bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cerebellar corticovestibular fibers of the posterior lobe in a prosimian primate, the lesser Bushbaby (Galago senegalensis)
Authors: Haines Duane E. 
Published: January 2005

AbstractThe organization of cerebellar corticovestibular fibers was studied in a prosimian primate (Galago senegalensis) using the Fink and Heimer (1967) method. The vestibular complex of Galago is larger than in other mammals and some higher primates. Vermis lobule IX contributes the largest number of fibers to the ipsilateral vestibular complex. Lobules VI and VIII give rise to lesser, but similar, numbers of fibers which also pass into the ipsilateral vestibular nuclei. Vermis lobule VII and the paravermal and lateral cortices contribute extremely sparse numbers of fibers to the dorsal area of the ipsilateral vestibular complex. All degenerated fibers enter the vestibular nuclei through a large diffusely organized juxtarestiform body.Fibers from vermis lobule VII and the paravermal and lateral cortices terminate in dorsal areas of the ipsilateral vestibular nuclei. Vermis lobule VI projects into dorsal and lateral regions of the ipsilateral SVN, LVN and SpVN. Vermis lobules VIII and IX project into the dorsal and into progressively more central and medial regions of the ipsilateral SVN, LVN and SpVN. This gives the clear impression of a rostro‐caudal origin of fibers from the posterior lobe vermis which terminate in an overlapping lateral to medial sequence in the vestibular nuclei, lesions of vermis lobule IX also elicit degeneration in dorsal areas of the ipsilateral medullary reticular formation and in the ipsilateral parabrachial nuclei.
Relations between auditory nerve endings and cell types in the cat's anteroventral cochlear nucleus seen with the Golgi method and nomarski optics
Authors: Brawer James R. , Morest D. Kent 
Published: January 2005

AbstractRapid Golgi impregnations of the ascending branches of the auditory nerve fibers and of the types of neurons in the anteroventral cochlear nucleus (AVCN) were studied. Entire ascending branches could be observed; some of these branches project to each subdivision, others do not. There are two main types of large neurons: the bushy and stellate cells. Criteria were established for identifying unimpregnated bushy and stellate perikarya by means of Nomarski optics, and these criteria were checked by Nomarski observations on neurons which had either impregnated dendrites and unimpregnated cell bodies or impregnated portions of perikarya. In this way, the relations of unimpregnated cell bodies to auditory nerve endings were observed. Furthermore, with Nomarski optics, the cytoarchitectonic subdivisions of AVCN could be determined. Differences in the end‐bulbs and collateral endings formed by the auditory nerve fibers were distringuished in three of the cytoarchitectonic subdivisions of the AVCN. End‐bulbs in the anterior division were much larger than those in the dorsa and ventral parts of the posterior division. The large end‐bulbs of held in the anterior division of the AVCN were consistently associated with the perikarya of bushy cells and not with those of stellate cells. The large end‐bulbs are not observed in the posterior division. Thus, bushy cells in the posterior division, although morphologically similar to those in the anterior division, must have a different synaptic organization. This difference may correspond to electrophysiological distinctions in the time‐patterns of response recorded in these regions following acoustic stimulation.
The inferior olivary nucleus of the opossum (Didelphis marsupialis virginiana), its organization and connections
Authors: Martin George F. , Dom R. , King J. S. , Robards M. , Watson C. R. R. 
Published: January 2005

AbstractAlthough the inferior olivary nucleus of the opossum is small, sections stained either for Nissl substance, normal axons or cholinesterase activity reveal distinct medial, dorsal and principal nuclei. The medial nucleus contains three major subdivisions (labelled a, b, c after Bowman and Sladek, 1973) and a group of neurons which is comparable to the cap of Kooy. In contrast to the cat and monkey, the major portion of the “medial” nucleus (subgroup a) lies lateral to the principal nucleus in rostral sections. The dorsal nucleus can also be subdivided, as can the principal nucleus which contains distinct dorsal and ventral lamellae. A small area is identified which based on position and connections may conform to the dorsal medial cell group.The experimental portion of the study provides evidence for an olivary projection from the motor‐sensory cortex and a massive input from the midbrain (red nucleus, pretectum, midbrain tegmentum). In addition, the opossum inferior olive receives fibers from the deep cerebellar nuclei (cerebellar feedback loops), the spinal cord and the dorsal column nuclei. Of particular interest is the finding that fibers from the nucleus cuneatus and nucleus gracilis have distinctly different olivary targets and that those from the nucleus gracilis, but not the cuneate nucleus, overlap (in part, at least) with the direct spinal fibers. Other examples of overlapping fields of terminal degeneration are present and are discussed. In general our results reveal that although certain relationships between the nuclear divisions are different, the opossum olive conforms well to that of placental mammals and provides a basic mammalian model for future experimental electron microscopic and physiological studies.
Cell death in the development of the lateral motor column of the chick embryo
Authors: Hamburger Viktor 
Published: January 2005

AbstractCell counts were made in the lumbar lateral motor column (l.m.c.) of chick embryos of 5.5, 6, 7, 8, 9, 12, 18 days of incubation and five days posthatching (n = equals; 68). Only nuclei with nucleoli were counted and corrections were made for double counting (Abercrombie, 1946). The population attains a peak value of over 20,000 cells (corrected figure: over 17,000) at 5.5–6.5 days = stages 28 and 29 (Hamburger and Hamilton, 1951). The l.m.c. loses between 7,000 and 8,000 cells between days 6.5 and 9.5, (between stages 29 and 36). In other words, 60% of the population survive. A plateau of approximately 12,300 cells (corrected figure: 10,300) is maintained throug five days posthatching. Massive cell degeneration was observed in 7‐ and 8‐day embryos. Counts of distinctly pyknotic cells indicate that at least 5–6% of the total population is in the process of degeneration at any particular time. This figure is probably an underestimation; hence it is virtually certain that the depletion of the l.m.c. is due entirely to cell death. Arguments are presented in support of the hypothesis that the naturally occurring cell death in the l.m.c. is due to the failure of their axons to survive in a competion process at the periphery. Observations of the time pattern of muscle differentiation and their neurotization in the leg further endorse this hypothesis. However, it is not clear whether the axons compete for contact sites on muscle fibers or for a “trophic” agent.
Locus ceruleus in rhesus monkey (Macaca mulatta): A combined histochemical fluorescence, Nissl and silver study
Authors: German Dwight C. , Bowden Douglas M. 
Published: January 2005

AbstractThe locus ceruleus (LC) of the rhesus monkey (Macaca mulatta) was investigated using the histochemical fluorescence method and Nissl and ammoniacal silver stains. Caudally, a few fluorescent cells were observed in the lateral wall of the ventriculus quartus near the velum medullaris superior. Rostrally, the fluorescent cells were compactly clustered and reached their greatest density medial and, to a lesser extent, lateral to the tractus mesencephalicus n. trigemini at the level of the decussation of the nervus trochlearis. In the most rostral plane, fluorescent cells were more diffusely scattered ventral and medial to the pedunculus cerebellaris superior with a few cells situated near the nervus trochlearis. Nissl staining of tissue previously used for histochemical fluorescence showed that fluorescent cells were largely found in a region labelled LC in two rhesus monkey brain atlases and erroneously labelled nucleus tractus mesencephalicus n. trigemini in one brain atlas. Ammoniacal silver staining resulted in a dense accumulation of silver granules in the cells found to display a positive reaction for monoamines. The silver stains therefore offer an alternative to the histochemical fluorescence method for identifying the monoamine‐containing LC neurons.
Olivocochlear and vestibular efferent neurons of the feline brain stem: Their location, morphology and number determined by retrograde axonal transport and acetylcholinesterase histochemistry
Authors: Warr W. Bruce 
Published: January 2005

AbstractAnterograde degeneration studies have shown that the cochlear and vestibular receptor organs receive an efferent innervation from neurons in the brain stem. This pathway may provide a mechanism by which the CNS could modulate its own afferent input. The neurons which provide this innervation have so far escaped positive identification with methods which depend on retrograde cell changes after axotomy. In the present study, horseradish peroxidase (HRP) was injected into the labryinths of kittens and after allowing 24 hours for the retrograde axonal transport of this tracer, its presence in neurons of the brain stem was demonstrated histochemically. Because there is evidence that the efferent innervation of the labyrinth is cholinergic, acetylcholinesterase (AChE) was also demonstrated histochemically in the same or in adjacent tissue sections. Neurons labelled with HRP were found bilaterally in most periolivary cell groups of the superior olivary complex (cochlear efferents) and in the parvocellular reticular nucleus lateral to the abducens nucleus (vestibular efferents). Counts of labelled neurons yielded estimated totals of 1,700–1,800 cochlear and 400–500 vestibular efferent neurons. Approximately 60% of the neurons in each total were located on the side ipsilateral to the injection. The distribution of HRP‐labelled neurons was virtually identical to that of AChE‐positive neurons found in adjacent sections, and in those regions with predominantly ipsilateral or contralateral projections, there was an approximate correspondence in number of HRP‐ and AChE‐positive neurons. In tissue sections processed successively for demonstration of HRP and AChE, virtually all HRP‐labelled neurons were found to be AChE‐positive. These findings suggest that a number of current conceptions regarding labyrinthine efferent systems may need revision.
Behavioral and morphological evidence for binocular competition in the postnatal development of the dog's visual system
Authors: Sherman S. Murray , Wilson James R. 
Published: January 2005

AbstractTwo normally‐reared dogs and five dogs reared with monocular eyelid closure were studied. The two normal dogs and three of the deprived dogs were tested with a perimetry technique for the extent of behavioral visual field, and all of the dogs were studied histologically to determine the size of cell somata in the lateral geniculate nucleus.Behaviorally, the normal dogs saw with each eye approximately from 120° ipsilateral to 30° contralateral. The deprived dogs had a normal field of view for the non‐deprived eye, but with the deprived eye they saw only in the monocular segment (i.e., approximately 120° to 30° ipsilateral).Histologically, geniculate cells in the monocular segment of deprived dogs were of normal size. In the deprived laminae of the binocular segment, however, cells averaged about two‐thirds normal size, and in non‐deprived laminae of this segment, neurons were hypertrophied. The hypertrophy was greater for cells in lamina A (40%) than for those in lamina A1 (17%).These data indicate that in monocularly deprived dogs, the monocular segment of the visual system develops normally, but the binocular segment does not. Therefore, we conclude that binocular competition operates in the developing dog's visual system much as it does in the cat's.
Projections of the dorsal column nuclei and the spinal cord on the inferior olive in the cat
Authors: Boesten A. J. P. , Voogd J. 
Published: January 2005

AbstractThis study demonstrates partially overlapping fiber termination areas in the inferior olive originating from the dorsal column nuclei and the spinal cord.Based on the distribution of the terminations the dorsal accessory olive can be divided into a rostral and a caudal part. In the caudal part terminations are found of fibers originating in the contralateral gracile nucleus and in the lumbar and cervical spinal cord. Terminations in the rostro‐medial part of the dorsal accessory olive arise from the contralateral internal cuneate nucleus and from the opposite intermediate grey at C.1. Fibers from more caudal regions of the internal cuneate nucleus terminate in the dorsal accessory olive caudal to those originating from more rostral regions of this nucleus. The gracile nucleus and the lumbar spinal cord project to the rostro‐lateral portion of the dorsal accessory olive.The terminations in the medial accessory olive from the lumbar spino‐olivary fibers are found in a laterally located zone in the caudal one‐third of the nucleus. This spino‐olivary termination area extends more rostrally and medially after interruption of the cervical spino‐olivary fibers. Fibers from the contralateral gracile nucleus terminate in a medial zone in the caudal half of the medial accessory olive, while terminations of the contralateral internal cuneate nucleus are found at a more rostral level in the medial part of the medial accessory olive.Connections between the inferior olive and the caudal part of the spinal trigeminal nucleus, the lateral cervical nucleus and the cervical dorsal horn could not be demonstrated.
Translaminar growth of axons in the kitten dorsal lateral geniculate nucleus following removal of one eye
Authors: Hickey T. L. 
Published: January 2005

AbstractThe distribution of retinal afferents to the dorsal lateral geniculate nucleus of the cat following the early removal of one eye has been studied using autoradiographic as well as degeneration techniques. The degeneration techniques have confirmed earlier observations that axons from the remaining, normal eye grow across laminar borders into the deafferented lamina A. Autoradiographic techniques, however, have shown further examples of translaminar growth between lamina A and lamina A1 as well as between lamina A1 and lamina C. Although the possibility exists that such growth also occurs between the other C laminae (C1, C2 and C3) such growth is harder to demonstrate since no well defined interlaminar regions exist in this part of the nucleus.In the monocular segment of the nucleus degeneration techniques have shown some translaminar invasion of the deafferented lamina A. Autoradiographic techniques have demonstrated similar growth as well as an abnormal invasion of the most lateral parts of the monocular segment. This latter growth originates in the optic tract as it curves around the nucleus on the way to the superior colliculus.
The development of half‐eyes in Xenopus tadpoles
Authors: Feldman Joan D. , Gaze R. M. , MacDonald Neil 
Published: January 2005

AbstractWhen the nasal or temporal half of a developing eye in Xenopus larvae between stages 32 and 38 was removed, the remaining fragment became rounded up and subsequently developed into a normal eye by mid‐larval stages. The contralateral retinotectal projection was normal in approximately two‐thirds of the animals, when mapped in later tadpole life. The remaining animals showed either some form of mirror reduplication in the visual map or else some degree of lack of order, as compared with a map taken from a normal tadpole of equivalent age. We conclude that the regulative powers of the larval Xenopus eye extend to much later stages (stage 38) than was previously thought; and a possible mechanism for the production of reduplicated maps from half‐eyes is considered.
A cytoarchitectonic and Golgi stody of the red nucleus in the rat
Authors: Reid J. M. , Gwym D. G. , Flumerfelt B. A. 
Published: January 2005

AbstractThe cytology of rubral neurons was investigated using both paraffin and 1 μ thick Epon sections. The neurons were divided into four size categories which form a continuum with regard to cellular characteristics. Giant neurons ( >40 μ) and large neurons (26–40 μ) predominate in the caudal one‐third of the nucleus. Large neurons extend up the ventral, medial and lateral borders of the nucleus into its middle one‐third. The caudal one‐third of the nucleus together with this extension of large cells is designated as the magnocellular part of the nucleus. The more rostral part of the nucleus con tains predominantly small (<20μ) and medium size (20–25 μ) neurons, and this constitutes the parvocellular part or the nucleus. The characteristics of each cell type are described. Camera lucida drawings of the rubral neurons were made in three different planes of section, and the extent of the magnocellular and parvocellular portions of the nucleus was determined. Dorsomedial and ventrolateral subgroups of the manocellular part of the nucleus are found 300–400 μ from the caudal pole. A lateral horn of small and medium size neurons with the addition of a few large neuraons extends from the lateral part of the nucleus 500–700 μ from the caudal pole.Golgi preparations of the red nucleus were examined in three planes of section. Giant and large neurons display short spines on the soma and also, along the entire length of the dendrites. In addition, more elongate spinous processes are seen on these dendrites and are frequently aggregated into tufts at loci on the dendrites or at their terminations. The dendrites of these neurons radiate in all directions from the soma but remain within the confines of the nucleus. Medium size neurons demonstrate radially arranged dendrites. Sparsely positioned spines are seen along the length of the dendrites but are absent on the soma. A number of such neurons demonstrate tufts of elongate spines on their dendrites. The dendrites. The dendrotes of such neurons branch infrequently and remain within the confines of the nucleus. A few dendritic but no somatic spines are seen in association with these neurons.
Golgi studies of the substantia gelationsa neurons in the spinal trigeminal nucleus
Authors: Gobel Stephen 
Published: January 2005

AbstractThis Golgi study identifies three neuronal cell types in the substantia gelatinosa (SG) layer of the spinal trigeminal nucleus. The SG neurons are distinguished from each other based on: (1) dendritic branching pattern, (2) dendritic spine distribution, (3) geometric shape of the dendritic tree, (4) laminar distribution of the dendrites, (5) axonal branching pattern and (6) laminar distribution of the axonal arbor.The islet cell is found in small clusters and its dendrites and axonal arbor are confined within the SG layer. Its dendrites span the full width of the SG layer and extend up to 500 μm in the layer. Dendritic spines are generally sparse with small clustrs of spines found on the higher order dendritic branches. The islet cell axon extends for at least 1 mm in the long axis of the layer. Each of its collaterals divide every 50–100 μm with one branch doubling back in the direction of the cell body and the other branch continuing on in the direction of its parent. In this manner each islet cell generates a profuse axonal plexus in the SG layer.The stalked cell is found individually within the SG layer. Its cell body is usually found in the inner half of the SG layer and its sinuous dendrites cross the SG layer and enter the marginal layer. The stalked cell dendrites emit numerous fine stalk‐like branches and dendritic spines. Its axon emits branches in the SG and marginal layers.The spiny cell is found singly between groups of islet cells. Its extensive dendritic tree spans up to 500 μ rostrocaudally and mediolaterally crossing into both the marginal and magnocellular layers. Spiny cells have evenly distributed dendritic spines along their dendrites in the SG layer. The spiny cell axon sends branches into all three layers of nucleus caudalis. Numerous branches enter the outer 300 μm of the magnocellular layer where they undergo further branching with some branches returing in recurrent fashion toward the SG layer.The three neuronal cell types of the SG layer satisfy all of the morphological criteria for Golgi type II interneurons. Their dendrites are confined within small foci in nucleus caudalis. Their highly branched axone generate many collaterals within the confines of their dendritic trees and do not project out of nucleus caudalis. The SG neurons are considered to be inhibitory interneurons interposed between V nerve primary afferent axons which arborize in the SG layer and second order projection neurons of nucleus caudalis.
Olfactory relationships of the telencephlaon and diencephalon in the rabbit. 1. An autoradiographic study of the efferent connections of the main and accessory olfactory bulbs
Authors: Broadwell Richard D. 
Published: January 2005

AbstractThe efferent connections of the main and accessory olfactory bulbs in the female albino rabbit have been studied using the autoradiographic method for tracing axonal pathways. Following unilateral injections of 3H‐leucine into the main olfactory bulb, radioactively labeled material transported intraaxonally by axoplasmic flow in an anterograde direction from soma to axon terminal is present ipsilaterally in the superficial half of the plexiform layer (IA) of: the entire circumference of the olfactory peduncle, the tenia tecta, the full mediolateral extent of the olfactory tubercle, the entire length of the prepyriform cortex, a transition area between the prepyriform cortex and the horizontal limb of the nucleus of the diagonal band, the nucleus of the lateral olfactory tract, the anterior cortical and posterolateral cortical amygdaloid nuclei (periamygdaloid areas 1, rostral half of 2, 5 of Rose, '31), and the ventrolateral entorhinal cortex (entorhinal areas 1, 2, 4, 5, 7 of Rose, '31). No subcortical or contralateral projection of main bulb efferents was found.After a unilateral injection of 3H‐leucine into the accessory olfactory bulb, transported material could be followed caudally along the dorsal surface of the ipsilateral lateral olfactory tract. This heavily labeled projection is distinct from the unlabeled lateral olfactory tract and has been termed the accessory olfactory tract. Beginning at the level of the caudal third of the olfactory tubercle and extending caudally to the nucleus of the lateral olfactory tract is a group of small neurons intimately associated with the accessory olfactory tract. This cell group is referred to as the bed nucleus of the accessory olfactory tract. Projection sites of the accessory bulb include the bed nucleus of the accessory olfactory tract and layer IA of the medial nucleus and the posteromedial cortical nucleus of the amygdala (periamygdaloid areas 3, 4, PAM, caudal half of 2, 6 of Rose, '31). An additional accessory bulb efferent projection was found to enter the stria terminalis at the level of the medial amygdaloid nucleus and could be traced to a posterior segment of the bed nucleus of the stria terminalis.The autoradiographic findings indicate that the accessory olfactory bulb connects with portions of the amygdala that do not receive afferent input from the main olfactory bulb and provide evidence for the existence of two distinct and separate olfactory systems.