bluuebunny/crossref_metadata_2025_split huggingface dataset:
The embryonic development of the inferior olivary complex in normal and reeler (rlORL) mutant mice
Authors: Goffinet A. M. 
Published: January 2005

AbstractThe development of the inferior olivary complex has been studied comparatively in normal and reeler mutant mice, from embryonic day 14 to birth. In both genotypes, cells migrate tangentially, from the lateral recess of the fourth ventricle, until they reach the ventral rhombencephalon where they enter the olive radially. Some cells also enter the olive laterally, from its external side. In both genotypes, olivary neurons differentiate following the same morphological sequence, both in terms of dendritic deployment and of axonal growth. Olivofugal axons cross the midline as early as E14. Synapses are rare in the inferior olivary complex during the prenatal period. Radial glial cells and the first stages of astrocytogenesis appear similar in both genotypes.The process of olivary maturation begins at E15. In normal embryos, this occurs concurrently with a subdivision of the olivary complex, clearly defined at birth: the principal olive (PO) is “U” shaped and located between the medial accessory olive (MAO) and the dorsal accessory olive (DAO). In reeler mutants, there are abnormalities in the configuration of the inferior olivary complex. Even the earliest lobulated contours are anomalous. The ultimate configuration, though containing the principal elements of the normal complex, is blunted, compact, and very much less “calligraphic” in its undulation than in the normal animal. The reeler dysplasia is mild at E15 and becomes increasingly evident at later developmental stages.These observations show that the reeler gene primarily affects the position of neuronal cells relative to other cellular elements and to fiber strata, while leaving relatively intact the phenomena of cell migration and differentiation. Afferent fibers from spinal and midbrain origin are probably involved in the division of the olivary complex into its components (Martin et al., '80). In addition, the development of the cerebellar cortex could influence the morphogenesis of the olivary nuclei. However, the architectonic malformation of the reeler inferior olive can hardly be exclusively attributed to perturbations of its hodological relationships. It is proposed that the abnormal development of the inferior olive in reeler mutants is largely dependent on a local, intrinsic action of the mutant gene on the olivary primordium.
The growth of neurites from explants of brachial spinal cord exposed to different components of wing bud mesenchyme
Authors: Nurcombe V. , Bennett M. R. 
Published: January 2005

AbstractThe extension of peripheral axons from the brachial spinal cord into the embryonic chick wing bud suggests that the target premuscle cell masses may act as the source of an adhesion gradient which establishes selective nerve pathways. Wing premuscle cell masses were explanted from different stage embryos and tested against age‐matched brachial spinal cord for their ability to promote directional neurite outgrowth. It was found that target premuscle which does not contain myotubes could still elicit directional outgrowth in vitro. In contrast, skin and precartilage were unable to promote neuritic outgrowth significantly. Serum‐free conditioned media were prepared from stages 20‐38 premuscle and tested against age‐matched spinal cord explants. There was an increase in the effects of conditioned media on neuritic outgrowth up to stage 35; conditioned media from older‐stage pre‐ muscles had less effect than that of stage 35 premuscles. These results were shown to be dependent on the maturation of the premuscles and not on that of the spinal cord. When the premuscle conditioned media were preincubated over polylysine substrata, the ability to induce neuritic outgrowth was abolished from media derived from premuscle at stage 27 and older. Conditioned media derived from premuscle at stage 27 or older contain a polylysine‐binding neurite‐promoting factor which is present in greater amounts in more differentiated muscle. The time of first detection of neurite‐ promoting factors in stage 27 premuscle conditioned media correlates with the in vivo stages at which muscle‐specific nerves branch from the main nerve trunks.
Characterization and quantification of peptidergic amacrine cells in the turtle retina: Enkephalin, neurotensin, and glucagon
Authors: Eldred William D. , Karten Harvey J. 
Published: January 2005

AbstractImmunocytochemical methods were used for selective labeling and characterization of amacrine cells of the turtle (Pseudemys scripta elegans) retina which contained neuropeptide‐like immunoreactivity (leu‐enkephalin, glucagon, and neurotensin). Processes of amacrine cells arborized in specific strata of the inner plexiform layer (IPL). Different strata were defined in relation to the boundaries of the IPL. Zero represented the strata nearest the inner nuclear layer and 100 represented the strata nearest the ganglion cells.Antisera directed against leu‐enkephalin labeled approximately 7,300 amacrine cells in a single turtle retina which were concentrated in the region of the visual streak and decreased in density toward the periphery. In retinal regions outside the visual streak the labeled neurons were similar in size and shape with dendritic arbors which lacked a particular orientation. In contrast, in the visual streak, there were particular neurons which were labeled with enkephalin antiserum which had elongated dendritic arbors that ran parallel to the streak. Both types of amacrine cells with enkephalinergic immunoreactivity sent their dendrites into the 0–20 region and the 65–100 region of the IPL.Antisera directed against glucagon labeled approximately 2,500 amacrine cells in a single turtle retina. These cells were concentrated in areas near the visual streak. Amacrine cells labeled with glucagon antiserum had dendritic arbors which were asymmetrically skewed toward one end of the cell and ramified in the 0–20 strata with sparse projections at the 40 and 80 strata of the IPL.Antisera directed against neurotensin labeled 12,800 amacrine cells in a single turtle retina These cells were concentrated in the region of the visual streak. Two distinct amacrine cell types were labeled selectively. One type had a large, vertically oriented cell body (10 × 14 μm) which gave rise to a single 2‐μm‐thick process that branched and ramified within the 45–70 strata. The other amacrine cell type with neurotensin‐like immunoreactivity had a smaller cell body (8 μm) that sent numerous thin dendrites into the same 45–70 strata.The present results indicated that various neuropeptides were present in amacrine cells of the turtle retina and that a specific neuropeptide could be found in more than one anatomical type of amacrine cell. Each anatomical type of amacrine cell had a unique dendritic arborization which ramified within particular strata within the IPL.
A stereotaxic atlas of the brain of the cynomolgus monkey (Macaca fascicularis)
Authors: Szabo J. , Cowan W. M. 
Published: January 2005

AbstractOutline drawings of representative frontal sections of the Macaca fascicularis brain are presented in stereotaxic coordinates. The levels extend from the rostral tip of the neostriatum to the posterior end of the deep cerebellar nuclei. The illustrations are based on photographs of unstained frozen sections of three formalin‐fixed brains in which stainless steel needles were inserted to mark the horizontal zero and several anteroposterior positions. The sections were not stained in order to prevent shrinkage. Stereotaxic measurements were taken in situ of the highest points on the cortical surface, the position of the central and lunate sulcus, and of certain landmarks at the base of the cranium in a large number of monkeys. These data along with brain dimensions and the weight of animals are displayed in tables to indicate individual variations and to aid investigators in determining the best stereotaxic coordinates for a given structure. It is recommended that the cortical point of entry for an electrode or needle be routinely noted and be compared to the parameters in the atlas to compensate for deviations in the horizontal plane.
The large fourth abdominal intersegmental interneuron: A new type of wind‐sensitive ventral cord interneuron in locusts
Authors: Pflüger Hans‐Joachim 
Published: January 2005

AbstractA large interneuron in Locusta migratoria is described that extends from the fourth abdominal ganglion to the brain. The morphology was revealed by injection of cobaltous ions or Lucifer yellow into the cell. As its cell body lies within the fourth abdominal ganglion it is named A4I1, the first identified intersegmental interneuron of the fourth abdominal ganglion. This neuron receives input from highly flexible, wind‐sensitive hairs on the prosternum, the pronotum, and the head (field 1). Sensory connections with A4I1 are made within the prothoracic ganglion. Stimulation of the receptive field initiates spikes in A4I1 which travel anteriorly and posteriorly from the prothoracic ganglion. Intracellular recording from the axon and the soma shows that the cell membrane becomes inactive within the fourth abdominal ganglion. Spikes could be generated within the fourth abdominal ganglion by current injection into the soma. Occasionally excitatory postsynaptic potentials were observed in a soma recording, but up to now there is no evidence for a second spike initiation site.By intracellular current injection into the soma of the left and right A4I1 cell it is shown that the two cells are not electrically coupled.
Occurrence of neurotensinlike immunoreactivity in subpopulations of hypothalamic, mesencephalic, and medullary catecholamine neurons
Authors: Hökfelt Tomas , Everitt Barry J. , Theodorsson‐Norheim Elvar , Goldstein Menek 
Published: January 2005

AbstractBy using indirect immunofluorescence histochemistry combined with the elution‐restaining technique, the presence of a neurotensinlike peptide in some catecholamine neurons in the rat brain has been demonstrated. At the level of the medulla oblongata neurotensinlike immunoreactivity was observed in most of the small‐sized catecholamine (adrenaline) cell bodies in the dorsolateral part of the nucleus of the solitary tract and in some catecholamine (noradrenaline) cells in the medial part. Neurotensin‐positive fibers were found throughout the solitary tract nucleus with increasing concentrations in the rostral direction. Very few neurotensin fibers were seen in the vagal dorsal motor nucleus, which contained a dense network of adrenaline fibers. In the ventral mesencephalon, neurotensinlike immunoreactivity was seen mainly in dopamine cell bodies in the ventral tegmental area, including midline structures, with only single examples of coexistence in the substantia nigra. The dopamine cell bodies of both the A9 and A10 cell groups were surrounded by dense to medium‐dense networks of neurotensin fibers. In the hypothalamus numerous dopamine neurons in the arcuate nucleus exhibited neurotensinlike immunoreactivity. Neurotensin‐positive nerve terminals, partially overlapping catecholamine (mainly dopamine) fibers, were seen in the external layer of the median eminence. The present results demonstrate coexistence of neurotensinlike immunoreactivity and catecholamines in populations of neurons in some of the central catecholamine cell groups and provide a morphological basis for interactions between the peptide and amines.
Neuronal organization of the lateral and basolateral amygdaloid nuclei in the rat
Authors: McDonald Alexander J. 
Published: January 2005

AbstractThe neuronal organization of the lateral (L) and basolateral (BL) amygdaloid nuclei was studied in the rat by using Golgi techniques. All nuclear subdivisions, which were identified in Nissl and acetylcholinesterase preparations, contain spiny class I neurons and spine‐sparse class II neurons. Three of four neurogliaform class III neurons observed were located in the anterior division of BL (BLa). The exact arrangement of class I and class II neurons varies in different portions of L and BL. At the periphery of these nuclei, where L and BL border fiber bundles, major dendrites tend to be oriented parallel to nuclear borders. Many smaller dendritic branches, however, may extend into the adjacent fiber bundles. At most borders between nuclear subdivisions dendritic overlap is minimized by the fact that major dendrites tend to run parallel to subdivisional boundaries. One exception is the junction of BLa with the posterior division of BL (BLp), where unrestricted dendritic overlap of both class I and class II neurons occurs. Within most nuclear subdivisions dendrites of class I and class II neurons ramify freely and exhibit little order. In caudal portions of BLp, however, almost all class I neurons are pyramidal cells with vertically oriented apical dendrites. Dendrites of class II neurons in this region tend to be oriented horizontally, perpendicular to apical dendrites of class I cells. Class II neurons were not evenly distributed in Golgi preparations but were concentrated at the BLa‐BLp border, near the boundary between the dorsolateral and ventromedial subdivisions of L and in the dorsal portion of BLp. The latter cells blend with similar spine‐sparse neurons contained within the external capsule. Analysis of Nissl preparations reveals that small neurons, which correspond to small class II and class III cells, are sometimes observed in a clustered arrangement.
Projections from the periaqueductal gray matter to the B3 cellular area (nucleus raphe magnus and nucleus reticularis paragigantocellularis) as revealed by the retrograde transport of horseradish peroxidase in the rat
Authors: Fardin V. , Oliveras J. L. , Besson J. M. 
Published: January 2005

AbstractAfferent projections from the periaqueductal gray matter (PAG) to the B3 region (nucleus raphe magnus, NRM; and nucleus reticularis paragigantocellularis, NPG) were examined by means of the horseradish peroxidase (HRP) method revealed by using the tetramethylbenzidine (TMB) procedure. Following iontophoretic injection of HRP into the B3 cellular area, numerous labeled neurons were found between the third oculomotor complex and the rostral part of the tegmental nucleus dorsalis of Gudden. The most densely labeled regions were the lateral parts of the dorsal raphe nucleus (wings of the DRN) and Hamilton's nucleus dorsalis of the PAG. Very few neurons were found within the medial part of the DRN. In contrast, results with control injections performed outside the B3 area gave a different distribution of labeled neurons.The functional significance of these connections, particularly those emanating from the wings of the DRN which represent new information, is briefly discussed with regard to mechanisms operative in the control of pain.Although the major PAG‐B3 direct projections could underlie a role for the B3 area in PAG‐induced analgesia, the comparison of our anatomical and behavioral results points out some problems. Indeed, there is no strict correlation between the location of stimulation sites which induce analgesia in the freely moving rats and the distribution within the PAG of B3 projections. These observations lead us to question the role of direct PAG‐B3 connections in the antinociception induced by PAG stimulation and alternative hypotheses are proposed.
The central projections of tooth pulp afferent neurons in the rat as determined by the transganglionic transport of horseradish peroxidase
Authors: Marfurt Carl F. , Turner Dennis F. 
Published: January 2005

AbstractTransganglionic transport of horseradish peroxidase (HRP) or horseradish peroxidase‐wheat germ agglutinin conjugate (HRP‐WGA) was used to map in detail the central projections of trigeminal primary afferent neurons that innervate the dental pulp organ of the rat. In each of ten animals, 0.5–2.0 μl of enzyme solution was injected into the pulp chamber of the first maxillary molar tooth. Postmortem examination of the decalcified teeth in all cases showed that the HRP/HRP‐WGA remained confined to the pulp chamber and pulp roots, with no spread of enzyme into periapical tissues.HRP‐labeled tooth pulp afferent fibers projected to all four rostrocaudal subdivisions of the ipsilateral trigeminal brainstem nuclear complex (TBNC) and to the upper cervical spinal cord. The labeled terminal fields formed a column that stretched relatively uninterrupted from just caudal to the rostromedial tip of the trigeminal principal sensory nucleus to at least the C2 segment of the spinal cord. The density of the afferent projection varied markedly from one rostrocaudal level of the TBNC to the next but was heaviest in an area encompassing the caudal one‐half of the principal sensory nucleus and the rostral two‐thirds of pars oralis. Fibers projected only lightly to pars caudalis, where they terminated preferentially in laminae I, IIa, and the junctional zone between laminae IV and V. HRP‐labeled terminals in C1 and C2 were located almost exclusively in laminae I. In the dorsoventral axis, the terminal fields in the TBNC were located in a surprisingly dorsal part of the complex, well within what has been shown by others to be largely an area of termination for mandibular division fibers. Most fibers ended in medial parts of the TBNC, with the exception of two modestly labeled terminal fields located in the lateral aspects of rostral pars oralis and rostral pars caudalis. No labeled fibers terminated in the contralateral TBNC or contralateral cervical spinal cord.
Neuroanatomical effects of neonatal transection of the corpus callosum in hamsters
Authors: Lent Roberto 
Published: January 2005

AbstractNewborn hamsters were subjected to surgical transection of their corpora callosa under hypothermic anesthesia. After completion of their development, one group of animals had their brains prepared for cyto‐ and myeloarchitectonic analysis. Another group had a small pellet of polyacrylamide gel containing horseradish peroxidase (HRP) implanted in different cortical loci. All were perfused with fixatives and had their brains cut into serial sections. The operated brains showed the following anatomical features: (1) The corpus callosum was partially or totally absent; (2) an abnormal longitudinal bundle was present bilaterally underneath the white matter; and (3) except for the physical displacement of some medial structures, the general architecture of the brain appeared unchanged. Analysis of HRP material revealed that (1) the longitudinal bundle contains cortical fibers, of which at least some are commissural; (2) these cortical fibers display a topographic arrangement within the bundle. Results suggest that brain anatomy of “surgical” acallosal hamsters compares closely with that observed in mice with congenital defects of the corpus callosum, a spontaneous condition which also occurs in humans.
Adult testosterone levels influence the morphology of a sexually dimorphic area in the mongolian gerbil brain
Authors: Commins Deborah , Yahr Pauline 
Published: January 2005

AbstractThis research shows that the medial preoptic area‐anterior hypothalamus (MPOA‐AH) of the gerbil contains a sexually dimorphic area (SDA) whose morphology is influenced by adult gonadal steroids. The characteristics of the SDA were studied initally in gonadally intact males and females and later in males and females that had been gonadectomized or gonadectomized and given testosterone. Coronal sections through the MPOA‐AH were stained with thionin to visualize the SDA. In male gerbils, the SDA is a darkly staining, hook‐shaped structure on either side of the third ventricle, above the suprachiasmatic nuclei and below the anterior commissure. Within the male SDA lies a small, dense cluster of cells, the SDA pars compacta (SDApc). In female gerbils, the SDA is more ovoid and diffuse and the SDApc is absent. Camera lucida tracings and planimeter measurements of the SDA showed that the total volume of the SDA is similar in the two sexes, but the proportion of the SDA that stains darkly and/or stands out clearly from the surround (dark volume) is larger in males. Gonadectomy decreases both total and dark volume of the SDA in both sexes and decreases the volume of the SDApc in males. Testosterone treatment prevents these changes. This is the first report of changes in the gross morphology of the mammalian brain after steroid hormone manipulations in adulthood. The changes in the SDA may be related to testosterone activation of scent marking behavior.
Dorsal cochlear nucleus projections to the inferior colliculus in the cat: A light and electron microscopic study
Authors: Oliver Douglas L. 
Published: January 2005

AbstractIn the Present report retrograde and anterograde labeling techniques are used to study the Projections of the dorsal cochlear nucleus (DCN) to the inferior colliculus in the cat. Horseradish peroxidase (HRP) or wheat germ agglutinin (WGA‐HRP) injections into the inferior colliculus produce large numbers of labeled neurons in the DCN on the opposite side. Labeled cells with projections to the colliculus are identified as fusiform and giant cells and are organized into rostrocaudal bands. The axons of these DCN neurons are labeled by anterograde transport of 3H‐leucine and/or proline and studied in light and electron microscopic autoradiographs. Axons from the DCN terminate within the central nucleus of the inferior colliculus in densely labeled, rostrocaudally oriented bands. Less heavily labeled extensions of these bands are found in the deepest layer of the dorsal cortex, and light labeling is found adjacent to the bands in the central nucleus and in the ventrolateral nucleus. Cells in the dorsomedial DCN project to the most ventromedial part of the central nucleus while progressively more ventrolateral cells in the DCN project to more dorsolateral parts of the central nucleus. This present evidence suggests that the DCN sends afferents to only two of the four subdivisions of the central nucleus. Within these regions, the axons from the DCN form terminal boutons or boutons de passage characterized by medium‐sized, round synaptic vesicles. The labeled endings nearly always make asymmetric synaptic contacts on the dendrites of disc‐shaped and stellate cells in the central nucleus. A few axosomatic contacts are found on one particular cell type, possibly the stellate variety.The results support the hypothesis that each subdivision of the central nucleus receives afferents from a different set of cell types in the auditory nuclei of the lower brainstem. The banding patterns of the efferent cells in the cochlear nucleus and the axons within the central nucleus suggest that these inputs are congruent to the fibrodendritic layers of the central nucleus and may contribute to tonotopic organization in the central nucleus. Finally, the results suggest that each of the two major classes of cells in the central nucleus receives different patterns of inputs from the DCN. These morphological differences could contribute to different electrophysiological responses to the sound stimuli by these cells.