termination patterns of these associative corticopontine projections, it would appear that the corticopontine system consists of segregated and partially overlapping pathways, which are to some extent distinguishable anatomically at each stage of their trajectory from origin to destination. Furthermore, the existence of a common area through which all parasensory associative input to pons is transmitted suggests that a precisely located lesion in this part of the corticopontocerebellar circuit may disrupt the cerebellar access to higher order information derived from the parasensory associative regions. © 1992 Wiley‐Liss, Inc.
Topographic organization of cardiovascular responses to electrical and glutamate microstimulation of the parabrachial nucleus in the rat
Authors: Chamberlin Nancy L. , Saper Clifford B. 
Published: January 2005

AbstractWe examined the functional organization of the parabrachial complex (PB) by mapping the cardiovascular and respiratory responses to PB microstimulation in anesthetized rats. The PB was explored with 100 m̈m resolution, at threshold doses of electrical current (5 m̈A) and glutamate (10‐500 pmols), and the locations of stimulation sites were identified by small iontophoretic or pressure injections of biocytin or Phaselous vulgaris leucoagglutinin. Threshold doses of either L‐glutamate or electrical current pulses caused pressor‐tachycardic responses that mapped to the outer edge of the external lateral subnucleus while depressor bradycardic responses were elicited from stimuli near the dorsal lateral subnucleus. Pressor responses persisted in paralyzed, ventilated animals and were thus not dependent upon concomitant respiratory changes. Cardiac arrhythmias sometimes occurred during large pressor responses and during augmented breaths that occurred during or following PB stimulation. These observations indicate that the PB contains at least two distinct neuronal systems that are potently and opposingly involved in cardiovascular control. The locations of the sites giving the most potent responses implicate specific ascending and descending pathways as substrates for the cardiovascular responses. © 1992 Wiley‐Liss, Inc.
Postnatal development of tyrosine hydroxylase immunoreactive amacrine cells in the rabbit retina: II. Quantiative analysis
Authors: Casini Giovanni , Brecha Nicholas C. 
Published: January 2005

AbstractTyrosine hydroxylase (TH)‐immunoreactive (IR) amacrine cells of the rabbit retina mature during the first four postnatal weeks, and their cellular development is described in the preceding paper (Casini, G., and N.C. Brecha, J. Comp. Neurol. 326:283–301, 1992). The present investigation is a quantitative analysis of the postnatal development of the TH‐IR amacrine cell population. TH‐IR amacrine cells gradually increase in size from birth (soma area of 44.7 ± 12.4 ± μm2, mean ± standard deviation) to adulthood (144.2 ± 28.0 μm2). Cell density slightly increases from postnatal day (PND) O (41.9 ± 9.5 cells/mm2) to PND 6 (47.2 ± 7.2 cells/mm2), then markedly decreases from PND 6 to adulthood (17.8 ± 5.3 cells/mm2) as a consequence of retinal growth. TH‐IR cell number almost doubles from PND O (about 4, 100 cells/retina) to adulthood (about 7,850 cells/retina). The increase in the total number of TH‐IR amacrine cells can be explained by the generation of new TH‐IR cells in the inner nuclear layer, a delay in the expression of the TH phenotype after neurogenesis by cells committed to be dopaminergic, or the acquisition of this dopaminergic phenotype by uncommitted cells. The development of the TH‐IR amacrine cell mosaic was assessed by an evaluation of the distribution of nearest neighbor distances of TH‐IR cells. There is a poor correlation between this distribution and a theoretical nonrandom distribution before PND 12. After this age, the nearest neighbor distance distribution shifts towards a nonrandom distribution, and is similar to that of the TH‐IR amacrine cell population in the adult retina. The establishment of the TH‐IR amacrine cell population mosaic is likely to be achieved through different interacting events, including intrinsic (e.g., genetic) factors, environmental influences, and nonuniform retinal growth. Overall, the population parameters analyzed in the present study approach adult values about the time of eye opening (PND 12) and they reach adult values by PND 26. © 1992 Wiley‐Liss, Inc.
Thalamic connections of the vestibular cortical fields in the squirrel monkey (Saimiri sciureus)
Authors: Akbarian S. , Grüsser O.‐J. , Guldin W. O. 
Published: January 2005

AbstractThe afferent thalamic connections to cortical fields important for control of head movement in space were analysed by intracortical retrograde tracer injections. The proprioceptive/vestibular area 3aV, the neck‐trunk region of area 3a, receives two thirds of its thalamic projections from the oral and superior ventroposterior nucleus (VPO/VPS), which is considered as the proprioceptive relay of the ventroposterior complex (Kaas et al., J. Comp. Neurol. 226:211–240, 1984). The parieto‐insular vestibular cortex (PIVC, area retroinsularis, Ri) receives its main thalamic input from posterior parts of the ventroposterior complex and from the medial pulvinar. Anatomical evidence is presented that the posterior region of the ventroposterior complex is a special compartment within this principal somatosensory relay complex. The parietotemporal association area T3, mainly involved in visual‐optokinetic signal processing, receives a substantial input from the medial, the lateral, and the inferior pulvinar.Dual tracer experiments revealed that about 5% of the thalamic neurons projecting to 3aV were spatially intermingled with neurons projecting to areas PIVC or T3. This spatial intermingling was distributed over small but numerous, circumscribed thalamic regions, called “common patches,” which were found mainly in the intralaminar nuclei, the posterior group of thalamic nuclei, and the caudal parts of the ventroposterior complex. The “common patches” may indicate a functional coupling of area 3aV with the PIVC or area T3 on the thalamic level.In control experiments thalamic projections to the granular insula Ig and the anterior part of area 7, two cerebral structures connected with the vestibular cortical areas, were studied. Some overlap in the thalamic relay structures projecting to these areas with these areas with those projecting to the vestibular cortices was found. A quantitative evaluation of thalamic regions projecting to different cortical structures was performed by constructing so‐called “thalamograms.” A scheme was developed that describes the afferent thalamic connections by which vestibular, visual‐optokinetic, and proprioceptive signals reach the vestibular cortical areas PIVC and 3aV. © 1992 Wiley‐Liss, Inc.
Transneuronal transfer of herpes simplex virus type 1 (HSV 1) from mixed limb nerves to the CNS. I. Sequence of transfer from sensory, motor, and sympathetic nerve fibres to the spinal cord
Authors: Ugolini G. 
Published: January 2005

AbstractThe time course of transneuronal transfer of Herpes simplex virus type 1 (HSV 1) from sensory, motor, and sympathetic nerve fibres to connected spinal neurones was examined. After injection of a constant number of infectious units into distal forelimb or hindlimb nerves of inbred rats of the same age, the extent of viral transfer was strictly dependent on the survival time postinoculation (p.i.). Retrograde transport to somatic motoneurones occurred at 28–29 hours p.i. (stage 1), in synchrony with anterograde transneuronal transfer via small cutaneous afferents (to laminae I–II). At 36–43 hours p.i. (stage 2), retrograde transneuronal transfer from sympathetic nerve fibres first labelled sympathetic preganglionic neurones. At 48–51 hours p.i. (stage 3), transfer via sensory and sympathetic axons became more extensive, labelling laminae III7ndash;IV and other preganglionic neurones. Transneuronal transfer from large muscle afferents and motoneurones (to Clarke's columns and the spinal intermediate zone) occurred only at 66–78 hours p.i. (stage 4). Further increases in distribution (stages 5–6) obtained between 78 and 97 hours p.i. may reflect both specific labelling of second and third order neurones and a gradual local loss of specificity. These results indicate that transfer of HSV 1 occurs through all main classes of peripheral axons, but that both anterograde and retrograde transneuronal transfer from small(unmyelinated and fine myelinated) cutaneous and sympathetic axons precedes transfer from large (myelinated) cutaneous and muscle afferents and motor axons. Analysis of viral transfer at sequential intervals is required to distinguish serially connected neurones, determine the route of labelling, and ensure its specificity. © 1992 Wiley‐Liss, Inc.
A quantitative study of the human cerebellum with unbiased stereological techniques
Authors: Andersen Birgitte Bo , Korbo Lise , Pakkenberg Bente 
Published: January 2005

AbstractEstimates of total number of different neuron and glial cell types in the dentate nuclei and the four major regions of the human cerebellum were obtained by new stereological methods. With the optical disector and Cavalieri methods, the total number of neurons and glial cells in the human cerebellum of five elderly men was estimated to be 105,000 × 106 (coefficient of variation, CV = 0.13). Of this total, the granule cells comprised 101,000 × 106 (CV = 0.13) and the Purkinje cells comprised 30.5 × 106 (CV = 0.13) of the neurons. The mean of the total number of neurons in the dentate nucleus was 5.01 × 106 (CV = 0.28). The average surface area of the human cerebellum was estimated to be 1160 cm2 (CV = 0.29).The rationale for the different sampling schemes used to quantify the various cell types is described. © 1992 Wiley‐Liss, Inc.
PHA‐L analysis of projections from the supramammillary nucleus in the rat
Authors: Vertes Robert P. 
Published: January 2005

AbstractThe projections of the supramammillary nucleus (SUM) were examined in the rat by the anterograde anatomical tracer Phaseolus vulgaris leucoagglutinin (PHA‐L). The majority of labeled fibers from SUM ascended through the forebrain within the medial forebrain bundle. SUM fibers were found to terminate heavily in the hippocampal formation, specifically within the granule cell layer and immediately adjoining molecular layer of the dentate gyrus. In addition, SUM fibers were shown to distribute densely to several structures with strong connections with the hippocampus, namely, the nucleus reuniens of the thalamus, the medial and lateral septum, the entorhinal cortex, and the endopiriform nucleus.SUM fibers were also shown to project significantly to several additional subcortical and cortical sites. The subcortical sites were the dorsal raphe nucleus, the midbrain central gray, the fields of Forel/zona incerta, the dorsomedial hypothalamic area, midline/intralaminar nuclei of the thalamus (posterior paraventricular, rhomboid, central medial, intermediodorsal, and mediodorsal), the medial and lateral preoptic areas, the bed nucleus of the stria terminalis, the substantia innominata, the vertical limb of the diagonal band nucleus, and the claustrum. The cortical sites were the occipital, temporal, parietal, and frontal cortices.Some notable differences were observed in projections from the lateral as compared to the medial SUM. For example, fibers originating from the lateral SUM distributed heavily to the hippocampal formation and parts of the cortex, whereas those from the medial SUM projected sparsely to these two regions.The SUM projections to the hippocampal formation and associated structures may serve as the substrate for a SUM involvement in the generation of the theta rhythm of the hippocampus and the gating of information flow through the hippocampal formation. © 1992 Wiley‐Liss, Inc.
Developmental expression of the prothoracicotropic hormone in the CNS of the Tobacco Hornworm Manduca sexta
Authors: Westbrook Anne L. , Regan Sheila A. , Bollenbacher Walter E. 
Published: January 2005

AbstractThe prothoracicotropic hormone is an insect neuropeptide released into the hemolymph to signal molting and metamorphosis through its stimulation of steroidogenesis. The only known source of the prothoracicotropic hormone in the tobacco hornworm, Manduca sexta, has been a group of lateral cerebral neurosecretory cells, the L‐NSC III. In this study, the developmental and spatial distribution of the prothoracicotropic hormone was examined throughout the life cycle of Manduca. In common with many vertebrates and invertebrates in which neuropeptides are located in several regions within the central nervous system (CNS), the prothoracicotropic hormone phenotype in Manduca is expressed by CNS neurons in addition to the L‐NSC III. These neurons are located in the brain, frontal ganglion, and subesophageal ganglion. One cerebral neurosecretory cell group, the ventromedial neurons, expresses the prothoracicotropic hormone phenotype and the behavioral neurohormone, eclosion hormone. Whereas the L‐NSC III and the ventromedial neurons express the peptide phenotype throughout the life cycle, the other neurons express the peptide only during the embryonic and larval stages. This precise spatial and temporal expression of the prothoracicotropic hormone by different groups of neurosecretory cells raises the possibility that in Manduca the peptide may, in addition to its known neuroendocrine function, play other physiological roles in different ways at different stages of the life cycle. © 1993 Wiley‐Liss, Inc.
Cholinergic innervation of the mediodorsal thalamic nucleus in the monkey: Ultrastructural evidence supportive of functional diversity
Authors: Schwartz Michael L. , Mrzljak Ladislav 
Published: January 2005

AbstractThe ultrastructural organization of association nuclei in the primate thalamus is largely unexplored. In the present study we have combined electron microscopy with immunocytochemistry for the acetylcholine synthesizing enzyme choline acetyltransferase (ChAT) to assess the cholinergic synaptic organization of the mediodorsal (MD) nucleus in macaque monkeys. The cholinergic innervation of the MD nucleus showed striking regional variations with the greatest density of immunoreactive axons and varicosities found within the parvicellular division. Electron microscopic examination revealed that these ChAT immunoreactive (ChAT‐IR) axons were primarily small and unmyelinated. The majority of immunoreactive synaptic profiles were found within the extraglomerular neuropil (80.5%), with the remainder present in glomerular regions. Within the glomerular and extra‐glomerular neuropil ChAT‐IR profiles made contact with both conventional, presumably relay cell dendrites (CD), as well as with synaptic vesicle containing dendrites (SVCD) of local circuit neurons. In the glomeruli the frequency of synapses was approximately equal for CDs and SVCDs while in the extraglomerular areas 75% of the synaptic contacts were with CDs. ChAT‐IR synaptic profiles had a diversity of junctional complex morphologies. Within glomeruli they made symmetric synapses with CDs and predominantly asymmetric with SVCDs. The majority of extraglomerular contacts (60%) were classified as asymmetric and these as well as the smaller number of symmetric synapses contacted both CDs and SVCDs.In accord with results of physiological studies, these anatomical data indicate that cholinergic input to thalamic nuclei influences relay cell activity both directly and indirectly via local circuit neurons. © 1993 Wiley‐Liss, Inc.
Fine structure of the dorsal cap of the inferior olive and its GAB aergic and non‐Gabaergic input from the nucleus prepositus hypoglossi in rat and rabbit
Authors: De Zeeuw C. I. , Wentzel P. , Mugnaini E. 
Published: January 2005

AbstractThe dorsal cap of the inferior olive is involved in the control of eye movements and is excited by inputs from the midbrain. In the present study we attempted to determine the inhibitory input to this nucleus in rat and rabbit.The projection from the nucleus prepositus hypoglossi to the dorsal cap was studied in the light microscope by anterograde tracing of Phaseolus vulgaris‐leucoagglutinin and lesioninduced depletion of glutamic acid decarboxylase immunoreactivity, and in the electron microscope by anterograde tracing of wheat germ agglutinin‐coupled horseradish peroxidase combined with GABA immunocytochemistry. We show that the nucleus prepositus hypoglossi projects bilaterally to the dorsal cap, contralaterally to the ventrolateral outgrowth, and ipsilaterally to the medial accessory olive. After lesioning of the nucleus prepositus hypoglossi, the caudal dorsal cap was depleted of most of its glutamic acid decarboxylase‐immunoreactive terminals while the rostral dorsal cap and the ventrolateral outgrowth were depleted of a minor part. Ultrastructural analysis indicates that the majority, but not all, of the terminals from the nucleus prepositus hypoglossi in the dorsal cap are GABA‐positive. These GABA‐positive and GABA‐negative terminals form predominantly symmetric and asymmetric synapses; most of them synapse on dendrites outside and inside glomeruli, frequently in association with dendrodendritic gap junctions, while a small minority are axosomatic. None of the terminals from the nucleus prepositus hypoglossi was found to form a crest synapse, although synapses of this kind were predominantly formed by GABAergic terminals.This study shows that the dorsal cap receives a major inhibitory input from the nucleus prepositus hypoglossi, the terminals of which are located at strategic positions on the olivary neurons. © 1993 Wiley‐Liss, Inc.