bluuebunny/crossref_metadata_2025_split huggingface dataset:
The development of the septal region in the rat. I. Neurogenesis examined with 3H‐thymidine autoradiography
Authors: Bayer Shirley A. 
Published: January 2005

AbstractNeurogenesis in the rat septal region was examined with3H‐thymidine autoradiography. The rats in the prenatal groups were the offspring of pregnant females given two injections of 3H‐thymidine on consecutive days in an overlapping series: embryonic day (E) 13 + E14, E14 + E15, … E21 + E22. The rats in the postnatal groups were injected in a nonoverlapping series: the day of birth and postnatal day (P) 1, P2 + P3, P3 + P4. On 60 days of age, the percentage of labelled cells and the proportion of cells added during each day of formation were determined at several anatomical levels within the midline nuclear group (nucleus of the diagonal band, medial and triangular septal nuclei), the lateral septal nucleus, and the ventrolateral nuclear group (nucleus accumbens, bed nuclei of the stria terminalis and the anterior commissure). The neurons within each nuclear group form in significantly different waves, those of the midline group forming between E13‐E17, the lateral septal nucleus between E15‐E19, the bed nuclei of the stria terminalis and anterior commissure between E14‐E18, the nucleus accumbens between E17‐P2. All nuclei and nuclear groups show characteristic gradients of formation. Both the midline nuclear group and the bed nucleus of the stria terminalis (including the commissural bed nucleus) have their earliest forming neurons lying near the crossing of the anterior commissure; younger neurons are located both rostrally and caudally with the youngest neurons lying in the most rostral extension of the diagonal band nucleus and the strial bed nucleus. The lateral septal nucleus forms along a strong mediolateral gradient throughout its length after neurogenesis is almost complete in the midline nuclear group. Throughout the length of the nucleus accumbens, the oldest neurons are located ventrally while progressively younger cells are found dorsally beneath the inferior horn of the lateral ventricle.
Vibrissae representation in subcortical trigeminal centers of the neonatal rat
Authors: Belford Gary R. , Killackey Herbert P. 
Published: January 2005

AbstractIn the neonatal rat differential activity levels of the metabolic enzyme succinic dehydrogenase (SDH) reveal intricately detailed segmentation in the neuropil of the spinal and principal trigeminal nuclei of the brainstem and in the ventrobasal complex of the thalamus. The segmentation occurs in the portions of these nuclei that electrophysiological evidence has indicated to be related to the mystacial vibrissae and sinus hairs on the face of the rat. Indeed, the pattern of segmentation in each nucleus replicates the topographic distribution of the vibrissae and sinus hairs. Further, within the spinal trigeminal nucleus, there appear to be two distinct representations of the vibrissae, one in the subnucleus caudalis and a second in the subnucleus interpolaris. Examination of these patterns of segmentation indicates that the large mystacial vibrissae and sinus hairs on the face of the young rat are somatotopically represented three times within the trigeminal complex, as straight cylinders of neuropil, and once in the ventrobasal complex, as curved cylinders of neuropil.Neonatal vibrissae damage leads to an aberrant organization of the segmentation in the spinal trigeminal nucleus and the ventrobasal complex. In the spinal trigeminal nucleus, the SDH activity in areas associated with damaged vibrissae is of a lower than normal density, and patterns are indistinct. However, rows of clusters associated with the adjacent normal vibrissae are apparent and appear to be enlarged. In the ventrobasal complex, vibrissae damage results in bands of normal density SDH activity where rows of segmented clusters would normally be present. Comparison of these data to the cortical data in the previous paper (Killackey and Belford, '79) indicates that cortical and nuclear structures can have aspects of their development controlled by similar mechanisms.
Ascending projections to the inferior colliculus
Authors: Adams Joe C. 
Published: January 2005

AbstractCells that send ascending projections to the inferior colliculus were identified following injections of horseradish peroxidase into the colliculus. Labelled cells were found in all subcollicular auditory nuclei. Virtually all cells of the ipsilateral ventral nucleus of the lateral lemniscus and medial superior olive appear to project to the colliculus. Very few cells in these nuclei were labelled on the contralateral side. Heavy labelling on the contralateral side was found in the dorsal nucleus of the lateral lemniscus and cochlear nucleus, with less labelling being found ipsilaterally in these nuclei. The lateral superior olive was approximately evenly labelled on the two sides, with about half the cells from each side projecting to each colliculus. Cells in all periolivary cell groups were labelled, with most being found adjecent to the medial superior olive. An effort was made to identify individual cell types that were labelled and some 24 cell types were identified. In the cochlear nucleus there were marked differences between cell types in the extent of their labelling. Topographic projections matched previously described tonotopic organization of the colliculus and all major subcollicular nuclei except the ventral nucleus of the lateral lemniscus. A description of the cells in the nucleus is provided.
The parasagittal zonation within the olivocerebellar projection. II. Climbing fiber distribution in the intermediate and hemispheric parts of cat cerebellum
Authors: Groenewegen H. J. , Voogd J. , Freedman S. L. 
Published: January 2005

AbstractOlivocerebellar fibers from different subnuclei of the rostral inferior olive decussate in the brain stem and terminate as climbing fibers in one or two narrow, longitudinally arranged zones of the cerebellar cortex. These fibers issue collaterals to the central cerebellar nucleus that receives its afferents from the same cortical zone in which the parent fibers terminate. The rostral medial accessory olive projects to zone C2 and sends collaterals to the posterior interposed nucleus. A differentiation can be made between the rostral pole of this subnucleus which projects primarily to the paraflocculus and the ansiform lobule. More caudal areas connect with zone C2 in the anterior lobe and the paramedian lobule. The dorsomedial cell column projects to a lateral zone (zone A2) of lobule IX and more rostrolateral portions of the medial accessory olive supply a still more lateral zone of this lobule. The rostral half of the dorsal accessory olive sends fibers to zones C1 and C3. These fibers issue collaterals to the anterior interposed nucleus. A distinction can be made between the ventrolateral dorsal accessory olive, projecting to lobules II‐IV and the ventral folia of the paramedian lobule and the dorsomedial portion of the rostral dorsal accessory olive that connects with lobules V, VI and the dorsal folia of the paramedian lobule. The most rostral part of the dorsal accessory olive provides more fibers into zone C3, more caudally located cells distribute primarily to zone C1. The rostral principal olive is connected with zone D and collateral terminations are found in the lateral cerebellar nucleus. In the paraflocculus the D zone can be divided into subzones D1 and D2. This study further substantiates the similarity in the organization of corticonuclear and olivocerebellar connections. The results are in general agreement with other recent investigations on the olivocerebellar system (Armstrong et al., '74; Brodal et al., '75; Brodal, '76; Hoddevik et al., '76; Brodal and Walberg, '77a,b; Oscarsson, '73, '76; Oscarsson and Sjölund, '77a,b).
Influences of thyroxine on cell proliferation in the retina of the clawed frog at different ages
Authors: Beach D. H. , Jacobson Marcus 
Published: January 2005

AbstractThe change in spatial pattern of retinal cell production that occurs after midlarvae stages in Xenopus is shown to occur because of a greater proliferative response to thyroxine in the ventral than in the dorsal margin of the retina. The asymmetry of retinal cell production is not caused by a dorsoventral difference in the duration of the mitotic cycle. It is concluded that the asymmetry is due to differences in the number of proliferative cells in different parts of the retinal margin.
An autoradiographic study of the efferent connections of the lateral hypothalamic area in the rat
Authors: Saper C. B. , Swanson L. W. , Cowan W. M. 
Published: January 2005

AbstractThe efferent connections of the lateral hypothalamic area (LHA) have been analyzed in a series of 30 rat brains with injections of 3H‐amino acids into different parts of the area and the surrounding regions. Our findings indicate that all parts of the LHA contribute ascending and descending fibers to the medial forebrain bundle, and also project medially to certain of the adjoining hypothalamic nuclei. All levels of the LHA appear to send some fibers to a continuous group of structures that extends from the medial septal‐diagonal band complex rostrally, through the lateral preoptic and lateral hypothalamic areas to the mammillary complex and the ventral tegmental area caudally. In addition, it is evident that cells at different levels within the LHA may have differential projections. Thus, the anterior and lateral parts of the LHA also appear to project substantially to the anterior hypothalamic area, the ventromedial and dorsomedial hypothalamic nuclei, the parataenial and paraventricular nuclei of the thalamus, and the medial part of the lateral habenular nucleus. Similarly, cells in the tuberal and posterior parts of the LHA project to the central gray, the longest projections from the posterior region reaching as far caudally as the central tegmental field, the parabrachial nucleus, the locus coeruleus, and the superior central and dorsal nuclei of the raphe. Viewed as a whole, the LHA is therefore well‐suited to integrate inputs from the limbic system and brainstem and to relay them on the one hand to the medial zone of the hypothalamus and on the other to virtually every structure closely associated with the medical forebrain bundle and to the nuclei of origin of the major ascending monoaminergic systems.
Anomalous ipsilateral retinotectal projections in syrian hamsters with early lesions: Topography and functional capacity
Authors: Finlay Barbara L. , Wilson Karen G. , Schneider Gerald E. 
Published: January 2005

AbstractRetinotectal topography, response properties of neurons in superior colliculus, and visual orienting behavior were studied in hamsters whose superior colliculi were innervated by one or the other of two types of anomalous ipsilateral projections.For the first type, an abnormally large uncrossed projection was created by monocular enucleation on the day of birth. This projection extended over the superficial part of the rostral half of the colliculus. The upper visual field was represented medially, and the lower visual field laterally, which corresponds to a normal projection. The rostrocaudal axis was disordered, but showed a slight tendency for nasal visual field to be represented rostrally and temporal field caudally; this tendency corresponds to an inversion of the normal ipsilateral projection, fitting instead the pattern of a contralateral projection.For the second type of anomalous ipsilateral projection, an abnormal intertectal decussation of optic tract fibers was created by neonatal ablation of the superficial layers of one superior colliculus and removal of the ipsilateral eye (Schneider, '73). Retinotectal topography observed in this recrossing projection was predominantly mirror‐symmetric to the normal contralateral projection; however, some distortions in retinotopic order were observed, including misplaced fields and local inversions of the mirror‐symmetric topography, and distortions of local magnification factor. Response properties of single units found medially in the left colliculus were similar to those found in normal colliculus. Units found more laterally were underresponsive, showing response decrements with repeated stimulation which is abnormal for units in the superficial gray, and many had abnormally large receptive fields. This physiological pattern was reflected in the pattern of errors made in visual orienting to small targets.It was concluded that polarity cues exist in the tectum sufficient to order the terminals of the retinotectal projection independent of the direction of fiber arrival or order in the optic tract as it enters the tectum. In addition, the functional competence of the abnormal recrossing retinotectal projection has been demonstrated by both electrophysiological and behavioral methods.
Correlation of variability in structure with variability in synaptic connections of an identified interneuron in locusts
Authors: Pearson Keir G. , Goodman Corey S. 
Published: January 2005

AbstractNumerous reports have described variability in the morphology of identified neurons; none, however, has previously reported variability in the pattern of synaptic connection. In this report we describe variability in the synaptic connections of an identified interneuron in two species of locust (Locusta migratoria and Schistocerca gregaria) and show that this variability is associated with a large variation in the structure of the interneuron.The morphology of the descending contralateral movement detector (DCMD) interneuron was determined in the thoracic ganglia by intracellularly staining with cobalt sulphide followed by Timm's silver‐intensification of whole‐mount preparations. The striking characteristic of the structure of this interneuron was the variability from animal to animal. This was so large we were unable to describe a “normal” structure. However, five distinct branches of the interneuron were identified in the metathoracic ganglion. In each animal the structure of DCMD could be described by specifying which of these branches were present. One or more of these branches were usually absent, and there were differences in the probability of any particular branch being absent.Corresponding to the variation in the structure of DCMD there was a large variation in the synaptic connections made by this interneuron. DCMD can make monosynaptic connections to the fast extensor tibiae (FETi) motoneuron, fast and intermediate flexor tibiae motoneurons, and depressor and elevator flight motoneurons. These functional connections were not found in all animals. The absence of an EPSP from DCMD in FETi was associated with either the complete absence of a ventral branch or with the absence of an identifiable process of a ventral branch, and the absence of an EPSP from DCMD in flight motoneurons was associated with the absence of the dorsal branch. The connection of each of these specific branches of DCMD to FETi and flight motoneurons respectively was confirmed by double staining the motoneurons and DCMD in cases which had the functional connection. The implication of our findings is that the connections of interneurons in invertebrates may, in some cases, be far more variable than is generally believed at the present time.
The brainstem projection of the vestibular nerve in the cat
Authors: Korte Gary E. 
Published: January 2005

AbstractThe projection of the vestibular nerve to the brainstem of the cat was re‐examined with silver degeneration methods after complete lesions of the vestibular ganglion. Whereas previous investigations emphasize that only parts of the major vestibular nuclei are innervated by the vestibular nerve, the present investigation shows that only the dorsal division of the lateral vestibular nucleus is uninnervated. Thus, the terminal field of the vestibular nerve extends to the cytoarchitectonic boundaries of the superior, medial, descending, and the ventral division of the lateral vestibular nuclei. Vestibular nerve fibers were also traced to discrete terminal fields in the reticular formation lateral to the abducens nucleus and in the rostral, lateral parts of the accessory cuneate nucleus. These observations indicate a more widespread distribution of vestibular nerve fibers in the brainstem of the cat than previously believed.
Remodelling of optic nerve myelin sheaths and axons during metamorphosis in Xenopus laevis
Authors: Cullen Michael J. , Def. Webster Henry 
Published: January 2005

AbstractWhole mounts and transverse sections of Xenopus optic nerves were examined with the light and electron microscopes before, during, and after metamorphosis. In stage 52‐58 tadpoles, almost all myelin sheaths were circular in transverse sections. Early in metamorphosis (stages 60‐61) large redundant myelin loops surrounded many large axons in central regions of the nerve. The loops subsequently were broken down into ovoids and lamellar segments that remained mostly within oligodendrocytes. These myelin changes were not observed in the chiasm or next to the eye. They were not associated with significant axonal degeneration and were no longer apparent in optic nerves of young frogs. Xenopus optic nerves also became shorter during metalmorphosis. We therefore suggest that myelin sheaths with redundant loops which degenerate and disappear are being remodelled as the nerve decreases in length.
Effects of early vibrissae damage on neurons in the ventrobasal (VB) thalamus of the mouse
Authors: Woolsey Thomas A. , Anderson James R. , Wann Janice R. , Stanfield Brent B. 
Published: January 2005

AbstractWe have examined the effects of vibrissal damage on the structure of the VB of the murine thalamus. The findings are: (1) The barreloid (Van der Loos, '76) pattern can be recognized in the normal adult mouse thalamus. On the basis of size, the population of VB neurons in bimodal, the larger neurons–presumed to be thalamocortical relay cells (TCR's)–outnumbering the smaller neurons–presumed to be thalamic interneurons–by 3:1. (2) Damage to vibrissa Row‐C on PND‐1 (postnatal day‐1) results in an altered cytoarchitectonic pattern in the barreloids in the contralateral VB, which is qualitatively similar to the altered pattern of barrels in the cortex. The middle row of large barreloids is affected, which is anatomical evidence for the pattern of somatotopic organization in mouse VB. (3) The time course of alterations in thalamic architecture is different than that for the barrels in the cortex. The barreloids show progressively less severe alteration with increasing age at the time the peripheral lesions are made, like the barrels in the cortex. However, the thalamus of animals lesioned on PND‐4 or later appears normal, while the cortex of animals lesioned on PND‐4 and PND‐5 still can be altered. Thus, in the thalamus, as in the cortex, there is a “critical period” during which vibrissal damage alters cytoarchitectonic patterns, but the thalamic “critical period” ends about two days before that in the cortex. (4) Measurements of TCR's in the barreloids did not reveal any statistically significant size differences between neurons in different sectors of the experimental thalami. In particular, we could find no evidence for increases of TCR size in barreloids bordering affected Row‐C barreloid zones or for reductions in TCR size in barreloids in the C‐zones. (5) In Timm's stained normal material there is a parallel development of Timm's positive staining in the thalamus and in the cortex. Barreloid related Timm's positive staining appears by PND‐4, while Timm's staining in the cortical barrel hollows appears later by PND‐8. Of particular interest is the difference in the appearance of the barrels with the Timm's stain in the PND‐8 animals and in adults. In the former, the barrel hollows are filled with granular precipitate, while in the latter they are practically devoid of Timm's precipitate, suggesting a major changeover in the staining pattern (and possibly the functional attributes) of the terminal fields of the thalamocortical afferents in postnatal development.
Electron microscopic studies of serially sectioned cat spinal α‐motoneurons. IV. Motoneurons innervating slow‐twitch (type s) units of the soleus muscle
Authors: Conradi S. , Kellerth J‐O. , Berthold C‐H. , Hammarberg C. 
Published: January 2005

AbstractTwo intracellularly stained cat α‐motoneurons of the soleus‐S type (Burke et al., '74) were studied ultrastructurally. The architecture and synaptology of the cell body and proximal parts of the dendrites were analyzed from a long series of sonsecutive sections (Conradi et al., '79). Only few of the dendrites had a base diameter exceeding 10 μm. The proportion of the membrane surface of the cell body and dendrites covered by boutons was 40‐45% and 50‐80%, respectively. Out of this, 15‐20% was constituted by S‐boutons and 70‐75% by F‐boutons in both regions. In contrast to the situation in the gastrocnemius FR‐neurons (Kellerth et al., '79) the large boutons of the C‐type showed no clustering around the dendritic roots and were absent on the axon hillock. In addition, the M‐boutons of dorsal root origin were more sparse on the proximal parts on the dendrites of the soleus‐S neurons.
The developmental morphology of Torpedo marmorata: Electric organ—electrogenic phase
Authors: Fox Geoffrey Q. , Richardson Guy P. 
Published: January 2005

AbstractThe electrogenic developmental phase of the electric organ of Torpedo marmorata begins at 40 mm of embryo length and is characterized by a horizontal flattening of the vertically orientated myotubes. The first sign of this process is a rounding up of the ventral poles of the myotubes and a disassembly of the myofibrils located therein. Occurring concomitantly with this is a migration of the nuclei to the cell center which results in a horizontal plane of nuclei. Filament bundles are then found within the ventral cytoplasm often projecting upwards from the ventral plasma membrane. The filaments of the bundles are dimensionally similar to the myofilaments of muscle and it is suggested that the bundles play a role in cellular transformation.In contrast the dorsal pole of the cell appears to be integrated “passively” with the final cell shape as no morphological correlates of a retraction process have been found. A canalicular system, composed of a complex network of irregular tubules and vacuoles, appears just below the dorsal plasma membrane characterizing this region of the cell. A mononucleated satellite cell population lies in close proximity to the dorsal surface of the differentiating cell and fusion between the two cell types occurs throughout development.Cell shape transformation is complete by 55 mm of embryo length and the intercolumnar nerves begin to invade the interelectrocyte space. The ingrowing neurites preferentially course along the ventral electrocyte surface establishing junctions similar to motor endplates.