bluuebunny/crossref_metadata_2025_split huggingface dataset:
A study of fine and coarse retino‐fugal axons terminating in the geniculate C laminae and in the medial interlaminar nucleus of the mink
Authors: Guillery R. W. , Oberdorfer M. D. 
Published: January 2005

AbstractWhen retino‐geniculate axons of mink are labelled with 3H proline, the laminar structure of the dorsal lateral geniculate nucleus is seen to resemble that previously described in the cat. Layers A, C and C2 receive a crossed input and layers A1 and C1 receive an uncrossed input. The parvocellular layer C2 is relatively thicker in the mink than it is in the cat, and studies of retino‐geniculate fiber degeneration show that it receives fine caliber retinal afferents, whereas layers A and C receive mainly coarse afferents. The medial interlaminar nucleus receives two quite distinct crossed retino‐geniculate inputs. There is a coarse fibered component, which is continuous with lamina C, and a fine fibered component, continuous ventrolaterally with lamina C2 and extending rostro‐dorsally as a narrow streak along the margin of the nucleus lateralis posterior. The uncrossed afferents to lamina A1 are as coarse as the crossed axons to layers A and C. The uncrossed afferents to lamina C1 are somewhat finer, but are not as fine as the afferents to lamina C2. There are not many uncrossed fibers to the medial interlaminar nucleus and the distinction between coarse and fine components is not shown clearly. However, it is possible to recognize fine axons extending towards the margin of the nucleus lateralis posterior. We interpret these results as showing that there are two functionally distinct inputs to the medial interlaminar nucleus, and that the rest of the lateral geniculate nucleus may be divided into two distinct systems: A magnocellular, receiving coarse axons, and a parvocellular, receiving fine axons. The magnocellular system has one “ipsilateral” layer (A1) flanked by two “contralateral” layers (A and the dorsal part of C), while the parvocellular system similarly consists of a single “ipsilateral” layer (C1) flanked by two “contralateral” layers (C2 and the ventral part of C).
A brainstem atlas of catecholaminergic neurons and serotonergic perikarya in a pygmy primate (Cebuella pygmaea)
Authors: Jacobowitz David M. , MacLean Paul D. 
Published: January 2005

AbstractThe present paper provides a brainsem atlas showing the disribution of catecholaminergic cells and processes, as well as serotonergic perikarya, in the pygmy marmoset. The findings revealed by the Falck and Hillarp histofluorescence method conform in essential details to what has been described in rodents. These and other comparative data indicate that a prototypical pattern of organization of aminergic systems has been retained in the evolution of primates.
The distribution of substance P immunoreactive fibers in the rat central nervous system
Authors: Cuello A. Claudio , Kanazawa Ichiro 
Published: January 2005

AbstractA detailed account of the distribution of immunoreactive substance P‐containing structures in the rat central nervous system is presented, from results obtained by applying an indirect immunofluorescent technique. High densities of substance P‐containing nerve terminals were present in sensory nuclei and other non‐sensory structures such as thalamus, hypothalamus and extrapyramidal system. Substance P‐reactive neuron cell bodies were present in spinal root ganglia, nucleus habenulae medialis, nucleus interpeduncularis, caudoputamen and globus pallidus. Most of the neocortex and the cerebellar cortices had no substance P‐positive elements. The results support the hypothesis that substance P may be a widespread neurotransmitter in the central nervous system.
Depth‐marking in the proximal negative response in the pigeon retina
Authors: Hayes B. P. , Holden A. L. 
Published: January 2005

AbstractThe depth distribution of proximal negativity in the pigeon retina was investigated with a dye‐marking technique. Proximal negativity is recorded in three stages as the retina is penetrated. At the near the surface (level 1) the response is small and phasic: next, during “level 2” the on response exceeds the off response in amplitude: then, at “level 3” the off response exceeds the on response in amplitude. The dye marks were located in thin light microscope sections; they were about 20 μ in diameter, and were associated with larger areas of tissue damage. Level of 3 dye marks were centred at the middle of the inner plexiform layer, and level 2 dye‐marks were distributed more proximally. The amplitude maxima of the PNR are close to the middle of the inner plexiform layer, and are separated by approximately 15 μm.
Golgi studies on Purkinje cell development in the frog during spontaneous metamorphosis I. General pattern of development
Authors: Uray Náandor J. , Gona Amos G. 
Published: January 2005

AbstractThe development of Purkinje cells was studied in the bullfrog from prometamorphic tadpoles to 10‐week‐old postmetamorphic froglets by the Golgi‐Kopsch method. In this species, the rate of Purkinje cell development is unusually slow and proceeds in two waves. The first wave of development begins prior to the establishment of the external granular layer (EGL), and proceeds slowly for two to three months during the formation of the EGL; then accelerating as metamorphosis is being completed, the cells reach near‐adult dimensions a month later. Even prior to the formation of the EGL these cells are already present in the stage of dendritic orientation and flattening which, however, varies from the norm. The second wave of Purkinje cell development begins during metamorphosis and proceeds at a more rapid pace until two months after metamorphosis, at which time they appear to have reached adult dimensions. In these cells the development of the apical dendrite does not always coincide with the stellate stage but may proceed directly to the stage of dendritic orientation and flattening which, in accordance with the norm, is towards the pia and in the sagittal plane.Many variations are present in the dendritic trees and orientation of the dendritic branches of Purkinje cells throughout their development. These variations are similar to those seen in mammals, however, since the frog cerebellum consists of a simple plate, they cannot be attributed to a Cartesian transformation of dendrites to accommodate the curvatures of a folial pattern. Similarly, since these morphological variations occur in the course of normal development they cannot be attributed to a reaction to, or recovery from, injury during development.
The effects of dark rearing on the development of the visual cortex of the rat
Authors: Borges S. , Berry M. 
Published: January 2005

AbstractThe effects of dark rearing on the development of the visual cortex has been studied in Wistar rats, as have the effects of subsequent light exposure on recovery. Five groups of animals were used: (1) light exposed until 30‐40 days post partum (dpp) (2) dark reared until 30‐40 dpp (3) dark reared until 80‐120 dpp (4) dark reared to 21 dpp, then light exposed until 40 dpp (5) light exposed to 21 dpp and then dark reared until 40 dpp. Golgi‐Cox impregnations of layer IV stellate cell dendritic fields were analysed and total neuronal and glial counts were also done within layer IV of the primary visual cortex.Normal visual stellate cell dendritic fields were radially organised, with the highest dendritic density being recorded below the soma. In short term visually deprived animals and in those exposed only for 21 dpp and then reared in light until 40 dpp the radial distribution of dendrites was maintained but the peak density shifted to above the soma. In all other experimental groups this abnormal polarisation was still present but not as marked. Measurement of branching indices suggested that these field changes resulted from increased branching and growth in the superficial domain and not from the reorientation of dendrites. Differential glial counts revealed a significantly higher number of microglia in dark reared animals than in controls. Neuronal numbers were not affected.
Sequence of neuron origin in experimentally distorted brains of chick embryos
Authors: Wilson Doris B. 
Published: January 2005

AbstractThe effects of proliferative disorders on the time and sequence of neuron origin in the optic tectum were studied in chick embryos in which “overgrowth” had been experimentally induced. Sixteen normal and fourteen abnormal embryos ranging in age from four through ten days of incubation were each given a single dose of thymidine[3H]. Comparisons were then made between 16‐day normal and abnormal chick embryos with respect to the distribution of unlabeled and labeled neurons in the dorsolateral regions of the optic tectum midway between its rostral and caudal boundaries. In the normal and abnormal tecta layers I‐IV were generated on days 3–6. Differences occurred in the generation of the remaining layers. In the normal embryos layers V‐VII arose on days 5–8 and layers VIII‐XV on days 4–7; in the abnormal embryos layers V‐VII originated on days 6–8 and layers VIII‐XV on days 5–8. In addition to the delay in onset of neuron origin, the abnormal tectum also showed distorted lamination, particularly in layers VIII‐XV which constitute the superficial regions of the stratum griseum and fibrosum superficiale. Despite the defect in time and sequence of neuron origin, the rostroventrolateral to caudodorsomedial gradient of maturity characteristic of the normal tecta was not disturbed in the abnormal tecta.
Retrograde responses of developing lateral motor column neurons
Authors: Decker Robert S. 
Published: January 2005

AbstractRemoving the right hind limb of Rana pipiens larvae at different stages during development initiates diverse responses within lateral motor column (LMC) neurons whose axons have entered the limb and are forming neuromuscular junctions. Severing the hind limb at stage V inhibits the future differentiation of LMC neurons and, ultimately, 95% of the presumably injured cells degenerate. Ultrastructural observations indicate that the affected neurons become pyknotic, but display little evidence of lysosomal involvement. However, a quite different reaction is encountered when limb ablation is delayed to stage X. At this stage, LMC neurons rapidly disclose an intense retrograde response, which includes the genesis of numerous secondary lysosomes in degenerating cells. If, however, limb removal is postponed until stage XV or XX then a classic chromatolysis can be recognized in axotomized neurons. The intensity of the chromatolysis appears to be inversely related to the age of the neurons. This investigation tends to support the premise that differentiating LMC neurons pass through three crucial stages in their development which can be identified following axotomy.
Projections to the visual cortex in the golden hamster
Authors: Dürsteler M. R. , Blakemore Colin , Garey L. J. 
Published: January 2005

AbstractRetrograde transport of horseradish peroxidase (HRP) was used to determine the origins of afferent connexions to the visual cortex (areas 17, 18a and 18b) in the hamster. The distribution of neurons projecting to the visual cortex from other cortical areas, from the thalamus and from the brainstem was studied using a computer technique for three‐dimensional reconstruction.There is a topographically organized projection from the dorsal lateral geniculate nucleus to area 17, but probably to no other of the areas studied. The lateral posterior nucleus of the thalamus (LP) projects to area 18a and weakly to area 17. The lateral nucleus (L) projects to area 18b and also, probably, weakly to area 17. The cortical projections from LP and L are also organized topographically but relatively grossly compared with the geniculo‐cortical pathway.There are reciprocal association projections between area 17 and areas 18a and 18b. Area 18a projects weakly to 18b. The main commissural connexions of the posterior neocortex are between the area 17/18a boundary zones in the two hemispheres, with little between the bodies of area 17.Labelled neurons were found bilaterally in the locus coeruleus, more ipsilaterally than contralaterally, after multiple injections into the visual cortex: single, small injections sometimes resulted in the labelling of a single cell body in the locus coeruleus.
Unmyelinated axons in the trigeminal motor root of human and cat
Authors: Young Ronald F. , Stevens Richard 
Published: January 2005

AbstractThe fiber composition of the human and cat trigeminal “motor roots” were studied utilizing the electron microscope. Twelve to twenty percent of fibers in the human trigeminal motor root are unmyelinated whereas 9–15% are unmyelinated in the cat. The only previous examination of the fiber composition of the peripheral trigeminal motor nerve utilized the light microscope and indicated that less than 5% of fibers were unmyelinated in cat. No study of the fiber composition of the motor nerve root is available. The present results are similar to those recently obtained by others for spinal ventral roots. The function of unmyelinated fibers in the trigeminal “motor root” is unknown, however indirect evidence, both laboratory and clinical, suggests a potential sensory function for them. The findings question seriously the concept that the functional separation of the nervous system into motor and sensory systems has anatomical correlates in the spinal and cranial nerve roots. The results relate directly to our conceptualization of the nervous system and also to the design of methods for the treatment of intractable pain.
The organization of afferents to the cerebellar cortex in the cat: Projections from the deep cerebellar nuclei
Authors: Gould Barbara Brown 
Published: January 2005

AbstractThe topography of the cerebellar nucleo‐cortical projection was investigated in the cat by experiments employing the horseradish peroxidase (HRP) technique or by combined HRP‐autoradiographic methods. The results of the HRP studies extend previous findings showing that neurons in the deep nuclei project to the cerebellar cortex in an orderly way. Thus, it appears that the cortex of the vermis‐proper receives projections fron neurons located predominately in the fastigial nucleus. Intermediate and lateral zones of mid‐vermal cerebellar cortex are projected on by neurons located in the interposed and dentate nuclei. Crus II receives input from neurons located predominately in the dentate nucleus, while the paramedian lobule is projected on by neurons located in a large postero‐dorsal sector of the interposed nucleus and in a smaller medial strip of the dentate nucleus. Neurons in the ventral part of the dentate nucleus and the lateral part of the interposed nucleus send fibers to the paraflocculus. The nucleo‐cortical pathway to the flocculus and nodulus arises largely from a population of neurons located in a ventral region stretching from the medial border of the dentate nucleus to the lateral border of the fastigial nucleus.The results of experiments using the combined HRP‐autoradiographic method show that clusters of neurons in the deep cerebellar nuclei project back to the cerebellar cortical areas from which they receive input, establishing a fairly precise feedback loop between the cerebellar cortex and deep nuclei.
A study of the synaptogenesis in the cerebellar cortex through chronic treatment and immunocytochemistry of β‐Bungarotoxin
Authors: Hirokawa Nobutaka 
Published: January 2005

AbstractThe mechanism of synaptogenesis between dendritic spines of Purkinje cells and parallel fibers in the chicken cerebellum was studied through chronic treatment and immunocytochemistry of β‐Bungarotoxin (β‐BT). Attention was directed to the question of whether the presynaptic specializations (presynaptic vesicular grids composed of presynaptic dense projections and associated vesicles) of the parallel fibers can differentiate in the absence of the Purkinje cells.Normal cerebella from 18‐day and 21‐day chick embryos, incubated with β‐BT and reacted with HRP‐labeled anti β‐BT guinea pig IgG, showed a positive HRP reaction on Purkinje cells but not on external and internal granule cells. Thus, in chicken cerebellum, β‐BT primarily affects Purkinje cells.When β‐BT was applied to chick embryos at 3‐day intervals, beginning on the 4th day of incubation, the cerebella were markedly reduced in size and most of the Purkinje cells as well as the nerve fibers in the white matter disappeared between the 18th and the 21st day of incubation. Folia of the 21st day experimental cerebella were irregular in shape and the area of the midsagittal section was one fourth that of the controls. In the 21st day cerebella treated with β‐BT, the majority of Purkinje cells disappear. However, the external granule cells remain intact and showed the usual mitotic activity. The majority of the inner granule cells were normal. Some of the parallel fibers, which display presynaptic vesicular grids, established synaptic contact with stellate cells and the dendritic spines of the few Purkinje cells that survived the treatment. However, vast areas of the molecular layer contained neither dendrites of Purkinje cells, nor parallel fibers displaying presynaptic vesicular grids devoid of their postsynaptic counterpart. In such areas, the molecular layer consisted of parallel fibers of uniform diameter, some of which contained accumulations of vesicles, but displaying no presynaptic dense projections. This suggests that parallel fibers may not be able to completely develop the presynaptic vesicular grids in the absence of their target cells.
Two modes of cutaneous reinnervation following peripheral nerve injury
Authors: Devor M. , Schonfeld D. , Seltzer Z. , Wall P. D. 
Published: January 2005

AbstractThe return of sensation to the foot following sciatic nerve crush injury was analyzed behaviorally and electrophysiologically in the rat. Functional recovery begins within four days. Its early phase is accounted for by expansion of the functional distribution of intact neighboring fibers of the saphenous n. It occurs even if the sciatic n. is ligated, and it disappears with section of the saphenous n. Accompanying this functional expansion we began to encounter in electrophysiological recordings from the saphenous n., fibers with unusually large receptive fields (RF's) extending onto the plantar surface of the foot, well beyond their limits in intact rats. All of the expanded RF's were high threshold mechanoreceptors. On about the twentieth day after crushing, the regenerating sciatic n. began to make a functional contribution. This was seen by return of sensation to zones not invaded by the saphenous n. and by the onset of sensation in rats in which the saphenous n. had previously been ligated. With return of the sciatic n. the expanded distribution of the saphenous n. went back to its original boundaries. Correspondingly, we could no longer find expanded saphenous n. RF's. We conclude that cutaneous reinnervation begins with the collateral expansion of high threshold afferents from intact neighboring nerves. This alien innervation is later replaced upon regeneration of the original nerve.
Projections from cortex to tectum in the tree shrew, Tupaia glis
Authors: Casseday J. H. , Jones D. R. , Diamond I. T. 
Published: January 2005

AbstractSensory neocortex of the tree shrew was divided into three main areas: the visual field, the auditory field, and the somatic field which includes motor cortex. Cortical cells which project to the tectum were identified by injecting HRP into superficial or deep layers of the superior colliculus and into various parts of the inferior colliculus. The main result is that these descending projections are well organized according to their origin in the three main sensory fields of the cortex. (1) Auditory field: labeled cells are found only in the core or auditory koniocortex, after injections of HRP in the pericentral area of the inferior colliculus; labeled cells are found in auditory belt areas after injections in posterior parts of the intermediate and deep layers of the superior colliculus, adjacent to the inferior colliculus. (2) Somatic field: labeled cells are also found in the somatic field after injections in the intermediate and deep layers of the superior colliculus, so that auditory and somatic fields probably overlap to some extent. The results do not exclude the possibility that somatic koniocortex has an exclusive target in the intermediate or deep layers of the superior colliculus. (3) Visual field: labeled cells are found only in the core or striate cortex after injections in the superficial layers of the superior colliculus. Labeled cells are found in the visual belt after injections in the rostral parts of the intermediate layers of the superior colliculus. When these results are related to ascending sensory pathways a picture emerges of a series of circuits or loops which interconnect parallel sensory pathways. These loops eventually reach the deep layers of the superior colliculus which of course have indirect access to motor neurons.
Development of abnormal recrossing retinotectal projections after superior colliculus lesions in newborn Syrian hamsters
Authors: So Kwok‐Fai 
Published: January 2005

AbstractThe development of the retinal projections to the roof of the midbrain was studied in Syrian hamsters after right superior colliculus (SC) lesions on the day of birth, using both autoradiographic and degeneration techniques. The dead tissue resulting from the heat lesion is not completely removed until the eighth day after birth. Normally the midline of the SC is defined by a pia‐lined fissure separating the left and right colliculi, but in the animals with early unilateral lesions, the pia at the midline is damaged. When it regrows, together with vascular and other meningeal tissues, it forms a flat tissue bridge across the midline as early as two days after the lesion.When the axons from the left eye reach the right SC, they encounter the dead tissue and separate into two bundles. One bundle courses over the surface of the dead tissue and one grows underneath it. It is not until the third to fourth day that axons in the dorsal bundle cross the midline, via the tissue bridge, to terminate anomalously in the medial wall of the left SC. When the quantity of such recrossing axons is small, they overlap extensively with the optic tract fibers from the other (right) eye which normally have innervated the entire SC by day 3. However, it appears that as the density of the recrossing axons increases they displace the axons originating in the other eye from the medial wall of the left SC. Thus, eventually fibers from both eyes terminate in the left SC, occupying separate territories with little, if any, overlap.Axons in the ventral bundle begin to innervate the deep layers of the right SC on day 2. These axons were never observed to recross the midline.These results indicate that mechanical guidance and axonal segregation dependent on relative densities are two processes that govern the development of retinotectal projections after early SC lesions in hamsters.