bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prenatal development of the cerebellar system in the rat. I. Cytogenesis and histogenesis of the deep nuclei and the cortex of the cerebellum
Authors: Altman Joseph , Bayer Shirley A. 
Published: May 2005

AbstractPrenatal cerebellar development was investigated with three approaches. In normal embryos sectioned in three planes morphological and cytological changes were determined at daily intervals beginning on embryonic day 13 (E13). A similar series of X‐irradiated embryos was used to study changes in neuroepithelial organization and in the location of primitive (radiosensitive) or differentiated cells. Finally, to quantify the time of origin of different classes of cerebellar neurons with the progressively delayed labelling procedure, we used autoradiograms from adult rats whose mothers were injected with two successive daily doses of 3H‐thymidine on overlapping days from day E13 on.The cerebellar anlage was delineated in the dorsal metencephalon by the collapse of its ventricular lining after X‐irradiation. This “collapsing neuroepithelium” was located laterally on day E13, then it spread medially and reached the midline on day E16. Deep nuclear neurons began to differentiate on day E13, with two‐thirds forming on day E14; Purkinje cell formation peaked on day E15, with a few cells still forming on day E16. It was postulated that the deep nuclear neurons settled first in the superficial “nuclear zone,” and that the Purkinje cells gathered temporarily in the underlying “transitory zone,” adjacent to the collapsing neuroepithelium.In the next period of cerebellar development four major events were recognized. (1) Beginning on day E17 the cells of the nuclear and transitory zones became intermingled. It was postulated that the Purkinje cells were migrating radially through the ranks of the stationary deep nuclear neurons and assembled under the spreading canopy of a fibrous plexus and the external germinal layer. (2) It was also on day E17 that the external germinal layer began to form as one of the prongs of the “germinal trigone” in the posteroventral aspect of the cerebellum. On the succeeding days the external germinal layer spread over the surface of the cerebellum; in the vermis in a rostral direction. (3) Two cell types destined to settle in the future granular layer, the pale cells and the Golgi cells, began to form at a relatively slow rate on day E19. Chronological considerations suggested that they were generated in the regressing, noncollapsing neuroepithelium of the cerebellar ventricle. (4) From the beginning (day E17) of its genesis posteroventrally, the primitive cerebellar cortex bridged the midline. As the fused cortex spread rostrally, the vertical ventricular cleft separating the underlying portions of the cerebellum became shallower and then disappeared; the process was completed in the anterior cerebellum by day E22. By the time of birth the maturation of the neurons of the deep nuclei appeared advanced but the maturation of the prenatally produced neurons of the cortex does not start until after birth when a new class of neurons is generated in the external germinal layer.
The neurons in the gelatinosal complex (laminae II and III) of the monkey (Macaca mulatta): A golgi study
Authors: Beal John A. , Cooper Margaret H. 
Published: May 2005

AbstractThe nerve cells of the gelatinosal complex (laminae II and III) were examined in various planes of section in Golgi and Nissl preparations of the lumbosacral spinal cord of the adult monkey. An attempt was made to characterize the neurons based on morphological variations and establish criteria for consolidation or separation of laminae II and III. In Nissl preparations the laminae essentially conform to Rexed's ('52) description for the cat. In Golgi preparations impregnated neurons of the gelatinosal complex show a spectrum of morphological variation. These variations, however, are not restricted by Rexed's border between laminae II and III. In either lamina the cells vary in size from small (12 µm × 8 µm) to medium (30 µm × 25 µm) and in shape from fusiform to polygonal. Polygonal neurons are prevalent in the dorsal part of lamina II (Rexed's outer zone) and some have craggy contours.Axons of the cells of the gelatinosal complex vary in diameter, but most measure around 1.0 µm with some up to 2.0 µm. Their course is often a meandering one which cannot be followed. Those from cells in the outer zone of lamina II are different. They issue collaterals to lamina I then immediately enter the overlying white matter. Golgi type II (short axoned) cells were not definitively demonstrated. Nonetheless, the neurons of the gelationosal complex display stalked dendritic appendages and axon‐like processes which are similar to those described on Golgi type II interneurons elsewhere in the central nervous system. For this reason, in spite of the long axons and relatively large dimensions of the neurons of the gelationosal complex, their circuitry is suspected to be similar to that of local circuit interneurons.The dendritic arbor of the cells of the gelatinosal complex, as viewed in horizontal sections, generally extends longitudinally with little mediolateral spread. In sagittal sections a stratified pattern of dendritic arborization divides the gelatinosal complex into three regions: (1) an outer region which corresponds to Rexed's ('52) outer zone of lamina II, (2) a middle region composed of the remainder of lamina II and the dorsal portion of lamina III, and (3) an inner region or ventral part of lamina III. A large portion of the dendritic arbors of cells in the outer region spread ventrally at oblique angles while those from the inner region spread dorsally. Dendrites arising from cells in the middle region, on the other hand, extend almost exclusively in the longitudinal plane, are often of considerable lengths, and give rise to unique recurrent branches. The dendritic arborization is discussed in relation to the primary afferents to the gelatinosal complex.
The sensory trigeminal system of a snake in the possession of infrared receptors. I. The sensory trigeminal nuclei
Authors: Molenaar Gerard J. 
Published: May 2005

AbstractThis study was undertaken to examine the relation between the possession of the so‐called pit organs, which are sensitive infrared receptors innervated by the trigeminal nerve, and the sensory trigeminal nuclei. The sensory trigeminal system of Python reticulatus was investigated by means of myelin and Nissl staining techniques.It appears from the study that the sensory trigeminal system consists of two separate components. One of these resembles the sensory trigeminal system, known of other vertebrates, and is referred to as the common sensory trigeminal system. It comprises a short ascending part to the principal sensory trigeminal nucleus and a longer descending part to the nucleus of the descending trigeminal tract and upper cervical segments. The subdivision of the trigeminal system, as proposed by Olszewski ('50) for mammals, could be applied to the common sensory trigeminal system of the python.The second component is situated laterally to the common descending system. It is composed of descending fibres which terminate in a huge, separate nucleus. This is called the nucleus of the lateral descending trigeminal tract. This component was initially recognized in snakes possessing infrared receptors, but seems not to be restricted to these animals.
Golgi‐staining of “primary” and “secondary” motoneurons in the developing spinal cord of an amphibian
Authors: Blight Andrew R. 
Published: May 2005

AbstractThe Golgi technique was used to study the morphology of spinal motoneurons at various stages in the early development of swimming behavior in embryos and larvae of the palmate newt, Triturus helveticus (Razoumowsky). The earliest motoneurons stained appeared to be Associated with the Mauthner‐cell system. The overall morphology of these “primary” motoneurons seems to be similar throughout the lower vertebrates and the distinctive characteristics found in earlier descriptions of those from caudate amphibia were probably due to misinterpretation. At about the time of hatching and the development of low‐frequency swimming behaviour, other motoneurons were found to innervate the axial musculature, cells with a central morphology different from those of the “primary” type. It was found likely that these “secondary” motoneurons innervate a separate muscle system concerned with tonic and “slow phasic” activity, while “fast phasic” activity in rapid swimming is supplied by “primary” cells.
Gustatory pathways in the bullhead catfish. II. Facial lobe connections
Authors: Finger Thomas E. 
Published: May 2005

AbstractThe second order projections of the gustatory system in catfish were examined using both retrograde (HRP) and anterograde (degeneration and autoradiographic) hodological methods. Golgi‐stained material was used to demonstrate the different cell types in the primary gustatory sensory area, the facial lobe.Efferents from the facial lobe gather into ascending tract terminates largely in the medial funicular nucleus and the commissural nucleus of Cajal in the region of the obex. A small portion of the descending tract continues caudally to terminate in the dorsal horn of the spinal cord. The ascending secondary gustatory tract terminates mostly in the ipsilateral superior secondary gustatory nucleus in terminate in the isthmic region. A small portion of the ascending tract continues rostrally to terminate in the posterior thalamic nucleus and in the region of the nucleus lobo‐bulbaris. Sparser contralateral projections are also seen in the posterior thalamus and isthmic gustatory regions.Three cell types can be discerned in the facial lobe: small, medium and large. The small cells are intrinsic neurons, the medium cells project to the isthmic gustatory nucleus, and the large cells send fibers to the other terminal areas described above, as summarized in figure 19.
Internal organization of membranes at end bulbs of held in the anteroventral cochlear nucleus
Authors: Gulley R. L. , Landis D. M. D. , Reese T. S. 
Published: May 2005

AbstractThe end bulb of Held in the rostral ventral cochlear nucleus of the chinchilla and guinea pig was studied with the freeze‐fracture technique. The end bulb has multiple, small active zones which are uniformly distributed within the calyceal portion of this terminal. Single or small groups of active zones are surrounded by enlarged channels of extracellular space often containing processes of astrocytes. Small plasmalemmal deformations occur at these active zones. The number of these deformations is thought to be indicative of exocytotic transmitter release because they are more frequent in animals fixed in a noisy environment compared to animals fixed in a quiet environment. Thus, our study provides a basis for the quantitative study of changes in transmitter secretion at a central nervous system synapse driven by a controllable natural stimulus.The postsynaptic active zone at end bulbs resembles other excitatory synapses in the central nervous system in having an aggregate of large particles on the external membrane leaflet. This junctional aggregate of particles is coextensive with the presynaptic active zone and with the postsynaptic density seen in thin sections. Several perisynaptic aggregates of particles are deployed around each active zone on the external membrane leaflet. These irregularly‐shaped aggregates occur preferentially opposite the channels of enlarged extracellular space and along the edge of the end bulb and are not components of intercellular junctions or plasmalemmal contacts with cytoplasmic organelles. Although the function of the different particle aggregates on the postsynaptic membrane is not clear, our findings provide a basis for studying the factors controlling and maintaining their structure as well as more evidence that a consistent relationship exists between types of synaptic action and structure of the postsynaptic membrane.
Sites of termination of the saccular macula of auditory nerve fibers in the goldfish as determined by intracellular injection of procion yellow
Authors: Furukawa Taro 
Published: May 2005

AbstractProcion yellow dye was injected intracellularly into large auditory fiber of goldfish to investigate the relationship between the response type of these fiber and their site of termination in the saccular macula.Fibers which responded to the rarefaction phases of sound were found to terminate on the hair cells located in the ventral half of the saccular macula, while those which responded to the compression phases were found to terminate on the dorsally locate hair cells. A third group of fibers, which responded to both sound phases, was found to bifurcate outside the saccular macula and terminate on both dorsally and ventrally located hair cells. Some of the fibers of this group were found to trifurcate before entering the sacular macula. Results obtained in the present study, in conjunction with the findings on the orientation of hair cells within the sensory macula, can explain the mechanism underlying the presence of three different response types of fibers in the auditory nerve of the goldfish.
Reconstruction of trajectory of primary afferent collaterals in the dorsal horn of the cat spinal cord, using golgi‐stained serial sections
Authors: Hamano Kenzo , Mannen Hajime , Ishizuka Norio 
Published: May 2005

AbstractUsing Golgi‐stained serial sections obtained at the sacro‐caudal levels of the cat spinal cord, it was possible to reconstruct the trajectory of primary afferents. They were classified into two groups: reliable primary afferents directly traced from the dorsal root and probable primary afferents traced from the dorsal funiculus or Lissauer's tract.The diameters of the reliable primary afferents vary from 0.88–1.88 μm. According to their courses, reliable primary afferents as well as probable primary afferents were classified into three groups: the first is distributed to both medial and lateral halves of the dorsal horn, the second to the medial half, and the third to the lateral half. Commissural fibers were also observed among the probable primary afferents. The rostro‐caudal and medio‐lateral extents of reliable primary afferents are found to be between 250 and 950 μm and 270 and 700 μm respectively, while those of the probable primary afferents were between 125 and 670 μm and 270 and 1,640 μm respectively. These primary afferent fibers are connected with at least two or more laminae of the dorsal horn gray matter.
The distribution and orientation of noradrenergic fibers in neocortex of the rat: An immunofluorescence study
Authors: Morrison John H. , Grzanna Reinhard , Molliver Mark E. , Coyle Joseph T. 
Published: May 2005

AbstractA homologous antiserum directed against rat dopamine‐β‐hydroxylase (DBH) was employed in the indirect immunofluorescence technique of Coons ('58) to describe the distribution and orientation of noradrenergic (NA) axons in the cerebral neocortex of the adult albino rat. DBH is the terminal enzyme in the biosynthesis of noradrenaline and is a sensitive anatomic marker for NA neurons and their processes. Cryostat sections in three standard planes (coronal, sagittal and tangential) taken from four cortical fields (somatosensory, motor, visual and anterior cingulate) were processed for immunofluorescence, and adjacent sections were stained with a Nissl method to relate the pattern of NA axons to specific cortical laminae. Noradrenaline levels and DBH activity were measured in the same cortical fields by radioenzymatic assays.A rich network of DBH immunoreactive axons was observed throughout all cortical layers in each of the areas examined. The pattern of NA distribution is not diffuse, but is characterized by a geometric orderliness that is uniform throughout the neocortex, with only minor regional variations. In layer I the DBH‐positive fibers are predominantly parallel to the pial surface and thus form a tangential grid‐like pattern. Layers II and III are characterized by straight, radial fibers that rarely extend through layer IV to the infragranular layers. There appears to be a NA terminal field in layers IV and V where there is a network of short, oblique or tortuous axon segments, especially prominent in lateral neocortex. Layer VI is unique in that the prevailing orientation of NA fibers is in the anterior‐posterior direction. This band of fibers does not extend into the sub‐cortical white matter, where very few NA fibers are seen. The strong tangential projection of the NA neurons, particularly in layers I and VI, emerges as a dominant feature of this afferent system and appears to be superimposed on the predominantly vertical organization of the cortex. This tangential pattern of organization may allow the locus coeruleus to modulate the activity of adjacent columns synchronously over a vast expanse of cerebral cortex.
Effect of neonatal deafferentation on synaptogenesis in the rat interpeduncular nucleus
Authors: Lenn Nicholas J. 
Published: May 2005

AbstractChanges in the normal synaptogenetic pattern of the interpeduncular nucleus (IPN) were induced by destruction of one or both habenular nuclei in neonatal rats. The S synapses, the principal habenulointerpeduncular (H‐IPN) afferents, were reduced in number and delayed in time of appearance by unilateral lesions. They were eliminated by bilateral lesions. The crest synapses, also of habenular origin, appeared at ten days of age and were apparently normal in structure after unilateral lesions. However, this actually represented a change in connectivity, since normal crest synapses are of bilateral origin. Following bilateral habenular lesions abnormal crest synapses appeared at 28 days of age. These had normal postsynaptic structure, but presynaptically were formed by non‐habenular axons, usually of two different types at each crest synapse. Lesions induced an early appearance of F synapses, at three days, instead of the normal time after six days of age. Apparently similar processes containing flattened vesicles formed somatic contacts only in lesioned animals beginning at 21 days of age. The axosomatic synapses which were only occasional appeared in the adult appeared at the normal time in lesioned animals. At 28 days of age in both unilaterally and bilaterally lesioned animals these was an increase in number of somatic synapses. This increase was due to an increase of the normal somatic endings plus the appearance of somatic synapses containing flattened vesicles. Both types of somatic contacts were found in similar numbers at subsequent ages up to three months.The changes in S synapses represent Wallerian degeneration. The formation of unilaterally derived crest synapses in unilaterally lesioned animals is interpreted as evidence for a specific recognition mechanism. A postsynaptic control mechanism is proposed to explain the formation of heterologous crest synapses, with the usual distinctive geometry but involving abnormal, non‐habenular presynaptic elements four weeks following neonatal bilateral lesions. The increase in axosomatic synapses is unusual since the dendrites of IPN neurons were deafferented, not their somata. The factors leading to the changes in somatic synapses are discussed. The findings reveal new examples of the complexity of neuronal adaptation to CNS lesions in early life.
Cerebellar afferents in teleost catfish (lctaluridae)
Authors: Finger Thomas E. 
Published: May 2005

AbstractThe cerebellar afferents in the bullhead catfish (Teleostei) were labeled by relying on the retrograde transport of horseradish peroxidase (HRP). Retrogradely labeled neurons were seen in: spinal cord, lateral cuneate nucleus, inferior olive, reticular nuclei, vestibular nuclei, nucleus subeminentialis, n. lateralis valvulae, locus coeruleus, n. mesencephalicus dorsalis, the basal optic nuclei, and a nucleus at the isthmic level which may be equivalent to the pontine nuclei of birds and mammals. Inputs to the molecular layer arise from the inferior olive, locus coeruleus and n. lateralis valvulae in addition to subjacent granule cells.No projections to cerebellum were seen to arise from either the optic tectum or from the inferior lobe. The so‐called “lobo‐cerebellar” tract in teleosts was reported by Goldstein, amongst many others, who mistook the superior secondary nucleus for a deep cerebellar nucleus.
Myelin sheath thickness and conduction latency groups in the cat optic nerve
Authors: Freeman Brian 
Published: May 2005

AbstractIn many animals, the optic nerve has multiple conduction latency groups of fibres yet displays a unimodal frequency distribution of fibre sizes. An attempt has been made to resolve this discrepancy in the cat.Examination of teased preparations of fixed cat optic nerve fibres by polarizing interference light microscopy indicated that a fiber's size may change abruptly along its length. Furthermore, the diameters of single nerve fibres followed for distances of up to 30 μm in serial transverse sections of cat optic nerve showed variations of up to 100% of a fibre's average diameter over that distance. On the other hand, the myelin sheath thickness of these fibres appeared to be relatively constant along any one fibres.A population of cat optic nerve fibres which had a unimodal axon diameter frequency distribution was found to have a myelin sheath thickness frequency distribution with five modes. These modes have been interpreted as indicating the existence of five groups of fibres in the cat optic nerve. Four of these groups may be related to four negative peaks seen in the antidromic compound action potential recorded at the margin of the cat optic disc following stimulation of the optic chiasm. The fifth myelin thickness group appears to represent the slowly conducting fibres which do not make an obvious contribution to the antidromic compound action potential.It is concluded that for the cat optic nerve, the conclusion latency groups seen in the compound action potential may be more directly correlated with the frequency distribution of fixed nerve myelin thickness than with the frequency distribution of fixed nerve fibre diameter.