bluuebunny/crossref_metadata_2025_split huggingface dataset:
Autoradiographic study of histogenesis in the mouse olfactory bulb I. Time of origin of neurons and neuroglia
Authors: Hinds James W. 
Published: January 2005

AbstractTime of origin (final cell division) of neurons and neuroglia of the mouse olfactory and accessory olfactory formations was determined by autoradiography. Animals were injected with thymidine‐H3 at various developmental stages and killed at or near maturity. In the olfactory formation mitral cells (the largest neurons) arise first, mainly over the three day period from the eleventh day of gestation (E11) to E13, tufted cells chiefly from E13 to E18, and granule cells (the smallest neurons) mainly from E18 to postnatal day 20. Most of the smaller and more superficial peripheral tufted cells arise later than the deeper and larger middle and internal tufted cells. All three types of granule cells have a time of origin extending well into postnatal life, with internal granule cells arising over a longer and later period than periglomerular cells or granule cells of the mitral cell layer. Neuroglial precursors undergo final cell division chiefly between E17 and P10. In the phylogenetically less evolved accessory olfactory formation, mitral cells originate earlier than their homologues in the olfactory formation; mitral cells principally from E10 to E12 and granule cells chiefly from E12 to E18. The results support the concept that some germinal layers of the central nervous system are programmed to produce a succession of cell types, larger cells before smaller ones.
Relationship of myelin internode elongation and growth in the rat sural nerve
Authors: Schlaepfer William W. , Myers Fay K. 
Published: January 2005

AbstractThe lengthening of myelin internodes along peripheral nerve fibers was studied in rat sural nerve during the period of myelination and subsequent growth. Sural nerves were examined from 34 animals ranging in age from 2 to 140 days. Analyses of osmicated, epon‐embedded and transversely sectioned nerves indicated that myclination of rat sural nerve commenced in the two to five day period and continued until day 20. Direct measurements of consecutive myelin internodes along representative teased fibers disclosed a progressive increase of internode length and fiber diameter. A direct relationship was shown between the rate of increment of the largest internodes and the longitudinal growth rate of the rat hind limb as determined by the combined lengths of the disarticulated femur and tibia. Increases of internode lengths among the entire population of myelinated fibers also appeared to correlate with the longitudinal growth pattern of the hind limb. This was assessed by comparing the size distribution of myelinated fibers in adult sural nerve with a theoretical distributional profile based upon the assumption that internode length is solely determined by amount of longitudinal growth after myelination. Assuming that internode elongation is determined by growth, it was shown that the quantity of longitudinal growth after myelination could account for the size and distribution of all myelin internodes in the adult sural nerve. In addition, the relationships between myelin internodes and fiber size at different ages was expressed by slopes of the regression lines. A significant change in this value for sural nerve fibers in the 30–40 day age period indicated that there was an increase of composite fiber diameter relative to internode length during the interval. During the remaining periods of growth, the diameters of myelinated fibers increased at a rate comparable to the increase of internode length.
Retinal structure in the smooth dogfish, Mustelus canis: Light microscopy of photoreceptor and horizontal cells
Authors: Stell William K. , Witkovsky Paul 
Published: January 2005

AbstractPhotoreceptor and horizontal cells in retinas of the smooth dogfish were impregnated by the rapid Golgi method. Cones as well as rods are present; there are hundreds of rods per cone. The rod synaptic endings are small spherules which send out basal processes (telodendria). The cone synaptic endings are large pedicles which also extend telodendria.Horizontal cells of three distinctive varieties are segregated in vertically separate layers. Horizontal cells of the first (external) row are thick and cuboidal. They send out processes which enter into the invaginations in rod spherules. These cells and their processes cover a circular to elliptical field measuring 75–125 by 125–200 μm. They probably contact every rod in this field. Horizontal cells of the second (intermediate) row are flattened and stellate. Their processes also enter into the rod spherules. These cells cover a circular to elliptical field slightly larger than that covered by cells of the first row. Although they appear not to contact every rod in their field, the fields of adjacent cells of this type overlap. Every rod, therefore, probably contacts one horizontal cell of the second row as well as one of the first row. Horizontal cells of the third (internal) row are stellate, with a few long cylindrical horizontal processes. Finer vertical processes go from these to contact cone pedicles. Probably each cone contacts one such process, and each third‐row horizontal cell contacts on the order of ten cones. Although somewhat uncertain, the size, shape, and degree of overlap of the fields covered by third‐row cells are probably not very different from those of first‐ and second‐row cells. The vertical sequence of horizontal cells which contact rods or cones in dogfish is inverted from that in teleosts.
The ascending fiber projections from the principal sensory trigeminal nucleus in the rat
Authors: Smith Ronald L. 
Published: January 2005

AbstractPersisting reports of uncrossed secondary trigeminothalamic pathways originating from the principal sensory trigeminal nucleus (PrV) are based mainly on data obtained from surgically induced lesions analyzed by methods other than reduced silver impregnation techniques. After complete stereotaxic or direct surgical lesions of PrV, degenerating fibers proceed ventrally and rostrally from the nucleus and cross the midline in the rostral pons, completing their decussation caudal to nucleus interpeduncularis. These fibers form a large trigeminal lemniscus that ascends through the midbrain dorsomedial to the smaller medial lemniscus. PrV fibers terminate in the posterior thalamic nucleus and throughout the medial two‐thirds of the ventrobasal thalamic complex (VBm) contralateral to the side of the lesion. Connections with the ventral part of zona incerta were also found similar to those reported for the medial lemniscus.Another fiber system proceeds dorsad from the parvicellular reticular formation in the PrV region and terminates on cells of the ipsi‐and contralateral motor trigeminal nuclei and the adjacent contralateral parvicellular reticular formation. Differential lesions indicate that these “intertrigeminal” commissural connections arise chiefly from the parvicellular reticular formation that lies between PrV and the motor trigeminal nucleus.These experiments, which also included selective lesions of dorsal and rostral portions of PrV, failed to produce any evidence supporting the existence of an uncrossed principal sensory trigeminothalamic pathway in the rat. While selective, ventral zona incerta PrV connections can be demonstrated, no PrV intralaminar projections appear to exist. Initial findings show that comparable fully decussated PrV–VBm connections also exist in the guinea pig but that some ipsilaterally ascending fibers occur in monkeys (Smith, '72). These and other recent data demonstrate that phyletic neural variations exist in the PrV‐thalamic projections in various mammalian species.
Visual intensity and pattern discrimination after lesions of the thalamofugal visual pathway in pigeons
Authors: Hodos William , Karten Harvey J. , Bonbright James C. 
Published: January 2005

AbstractTwenty‐seven pigeons were trained to discriminate between stimuli that differed in intensity or pattern. In 16 cases, bilateral, electrolytic, stereotaxic lesions were made in the nucleus opticus principalis thalami (OPT), which is the main thalamic terminus of the optic tract. In some cases, the lesions also interrupted the efferent fibers of nucleus rotundus thalami, which receives major input from the optic tectum. In an additional 11 cases, bilateral telencephalic lesions were made by aspiration. These lesions were in the accessory hyperstriatum, which contains the nucleus intercalatus, hyperstriati accessorii (IHA), which is the telencephalic target of OPT. Extensive destruction of either IHA or OPT produced little or no impairment of discrimination performance. However, those cases in which both OPT and nucleus rotundus were involved showed serious performance losses.
Experimental reorganization of the cerebellar cortex. II. Effects of elimination of most microneurons with prolonged x‐irradiation started at four days
Authors: Altman Joseph , Anderson William J. 
Published: January 2005

AbstractThe heads of Long‐Evans rats were irradiated from the fourth day after birth with a schedule of repeated doses of low‐level x‐ray which essentially prevented the formation of basket, stellate and granule cells in all except the earliest‐forming lobules (nodulus and uvula). The morphogenic and synaptogenic effects of this treatment were examined with light and electron microscopy in 30 day old animals, with particular attention paid to the pyramis. Although when irradiation was started the Purkinje cells formed a monolayer and had upward oriented apical poles, they became scattered later and had randomly oriented dendrites. This secondary disorientation was attributed to insufficient space available in the arrested cerebellum for the rapidly expanding Purkinje cells. Although basket cell terminals were scarce, basket cell‐like terminals were formed on the somata of Purkinje cells, apparently by recurrent axon collaterals of these cells. The most common synapses with the thorns of Purkinje dendrites were formed by climbing fibers but other elements, including glial processes, were also in contact with postsynaptic loci on the thorns. Many mossy fiber terminals reached the surface. Where parallel fibers were present they were often thicker than in unirradiated animals and contained neurofilaments. No pathological changes were seen in these cerebella, with the possible exception of excessive lobulation of the nuclei of many Purkinje cells.
The organization of the seventh lumbar spinal ganglion of the cat
Authors: Burton Harold , McFarlane John J. 
Published: January 2005

AbstractThe organization of the seventh lumbar dorsal root ganglion (DRG) of the cat has been investigated both anatomically and electrophysiologically. In the first two series of experiments an attempt was made to relate the topographic location of identified groups of cells in the ganglion with the rostro‐caudal position of their central processes in the filaments of the dorsal root. 3H‐proline was injected into various sectors of the ganglion and the distribution of the axonically transported proteins, in individual dorsal rootlets, was determined by means of liquid scintillation spectroscopy and the location of the injections was determined by autoradiography of the sectioned ganglia. The projection pattern was also determined by antidromically activating DRG cells in various parts of the ganglion by sequentially stimulating each of six dorsal root filaments. The results of both groups of experiments indicate that cells located in the medial (caudal) parts of the ganglion project into the most caudal rootlets of the dorsal root; cells in the most lateral (rostral) parts of the ganglion project into the most rostral rootlets, while cells in the intermediate parts of the ganglion project into the middle rootlets. In a third series of experiments, a shifting pattern of overlapping receptive fields was demonstrated for a series of recordings that traversed the ganglion from medial to lateral. This pattern was shown to be nearly equivalent to the organization of receptive fields previously demonstrated by Kuhn ('53) for a rostral to caudal sequence of dorsal rootlets, i.e., foot and leg preaxial fields predominated in the lateral sectors, while postaxial fields were found in the medial sectors of the ganglion.
Fluorescence and electron microscopic studies of the early development of the substantia nigra and area ventralis tegmenti in the fetal rabbit
Authors: Tennyson Virginia M. , Mytilineou Catherine , Barrett Robert E. 
Published: January 2005

AbstractThe anlage of the substantia nigra compacta and the area ventralis tegmenti appears as a fluorescent zone in the midventral proliferation in the caudal mesencephalon of the rabbit at day 14 of gestation. Fluorescence is present in cell bodies and their processes in the mantle layer of the basal plate just ventral to the ependymal zone. By day 16 of gestation, the number of fluorescent cells and processes has increased, and they form an inverted “V” shaped zone in the midline mantle layer. A fluorescent fiber tract, the presumptive mesolimbic and nigroneostriatal pathway, extends from the fluorescent zone through the lateral hypothalamus as far as the caudal portion of the telencephalon. Electron microscopic studies of the inverted “V” shaped anlage show that most of the cells are spindle‐shaped bipolar neuroblasts, but some globular neuroblasts are present as well. The large 800 to 1000 Å dense core vesicle is found in the perikarya of the neuroblasts and also in processes in the neuropil. Axonal growth cones are common, but synaptic profiles are rare.By day 18 of gestation, some of the fluorescent cell bodies have migrated lateral to midline and as far rostral as the central portion of the midbrain. Fluorescent axons of the presumptive nigroneostriatal pathway have reached the putamen and have formed minute varicose terminals. These axons, therefore, have reached their terminal nucleus before their cell bodies have finished migrating to their final positions. Electron microscopic study of the anlage located lateral to midline shows that the cells are multipolar and exhibit extensive new growth of dendrites. Immature synaptic profiles and a few mature junctions are occasionally found in the neuropil.By day 20 of gestation, a distinct substantia nigra compacta and reticulata can be recognized lateral to the area ventralis tegmenti. The neurons of the substantia nigra have relatively abundant perikaryal cytoplasm and the cells are frequently adjacent to one another. The perikarya of the area ventralis are some what smaller and they are spaced more widely apart. Large dense core vesicles are present in some perikarya of both regions. Synaptic terminals are more common, but still not numerous. The meso‐limbic and nigroneostriatal pathway are well established at this stage.
The effects of monocular lid suture upon the development of the visual cortex in squirrels (Sciureus carolinensis)
Authors: Guillery R. W. , Kaas J. H. 
Published: January 2005

AbstractThree infant squirrels had the lids of one eye sutured prior to eye opening. The animals were killed when they were adults and the cells in the visual cortex were studied after Nissl staining.On the side contralateral to the suture, the cortical nerve cells were more closely packed than on the side of the suture. This asymmetry was clearly evident in cortical layers II–VI, and it was as marked in the regions of cortex receiving from the monocular crescent of the visual field as it was in the binocular segments. Thus, these cortical changes cannot be dependent upon the geniculate cell changes, since the latter occur in the binocular but not the monocular segments of the nucleus.
Ontogeny of monoamine neurons in the locus coeruleus, raphe nuclei and substantia nigra of the rat. I. Cell differentiation
Authors: Lauder Jean M. , Bloom Floyd E. 
Published: January 2005

AbstractThe onset of cell differentiation in the locus coeruleus, dorsal and medial raphe nuclei, and substantia nigra (zona compacta) was studied using the technique of long‐survival H3‐thymidine autoradiography to date neurogenesis. Pregnant female rats were injected with isotope on day 10, 11, 12, 13, 14, 15, 16 or 17 of gestation. Litters were born on day 22 and allowed to survive for 30 days. Brains were prepared for the fluorescence histochemical demonstration of monoamines or fixed by formalin perfusion. Autoradiography was carried out on sections adjacent to those in which monoamine‐nuclear groups were identified by the fluorescence method and also on sections from perfused brains, which were used to facilitate cell counting. The norepinephrine cells of the locus coeruleus began to differentiate (presence of heavily labelled cells) on days 10–13 of gestation, with a peak of heavy labelling on day 12, whereas the 5‐HT cells of the raphe nuclei and the dopamine cells of the substantia nigra began differentiating on days 11–15. In the dorsal raphe nucleus, the peak of heavy labelling occurred on day 14, whereas in the medial nucleus this took place on days 13–14. The substantia nigra, on the other hand, peaked on day 13.Cell differentiation was also studied in the cerebellar Purkinje cells and hippocampal macroneurons (pyramidal and polymorph cells) of areas CA3 and CA4, to which the locus coeruleus has been reported to project. Differentiation of these cells commenced on days 14–15 (Purkinje cells) and 13–18 (hippocampal cells), with both cell types peaking on day 15, a full three days after the peak of heavy labelling in the locus coeruleus.Evidence is discussed for the possible neurotrophic role of monoamine neurons in the neurogenesis of monoaminergic receptive cells.
An autoradiographic study of retinogeniculate pathways in the cat and the fox
Authors: Hickey T. L. , Gullery R. W. 
Published: January 2005

AbstractThe distribution of retinal afferents to the dorsal lateral geniculate nucleus of the cat and the fox has been studied using ocular injections of 3(H)‐leucine and autoradiographic techniques. Whereas fiber degeneration methods have shown only five distinct layers in the lateral geniculate nucleus, autoradiographs show six well defined layers in both species. Laminae A and C receive afferents from the contralateral eye, while laminae A1 and C1 receive from the ipsilateral eye. A retinal input to the region lying between lamina C1 and the optic tract could not be demonstrated by fiber degeneration methods, but this region can now be divided into two distinct layers. The antero‐dorsal of these two layers (lamina C2) receives afferents from the contralateral eye, while the postero‐ventral layer, nearest the optic tract, appears to receive no direct afferents from either eye.Since the rapid component of the axoplasmic transport labels axon terminals to a greater extent than fibers of passage, the autoradiographic method demonstrates, more successfully than fiber degeneration methods, that there is no significant binocular overlap between the retinal projections to alternate geniculate layers.
Topographic atlas of catecholamine and acetylcholinesterase‐containing neurons in the rat brain. I. Forebrain (telencephalon, diencephalon)
Authors: Jacobowitz David M. , Palkovits Miklos 
Published: January 2005

AbstractTransverse sections of the rat forebrain have been studied by the histofluorescence and acetylcholinesterase histochemical methods. A detailed stereotaxic atlas of the catecholaminergic and acetylcholinesterase‐containing neural structures.
Locomotor behavior of decerebellated arboreal mammals — Monkey and raccoon
Authors: Wirth Fremont P. , O'Leary James L. 
Published: January 2005

AbstractTotal and partial cerebellectomies were carried out on 36 arboboreal animals, 15 racoons and 21 rhesus monkeys. The animals were evaluated pre‐ and post‐operatively for ability to swim, walk‐run, leap, and climb. Tone, reflexes, strength and other aspects of behavior were also studied. Both species exhibited rapid recovery from the procedure and were self‐sufficient shortly after surgery. Adult racoons and monkeys rapidly regained their ability to climb, and six months after surgery were able to do so normally except for mild residual ataxia when hurried. Ability to walk or run was regained at a much slower rate and was incomplete at six months, although at one year monkeys were not greatly incapacitated in walking. These differences indicated greater impairment of physiological extensor muscle groups than of flexors following cerebellectomy. The vestibular aspect of cerebellar deficit appeared to be related to recovery to a lesser extent. Swimming was very little altered by cerebellectomy.Muscular strength was recoverable in the monkey following cerebellar ablation. Power and force were measured before and after cerebellectomy. The latter was evaluated by food reinforcement to occasion pulling a weighted lever by selected trained monkeys. Recovery of power, which involved return of rapid, effective movements was slower, but could also occur completely. Careful histological examination conducted on all deceased animals indicated that the anticipated removals were accomplished without significant brain stem injury. Hydrocephalus was observed to develop in a significant number of animals following cerebellectomy. This factor has not been excluded in many previous reports, and may have contributed to failure to achieve effective compensation.
The optic system of the teleost Cichlasoma biocellatum
Authors: Anders Juanita J. , Hibbard Emerson 
Published: January 2005

AbstractThe retinal projections of the fresh water teleost. Cichlasoma biocellatum, were examined using a modification of the Nauta‐Gygax method following unilateral enucleations and removal of retinal quadrants. After the unilateral enucleations, degeneration was found in the fasciculus medialis nervioptici, fasciculus geniculatus tractus optici, fasciculus dorsomedialis tractus optici, and the accessory optic tract. The pretectal nucleus, nucleus corticalis, and accessory optic nucleus contained debris of terminal degeneration. The majority of the optic fibers terminated in five layers in the optic tectum. The quadrant removals showed that fibers from the retinal quadrants formed layers in the ribbon shaped optic nerve running the width of the nerve. The dorsal to ventral arrangement of the fibers was: dorsal nasal quadrant; dorsal temporal quadrant; ventral nasal quadrant; and the ventral temporal quadrant. The fibers from only the posterior half of the retina supplied the fasciculus geniculatus tractus optici and the corpus geniculatum laterale. Fibers from the anterior half of the retina supplied the accessory optic tract and nucleus. All other tracts and nuclei examined received fibers from all the retinal quadrants. The projection of the retinal quadrants to the tectal quadrants was specific and always formed five layers of degeneration.