bluuebunny/crossref_metadata_2025_split huggingface dataset:
Axonal guidance of developing optic nerves in the frog. II. Electrophysiological studies of the projection from transplanted eye primordia
Authors: Constantine‐Paton M. , Capranica Robert R. 
Published: January 2005

AbstractWhen a primordial eye was transplanted to the ear position in Rana pipiens embryos, the optic nerve from the ectopic eye penetrated the medulla and invariably established a tract in the dorsolateral white matter of the ipsilateral spinal cord. In response to visual stimulation of the transplanted eye, extracellular recordings with metal microelectrodes were conducted within the spinal cords of post‐metamorphic animals.Visual activity in the spinal cord could only be recorded in those experimental animals in which the transplanted optic nerve succeeded in penetrating the medulla. This activity was frequently encountered in the gray matter of the cord well below the dorsolateral position of the transplanted optic tract. The discharge characteristics and adaptation properties of the visual activity were often similar to that of optic nerve fibers from normal eyes suggesting that axons or their collaterals branch off from the transplanted optic tract and arborize within the spinal cord. However, occassionally stimulation of the transplanted eye evoked activity with adaptation and/or response characteristics unlike that of normal optic nerve fibers.Visual activity in the spinal cords of our experimental animals could be driven by moving small dark objects within circumscribed regions in the visual field of the transplanted eye. However we were unable to find any evidence of a systematic mapping of the transplanted retina within these abnormally penetrated spinal cords.
Areal changes in mouse cortical barrels following vibrissal damage at different postnatal ages
Authors: Woolsey Thomas A. , Wann Janice R. 
Published: January 2005

AbstractThe normal cytoarchitectonic pattern of barrels in layer IV of mouse SmI face cortex is altered by early damage to the mystacial vibrissae (Van der Loos and Woolsey, '73). In the present study, the middle row of vibrissae (row‐C) on one side of the face in groups of Swiss mice was cauterized on the day of birth (postnatal day [PND] – 1) or on PND's – 2, 3, 4, 5, 7, 10, 12, 15, 20 and 30; littermates in each group served as controls. All animals were perfused on PND‐60 and the brains sectioned parallel to SmI layer IV. For each specimen, the posteromedial barrel subfields (PMBSF) of the two hemispheres were reconstructed with a camera lucida and the cross‐sectional areas of individual barrels measured using a small computer.The findings are: (1) The hemispheres ipsilateral to the vibrissal damage are quantitatively indistinguishable from the littermate controls indicating that the ipsilateral hemispheres in lesioned animals can serve as controls for observations of the type reported in this paper. (2) There are no consistent differences in the cross‐sectional areas of the PMBSF's as a whole in the hemispheres ipsi‐ and contralateral to the peripheral damage, suggesting that there is no net loss of cortex as a result of the lesions. (3) The contralateral row‐C barrels are reduced in size. Expressed as a percentage of normal values; row‐C is reduced to 17% for animals lesioned on PND‐1, 16% on PND‐2, 38% on PND‐3, 52% on PND‐4, and 79% on PND‐5; on PND‐7 and later the cross‐sectional areas of row‐C barrels are normal. This implies that the barrel field of the SmI face cortex becomes progressively refractory to the effects of peripheral damage during the first postnatal week and in the period prior to PND‐6, an intact periphery is necessary for normal cortical development. (4) In every case, the decreased cross‐sectional area of row‐C is accompanied by precisely increased cross‐sectional areas of the barrels in adjacent rows‐B and D. In the case of the restricted peripheral damage which we produced, there is a “compensation” in the contralateral hemisphere, which can be correlated with patterns of the specific thalamocortical projections.
A study of afferent input to the inferior olivary complex in the rat by retrograde axonal transport of horseradish peroxidase
Authors: Brown James T. , Chan‐Palay Victoria , Palay Sanford L. 
Published: January 2005

AbstractUnder direct visualization, minute amounts of horseradish peroxidase were injected by controlled air pressure through glass micropipettes into the inferior olive of the albino rat. Well localized unilateral injections were obtained, without damage to other brainstem areas or spread into the adjacent reticular formation. After 24 to 36 hours, the entire brain and spinal cord were examined by light microscopy for labelled neurons supplying afferents to the inferior olive.With few exceptions, labelled somata rostral to the inferior olive were found ipsilateral to the injection site, the greatest number occurring in the subparafascicular nucleus and central gray substance around the caudal third ventricle, in the N. of Forel's field, Nn. of Darkschewitsch and Cajal, and adjacent reticular formation, and in the Edinger‐Westphal nucleus. Labelled cells were also noted in the sensorimotor cortex, red nucleus, peri‐aqueductal gray and all subdivisions of the pretectal complex. Caudal to the olive, labelled neurons were located primarily on the contralateral side in the lateral reticular nucleus, dorsal column nuclei and nucleus proprius of the spinal cord. At the level of the olive, numerous labelled cells occurred bilaterally, but mainly contralateral to the injection site in the lateral and interpositus nuclei of the cerebellum. A smaller number were seen in the N. prepositus hypoglossi and in the medial and spinal subdivisions of the vestibular complex ipsilaterally, in the N. spinal tract of V contralaterally, and in the gigantocellular reticular nucleus bilaterally. A few neurons in the N. raphe obscurus were also labelled. No positive cells were found in the caudate nucleus, globus pallidus, locus coeruleus, or medial cerebellar nucleus.The results are compared and contrasted, region by region, with previous studies of afferent olivary pathways and, where possible, correlations are made with physiologic data.
Neurons in layer I of the developing occipital cortex of the rat
Authors: Bradford R. , Parnavels J. G. , Lieberman A. R. 
Published: January 2005

AbstractThis paper describes the neurons in layer I of the rat occipital cortex, and traces postnatal changes in the numbers and morphology of the different cell types therein. Golgi‐Cox and Nissl material from adults and from 0.5, 2, 4, 6, 8, 10, 11,12, 13, 14, 15, 16, 18, 20, 24, 28 and 35 day‐old rats, was utilized. Horizontal, vertical and classical non‐pyramidal cells and cells without axons were recognized.Horizontal cells included foetal horizontal cells (Retzius‐Cajal cells) and persisting horizontal cells. The former were fully differentiated and numerous at birth and were bipolar, with dendrite and axon extending from opposite poles, and fine ascending (verticle) branches. Some such cells possessed two axons. Almost all degenerated and disappeared over the first two to three postnatal weeks. An analogy with Rohon‐Beard cells is drawn and it is suggested that these cells receive an early input which is subsquently withdrawn and/or concentrated cells receive an early input which is subsequently withdrawn and/or concentrated on cells in deeper layers. There is no evidence of transformation of foetal to persisting horizontal cells, which are not numerous and most commonly give rise to two dendrites from opposite perikaryal poles.Vertical cells, with spinous dendrites and descending axons, differentiate and reach adult numbers by the end of the first postnatal week. Classical non‐pyramidal cells include spinous and spine‐free varieties, resemble those in deeper layer, and are mature by the end of the third postnatal week. In the upper stratum of layer I are small number of cells without axons.
Growth of the adult goldfish eye. III. Source of the new retinal cells
Authors: Johns Pamela Raymond 
Published: January 2005

AbstractThe manner in which new cells are added to the growing adult goldfish retina was examined using 3H‐thymidine radioutography. Cell proliferation leading to the formation of neurons is restricted to the retinal margin at the ora terminalis. New retina is added in concentric rings, with slightly more growth dorsonasally. The rate of cell addition is variable, averaging 12,000 cells/ day. These new cells account for about 20% of the total increase in retinal area; the remaining 80% is due to hypertrophy, or expansin, of the retina. In contrast to all of the other retinal cells, the rods do not appear to participate in the retinal expansion. This hypothesized immobility of the rods would create a shearing strain between the retinal layers resulting in a shift in their position relative to the other cells. Were they to maintain synaptic contacts with the same horizontal and bipolar cells, the rod axons would have to be elongated peripherally or the post‐synaptic cell dendrites displaced centrally. Since neurons with this morphology have not been found in the goldfish retina, these observations suggest that the rods must be changing their synaptic connections as the retina grows.
Incorporation of 3H‐fucose into nerve and glial cells: Assessment by electron microscopic autoradiography
Authors: Reisert I. , Wagner H.‐J. , Pilgrim Ch. 
Published: January 2005

AbstractIncorporation of 3H‐fucose into hypothalamic tissue of rats was studied between ten minutes and seven days after intraventricular injection. In EM autoradiographs grain densities over perikarya of neurons, astro‐ and oligodendroglia, and neuropil were evaluated. Grain densities were consistently higher over both types of glial cells as compared to neurons. The glia/neuron ratio was especially high after short experimental intervals and declined with increasing time intervals. Concomitantly there was an increase of grain density over the neuropil. The discussion concentrates on the methodical aspects which have to be considered in interpreting the autoradiographic data. It is concluded that both astroglia and oligodendroglia exhibit a considerably higher synthesis rate of glycoproteins per unit volume than nerve cells. The implications of the results for the interpretation of biochemical data on glycoprotein metabolism of brain tissue are discussed.
The locus and cytoarchitecture of the projection areas of the olfactory bulb in Macaca mulatta
Authors: Turner Blair H. , Gupta Kailash C. , Mishkin Mortimer 
Published: January 2005

AbstractA study was made of the normal and experimental anatomy of the olfactory system of the young adult male rhesus monkey. The cytoarchitecture of the central olfactory areas was studies with cell and fiber stains, while the extent and pattern of the projections of the olfactory bulb were determined by the Fink‐Heimer and autoradiographic methods. The brain of one animal that had sustained damage to the olfactory bulb two days prior to sacrifice, and of one that had a transection of the olfactory tract ten days prior to sacrifice, were processed with the Fink‐Heimer technique. The first of these and four others received injections of 3H‐proline or 3H‐leucine into the olfactory bulb, and following a survival period of 18 hours, or 2, 4, 12, or 20 days, their brains were proceessed with the autoradiographic technique. The results were the same for both experimenal methods and for all survivalperiods.The projections of the olfactory bulb in this microsmatic animal are entirely ipsilateral. All of the structures that receive direct olfactory afferents have a laminar organization except for the anterior olfactory necleus, which is laminated only in its anterior, peduncular, portion. While the olfactory bulb projects to the entire extent and depth of the naterior olfactory nucleus, the olfactory afferents of all other structures are confined to layer IA of the plexiform layer. These structures are: all divisions of the olfactory tubercle; the frontal and temporal prepiriform cortices; the oral, medial, and dorsal divisions of the superficial amygdaloid nucleus; and polar and anterior entorhinal cortex. The rhesus monkey does not have a recognizable accessory olfactory bulb, and no projectiosns were seen to the taenia ecta or the ventral division of the superficial amygdaloid nucleus. With these exceptions, the projections of the olfactory bulb in the rhesus monkey are similar to those in macrosmatic species.
Some claustro‐cortical connections in the cat and baboon as studied by retrograde horseradish persocidase transport
Authors: Riche D. , Lanoir J. 
Published: January 2005

Abstract1. The mammalian Claustrun (Cl) is a convergent multisensory structure of unknown function, and disputed ontogenetic origin. Its cortical projections, hitherto unknown, have been studied in cat and baboon by means of the horseradish peroxidase (HRP) technique. HRP was injected into the gyrus proreus (frontal eye field) of cats, and separately into the frontal eye fields, visual areas, and motor‐premotor areas of the baboon cortex.2. Differential retrograde transport to the Cl was demonstrated, such that in the cat the ipsilateral dorsal Cl was shown to be the principal rogin of claustroproreate projections. In the baboon, the whole Cl projects onto area 8, while only the posteroventral part of the nucleus sends efferents to the visual cortes. The projection to the motor and premotor areas is present, but does not seem to be “essential.”3. Discussion of the physiological literature, togetehr with anatomical evidence of reciprocal cortico‐claustral projections to closely similar regions of the Cl lead to the suggestion that the Cl is concerned with the integration of messages subserving visually‐directed movements. Some other functional implications are also discussed.
Projections of auditory cortex upon the thalamus and Midbrain in the owl monkey
Authors: Fitzpatrick Kathleen A. , Imig Thomas J. 
Published: January 2005

AbstractTwo tonotopically organized cortical fields, the primary (AI) and the rostral (R) fields, comprise the core of auditory cortex in the owl monkey. Injections of tritiated proline were made into each of these fields to determine their efferent projections using autoradiographic methods. Both AI and R project to the principal and magnocellular divisions of the medial geniculate body. In addition, R projects to the posterior part of the dorsal division of the medial geniculate. AI sends axons to the dorsomedial region and laminated portion of the central nucleus of the inferior colliculus. Labeling in the central nucleus following AI injections appears as a band of silver grains oriented parallel to isofrequency contours. Axons from R terminate in the dorsomedial region of the central nucleus of the inferior colliculus and in the ppericentral and external nuclei of the inferior colliculus. In addition, the rostral field projects to a small area of the medial pulvinar just anterior to the brachium of the superior colliculus.
A contribution to the electron microscopic morphometric analysis of peripheral nerve
Authors: Bronson Roderick T. , Bishop Yvonne , Hedley‐Whyte E. Tessa 
Published: January 2005

AbstractSeveral aspects of data collection and analyses of peripheral nerve experiments employing light and electron microscopic morphometric techniques have not been adequately discussed in the literature. From statistical tests performed on nerve data, it was found that light compared with electron microscopic morphometry underestimates the number of small fibers. An optimum sampling strategy must take into account a potential bias toward small fibers introduced by measuring fibers from electronmicrographs. It must also take into account a potential bias introduced by the non‐random distribution of nerve fibers of different sizes in nerves. These biases are offset by sampling a large enough number of fibers from large enough area electron micrographs. A method is presented for analysing peripheral nerve data using the nested analysis of variance. This requires first dividing the usual bimodal nerve fiber distribution into component normally distributed parts. The number of fibers in the two portions of a bimodal distribution must be considered in data analysis. Knowledge of the variances of parameters to be studied in any particular nerve is necessary for optimum sampling strategies.
The representation of the body surface in somatosensory area I of the grey squirrel
Authors: Sur M. , Nelson R. J. , Kaas J. H. 
Published: January 2005

AbstractMicroelectrode mapping methods were used to determine the organization of primary somatosensory cortex, SmI, in grey squirrels. A systematic representation of the contralateral body surface was found within somatic koniocortex. This primary representation differs from maps of SmI in other mammals in at least two significant ways. The first way in which SmI of squirrels differs from the organization reproted for other mammals is that SmI of squirrels contains a double representation of the hand and parts of the forearm. The glabrous skin of the digits is represented twice in a mirror image fashion joined at the finger tips. The hairy skin of the digits, wrist, and parts of the forearm are also represented twice, once on each side of the joined representations of the glabrous skin. A second unique feature of SmI squirrels is that there is a small region of cortex completely surrounded by SmI that was unresponsive to light cutaneous stimuli under our recording conditions. This unresponsive zone is easily identified in brain sections by architectonic features that deviate from sensory koniocortex and approach motor cortex. A third significant finding was that the back is rostral to the belly in the representation of the trunk in SmI of squirrels. This is the reverse of the orientation reported elsewhere for SmI of mammals, but corresponds to the orientation of the trunk representation in Area 3b of owl monkey (Kaas et al., '76; Merzenich et al., '78). This similarity supports and earlier contention that the representation of the body in Area 3b of primates is the homolog of SmI in other mammals (Merzenich et al., '78).
The optic nerve of the brush‐tailed possum, Trichosurus vulpecula: Fibre diameter spectrum and conduction latency groups
Authors: Freeman Brian , Watson Charles R. R. 
Published: January 2005

AbstractThe principal findings of this report on the morphology and electrophysiology of the possum optic nerve are:
There are about 230,000 fibres in the optic nerve. This fibre count, based on electron microscopy, is slightly less than a previously reported estimate of the total number of ganglion cells in the possum retina.
The majority (> 98%) of the fibres of the optic nerve are myelinated axons of retinal ganglion cells. The diameters of these fibres range from 0.4–4.6 μm (axon diameter range: 0.3–3.8 μm) and the frequency distribution of the fibre diameters (and axon diameters) is positively skewed and unimodal.
The antidromic compound action potential of the possum optic nerve shows four negative peaks following stimulation of the optic chiasm. These peaks are associated with four conduction latency groups of fibres which have been designated t1, t2, t3 and t4 in order of increasing conduction latency.
The mean peak conduction velocities of the fibres in the conduction latency groups are 13.1 ms−1 (t1), 8.1 ms−1 (t2), 5.7 ms−1 (t3) and 3.1 ms−1 (t4).
There is no direct correlation between the frequency distribution of fibre (or axon) diameters as measured by electron microscopy of transverse sections of fixed optic nerve and the conduction latency groups.
The reconstruction of the possum optic nerve compound action potential on the basis of either axon or fibre diameter frequency distribution does not provide an acceptable, indirect correlation between the morphology and the electrophysiology of this optic nerve.
Electron microscopic analysis of postnatal histogenesis in the cerebellar cortex of staggerer mutant mice
Authors: Landis Dennis M. D. , Sidman Richard L. 
Published: January 2005

AbstractPostnatal development of the cerebellar cortex has been compared in staggerer mutant and unaffected littermate mice. From postnatal day 3 to about day 21 the external granular layer in staggerer mice is decreased in thickness and area, and the number of postmitotic granule cell neurons is reduced. Those granule cells that are generated seem to differentiate normally, with the remarkable exception that they from only primitive junctions with Purkinje cell dendritic shafts. These specialized junctions are not superseded by the normal parallel fiber: Purkinje spine synapses and disappear by the third week. Purkinje cell somata and dendrites are smaller than normal at all stages examined. The dendrites are not confined to the sagittal plane as in the normal and, unique among mutant or other animals described to date, they exhibit virtually no branchlet spines. All other cortical synaptic relations of granule and Purkinje cells, including climbing fiber: Purkinje spine synapses, appear qualitatively normal. However, by 28 days virtually all staggerer granule cells have degenerated. While the primary genetic defect remains unknown, we postulate that the morphological abnormalities may be attributable to a block in the normal developmental relationship between granule cells and Purkinje cells. The small cell size and failure to form branchlet spines suggest that the Purkinje cell abnormality may be closer to the primary effect of the mutant gene than the more flagrant hypoplasia and degeneration of granule cell neurons.
Electron microscopic demonstration of a supraependymal cluster of neuronal cells and processes in the hamster third ventricle
Authors: Card J. P. , Mitchell Jerald A. 
Published: January 2005

AbstractA supraependymal cluster of neuronal cells and processes consistently present on the floor of the hamster third ventricle was identified and characterized by means of correlative scanning (SEM) and transmission (TEM) electron microscopy. SEM revealed each cluster to be ovoid with the majority of its surface covered by dome‐shaped protrusions and fine beaded fibers. A number of processes traveling individually or in groups also entered or exited from the cluster at its base. As these processes passed over the ventricular surface, they contributed to an extensive network on the floor and ventral aspect of the ventricular wall. Some processes terminated on the ependymal surface in bulbous endings while others penetrated the ependyma. The neuronal nature of these clusters and their associated processes was confirmed at the TEM level. The dome‐shaped protrusions visible on the surface of the cluster in SEM corresponded to apical surfaces of neurons confined to the peripheral aspect of a core of loosely arranged processes. These cells exhibited a prominent nucleolus, stacks of rough endoplasmic reticulum (RER), polyribosomes, Golgi cisternae, mitochondria and microtubules (MT) and gave rise to dendritic processes which extended into the core. These dendrites gave off branches at acute angles and contained polyribosomes, single cisternae of RER and evenly spaced MT. Other profiles of processes within the core shared these characteristics, suggesting that they also were branches of the peripheral cells. Axons present within the core and on the cluster's surface exhibited vesicle‐filled varicosities which frquently established synaptic contact with the peripheral cells and their processes. The presence of an intraventricular cluster of neurons which potentially communicates with centers extrinsic to the ventricle may have important implications in the hypothesized role of cerebrospinal fluid and tanycytic ependyma in the neuroendocrine regulation of anterior pituitary function.