bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fiber analysis of the feline inferior cardiac sympathetic nerve
Authors: Emery Dennis G. , Foreman Robert D. , Coggeshall Richard E. 
Published: January 2005

AbstractThe left inferior cardiac nerves of nine adult cats were examined with the electron microscope. Electrical recordings were also made from four of these nerves. Most of the nerves contained between 25,000 and 40,000 unmyelinated fibers and 30 to 150 myelinated fibers. The diameters of the unmyelinated fibers ranged from 0.1 μ to 1.8 μ with mean diameters ranging from 0.47 to 0.78 μ in the various nerves. The myelinated fibers ranged in diameter from 1 μ to 9 μ with a mean diameter of approximately 3 μ. Electrical recordings showed two peaks in both the C fiber and the Aδ fiber compound action potentials. Conduction velocities of the two C fiber peaks were approximately 0.7 and 0.9 m/sec. The two groups of Aδ fibers had conduction velocities of approximately 7 and 16 m/sec.
Pallidothalamic projections in the rat
Authors: Severin C. M. , Young P. A. , Massopust L. C. 
Published: January 2005

AbstractThe purpose of this investigation was to examine pallidofugal projections to the thalamus of the rat using a selective silver degeneration method and autoradiography. Degenerating pallidothalamic projections emerging from the anterior part of the pallidum formed two diffuse groups of fibers; one coursed ventromedially directly through the internal capsule without forming a lenticular fasciculus and terminated uniformly in the reticular, VA, VD, VM and the medial part of the VE. The other group coursed ventrolaterally in the internal capsule and, without forming an ansa lenticularis, entered the zona incerta, swept medially through and ventral to the medial lemniscus, and terminated in the medial part of the VE and throughout the VD. Degenerating fibers from both of these groups also terminated in the rhomboid, gelatinous, and medial dorsal nuclei of the thalamus. Fibers from the intermediate and posterior parts of the pallidum crossed the internal capsule in diffuse bundles and terminated in the medial and posterior zones of the reticular nucleus respectively. Most of the fibers passed through the reticular nucleus and terminated uniformly in the VA, VD, VM and the ventral portion of the VE. Some terminated in the medial and midline thalamic nuclear groups. The character of terminal degeneration differed markedly. In the ventral aspect of the VE it had a fine dust‐like appearance whereas in the VA, VD, and VM it was coarsely granular. Autoradiography confirmed the course and terminations described above except that reduced silver grains were not observed in the rhomboid, gelatinous and medial dorsal nuclei of the thalamus. Also, autoradiography confirmed that the dust‐like terminal degeneration in the ventral VE was of the anterograde type since the leucine label was concentrated in precisely the same area.
Trans‐glial channels in ventral nerve roots of crayfish
Authors: Shivers Richard R. , Brightman Milton W. 
Published: January 2005

AbstractThe sheath around the roots of the sixth abdominal ganglion in the yentral nerve cord of the crayfish consists of concentric layers of thin glial processes alternating with wide clefts containing filamentous connective tissue. Regions of each glial lamella are perforated by single, short, tubular channels: the trans‐glial channels. In thin plastic sections examined in the electron microscope, the channels appear as slits that are 240 Å wide and 450–550 Å long which traverse glial lamellae less than 1,500 Å thick. Branched tubular channels cross glial sheets that are thicker than 1,500 Å. The thickest glial wrap is adaxonal; it closely encapsulates individual axons and its cell membrane is separated from the axolemma by a collagen‐free space of only 150 Å. The adaxonal glial cytoplasm contains unique, three‐dimensional networks of interconnected tubules. Separate tubular lattices occur along these thicker processes.In replicas of freeze‐fractured sheaths, the outer half of the plasma membrane belonging to the thin glial sheets exhibits many volcano‐like protrusions which represent cross fractures through the necks of trans‐glial channels. Corresponding depressions on the inner half of these membranes are sites where the plasma membrane invaginates to form the channels. Although some channels are randomly dispersed, others are lineraly positioned in restricted areas across successive glial layers. The number of channels is far more readily appreciated in replicas than in thin sections. The average frequency of channels is 16 per μ2 (range 8 to 33) in normal roots and does not differ significantly from the average of 13 per μ2 in proximal stumps of roots fixed three to four weeks after the roots were cut. The channels are not precisely aligned from one glial layer to the next but do appear to coincide approximately with the adaxonal tubular lattice. The combination of trans‐glial channels and adaxonal tubular lattices may provide a complex conduit that could facilitate a rapid, passive flow of electrolytes and nutrients across the nerve sheath to the axonal surface. Horseradish peroxidase solutions bathing the ventral roots enter the trans‐glial channels, extracellular clefts and finally the tubular lattices. This distribution supports the proposed role of the channels in a rapid extracellular passage of solutes. The channel profiles have a range of forms consistent with the supposition that they are not static but continually reforming.There are indications that, proximal to the cut, the areas of glial plasma membrane with channel profiles contain more junctional complexes between regenerating cells than between glial cells of normal sheaths. The channel profiles and aggregates of particles belonging to junctions are closely associated when they occupy the same region of the membrane.
Anatomical distribution of estrogen target cells in the avian CNS: A comparison with the mammalian CNS
Authors: Martinez‐Vargas M. C. , Stumpf W. E. , Sar M. 
Published: January 2005

AbstractThe distribution of labeled cells was investigated in the brain of the ring dove one hour after administration of 3H‐estradiol. Major areas of concentration of labeled cells were found in (1) the preoptico‐strial region: nucleus preopticus medialis and nucleus interstitialis of the dorsal olfactory projection, (2) the basal hypothalamic region: nucleus hypothalamicus posterior medialis and nucleus inferior, (3) the amygdaloid region: nucleus taeniae and adjacent portions of the archistriatum, and (4) the midbrain: substantia grisea surrounding the nucleus mesencephalicus lateralis, pars dorsalis. The findings support the phylogenetic homologies between the avian nucleus interstitialis of the stria dorsal olfactory projection and the mammalian nucleus interstitialis of the stria terminalis, the avian nucleus hypothalamicus posterior medialis and the mammalian nucleus ventromedialis hypothalami, as well as the avian nucleus inferior and the mammalian nucleus infundibularis‐premammillaris ventralis. The results also suggest that the nucleus taeniae and adjacent portions of the archistriatum correspond to the nucleus medialis and other more differentiated labeled areas of the mammalian amygdala.
The time of origin and the pattern of survival of neurons in the isthmo‐optic nucleus of the chick
Authors: Clarke P. G. H. , Rogers L. A. , Cowan W. M. 
Published: January 2005

AbstractThe time of origin of the cells in the isthmo‐optic nucleus (ION—the nucleus of origin of centrifugal fibers to the avian retina) has been determined in the chick by a variant of the cumulative labeling method, using 3H‐thymidine autoradiography. All the neurons of the ION are generated (i.e., pass through their last phase of DNA synthesis) over a 50‐hour period between the latter part of the fifth and the seventh days of incubation (stages 28–31 of the Hamburger and Hamilton [′51] series) but the cells come to be assembled with in the nucleus along a distinct temporo‐spatial gradient. The earliest‐formed cells occupy the ventrolateral part of the nucleus while the last neurons to be generated come to lie along its dorsomedial margin.When the nucleus is numerically complete, around the eleventh day of incubation, it contains about 22,000 neurons, but between the thirteenth and seventeenth days (stages 39 through 43) this number is reduced by nearly 60% to about 9,500 cells. Following the radical extirpation of one optic cup or the circumscribed removal of the neural retina early on the third day of incubation, the cell loss in the contralateral ION is greatly accentuated, so that by the eighteenth day of incubation no cells remain in the nucleus. Serial counts of the numbers of cells in the nucleus on the side of the eye (or retinal) removals show that it, too, undergoes additional cell degeneration, so that by the end of the phase of naturally occurring neuronal loss, only about half the normal number of cells persist in these experimental animals.
The development of the isthmo‐optic tract in the chick, with special reference to the occurrence and correction of developmental errors in the location and connections of isthmo‐optic neurons
Authors: Clarke P. G. H. , Cowan W. M. 
Published: January 2005

AbstractThe development of the centrifugal projection to the chick retina in the isthmo‐optic tract (IOT) has been studied by the retrograde transport of the enzyme marker horseradish peroxidase (HRP) injected into the eye at various times during the incubation period.Some neurons in the isthmo‐optic nucleus (ION — the cells of origin of the IOT) can first be labeled from the eye following injections on the tenth day of incubation; after injections on the twelfth day or later, about 95% of the neurons can be so labeled. It follows from this that the axons of virtually all the neurons in the ION (including the 60% which normally degenerate between the thirteenth and seventeenth days of incubation) reach the contralateral eye. Since in 12‐day old embryos the IOT is between six and seven millimeters in length and HRP can be identified in the perikarya of ION neurons within three and one‐half hours, the rate of retrograde transport in the system must be of the order of 48 mm/day. A similar time is required for HRP to appear in the perikarya of ION neurons in post‐hatched chicks in which the length of the IOT is estimated to be about 14 mm. This suggests that at some time during the latter half of the incubation period there is a significant acceleration in the rate of retrograde transport, similar to that found for anterograde axonal transport in the chick and rabbit visual systems.In addition to labeling neurons in the contralateral ION, intraocular injections of HRP before the sixteenth day of incubation label a significant number of cells (up to 650) which lie outside the borders of the nucleus, and a small number (10–100) in the ipsilateral ION. About 90% of the ectopic neurons and all of the cells in the ION which send their axons aberrantly into the ipsilateral eye, degenerate some time after the fifteenth day of incubation, apparently because they either do not make appropriate connections within the retina or else fail to receive an appropriate input from the optic tectum. After early removal of one optic cup, the number of neurons in the ipsilateral ION that can be labeled by HRP injected into the surviving eye is greatly increased (involving as many as 50% of the cells in the nucleus). Despite the fact that the axons of these cells reach the retina (albeit of the “wrong” side) the cells do not survive beyond the seventeenth day of incubation. However, during the period in which their axons are in the retina they appear to interfere with synapse formation by the axons of the neurons in the contralateral (“correct”) ION; only about half the normal number of ION neurons survive under these circumstances. These findings suggest: (i) that certain types of errors may be common during neural development, (ii) that they are generally transitory, being recognized and eliminated at later stages in development, and (iii) that although transitory, some errors may have long lasting sequelae.
The facial motor nucleus of the opossum: Synaptic endings on dendrites
Authors: Falls William M. , King James S. 
Published: January 2005

AbstractThe diameters of dendrites of large, medium and small neurons (Falls and King, '76) were measured from Golgi impregnations of the opossum facial motor nucleus in order to classify dendritic profiles sectioned in the transverse plane in electron micrographs. Three categories of dendrites are described: (1) proximal (4–7 μ in diameter); (2) intermediate (2–4 μ in diameter) and (3) distal (0.5–2 μ in diamter). The distribution of axodendritic synaptic endings was determined, recognizing that the neuronal source of individual dendritic profiles when seen in the transverse plane of section cannot be absolutely determined in view of the overlap in size of the dendrites issuing from the three types of neurons. Presynaptic terminals were categorized according to vesicle shape (spherical, pleomorphic or ellipsoidal), vesicle size, terminal size, junctional characteristics and post synaptic distribution. The vesicle size is expressed as a mean area (nm2) and was determined by using a cybergraphic tablet and a PDP‐12 computer system.In any given plane of section, synaptic terminals cover most of the membrane of proximal dendrites and decrease in number as intermediate and distal dendrites are encountered. In Golgi impregnations four classes of afferent fibers which ramify among the dendrites of facial neurons can be distinguished. As yet, their sources have not been identified. Possible sites of origin for presynaptic profiles are discussed in the context of previous light microscopic findings.
The supraoptic nucleus and the supraopticohypophysial tract in the monkey (Macaca mulatta)
Authors: Luqui Ivan J. , Fox Clement A. 
Published: January 2005

AbstractThe observations here on Golgi material are based on the study of fortunate impregnations in one horizontally sectioned and one frontally sectioned series found in the collection of Golgi preparations of the adult monkey brains (Macaca mulatta) available in this laboratory.The soma of the large supraoptic neurons have jagged protrusions and irregular crevices which give their surfaces a craggy appearance. Also they have a few somatic spines. Their dendrites, which usually arise from two or three dendritic trunks, emerging from the cell body, are moderately branched and have occasional dendritic spines. The axon emerges from a conical elevation either on the soma or a dendrite and is directed towards the supraopticohypophysical tract.In the present material there are a few neurons of the supraoptic nucleus impregnated that are definitely smaller than the larger neurons. They have short beaded axons, ending in the supraoptic nucleus a short distance from their point of origin.In the horizontal sections the supraopticohypophysial tract fibers can be seen passing over the posterior aspect of the optic tract. In the frontal sections, this fan‐shaped tract, wide above and constricted below, can be followed into the median eminence. Some of these axons in their intrahypothalamic course have short beaded collaterals.Electron micrographs reveal: (1) endings with spherical synaptic vesicles and endings with flattened synaptic vesicles synapsing on neurosecretory axons in the supraoptic nucleus; (2) a few myelinated fibers containing neurosecretory granules in the intrahypothalamic portion of the supraopticohypophysial tract.As can be seen in both Golgi and electron microscopic preparations the presence of fibrous astrocytes in the supraoptic nucleus and their abundance in the hypothalamic portion of the supraopticohypophysial tract is characteristic of this neurosecretory system. In the nucleus and in the tract processes of the fibrous astrocytes are intimately associated with neurosecretory fibers.
Functional organization in the visual cortex of the golden hamster
Authors: Y‐C Tiao , Blakemore Colin 
Published: January 2005

AbstractThe visual cortex of the golden hamster was studied by means of multi‐unit and single unit recording, which revealed three separate retinotopic maps of the visual field in the posterior cortex. V1, corresponding to cytoarchitectonic area 17, has the contralateral temporal field represented medially, the central visual field (extending about 10 deg ipsilateral) represented laterally and the lower field anteriorly. The borders of the map, especially for the upper field, seem to be more restricted than the whole visual field available to the contralateral hemiretina: V1 probably does not represent the extreme periphery of the field. A large fraction of V1 has binocular input, for up to about 50 deg lateral to the vertical midline. There is a retinotopic reversal near the representation of the vertical midline where V1 meets V2 (corresponding to the more lateral “area 18a”). There is another retinotopic reversal at the extremity of the contralateral field representation, where V1 meets Vm (the medial visual area, corresponding to “area 18”) V2 and Vm each contain a reduced mirror image version of the map in V1. Almost all isolated single units in V1 have receptive fields that can be classified as radially symmetrical (60%) or asymmetrical (35%) Symmetrical fields have ON (13%) OFF (4%) ON‐OFF (30%) or “SILENT” (12%) central areas when plotted with flashing spots. There are minor but not striking differences between these groups in their field sizes, velocity preferences and so on. They almost invariably prefer moving to stationary stimuli but are not selective for orientation or direction of movement. Asymmetrical fields are of four types, three of which (type 1, 11% type 2, 17% and type 3, 2%) are orientation selective and resemble simple, complex and hypercomplex cells in the cat cortex. Some of these have direction as well as orientation preference. Axial movement detectors (5%) have a selectivity for one axis of motion, and thus prefer one orientation of edge, but respond equally well to movement of a spot. Vertical and horizontal orientation preferences, especially the latter, are much the most common. There is some evidence of clustering of cells according to receptive field type and, possibly, preferred orientation. Asymmetrical cells are, relatively, somewhat rarer in the deeper cortical layers. Within the binocular segment, fully 89%of cells are binocularly driven and the receptive fields are similar in the two eyes. Receptive fields tend to increase in size away from the area centralis representation and, in a complementary fashion, the magnification factor decreases from up to 0.1 mm/deg at the area centralis representation to about 0.02 mm/deg for the peripheral field.
Functional organization in the superior colliculus of the golden hamster
Authors: Y‐C Tiao , Blakemore Colin 
Published: January 2005

AbstractThe superior colliculus of the golden hamster was investigated by means of multi‐unit and single unit recording. The retinotopic map, which probably embraces a projection from the entire retina of the contralateral eye, is organized as in other vertebrates, with the central field represented in the anterior colliculus, the upper field medially. Magnification factor is fairly uniform and is about 0.02 mm/deg. There is a small binocular segment (where almost half of all neurones have input from the ipsilateral eye) in the anterior colliculus, representing the area of field around the area centralis and the anterior pole of the field. In the more superficial layers, units have small (about 10 deg diameter) receptive fields, which can be classified as symmetrical, responding to slow movement (80%) very fast movement detectors (6%) directional movement detectors (13%) and axial movement detectors (%) In the deeper layers, below the stratum opticum, receptive field size increases dramatically and many cells habituate rapidly, making them sensitive only to new events. Receptive fields can be classified as movement detectors (89%) directional movement detectors (10%) and axial movement detectors (2%). All directional receptive fields, at least in the upper visual field, have an upward component in their directional preferences. About 42% of deeper layer cells have somatic sensory input, responding to light touch on the fur or whiskers of the contralateral half of the body. Some 5% of cells respond to complex sounds on the contralateral side of the animal. Many of these somatic and auditory cells also have visual receptive fields and, throughout the colliculus, there is general correspondence between the maps of visual space, auditory space and the body surface. This correlation may be important in the regulation of orienting behaviour towards novel peripheral stimuli.
Regeneration of Müller and Mauthner axons after spinal transection in larval lampreys
Authors: Rovainen Carl M. 
Published: January 2005

AbstractThe regeneration of large unmyelinated axons following transection of the spinal cord was studied in small larval sea lampreys (Petromyzon marinus) Individual Müller and Mauthner axons normally occur in a characteristic pattern in the spinal cord, but their positions were altered in the first several segments caudal to the lesion following regeneration. Müller axons grew out of the ventral tracts and sometimes looped back towards the brain or crossed the midline; maximum misdirection of axons occurred near the site of transection. Mauthner axons frequently bifurcated. Despite the aberrant and incomplete regeneration of axons, the larvae exhibited normal coordinated swimming, crawling, and coiling behavior.
Efferents from medial basal forebrain and hypothalamus in the rat. II. An autoradiographic study of the anterior hypothalamus
Authors: Conrad Lily C. A. , Pfaff Donald W. 
Published: January 2005

AbstractUsing tritiated amino acid autoradiography, the efferent projections of the anterior hypothalamic area (AHA) were studied in albino rats.Axons from AHA neurons were not confined to local projections in the hypothalamus. Ascending AHA axons ran through the preoptic region, joined the diagonal band and distributed in the lateral septum. Descending AHA efferents within the hypothalamus coursed in a bundle ventromedial to the fornix. Projections were observed to the dorsomedial, ventromedial, arcuate and dorsal premammillary nuclei, and to the median eminence. Sweeping dorsomedially in the posterior hypothalamus, some AHA axons distributed in the central grey. AHA axons staying ventral projected to the supramammillary region, ventral tegmental area, raphe nuclei and midbrain reticular formation. Other AHA efferents distributed to the periventricular thalamus, to the medial amygdala via the stria terminalis or supraoptic commissure, and to the lateral habenula through the stria medullaris.For comparison with the AHA, efferent projections from the paraventricular nucleus (PVN) and from the ventromedial nucleus and adjacent basal hypothalamus (VMR) were studied. Projections from PVN neurons were not restricted to the median eminence and neurohypophysis. PVN efferents also distributed to many of the same regions as did those of the AHA but had somewhat different fiber trajectories and longer descending projections. VMR efferents were more widespread than those of the AHA, with projections extending into the lateral zona incerta and pontine reticular formation.Projections from the AHA were distinct from those of the medial preoptic area (mPOA). For example, while AHA axons descended in a bundle ventromedial to the fornix, mPOA axons ran in the medial forebrain bundle. Such anatomical differences may underlie experimentally demonstrated functional differences between the mPOA and AHA, for instance, in mediation of male and female sex behaviors.