bluuebunny/crossref_metadata_2025_split huggingface dataset:
Age differences in the morphology of posterior tibial nerves of mice
Authors: Samorajski T. 
Published: January 2005

AbstractLight microscopic examination of posterior tibial nerves of C57BL/10 female mice at 3, 8 and 26 months of age revealed an age‐related decrease in the total number of myelinated fibers per nerve with a fairly uniform loss across all caliber of fibers present. However, the size of the individual nerves increased with age as did also mean axon diameter of individual fibers and the proportion of connective tissue between fibers in the older nerves. Ultrastructural comparisons revealed an increase in mean axone circumference of myelinated fibers between 3 and 8 months and, of unmyelinated fibers between 8 and 26 months. Also, there was a significant decrease in mitochondrial concentration in myelinated fibers between 8 and 26 months of age. There was no change in blood vessels, myelin sheath thickness, concentration of unmyelinated fibers per nerve, and in the concentration of filaments and tubules in myelinated and unmyelinated axons in relation to increasing age.
Behavioral, electrophysiological and morphological studies of binocular competition in the development of the geniculo–corticalpathways of cats
Authors: Sherman S. Murray , Guillery R. W. , Kaas J. H. , Sanderson K. J. 
Published: January 2005

AbstractCats were raised with one eye sutured and with a lesion in the retina of the other eye. In these cats the competitive interaction between the pathways that go to the cortex from each eye was tested by studying the behavioral capacities, the electrophysiological responses and the morphological appearance of the geniculo‐cortical pathways.Two parts of the visual system in which no binocular competition was possible were defined. One is the segment that receives inputs from the monocular crescent of the visual field, which has been called the monocular segment. The other is the artificial monocular segment created by the limited lesion of the non‐deprived retina, and this has been called the critical segment.In the binocular segments of the visual pathways we found, as have others, that: (1) behaviorally, cats do not respond to objects viewed by the deprived eye; (2) cortical cells tend not to respond to stimulation of the deprived eye; and (3) geniculate cells innervated by the deprived eye grow less than the normally innervated cells. However, we found that the deprived eye is more effective in driving neurons in contralateral than in ipsilateral cortex.Within the monocular and the critical segments of the visual pathways we found: (1) that cats orient appropriately to visual stimulation of the deprived eye, (2) that cortical cells respond to visual stimulation of the deprived eye, and (3) that geniculate cells grow more than the deprived cells in the binocular segment of the nucleus. Thus, the deleterious effects of visual deprivation of one eye can, to some extent, be prevented by damage to the other.
A multisomatic axon in the central nervous system of the leech
Authors: Frank Eric , Jansen Jan K. S. , Rinvik Eric 
Published: January 2005

AbstractThere is one particularly large axon in the medial bundle of the nerve cord of the leech. It extends along the entire length of the cord and is connected to a single cell body in each ganglion. The cell bodies in adjacent ganglia are tightly electrically coupled, and dye injected into one cell body can diffuse along the axon and into the cell body of the next ganglion. If the nerve cord is cut between two ganglia, neither end of the axon degenerates. Repair of the axon appears to occur by end‐to‐end fusion.
Deafferentation slows the growth of specific dendrites of identified giant interneurons
Authors: Murphey R. K. , Mendenhall Barbara , Palka J. , Edwards J. S. 
Published: January 2005

AbstractThe effect deafferentation has on the morphology of giant interneurons was studied in the abdominal nervous system of crickets (Acheta domesticus). The morphology of four uniquely identified giant interneurons was examined by iontophoresing cobalt chloride into the neurons of interest. A major source of afferents for these interneurons consists of mechanoreceptors located on paired abdominal sensory appendages—the cerci. Partial deafferentation of the giant interneurons was obtained by pinching off the cercus at hatching and maintaining the specimen in this deprived condition until adulthood.The interneurons of three groups of animals were examined; control specimeans which were not treated surgically, unilaterally treated specimens which has single cercus removed and bilaterlly treated specimens which had both cerci removed. Two types of morphological changes were detected. (1) Chronic removal of a cercus was correlated with a reduction in length of dendrites ipsilateral to the ablated cercus; however the general form of the dendritic branching pattern remained constant and recognizable. Two dendrites of a single neuron could be influenced independently if they were innervated by separate cerci. Thus deprivation did not have a generalized effect on growth of a neuron, rather it specifically influenced the dendrites deprived of afferents. (2) it was also observed that the projection of cercal sensory fibers in specimens reared with a single cercus differed from normal in that scattered fibers cross the midline in regions of the ganglion where none usually exist. It is suggested that modifications in the response properties of these deprived neurons are based on these two changes in morphology.
The basilar pontine gray of the opossum: A correlated light and electron microscopic analysis
Authors: Mihailoff Gregory A. , King James S. 
Published: January 2005

AbstractNeurons within the basilar pontine gray (BPG) of the American opossum can be subdivided into four major nuclei which are named medial, lateral, ventral and peripeduncular in accordance with previous studies. In addition, several smaller subnuclei, such as the median and dorsolateral cell groups, are present, as well as two longitudinal columns of neurons within the ventral nucleus. Neurons in the BPG range in size from 9 to 35 μ and appear randomly distributed so that none of the subdivisions contains exclusively nerve cells of the same perikaryal dimension. Projection neurons as shown in Golgi impregnations have a variable dendritic pattern; those in peripeduncular zones exhibit dendrites closely applied to the surface of the cerebral peduncle, whereas those in other regions generally have a radial type of arrangement. Certain projection neurons can be distinguished on the basis of their dendritic surface, which bears either claw‐like protrusions or stalked appendages. Smaller nerve cells measuring less than 18 μ may be intrinsic neurons, since axon‐like processes arise from their dendrites and course for some distance near the parent cell before becoming thin and beaded. Ultrastructural observations show profiles of neurons comparable in size to those seen in Golgi impregnations and suggest at least four classes of presynaptic profiles. One category ranges in size from 2 to 8 μ, contains round vesicles (average diameter 450 Å) and characteristically forms multiple asymmetric syaptic contacts with several small postsyaptic profiles, some of which appear to be the dendritic claws mentioned above. The other three types of axon terminals measure less that 2 μ in their greatest dimension and are distinguished by their synaptic vesicles; one group containing round vesicles with an average diameter of 380 Å, a second group exhibiting larger round vesicles with an average diameter of 500 Å and a third group containing flattened or eliptical vesicles. Transection of the superior cerebellar peduncle produces early filamentous and later electron dense degenerative chages in some, but not all, of the larger types of presynaptic profiles. Subsequent to large motor‐sensory cortex ablations both filamentous and dark degenerating profiles are simultaneously observed at all survival times. In one case with a cortical lesion restricted to the motor‐sensory cortex, mainly dark degenerating terminals are apparent in the ipsilateral pontine gray, whereas in a lesion confined to the visual cortex only filamentous degeneration was observed. It is suggested, therefore, that some of the dark degenerating profiles represent the terminals of collaterals of corticospinal axons and the filamentous boutons are terminal expansions of direct corticopontine fibers.
The role of supraspinal input in embryonic motility: A re‐examination in the chick
Authors: Oppenheim Ronald W. 
Published: January 2005

AbstractThe present experiments represent an attempt to further clarify the role of the brain in embryonic motility and behavior. By making high chronic cervical transections (“gaps”) at early prefuntional stages of incubation (i.e., 40–50 hours) and studying the subsequent emergence of motility in the chick it has been possible to determine that supraspinal input is not functional until about the tenth day of incubation. Acute cervical transections done at either 4–5 or 8–9 days lead to the same conclusion.At ten days and thereafter chronic cervical transection results in a modification of the temporal pattern (rhythm) of motility without affecting the frequency of activity. Qualitatively the movements of spinal embryos are indistinguishable from controls up to 16–17 days. At that time there are detectable differences in the character of spontaneous movements, in reflex responsivity and in hatching behavior; spinal embroyos are not able to initiate the coordinated Type III movements necessary for escape from the shell.Injection of strychinine into chronic cervical and control embryos at 10 days and at 16–17 days indicates that certain aspects of the typical strychnine response are lost following removal of brain input to the spinal cord.Finally, chronic thoracic gaps result in a clear modification of cyclic motility at 7‐days of incubation, whereas chronic cervical gaps have no effect at this age. These data suggest that propriospinal integration is present at least several days prior to the onset of supraspinal input in the chick spinal cord.
Projections from the nucleus and tractus solitarius in the cat
Authors: Cottle Merva K. Warren , Calaresu Franco R. 
Published: January 2005

AbstractAfter lesions in the nucleus of the tractus solitarius (NTS) in cats and kittens, the termination of degenerating fibers was localized using the Nauta and the Fink‐Heimer techniques. The distribution of degenerating fibers was compared with that seen after lesions of the dorsal nucleus of the vagus (DNV) and after section of the ninth and tenth cranial nerves. The projection from the NTS is to the nucleus ambiguus (A), the other divisions of the NTS including the medial NTS and the ventrolateral NTS, the DNV, the medial reticular formation ventral to the NTS (probably the paramedian reticular nucleus), the nucleus intercalatus (INC), and the intermediate nucleus (INT). The probable functional significance of projections from the NTS to these medullary nuclei is discussed in relation to pathways of cardiovascular reflexes. Of particular note is the projection to the INT which may be part of a descending pathway to spinal cardiovascular neurons in the intermediolateral horn.
Ascending projections from marginal zone (Lamina I) neurons of the spinal dorsal horn
Authors: Kumazawa T. , Perl E. R. , Burgess P. R. , Whitehorn D. 
Published: January 2005

AbstractA search for postsynaptic elements, excited only by slowly‐conducting afferent fibers (Aδ and C), was made by recording from the dorsal horn of cats and monkeys with dye‐filled microelectrodes. Units identified by afferent responsiveness were tested for antidromic invasion by electrical stimulation of the opposite ventrolateral funiculus at the midcervical level. Recording points were marked by iontophoretically passing dye from the recording electrode and subsequently located in histologically‐prepared material. Evidence for antidromic excitation from spinal cord stimulation was found for five of 21 units in cat and 13 of 31 neurons in monkey. Antidromically excited cells were located within the distribution of the large posteromarginal neurons of the dorsal marginal zone (Lamina I). Although recording loci for a number of the elements studied were unequivocally located within Laminae II (substantia gelatinosa) or III, none could be antidromically excited. All antidromically driven units received a powerful input from Aδ primary afferent units and upon testing with natural stimuli responded specifically to stimuli of the type initiating activity either for high threshold mechanoreceptors or for low threshold thermoreceptors. It is concluded that some Lamina I neurons form part of an ascending projection which follows the spinal pathway of the spinothalamic tract and thereby contribute to the mechanical nociceptive and thermoreceptive features of this pathway. The absence of antidromic response is argued to be uncertain and evidence for a lack of projection is open to alternative explanation.
Mode of distribution of aminergic fibers in the cerebellar cortex of the chicken
Authors: Mugnaini Enrico , Dahl Anne‐Lise 
Published: January 2005

AbstractThe cerebellar cortex of adult hens contains a dense plexus of thin varicose nerve fibers which display a formaldehyde‐induced green fluorescence. This plexus is not distributed at random in the cortical layers. Within the granular layer the plexus forms a netlike pattern. The fiber branches, which have numerous varicosities, are predominantly oriented in the traverse plane of the folium. In the molecular layer the fluorescent plexus shows some variations in the convex, flat and concave portions of the folia. Many of the fluorescent branches are oriented parallel to the course of the folium. They arise from a T‐division of radially oriented axons resembling parallel fibers in Golgi sections.The meshes of the fluorescent plexus in the granular layer measure 10–60 μ. In the molecular layer (top of the folia) there are about 30 fluorescent fibers per 100 μ2.The fluorescent fibers originate from the locus coeruleus and form a rostral and a caudal bundle in the cerebellar peduncle.The mode of distribution of the fluorescent fibers in the cortical layers seems to depend on the organization of the innervated tissue. Light microscopy suggests that the aminergic fibers innervate more than one class of cerebellar neurons.
An electron microscope study of the retino‐receptive layers of the pigeon optic tectum
Authors: Hayes B. P. , Webster K. E. 
Published: January 2005

AbstractThe fine structure of the superficial layer of the optic tectum of the pigeon, Columba livia, has been examined both in normal animals and after unilateral eye removal. Optic afferent terminals distributed throughout sublaminae IIa‐f, are principally concentrated at three depths in the retinoreceptive zone. At first, degeneration of optic afferent terminals occurs as swelling of synaptic vesicles and accumulation of neurofilaments and later as dense degeneration. There appear to be several classes of optic afferent terminals in the retino‐receptive zone, as would be expected from most previous studies of the avian tectum. The non‐optic components of the neuropil, which include glomerular and pleomorphic vesicle terminals, and the synaptic interrelationships between optic and non‐optic components are described. Optic afferent terminals mainly make synaptic contact with the branches of radial dendrites but also, in sublaminae IIb and IIc, with the dendrites of non‐radial cells. In sublamina IIc afferent terminals synapse onto the horizontal presynaptic dendrites of spindle cells and triplet synaptic arrays including optic afferent terminals, horizontal dendrites and radial dendrite profiles and radial dendrite profiles are found. This optic projection to non‐radial elements in IIb, c is discussed in relation to light microscope and electrophysiological studies.
The projections of different morphological types of ganglion cells in the cat retina
Authors: Kelly James P. , Gilbert Charles D. 
Published: January 2005

AbstractThe central projections of the retinal ganglion cells of the cat were examined using the method of retrograde transport of horseradish peroxidase. Peroxidase was injected into the lateral geniculate nucleus and into the superior colliculus by means of a recording micropipette. After injections at retinotopically homologous points in these two structures in separate animals, the patterns of retinal ganglion cell labeling were compared. We found that there were three populations of ganglion cells: small cells, that projected predominantly to the superior colliculus; medium‐sized cells, that projected predominantly to the lateral geniculate nucleus; and large cells, some of which projected to both structures, and some of which projected to the lateral geniculate nucleus alone. Quantitative studies showed that the average size of the cells in each population was smaller at the area centralis than in the periphery. These results could be directly related to physiological classifications of retinal ganglion cells proposed by other authors.
The effects of early tectal lesions on development in the retinal ganglion cell layer of chick embryos
Authors: Hughes W. Franklin , Lavelle A. 
Published: January 2005

AbstractThe possibility that the arrival of retinal ganglion cell axons in their efferent target field could influence the subsequent progress of cytomorphogenesis in the ganglion cells was tested by destroying all or portions of the primordial optic tectum at four or five days of incubation. The lesions were made essentially prior to the outgrowth of axons from the eye. Complete bilateral or unilateral destruction of the primordial tectal field did not detectably alter the morphogenesis of the inner retina or of the ganglion cells until 11 days of incubation. After this time, extensive loss of ganglion cells occurred within the retinas contralateral to the projection field that were destroyed. The cytology of this degeneration is described as seen with the light and electron microscope. After smaller lesions involving the anterior or posterior half‐tectum on one side, however, variable results occurred both in tectal development and in the retinal locus of ganglion cell degeneration observed in flat mount preparations. Many partial or punctate lesions, in fact, resulted in no detectable loss of cells from the ganglion cell layer. These results are discussed in regard to specification and possible regulatory capabilities of the tectum. Cell death in normal retinas, not previously reported in the chick, is also considered in relation to the experimental results.
Cell growth in the lateral geniculate nucleus of kittens following the opening or closing of one eye
Authors: Wan Yoke Kum , Cragg Brian 
Published: January 2005

AbstractClosing one eye of kittens at 23 days after birth resulted in paler Nissl staining of the deprived cells in the lateral geniculate nucleus (LGN) that was detectable two days later. Differences between the two sides of the brain in mean cell area increased to a peak in binocular lamina A at 4–6 days after eyelid suture, and then fell to a trough at eight days before rising progressively to a higher level at 31 days. In lamina A1 the peak and trough were later.Opening one eye of kittens after 23 days of binocular closure from birth resulted in more intense Nissl staining of the stimulated cells in the LGN that was detectable four days later. The stimulated cells grew faster than the cells connected to the eye that remained closed, and this differential growth reached a peak at 17 days in binocular lamina A and at 21 days in lamina A1 before falling to a trough at 26–31 days. These results are compared with the time course of anabolic changes that have been measured in other neurons during stimulation.The coefficient of variation of cell size was computed and found to be slightly decreased for deprived cells and increased for stimulated cells. This suggests that larger cells change their sizes proportionately more than smaller cells. The cells were measured in frozen sections without shrinkage, and the areas are at least 25% larger than those reported previously after paraffin or celloidin embedding.
Auditory cortex in the grey squirrel: Tonotopic organization and architectonic fields
Authors: Merzenich Michael M. , Kaas Jon H. , Roth G. Linn 
Published: January 2005

AbstractThe representation of sound frequency within auditory cortex has been investigated with microelectrode mapping techniques in grey squirrels. The cyto‐ and myeloarchitecture of mapped cortical surfaces was examined and related to recording data. Among the results were the following: (1) A primary field can be defined on the basis of both physiological and anatomical criteria. It occupies nearly half of the auditory responsive area in the squirrel. (2) The best frequency of neurons is relatively constant within vertical penetrations across the active middle cortical layer(s) of the primary field. (3) Best frequencies ranging from 190 Hz to 33 kHz were defined within the primary field. There is an orderly representation of sound frequency (and of the cochlear partition) within the field, with lowest frequencies represented rostrally and highest frequencies represented caudally. A given frequency band (sector of the basilar partition) is represented across a roughly straight belt of cortex of approximately constant width that crosses the mediol‐lateral dimension of the primary field. There is a proportionately greater surface area of representation of higher frequency octaves within the field. (4) In different squirrels, there is significant variation in the location of the primary field and in the orientation of the frequency representation within it. (5) Auditory responses were recorded within at least two secondary auditory fields. The total region responsive to tonal stimulation approximately corresponded with the anterior temporal field, as defined by Kaas et al. ('72).
The olivocerebellar projection in the cat as studied with the method of retrograde axonal transport of horseradish peroxidase. II. The projection to the uvula
Authors: Brodal A. 
Published: January 2005

AbstractFollowing injections of small quantities of horseradish peroxidase (HRP) suspension in the uvula of the cat, the distribution of labeled cells in the inferior olive has been mapped. The findings confirm the conclusion made on the basis of studies of retrograde cell loss in the olive following ablations of the uvula (Brodal, '40b) that two small olivary subdivisions, the nucleus β and the dorsomedial cell column project heavily to the uvula. In addition the HRP‐study shows that the uvula receives a smaller number of fibers from two circumscribed areas of the contralateral medial accessory olive. These areas appear to project to the lateralmost parts of the uvula (fig. 4). The findings thus support the presence of a longitudinal zonal subdivision in the uvula. Labeled cells are found in the nucleus β and the dorsomedial cell column also following injections of the fastigial nucleus and to a lesser degree of lobulus VII of the vermis (Hoddevik et al., '76). This may be due to collateral branching of olivary efferents. There is some evidence for a topographical correlation between dorsal and ventral parts of the uvula and rostral and caudal parts, respectively, of the nucleus β and the dorsomedial cell column. This may be related to functional differences between the two parts of the uvula.