bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fine structure and organization of the infrared receptor relay, The lateral descending nucleus of the trigeminal nerve in pit vipers
Authors: Meszler Richard M. , Auker Charles R. , Carpenter David O. 
Published: January 2005

AbstractThe morphology of the nucleus of the lateral descending tract of V has been studied in species of two genera of pit vipers, cottonmouth moccasin (Agkistrodon piscivorus piscivours), and rattlesnake (Crotalus ruber and Crotalus horridus horridus). The nucleus is the site of termination of primary afferent neurons forming the infrared receptors in the facial pits. It is located on the external surface of the common descending tract of V and contains somata that range in size from 7 to 22 μm in A. A. p. piscivorus and 7 to 27 μm in C. ruber.Electron microscopy reveals that the lateral descending tract contains both Aδ and C fibers. Degeneration experiments indicate that the Aδ fibers are primary afferents. The source of the C fibers is unknown.The lateral descending nucleus in both the cottonmouth and rattlesnake is fundamentally similar in organization. Afferent terminals containing clear spherical vesicles make synaptic contact with dendritic processes within the main neuropil. These axon terminals are also postsynaptic to boutons containing pleomorphic vesicles and some large dense‐core vesicles.The C fibers terminate in a neuropil at the margin of the lateral descending tract on small dendritic processes that appear to come from neurons within the nucleus. This neuropil is found external to the tract in the cottonmouth and internal to the tract in the rattlesnake. The terminals contain clear spherical vesicles and large dense‐core vesicles.The singularity of input to this nucleus is apparently reflected in the morphology. This is discussed in relation to the subnucleus caudalis of the mammalian brainstem.
Hematogenous cells in the central nervous system of developing human embryos and fetuses
Authors: Choi Ben H. 
Published: January 2005

AbstractExamination of large blocks of Epon‐embedded, 1.0‐μm sections of human embryos and fetuses reveal the presence of hematogenous cells in various stages of differentiation in neural tissue. In every embryo and fetus of 10 weeks ovulation age and younger, hematogenous cells are found randomly scattered in the cerebrum, cerebellum, and spinal cord. Many of these cells appear to undergo spontaneous degeneration in neural tissue and become rarer in older fetuses. Also identified in the neuropil of normal embryos and fetuses are cells with the typical morphological appearance of macrophage containing numerous inclusions of various kinds, both inside and outside the blood vessels. In addition, scattered in the subpial, perivascular, and perineuronal regions of the neural parenchyma are small cells with fusiform nuclei and a small amount of cytoplasm as well as cells with a moderate amount of elongated cytoplasm containing various inclusions and oblong nuclei. All of these cells have clumped heterochromatin along the nuclear membrane which differs from other neuroectodermal cells of the developing human CNS.Although there is no direct evidence to indicate transformation of macrophages to “microglia” or vice versa, the presence of cells having similar nuclear morphology and chromatin pattern while appearing to tbe transitional forms of macrophage, varying from undifferentiated to fully developed, suggest a common lineage of these latter types. It is concluded that migration of hematogenous cells into neural tissue is a ubiquitous developmental phenomenon in young human embryos and fetuses.
GABAergic amacrine cells in rat retina: Immunocytochemical identification and synaptic connectivity
Authors: Vaughn James E. , Famiglietti Edward V. , Barber Robert P. , Saito Kihachi , Roberts Eugene , Ribak Charles E. 
Published: January 2005

AbstractGABAergic neurons have been identified in light and electron microscopic preparations of rat retina by an immunocytochemical localization of the GABA‐synthesizing enzyme, glutamic acid decarboxylase (GAD). GAD‐positive neuronal somata are found only in the inner and middle parts of the inner nuclear layer, and GAD‐positive neuronal terminals are observed exclusively within the inner plexiform layer (IPL) and the outermost part of the ganglion cell layer. Dense aggregations of GAD‐positive terminals alternate with less dense zones to form a lamination of the IPL. GAD‐positive terminals contain pleomorphic synaptic vesicles and are the presynaptic elements of conventional synapses onto bipolar and amacrine cell processes, as well as onto the somata and dendrites of ganglion cells. In addition, GAD‐positive terminals are postsynaptic to unstained bipolar terminals and are components of synaptic dyads where they occasionally appear to form reciprocal synapses with the bipolar terminals, and serial synapses with unstained amacrine processes. Probable synaptic contacts between adjacent GAD‐positive terminals also have been observed. Most of the synaptic input to GAD‐positive terminals comes from bipolar cells, while the small remaining input mainly comes from other GAD‐positive terminals. The synaptic output of GAD‐positive terminals is greatest to bipolar cells, followed in decreasing order by GAD‐negative amacrine cells, ganglion cells, and other GAD‐positive cells. The total synaptic output of GAD‐positive cells appears to be more than twice as great as the total input to these cells.The location of GAD‐positive somata, the distribution of GAD‐positive terminals, and the synaptic relationships formed by these terminals all indicate that amacrine cells are the only GABAergic neurons in rat retina. Our observations also indicate that not all amacrines are GABAergic and suggest that GABAergic neurons may be limited to a narrow field subclass of amacrine cell. The findings concerning the synaptic connections of GABAergic amacrines suggest that such cells are the first link in several divergent pathways from bipolar to ganglion cells and that they probably serve more than one function since they feed synaptic activity forward directly upon ganglion cells as well as back upon bipolar cells.
Population magnitudes and distribution of the major modal classes of cat retinal ganglion cell as estimated from HRP filling and a systematic survey of the soma diameter spectra for classical neurones
Authors: Hughes A. 
Published: January 2005

AbstractA survey of diameter spectra in presented for classic neurones of the cat retinal ganglion cell layer. From these, with the aid of retrograde HRP filling for central retina, a set of density distribution maps has been prepared for each of the major modes of the neuronal diameter spectrum. The total population of classical neurones, the presumed ganglion cells of Hughes ('75), confirms published values with a minimum of some 207,000 comprised 5,600 cells in the γ mode, 80,700 cells in the β mode, and 120,700 cells in the γ mode.A proportion of classical neurones in the γ mode do not fill by retrograde transport of HRP from either optic nerve or superior colliculus. Their morphology is characteristic and includes a conspicuous basophilic nuclear bar or fold; they remain subsequent to ganglion cell retrograde degeneration and resemble some prifles of the amacrine layer. It is presumed that they represent a class of displaced amacrine cells.Estimates based on ganglion cell identification by HRP filling indicate populations of about 80,000 cells in both the γ and the β modes and a total count of about 170,000 ganglion cells; a good agreement with Hughes and Wässle's ('76) optic nerve fibre count, but lower than the classic neurone count.It is concluded that the distribution maps for ganglion cells in each of the three modes of the soma diameter spectra are similar in from and resemble that of the total neurone density map. The ganglion cell population of the γ mode in the visual streak is not found to increase in proportion relative to that of the β mode, as has been reported elsewhere.
A light microscopic investigation of the afferent connections of the lateral reticular nucleus in the cat
Authors: Hrycyshyn A. W. , Flumerfelt B. A. 
Published: January 2005

AbstractThe topographical organization of the projections to the lateral reticular nucleus (LRN) of the cat was investigated using the horseradish peroxidase (HRP), silver‐impregnation and autoradiographic tracing methods. Following injection of HRP into the LRN, labelled cells were found mainly within Rexed's laminae VII and VIII of the spinal cord, the contralateral red nucleus, the ventrorostral aspect of the contralateral fastigial nucleus and the contralateral anterior sigmoid and coronal gyri of the cerebral cortex. Animals with injections of tritiated amino acids placed within the pericruciate cortex, red nucleus or fastigial nucleus were processed for autoradiography. In a corresponding series of animals, electrolytic lesions were placed selectively into the above sources of reticular afferents, and terminal degeneration within the LRN was studied by light microscopy. An extensive input from the spinal cord was found to terminate predominantly on the ipsilateral side throughout the rostrocaudal extent of the LRN, except for a small ventromedial area of the rostral parvocellular division and a small rostromedial area of the magnocellular division. The cortical projection terminated diffusely within the middle one‐half of the contralateral magnocellular division, while the rubral projection terminated extensively within the contralateral subtrigeminal division and the dorsolateral region of the rostral magnocellular and neighbouring parvocellular divisions. The rubral projection did not overlap the cortical projection. The fastigial nucleus projected sparsely to the contralateral LRN, mainly to the medial aspect of the rostral two‐thirds of the magnocellular division, with less to the parvocellular and subtrigeminal divisions.The LRN therefore receives spinal and supraspinal projections within at least its rostral one‐half, and these terminate within specific areas in a partially overlapping fashion, whereas the caudal one‐half is primarily a spinal receiving region. No convergence of the rubral and sensorimotor cortical projections was evident.
Habenular asymmetry and the central connections of the parietal eye of the lizard
Authors: Engbretson Gustav A. , Reiner Anton , Brecha Nicholas 
Published: January 2005

AbstractHistochemical and autoradiographic analyses of the axonal transport of horseradish peroxidase and tritiated amino acids were employed to study the central connectivity of the lizard parietal eye. Somata and processes of centrifugal fibers to the parietal eye were localized in tissue of the dorsal sac and in the leptomeningeal sheath of the pineal gland. Analyses of series of transverse sections of the brain showed the left medial habenular nucleus to be subdivided into pars dorsolateralis and pars ventromedialis, and the right medial habenular nucleus not to be so subdivided. Centripetal fibers of parietal eye ganglion cells project to only the pars dorsolateralis of the left medial habenular nucleus and terminate there in two distinct fields. The asymmetry of the lizard habenula may be a specialization associated with the unilateral projection from the parietal eye.
Thalamocortical synapses of pyramidal cells which project from SmI to MsI cortex in the mouse
Authors: White Edward L. , Hersch Steven M. 
Published: January 2005

AbstractElectrolytic lesions were made of the nucleus ventralis posterior pars lateralis thalami and of the nucleus posterior thalami in male CD/1 mice to label thalamocortical axon terminals in mouse SmI cortex. Pyramidal cells in layers II through V of SmI cortex were labeled by the retrograde transport of horseradis peroxidase injected into ipsilateral MsI. Numerous pyramidal cells, particularly in the more superficial layers of SmI cortex, were filled with reaction product so that even their dendritic spines and local axon collaterals were clearly visible. Six well‐filled pyramidal cells with somata in layers III and IV were serial thin‐sectioned, and portions of their dendrites in layer IV were examined with the electron microscope to determine the distribution of their thalamocortical and other synapses. It was found that, in general, different dendrites of a single pyramidal cell formed similar proportions of thalamocortical synapses and that the six pyramidal cells, as a group, also formed similar proportions of thalamocortical synapses with their dendrites in layer IV. In contrast, when the thalamocortical connectivity of the six cells was considered as a function of their depths within the cortex, a clear trend was seen for the proportion of thalamocortical synapses to increase with increasing proximity of the cell body to layer IV. A hypothesis based on the timing of developmental events is proposed to account for this observation.
Locations of androgen‐concentrating cells in the brain of Xenopus laevis: Autoradiography with 3H‐dihydrotestosterone
Authors: Kelley Darcy B. 
Published: January 2005

AbstractThe distribution of hormone‐concentrating cells in the brains of South African clawed frogs, Xenopus laevis, was examined autoradiographically after the administration of 3H‐dihydrotestosterone. Hormone‐accumulating cells were found in cranial nerve nucleus IX‐X and adjacent smaller cells, a presumed medullary vestibular nucleus, a presumed sensory nucleus of cranial nerve V, dorsal tegmental area of the medulla, laminar nucleus of the torus semicircularis, ventral thalamus, and anterior pituitary.The pattern of dihydrotestosterone‐labelled cells differs from previously reported results following testosterone or estradiol administration. Unlike these latter hormones, dihydrotestosterone does not accumulate in anterior preoptic or ventral infundibular nuclei. Both androgens but not estradiol label medullary motor neurons; limbic telencephalic nuclei appear to concentrate only estradiol. Hormone‐concentrating brain nuclei in X. laevis have been implicated in neuroendocrine regulation and the control of male and female reproductive behaviors.
A study of Golgi preparations from the human lateral geniculate nucleus
Authors: Hickey T. L. , Guillery R. W. 
Published: January 2005

AbstractThe Golgi method was used to study nerve cells and their processes in the human lateral geniculate nucleus. Only a few axons were successfully impregnated. These enter the nucleus from the optic radiations and were tentatively indentified as corticogeniculate axons. In one brain from a 2‐week‐old infant these axons showed unusually dense terminal arbors, suggesting that significant developmental changes occur in this fiber system postnatally.Neurons in the magnocellular layers show a great variety of dendritic patterns, and are not readily grouped into well‐defined morphological classes. At one extreme are cells with a restricted dendritic arbor, having dendrites that run a sinuous course close to the perikaryon. At the other extreme, cells have a more extended dendritic arbor; their dendrites are long, relatively straight in some cells, markedly tortuous in others. There is a continuous range of intermediate cell types between the “restricted” and the “extended” cells. Many magnocellular dendrites cross freely into adjacent layers; whereas the short dendrites of restricted cells rarely cross from one layer to another, the dendrites of extended cells may either be confined to a single layer (intralaminar) or may have a translaminar distribution across two or even three layers. Small cells, with dendrites entirely confined to an interlaminar region, have been seen in the magnocellular division of the nucleus on either side of layer 2.Parvocellular elements also show a wide range of dendritic patterns, but the extreme forms of restricted and extended cells are not seen. Parvocellular dendrites commonly are oriented perpendicular to the layers and generally show an intralaminar distribution; translaminar dendrites are extremely rare. A minority of parvocellular neurons have most of their dendrites confined to an interlaminar zone. These “interlaminar” cells have large perikarya close to or in the interlaminar zones, and show a predominant dendritic orientation parallel to the layers. A few parvocellular elements with complex axoniform dendrites were seen, and these dendrites, too, tend to run parallel rather than perpendicular to the layers.
Brainstem innervation of prefrontal and anterior cingulate cortex in the rhesus monkey revealed by retrograde transport of HRP
Authors: Porrino Linda J. , Goldman‐Rakic Patricia S. 
Published: January 2005

AbstractThe cells of origin of projections from the brainstem to the dorsolateral and orbital prefrontal granular cortex and to the anterior cingulate cortex of the rhesus monkey were analyzed by means of retrograde axonal transport of the enzyme horseradish peroxidase (HRP). Following injections in various portions of the dorsolateral prefrontal and in the cingulate cortex, HRP‐positive neurons were found in three main locations: (1) the ventral midbrain including the anterior ventral tegmental area, the medial one‐third of the substantia nigra pars compacta, and the retrorubral nucleus; (2) the central superior nucleus and the dorsal raphe nucleus, primarily in its caudal subdivision; and (3) the locus coeruleus and adjacent medial parabrachial nucleus. Labeled neurons in the raphe nuclei and locus coeruleus were distributed bilaterally. A basically similar pattern of labeled somata was found in the brainstem with HRP injections in the orbital prefrontal cortex. Scattered HRP‐positive cells were found throughout the ipsilateral ventral tegmental area and in ventromedial portions of the retrorubral nucleus, and a large number of HRP‐positive cells were distributed bilaterally in the dorsal raphe and central superior nuclei as well as the dorsolateral pontine tegmentum. However, in contrast to the results obtained with injections on the dorsolateral and medial aspects of the hemisphere, labeled neurons were not found in any portion of the substantia nigra. The neurons labeled retrogradely after injection of HRP in these various regions of the frontal lobe in rhesus monkey correspond both in location and morphology to the monoamine‐containing neurons of the brainstem and are thus very likely the source of dopamine, norepinephrine, and serotonin found in the frontal cortex of the same species (Brown, R. M., A. M. Crane and P. S. Goldman (1979) Brain Res. 168:133–150).
Early development of the circumferential axonal pathway in mouse and chick spinal cord
Authors: Holley John A. 
Published: January 2005

AbstractThe early development of the circumferential axonal pathway in the brachial and lumbar spinal cord of mouse and chick embryos was studied by scanning and transmission electron microscopy. The cellular processes which comprise this pathway grow in the transverse plane and along the lateral margin of the marginal zone (i.e., circumferentially oriented), as typified by the early embryonic commissural axons. The first formative event observed was in the ventrolateral margin of the primitive spinal cord ventricular zone. Cellular processes were found near the external limiting membrane that appeared to grow a variable distance either dorsally or ventrally. Later in development, presumptive motor column neurons migrated into the ventrolateral region, distal to these early circumferentially oriented processes. Concurrently, other circumferentially oriented perikarya and processes appeared along the dorsolateral margin. Due to their aligned sites of origin and parallel growth, the circumferential processes formed a more or less continuous line or pathway, which in about 10% of the scanned specimens could be followed along the entire lateral margin of the embryonic spinal cord. Several specimens later in development had two sets of aligned circumferential processes in the ventral region. Large numbers of circumferential axons were then found to follow the preformed pathway by fasciculation, after the primitive motor column had become established. Since the earliest circumferential processes appeared to differentiate into axons and were found nearly 24 hours prior to growth of most circumferential axons, their role in guidance as pioneering axons was suggested.
Brain cells of the male rhesus monkey accumulate 3H‐testosterone or its metabolites
Authors: Rees Howard D. , Michael Richard P. 
Published: January 2005

AbstractAutoradiography was used to localize target cells for 3H‐testosterone or its labeled metabolites in the brain of the rhesus monkey. Two castrated males were injected intravenously with 3H‐testosterone (2 mCi/monkey) and were killed 1 hour later. In both animals, neurons that concentrated radioactivity in their nuclei were located in a well‐circumscribed system that included the bed nucleus (n.) of the stria terminalis, medial preoptic n., suprachiasmatic preoptic n., anterior hypothalamic area, ventromedial hypothalamic n., cortical, medial, and basal accessory amygdaloid n., mesencephalic reticular n., and periaqueductal gray matter. In contrast to reports in some nonprimate mammalian species, little or no cellular labeling was observed in the lateral septum, arcuate n.‐median eminence, motor nuclei of cranial nerves, or spinal cord.
Connections of vocal control nuclei in the canary telencephalon
Authors: Nottebohm Fernando , Paton John A. , Kelley Darcy B. 
Published: January 2005

AbstractConnections of two telencephalic vocal control nuclei, the hyperstriatum ventrale, pars caudale (HVc), and robust nucleus of the archistriatum (RA), were investigated in adult canaries. Methods used were transport of horseradish peroxidase and 3H‐adenosine and silver staining of degenerating axons. Three nuclei project to HVc: medial nucleus magnocellularis ofthe anterior neostriatum (MAN), nucleus interfacialis (NIf) of midneostriatum, and nucleus uvaeformis (Uva) of the diecephalon. Uva also projects to NIf. NIf and Uva have not been described previously. HVc projects to area X of lobus parolfactorius, to RA, and to field Avalanche of hyperstriatum ventrale. Nucleus RA receives projections from HVc and from lateral MAN. All these projections are ipsilateral. No gross male/female differences were apparent in the projections to and from HVc. Uptake of HRP by cell somata in HVc following localized injections of this substance into RA or HVc suggests that HVc is composed of rostrocaudally organized clusters of cells, with little lateral communication between them.