bluuebunny/crossref_metadata_2025_split huggingface dataset:
A cytoarchitectonic study of the diencephalon of the tegu lizard, Tupinambis nigropunctatus
Authors: Cruce J. A. F. 
Published: May 2005

AbstractNuclei in the hypothalamus, ventral thalamus, dorsal thalamus, epithalamus, and pretectum are described and named in the Tegu lizard, Tupinambis nigropunctatus. Many of the nineteen cell groups in the hypothalamus contain small, round cells located near the ventricle; two groups of magnocellular elements, nucleus supraopticus and nucleus paraventricularis, are also present. Of the eight cell groups in the ventral thalamus, nucleus geniculatus lateralis pars ventralis, located medial to the optic tract, is the most conspicuous. Six nuclei are described in the dorsal thalamus; nucleus rotundus and nucleus dorsolateralis anterior are very prominent. The epithalamus consists of medial and lateral habenular nuclei. In the pretectum, seven nuclear groups are recognized.
Axon numbers and distribution, myelin thickness, and the reconstruction of the compound action potential in the optic nerve of the teleost: Eugerres plumieri
Authors: Tapp R. L. 
Published: May 2005

AbstractThe optic nerve of Eugerres plumieri contains about 200,000 fibers. Only 2.5% are non‐myelinated and the majority of these are grouped into a single tract. The axon diameters of the myelinated fibres range between 0.2 μ and 7.6 μ (mode, 0.7 μ) and the external fibre diameters range between 0.26 μ and 9.2 μ (mode, 1.0 μ). The relationship between myelin thickness, t, and axon diameter, d, shows a mode at about 0.25 (d/D = 0.67) but the distribution is wide and skewed positively. The compound action potential can be reconstructed arithmetically from morphological data and correlates well with electrophysiological recordings.
Synaptogenesis in the outgrowth of rat cerebellum in organized culture
Authors: Privat A. , Drian M. J. , Mandon P. 
Published: May 2005

AbstractSynaptogenesis was studied in the outgrowth of newborn rat cerebellum, cultivated in vitro.As soon as the second day after explatation, membrane specializations were found between axons and dendrites. Synaptic vesicles were, at this age, absent from the vicinity of these contacts.Four days after explantation, axodendritic as well as axosomatic synapses were present, with usually a paucity of synaptic vesicles. Contacts without vesicles were again numerous at this age.Six to eight days after explanation, some of these synapses showed already a mature appearance, and characters reminiscent of those of their in vivo counterpart. For instance, typical “en passant” synapses of parallel fibers were found. Contacts without vesicles were rare at this age. A sequence of events leading to the onset of mature synapses is suggested.Finally, an attempt was made to correlate the ultrastructure of synapses as seen with transmission electron microscopy with scanning electron microscopic pictures.
Fluorescence histochemistry of monoamine‐containing cell bodies in the brain stem of the squirrel monkey (Saimiri sciureus). II. Catecholamine‐containing groups
Authors: Hubbard Jack E. , Carlo Vincenzo Di 
Published: May 2005

AbstractIn this second paper of the series on the monoamine‐containing cell bodies found in the brain stem of the squirrel monkey (Saimiri sciureus) by the fluorescence histochemical technique, a description is presented of the catecholaminergic neurons. The first paper was a report on the locus caeruleus (a norepinephrine containing group), which, in consideration of its physiological importance, was the object of a particularly detailed study. The other groups of catecholaminergic cell bodies were found to have a topographic distribution and general morphological characteristics quite similar to those described for the rat. In particular, in the squirrel monkey brain stem homologous groups of neurons were observed for each group described in the rat, with the exception of the weakly fluorescing group A3. In comparing the findings on the squirrel monkey with the description of the catecholaminergic cell groups in the cat some significant differences were noticed.
Corticorubral projections in the rat
Authors: Brown Leroy T. 
Published: May 2005

AbstractIn a series of young adult albino rats the terminal projections of corticorubral fibers were studied by light and electron microscopic methods following unilateral sensorimotor cortex suction ablation. Degenerating axons could be traced from the ipsilateral cerebral peduncle to the periphery of the red nucleus. Within the red nucleus the degeneration was sparse. No degeneration was seen contralaterally. With the electron microscope degenerating axons showed electron dense axoplasm and seemed devoid of their normal complement of organelles. Electron‐dense degenerating synaptic terminals, one to two per grid square, were found in the more rostral portions of the red nucleus. These terminals were of the asymmetrical type with increased density of the post‐synaptic membrane and made contact with small to medium sized dendrites. No degenerating axosomatic or axoaxonal knobs were seen. No degenerating terminals were seen in the caudal regions of the red nucleus. This study finds that following ablation of the sensorimotor cortex in the rat there is a projection to the ipsilateral red nucleus and that the contacts are primarily of the axodendritic type as revealed by the electron microscope.
Anatomical organization of pretectal nuclei and tectal laminae in the cat
Authors: Kanaseki T. , Sprague J. M. 
Published: May 2005

AbstractSeven nuclei of the pretectum in the cat have been identified and described using material stained for cytoarchitecture and myeloarchitecture, and these have been related to comparable nuclei in other species. These nuclei are termed (1) N. pretectalis anterior, pars compacta and (2) pars reticularis, (3) N. p. medialis, (4) N. p. posterior, (5) N. tractus opticus, (6) N. p. subopticus and (7) N. p. olivaris. Fink‐Heimer stains of terminal degeneration following enucleation indicate that retinopretectal fibers terminate primarily contralaterally in nuclei 4, 5 and 7, and in nuclei 5 and 7 ipsilaterally. At least seven laminae in the superior colliculus have been identified by cytoarchitecture: I. Stratum zonale (two sublayers), II. S. griseum superficiale (three sublayers), III. S. opticum, IV. S. griseum profundum, VII. S. album profundum. The lateral nucleus of the periaqueductal gray might be included as the eighth tectal lamina. Ninety percent or more of the terminal degeneration following enucleation is found on the contralateral side, primarily in the first sublayer of lamina II, with small amounts in the second sublayer; the sparse ipsilateral degeneration is limited to the second sublayer.
Corticofugal projections from the visual cortices to the thalamus, pretectum and superior colliculus in the cat
Authors: Kawamura S. , Sprague J. M. , Niimi K. 
Published: May 2005

AbstractSmall lesions were placed in visual cortical areas 17, 18, 19, 20, 21, 7, and Clare‐Bishop in the cat, and the sites of terminal degeneration seen with Fink‐Heimer technique were plotted in thalamus, pretectum and superior colliculus. No degeneration was found in these sites after area 20 lesions; lesions in the other cortical areas gave different patterns of degeneration. Two major patterns were present, one from lesions in 17–18, one from lesions in 21, 7 and C‐B, with degeneration from 19 forming a transition between the two groups.Areas 17, 18 and 19 project to the dorsolateral geniculate nuclear complex (LGNd); areas 21, C‐B and 7 do not. Area 17 projects to the laminar part, area 18 to both laminar and interlaminar (NIM) parts, and 19 only to NIM. The corticogeniculate projections from all three areas are topically organized anteroposteriorly, and at least that from area 17 is topically organized mediolaterally.Areas 17 and 18 project topically to a columnar locus of the medial pulvinar (=lateral posterior) nucleus which ventrally includes that area known as the posterior nucleus. Area 19 has a double columnar projection to this part of the thalamus, one in the medial and one in the lateral pulvinar area. The medial column lies medial to that from 17–18, and appears to overlap the termination of the ascending projection from the superior colliculus. Cortical areas 21, C‐B and 7 also have a double projection to the pulvinar.These findings indicate that the corticorecipient neurons in both medial and lateral sectors of the pulvinar are organized so that dorsal neurons are activated by stimuli in upper visual fields (lower retina) and ventral neurons by stimuli in lower fields (upper retina).Areas 17 and 18 project to the external layer of the ventrolateral geniculate (LGNv) nucleus, 19 to both external and internal layers, and 21, C‐B and 7 to internal layer only.The pretectal projection from 17–18 is limited to its caudal pole chiefly in the posterior pretectal nucleus (NPP), and also in the nucleus of the optic tract (NOT). Area 19 fibers terminate in NPP, NOT and also in the reticular part of the anterior pretectal nucleus (NPAr). Those from 21 and C‐B end primarily in NPAr, and from area 7 in both reticular and compact parts of NPA. These corticopretectal systems all appear to be organized topically.Areas 17, 18 and 19 have a double termination in the superior colliculus, a focal pattern in the superficial layers (chiefly lamina II), and a diffuse pattern in deeper layers (laminae IV, V, VI). The superficial pattern only provides the retinotopical matching with the optic afferents. All other cortical areas project diffusely to the deep layers. After lesions in 21 and C‐B, the superficial foci are larger and centered in lamina III; after area 7 lesions this focal degeneration is centered in laminae III and IV and spread over much of the width of the colliculus. Degeneration to pontine nuclei and inferior olive was not examined.
The organization of the retinal projection to the dorsal lateral geniculate nucleus in pigmented and albino rats
Authors: Lund R. D. , Lund Jennifer S. , Wise Renée P. 
Published: May 2005

AbstractThe retina maps over the dorsolateral and posterior surfaces of the contralateral dorsal lateral geniculate nucleus of albino and pigmented rats, such that the upper retina projects posteriorly and the lower retina projects over the dorsolateral surface. Nasal retina projects ventrolaterally and temporal retina dorsomedially. From the surface, lines of projection (demonstrated after either localised retinal or visual cortical lesions) tend to run deep and anteriorly within the nucleus.The area covered by the uncrossed optic pathway differs between pigmented and albino rats. In the pigmented animals it extends no more than 60° from the edge of the visual field represented in the crossed projection, while in albino animals it extends as far as 100° or more. The uncrossed projection in the albino strains tends to be deficient posteriorly (upper retinal representation) and dorsomedially, and the overall density is less than that found in the pigmented animals.Small lesions localised in the extreme peripheral temporal retina of both albino and pigmented rats have always produced degeneration in the contralateral as well as ipsilateral geniculate, even though some of the lesions map only as far as, or within the peripheral 20° on the contralateral colliculus. Most of these lesions in the albino rats give two patches of uncrossed degeneration in the geniculate with at least one focus of degeneration in the contralateral geniculate. Those made in the lower temporal retina of the albino rat give in addition to the uncrossed patches, two areas of crossed degeneration in the geniculate separated by about 50° in terms of visual field projection. These double projection aberrations do not occur in pigmented animals.The suggestion is offered that in albino rats the retina of each eye maps totally on the contralateral lateral geniculate nucleus. However, the vertical midline of the visual field is represented at about 40–50° from the medial edge of the nucleus. A normal (but sparse) uncrossed pathway maps lateral to this position, but also maps in duplicate medial to it. In addition, it appears that some crossed axons may also be abnormal in their termination, and project to both sides of the vertical meridian. If the above interpretation is correct, the anomalies of the albino rat may derive from a confusion of attempting both field and retinotopic maps on the same nucleus. The possibility exists that a comparable total crossed retinogeniculate projection exists in pigmented animals but that the retina temporal to the vertical midline projection is restricted in its connection to a small band on the medial border of the contralateral nucleus.
The upper layers of the superior colliculus of the rat: A Golgi study
Authors: Langer T. P. , Lund R. D. 
Published: May 2005

AbstractA number of questions deriving from a previous electron microscopic study of the superficial layers of the rat superior colliculus pointed out the need for a comprehensive study of the cell types of the superior colliculus and their detailed morphology. In the present Golgi study the cells of the superficial layers of the superior colliculus were found to be of five major types; marginal cells, horizontal cells, narrow field vertical cells, wide field vertical cells, and stellate cells. Some of these categories were further subdivided. Each cell type has a distinctive set of dendritic field characteristics, a regional distribution, and consistent axon characteristics. The horizontal cells were found to have a preference in the orientation of their dendrites along the vertical and horizontal axes of the visual field projection upon the superior colliculus. It is argued that the horizontal cells are the presynaptic elements in the majority of the dendrodendritic synapses.
Structure of layer IV in the somatosensory neocortex of the rat: Description and comparison with the mouse
Authors: Welker Carol , Woolsey Thomas A. 
Published: May 2005

AbstractThe cytoarchitecture of layer IV of SmI neocortex of the rat has been studied in sections parallel and perpendicular to layer IV. The neurons of layer IV are arranged into discrete multicellular units, called barrels, which we have previously described in both mouse and rat. Using the barrels as markers, it is possible to outline precisely a cytoarchitectonic field—the barrel field—which (1) is confined to SmI. (2) has a consistent appearance from hemisphere to hemisphere, and (3) contains at least 220 barrels. A special region of the barrel field has been identified—the posteromedial barrel subfield (PMBSF)—in which the barrels are arranged in five rows and are larger than elsewhere. However, in contrast to other barrels in the rat barrel field and to the barrels that make up the PMBSF in the mouse, the PMBSF barrels in the rat are filled with small neurons nearly throughout the thickness of layer IV.From experimental evidence, it has been possible for the first time to establish consistent homologies between small groups of neocortical neurons in layer IV. The most surprising finding is that homologous barrels in the PMBSF of two closely related species, the rat and the mouse, have such a different cytoarchitectonic appearance. On the basis of this observation, we suggest that a careful study of these PMBSF barrels in the mouse, the rat and other species may provide a clue to understanding how neocortical neuronal circuits of varying complexity are assembled.
The rubro‐olivary projection in the macaque: An experimental study with silver impregnation methods
Authors: Courville J. , Otabe S. 
Published: May 2005

AbstractThe rubro‐olivary projection in the macaque has been studied by making lesions in the red nucleus and mapping terminal degeneration with the method of Nauta‐Laidlaw. Lesions restricted to the parvocelluar region have been obtained and confirm that the tract originates from that portion of the red nucleus. The distribution is mainly in the principal olive and in this sub‐nucleus, more extensive than in the cat. Small projections to the medial accessory olive and dorsomedial cell column of the olive are also reported. A topographical arrangement of the rubro‐olivary fibers was found. The projection is made of fibers of fine caliber which degenerate slowly. Optimal survival time was around 16 days. A correlation of the rubro‐olivary projection with the distribution of the olivo‐cerebellar projection indicates that the rubro‐olivary fibers represent one of the links in reciprocal connections between the cerebellum and red nucleus.
Area specific reflexes from normal and supernumerary hindlimbs of Xenopus laevis
Authors: Hollyday Margaret , Mendell Lorne 
Published: May 2005

AbstractTwo area specific reflexes elicited by natural stimulation of different regions of the hindlimbs of Xenopus laevis have been identified. Light or intense mechanical stimulation of the foot evokes reflex activity in the ipsilateral knee flexor nerve; moderate pressure applied to the calf evokes reflex activity predominantly in the ipsilateral knee extensor nerve. The reflex responses have been recorded electrophysiologically to overcome the limitations of behavioral observations for determining the presence of activity in particular muscles. Normal area specific reflexes are elicited in the normal ipsilateral hindlimb by stimulation of grafted supernumerary hindlimbs innervated either by hindlimb (lumbar) or by non‐limb (thoracic) spinal cord segments. The area specific reflexes can be elicited only if the limb is grafted to a host younger than stage 54–55 of Nieuwkoop and Faber ('56), the stage at which reflex movements are first observed behaviorally. Abnormal reflex responses are evoked by stimulation of supernumerary limbs innervated by either thoracic or lumbar segments when the limb buds are grafted to older larvae. Supernumerary forelimbs grafted at early stages and innervated by either thoracic or lumbar spinal cord segments generally fail to elicit area specific reflex responses in the normal hindlimb. Single‐unit recordings of afferent fibers supplying the normal and supernumerary hindlimbs show that each limb receives a separate nerve supply. No evidence for branched afferent fibers has been found. The implications of these results for theories of neuronal specification are discussed, particularly the hypothesis that peripheral tissues are able to specify the central actions of afferent fibers that innervate them.
A block model of the cat cochlear nucleus
Authors: Kiang Nelson Y. S. , Godfrey Donald A. , Norris Barbara E. , Moxon Susan E. 
Published: May 2005

AbstractA three‐dimensional block model of the cochlear nucleus of the cat was constructed from histologic sections. Boundaries of various subdivisions, based on cytoarchitectonic criteria, were included in the model. Usage of the block model in correlating physiological and anatomical data is illustrated by localizing characteristic waveforms of gross evoked responses and characteristic frequencies of single units.
Dopaminergic neurons in the nematode Caenorhabditis elegans
Authors: Sulston J. , Dew M. , Brenner S. 
Published: May 2005

AbstractDopamine is the putative transmitter of eight neurons in the hermaphrodite form of the nematode Caenorhabditis elegans. These include the cephalic and deirid neurons, which are believed to be mechanosensory. The male has an additional six dopaminergic neurons in the tail. Mutants have been selected which have defects in the formaldehyde induced fluorescence and lack dopamine to varying degrees, but they are not insensitive to touch. The dopaminergic neurons of C. elegans are compared with the homologous neurons in Ascaris lumbricoides.
Postnatal development of the cerebellar cortex in the rat. IV. Spatial organization of bipolar cells, parallel fibers and glial palisades
Authors: Altman Joseph 
Published: May 2005

AbstractThe ontogeny of the spatial organization of some components of the molecular layer was investigated in cerebella sectioned systematically in the sagittal, coronal and horizontal planes.There is no discernible organization in the distribution of cells of the proliferative zone of the external germinal layer (EGL) but from birth the differentiating bipolar cells of the subproliferative zone are aligned parallel to the surface and to the long axis of the folium. While they are still in or at the base of the EGL, the bipolar cells emit long processes, the future parallel fibers. The next step is the outgrowth of a vertical process which may reach the base of the molecular layer before the granule cell nucleus becomes translocated. The idea that the cell body truly migrates through the molecular layer is not supported by the observations.Bergmann glia cells are frequently seen in Golgi material in neonates but they are probably less numerous than in older infants and their processes are not as well as aligned. It is only gradually that the EGL is perforated by glial endfeet which in older infants are occasionally organized into longitudinal rows. In mature cerebella the parallel fibers are separated by thin and relatively narrow, unstained spaces which are oriented in the longitudinal plane and can be traced from the pial surface to a zone just above the layer of Purkinje cells. It is postulated that these spaces are occupied by glial palisades formed by apposed thin vertical processes to which many Bergmann glia cells contribute. The alignment of these palisades is dependent on the orientation of parallel fibers. When the parallel fibers are reoriented by X‐irradiation the glial palisades become correspondingly realigned.These observations indicate that the orieted growth of parallel fibers, which follows the polarization of bipolar cells, determines the spatial organization of the glial framework of the molecular layer. They also suggest that the glial palisades mediate functions that are not primarily developmental in nature.
Comparative anatomical studies of the Sml face cortex with special reference to the occurrence of “barrels” in layer IV
Authors: Woolsey Thomas A. , Welker Carol , Schwartz Richard H. 
Published: May 2005

AbstractIn the SmI cortex of mice and rats there are cytoarchitectonically identificable groups of cells — called barrels — some of which have been shown to be directly related to whiskers and other sensory hairs on the contralateral face. In this study we have used a comparative approach to determine the incidence and variation of the barrels.The brains of 27 mammalian species have been examined histologically to determine whether barrels exist in layer IV of what is known or likely to be the face area of SmI. Thick sections (50–100 μm) were taken tangential to the pia overlying SmI and stained with thionin. The patterns of facial whiskers were also mapped by dissection of the facial skin. Barrels were seen only in brains of species belonging to three of the seven mammalian orders examined. We have confirmed Weller's ('72) observation of barrels in the Australian brush‐tailed possum but have not found barrels in two marsupials from the western hemisphere. Barrels were demonstrable in representatives of four of five rodent suborders examined and in the rabbit.From the study of the rodent brains, a number of trends emerge. (1) The organization of the barrel fields is “dictated” by the organization of the sensory periphery. Animals with five rows of large mystacial (moustache‐like) vibrissae have five rows of PMBSF (Posterom edial barrel sub‐field) barrels. (2) The barrels are confined to layer IV of (what is known or likely to be) the SmI face area. The pattern and cortical location of the barrel field is consistent among different specimens of the same species. (3) Certain behavioral patterns do not preclude the existence of the barrels. Species which possess well developed visual systems and behaviors (e.g., grey squirrel) and forms which do not actively explore the environment by whisking their vibrissae (e.g., guinea pig) have barrels. (4) Within a given rodent suborder, the barrels become more difficult to identify, as the brains become larger. We have not yet been able to demonstrate barrels in the largest rodent, the capybara.