bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fastigial efferent projections in the monkey: An autoradiographic study
Authors: Batton Robert R. , Jayaraman A. , Ruggiero David , Carpenter Malcolm B. 
Published: December 2004

AbstractBecause fastigial efferent fibers partially decussate within the cerebellum and cerebellar corticovestibular projections pass near, or through, the fastigial nucleus (FN), degeneration studies based on lesions in the nucleus leave unresolved questions concerning fastigial projections. Attempts were made to determine fastigial projections in the monkey using autoradiographic tracing technics. Cells in rostral, caudal and all parts of the FN were labeled with [3H] amino acids.Selective labeling of neurons in either rostral or caudal parts of the FN results in transport of isotope primarily via fibers of the contralateral uncinate fasciculus (UF) and the ipsilateral juxtarestiform body (JRB). Fastigial projections to the vestibular nuclei are mainly to ventral portions of the lateral (LVN) and inferior (IVN) vestibular nuclei, are nearly symmetrical and are quantitatively similar on each side.Fastigiovestibular projections to cell groups f and x arise from all parts of the FN and are mainly crossed; modest projections to the medial vestibular nucleus are uncrossed. No fastigial efferent fibers end in the superior vestibular nucleus on either side, or in dorsal regions of the LVN. Crossed fibers descending in IVN terminate in the nucleus parasolitarius. Fastigioreticular fibers arise predominately from rostral regions of the FN, are entirely crossed and project mainly to: (1) medial regions of the nucleus reticularis gigantocellularis, (2) the dorsal paramedian reticular nucleus and (3) the magnocellular part of the lateral reticular nucleus. Fastigiopontine fibers, emerge with the UF, bypass the vestibular nuclei and terminate upon the contralateral dorsolateral pontine nuclei. Crossed fastigiospinal fibers separate from fastigiopontine fibers and descend in the ventrolateral tegmentum beneath the spinal trigeminal tract; in the medulla and upper cervical spinal cord these fibers are intermingled with those of the vestibulospinal tract. Fastigiospinal fibers terminate in the anterior gray horn at C‐1 and probably descend further.Ascending fastigial projections arise from caudal parts of the FN, are entirely crossed and ascend in dorsal parts of the midbrain tegmentum. Label is transported bilaterally to the superior colliculi and the nuclei of the posterior commissure. Contralateral fastigiothalamic projections terminate in the ventral posterolateral (VPLc and VPLo) and in parts of the ventral lateral (VLo) thalamic nuclei. The major region of termination of fastigiothalamic fibers is in VPLo.Fastigiothalamic projections, probably conveying impulses concerned with equilibrium and somatic proprioception, appear to impinge upon thalamic neurons receiving inputs from less specialized receptors that signal information concerning position sense and body movement. More modest fastigial projections to VLo could directly influence activity of neurons in the primary motor cortex.
An autoradiographic analysis of postnatal cell proliferation in the normal and degenerative mouse retina
Authors: Blanks Janet C. , Bok Dean 
Published: December 2004

AbstractLight microscopic autoradiography, following injection of tritiated thymidine, was used to study the postnatal development of cells in the inner nuclear layer (INL) of the normal and rd (C57BL/6J‐rd le) mouse retina. Specific attempts were made to determine whether some bipolar cell degeneration occurs in conjunction with previously noted photoreceptor cell degeneration in the retina of the mutant (rd) mouse. A differential count of cell types in the INL of both the central and peripheral retina indicates that the same ratio of bipolar cells to Müller cells (3:1) exists in the normal and the rd retina during postnatal development. The density of cells in the INL was similar in both groups during development and similar decreases in width of the INL occurred in the normal and rd mouse during maturation. In addition, autoradiographic analysis of the proliferation of postnatally forming bipolar cells suggested that the rd gene is not lethal to the bipolar cell population which forms after birth. The labeling index (percent labeled cells) in the INL, determined as a function of the date of 3H‐thymidine injection and assessed in the mature retina (day 41), was similar in both mice. Analysis of the number of silver grains/nucleus presented a more complete picture of how the progenitor pool of cells contributes to the cell types formed postnatally in the retinas of both mice.The conclusion that bipolar cell death does not occur to any significant degree in the retina of the rd also suggests that transneuronal degeneration does not occur in the retina of the mutant mouse during the period (up to day 41) when most of the photoreceptor cells die. The observation in both groups of mice that cell density remains constant between postnatal day 14 and day 41, while the width of the INL changes tremendously, suggests that there is a significant redistribution of cells during growth of the eyeball and/or cell death which occurs in all cell types found in the INL in both the normal and mutant mouse.
Some visual and other connections to the cerebellum of the pigeon
Authors: Clarke P. G. H. 
Published: December 2004

AbstractBy anatomical techniques it has been shown that folia VIc‐IXc of the pigeon cerebellum receive inputs from the following groups of neurons: the medial and lateral pontine nuclei, the superficial synencephalic nucleus, the medial spiriform nucleus, the inferior olive, and the deep cerebellar nuclei. From all but the last of these, the projection is mainly crossed, though the uncrossed component from the lateral pontine nucleus is not insubstantial. The input from the superficial synencephalic nucleus provides a direct pathway from the retina to the cerebellum (folia VIc, VII, VIII and IXc). Less direct visual pathways reach the cerebellum via the following routes: (i) the superficial synencephalic nucleus projects ipsilaterally to the lateral pontine nucleus and sparsely to the inferior olive; (ii) the tectum projects ipsilaterally to the lateral and medial pontine nuclei, though the latter connection is sparse.In electrophysiological experiments, the importance of the tecto‐pontine component of the projection has been demonstrated by cooling the tectum while recording visual responses from the cerebellum. The visual receptive fields of pontine cells have been analysed. They vary in extent from 10° to the whole monocular field. They respond best to moving targets, preferring speeds of 20 to 60°/second, and are usually direction‐selective.
Localization of sensory neurons traversing the stellate ganglion of the cat
Authors: Oldfield B. J. , McLachlan Elspeth M. 
Published: December 2004

AbstractThe distribution of sensory cells whose axons traverse the stellate ganglion and project via sympathetic cardiac nerves to the heart of the cat has been examined quantitatively. Horseradish peroxidase (HRP) injected at multiple sites in the right stellate ganglion, or applied to the middle cardiac nerve, labelled small numbers of cells in the thoracic dorsal root ganglia (DRG) from T1 to T8. These cells were most numerous between T2 and T5 and were consistently small (< 40 μm) relative to other cells in the DRG. When HRP was applied to middle cardiac nerves, the numbers of labelled sensory cells always exceeded the numbers of myelinated axons counted in the same nerves from other cats. It is concluded that the distribution of the cells of cardiac sensory fibres is more extensive within thoracic DRG than has been previously reported, and it is suggested that such fibres travelling in the sympathetic cardiac nerves may be either myelinated or unmyelinated.
Development of the diencephalon in the rat. I. Autoradiographic study of the time of origin and settling patterns of neurons of the hypothalamus
Authors: Altman Joseph , Bayer Shirley A. 
Published: December 2004

AbstractGroups of pregnant rats were injected with two successive daily doses of 3H‐thymidine from gestational day 13 (E13+14) until the day before birth (E21+22). This double labelling procedure was combined with an injection schedule of a single day delay between groups (E13+14; E14+15; E1516.). The two injections assured the comprehensive labelling of practically all neurons of a given structure prior to the onset of their differentiation (comprehensive labelling), whereas the progressive daily delay in injections made it possible to estimate the proportion of neurons formed in various regions of the hypothalamus on a single day. Hypothalamic areas or nuclei were assigned into four classes on the basis of their cytogenetic isochronicity. Structures composed of the earliest arising (class 1) neurons constitute a lateral tier that includes the lateral preoptic and lateral hypothalamic areas, and the lateral mammillary nucleus. Structures composed of early arising (class 2) neurons form a heterogeneous collection of nuclear systems, including the Para ventricular, intern clear and supraoptic magnocellular neurons, and several intermediate tier nuclei of the anterior and posterior hypothalamus. The late arising (class 3) and latest arising (class 4) nuclei constitute a periventricular system anteriorly and a more extensive region posteriorly. The latter two nuclear systems may constitute the hypophysiotropic area of the hypothalamus. The nuclei of the mammillary system, which are produced sequentially, are distinguished from other hypothalamic structures by their more rapid generation time. Internuclear labelling gradients were used to infer the neuroepithelial site of origin and setting pattern of neurons. common sites of origin were indicated for the following structures: the magnocellular neurohypophysial neurons; the neurons of the dorsomedial and ventromedial nuclei; and the neurons of the tuberomammillary and arcuate nuclei. The sites of origin of these groups of nuclei were related to specialized ventricular linings in the mature hypothalamus.
Radial organization of thalamic projections to the neocortex in the mouse
Authors: Frost Douglas O. , Caviness Verne S. 
Published: December 2004

AbstractThe intracortical distributions of the thalamic projections to a large number of neocortical fields are studied by the anterograde degeneration method in the mouse. The basic radial distribution of terminating thalamofugal axons is uniform throughout the mouse cortex and is essentially the same as that encountered in other mammalian species. Terminating axons are concentrated in three tiers: an outer tier in layer I, a middle tier in layers IV and/or III, and an inner tier in layer VI. In most fields, terminating axons also extend, to some extent, into layer V. Variations are encountered from field to field, particularly in the density and degree of divergence of projections and in the radial extent of individual tiers with respect to cytoarchitectonic layers.In accord with other studies, the thalamic projections to each field appear to be composed of two general axon classes. Class I axons terminate densely in the middle tier, seem to be of large caliber, and often have collaterals to the other tiers. Class II axons do not terminate densely in the middle tier and seem to be of small caliber. Terminating class II axons may be distributed to one or more tiers and may be concentrated in the inner and/or outer tiers. The thalamic projection to each field has its origin in multiple nuclei. All thalamic nuclei projecting to the neocortex appear to have class II projections and many also have class I projections.Patterns of degeneration in the cortex associated with lesions in different positions in many nuclei suggest that thalamic relay neurons are organized along “lines of projection”–neurons in the same line projecting to the same tangentially restricted cortical region. The neurons of origin of class I and class II axons are intermixed along the lines of projection.
Neurotensin: Topographical distribution in rat brain by immunohistochemistry
Authors: Jennes Lothar , Stumpf Walter E. , Kalivas Peter W. 
Published: December 2004

AbstractThe anatomical distribution of neurotensin perikarya and fibers in rat brain, spinal cord, and pituitary has been studied by immunohistochemistry. Neurotensin immunoreactivity is widely distributed throughout the brain, especially in forebrain and midbrain limbic structures, but also in the pons, medulla, and spinal cord.Areas with low immunoreactivity, or lack of it, stand out and include most of the hippocampus, isocortex, ventromedial and dorsomedial hypothalamic nuclei, somatomotor nuclei, cerebellum, and dorsal column nuclei.Strong neurotensin immunoreactivity is found in accumbens‐caudateputamen, central and medial amygdaloid nuclei, ventrolateral septum, pars lateralis of the nucleus of the stria terminalis, paraventricular, periventricular, and lateral hypothalamus, median eminence, thalamic intralaminar and periventricular nuclei, ventral tegmentum, central gray, certain raphe nuclei, locus ceruleus, necleus parabrachialis medialis and lateralis, nucleus of the solitary tract and area postrema, spinal and trigeminal substantia gelatinosa, as well as certain cells in the anterior pituitary.The anatomical data suggest the existence of neurotensin circuits for (1) the control of autonomic‐endocrine functions, involving the nucleus tractus solitarii, area postrema, nucleus ambiguus, nucleus parabrachialis, nucleus paraventricularis, nucleus centralis amygdalae, and pars lateralis of the bed nucleus of the stria terminalis; and (2) for the transmission and modulation of certain somatosensory qualities, involving the spinal substantia gelatinosa, trigeminal sensory nuclei, and thalamic intralaminar nuclei.
Reissner's fiber in the sacral cord and filum terminale of the possum Trichosurus vulpecula: A light, scanning, and electron microscopic study
Authors: Tulsi R. S. 
Published: December 2004

AbstractThe ending of Reissner's fiber (RF) and structural features associated with gaps or fissures in the rostral part of the filum were investigated using light, scanning, and transmission microscopic techniques in young and mature possums of both sexes. To the best of the author's knowledge the report contains results of the first successful application of the SEM for a study of RF in the spinal cord. Some new observations suggest that while the bulk of RF is formed by the subcommissural organ and moved caudally, additional secretory products may be added by ependymal cells in the sacral and possibly other regions of the spinal cord. Evidence is provided in support of the view that RF may pass through gaps in the ependymal lining in the rostral part of the dorsal wall of the filum terminale and caudal end of the sacral cord to reach the periependymal loose tissue and possibly the subarachnoid space.The region of the gap shows the surface of the ependyma facing the lumen of the filum to be covered with microvilli and cilia, and to be in direct continuity with the external surface of the ependyma covered with basement membrane with glial processes and collagen fibers in close proximity. The present results confirm and extend observations reported by Wislocki et al. ('56).
Quantitative analysis of the optic nerve of the north american opossum (Didelphis Virginiana): An electron microscopic study
Authors: Kirby Michael A. , Clift‐Forsberg Lori , Wilson Paul D. , Rapisardi Salvatore C. 
Published: December 2004

AbstractOn the basis of an electron microscopic examination of the optic nerve of the North American opossum it was estimated that the nerve has approximately 100,000 axons, of which 98% are myelinated, The myelinated axons ranged from 0.3 to 6.7 μm in diameter (mean 1.6 μm), while unmyelinated axons were 0.2 to 1.6 μm in diameter (mean 0.6 μm). Axoplasm and axon (axoplasm plus myelin) diameter spectrums were unimodal and positively skewed. The mean of the ratio of axoplasm to axon diameter was 0.69. However, this ratio varied widely across axons and was nonlinearly distributed, decreasing with axon diameter. An inverse relationship between axon density and the proportion of large‐diameter axons was noted. A region having a low axon density and a high proportion of large‐caliber axons was located dorsally in a cross section obtained near the eye. However, in sections obtained near the optic chiasm, regions having the highest proportion of large‐diameter axons were in the ventral periphery of the nerve. It is suggested that within the 40‐mm length of the nerve, there may be a change from a retinotopic organization to an organization of axons according to their diamerer and central targets.
The developmental morphology of Torpedo marmorata: The electric lobes
Authors: Richardson Guy P. , Fox Geoffrey Q. 
Published: December 2004

AbstractThe development of the electric lobes of Torpedo marmorata has been investigated using light and electron microscopical techniques. The lobe Anlagen become visible in the rhombencephalon along the floor of the 4th ventricle at the 10‐mm stage. Many of the neuroepithelial cells in the Anlagen differentiate, becoming postmitotic and axonic by the 24 mm stage. Proliferative zones of neuroepithelial cells disappear from the electric lobes by the 30‐mm stage. After their initial, early differentiation the electromotor neurons remain monopolar until the 40‐mm stage when dendrite formation begins. The differentiation of the electromotor neuron from a mono‐ to an immature multi polar form occurs between the 40‐ and 55‐mm stages and involves, in addition to dendrite formation, a change from a pear‐shaped to a spherical cell body, a dramatic increase in cytoplasmic volume, a centralization of the nucleus, an enlargement of the nucleolus and its migration away from the nuclear membrane, and differentiation of the axon hillock. The electric lobes are invaded by sinusoids at the 24‐mm stage but formation of the capillary network by sprouting cords of endothelial cells begins later at the 40‐mm stage. Neuronal cell death (26–74‐mm stages) appears to be mainly an autolytic process and the debris is removed by immature glial cells. Afferent fiber growth cones are first recognized in the lobes at the 60‐mm stage but synapses are not observed until the 78‐mm stage. Myelination begins in the electric lobes concomitantly with the onset of synaptogenesis. A twofold increase in dendrite length occurs over the period when synapses begin to form in the lobes but dendritic maturation is not complete until the neonatal (120‐mm) stage. The results are discussed in relation to the development of the electric organs.
A Golgi and ultrastructural study of the monkey globus pallidus
Authors: Difiglia Marian , Pasik Pedro , Pasik Tauba 
Published: December 2004

AbstractGolgi preparations reveal that the most frequent type of pallidal neuron (principal cell), which has been recognized in all previous reports, is large (20–50 (Am)), fusiform, with dendrites up to 700 μm long. Large neurons of globular shape are less frequently impregnated. The morphology of dendrites varies considerably within the same neuron. Some exhibit numerous spines and protrusions and are seen to terminate in elaborate arborizations. A small interneuron (12 (μm)), with relatively short dendrites, up to 150 μm, and a short sparsely branching axon is observed less frequently. At least two types of afferent axons are present. A small‐diameter fiber from the neostriatum enters the pallidum in bundles and gives rise to numerous thin branching processes with varicosit es about 1 μm in size. The axon collaterals are oriented orthogonal to the main axon and parallel to the dendrites of principal cells. A large‐caliber fiber with clusters of 2–3‐μm swellings can also be seen in close proximity to large pallidal dendrites.Ultrastructurally, principal cell dendrites (trunks, spines, and protrusions) are totally covered by synapsing axon terminals. In contrast, some small dentrites, presumed to belong to interneurons, form very few synapses. At least six categories of profiles containing vesicles are observed. One group has cytologic features of dendrites and participates in serial and triadic synapses with other profiles in the pallidal neuropil.Results suggest that the synaptic organization of the globus pallidus may be viewed as a repetitive, geometric arrangement of striatal and other afferent axons ensheathing and synapsing with the dendrites of principal cells. This pattern is interrupted by the presence of presynaptic dendrites, probably belonging to interneurons, which participate in complex synaptic arrangements.
The fine structure of laminae IV, V, and VI of the macaque spinal cord
Authors: Ralston Henry J. 
Published: December 2004

AbstractThe normal fine structure of the deep dorsal horn (laminae IV, V, and VI) of the lumbosacral spinal cords of adult Macaque monkeys was examined. Axonal profiles with rounded synaptic vesicles (R) constitute about one‐fourth of the total synaptic population in lamina IV and gradually increase in number to comprise more than a third of the synaptic population in lamina VI. Conversely, profiles with flattened vesicles (F) make up two‐thirds of the synaptic population in lamina IV and slightly more than half in lamina VI. Axons which form the central profile (C) of synaptic glomeruli are more common in laminae IV and V than in lamina VI, and constitute about 5% of the total synaptic population. Profiles with large granular vesicles (LGV) are relatively uncommon in all the deep laminae.The vast majority of synaptic contacts are axodendritic. Axoaxonal synapses are formed between F, and R or C profiles, the F profile being the presynaptic component.It is concluded that there are both light and electron microscopic morphological differences among the deep laminae, as well as between the deep laminae and the superficial laminae of the spinal cord. Therefore, it appears that Rexed's original schema for laminar organization of the dorsal horn in the cat is also applicable to that of the monkey. In view of the relative paucity of LGV profiles in the deep dorsal horn, it is suggested that synapses in these laminae which contain monoamines or peptides are more likely to be associated with clear synaptic vesicles than granular synaptic vesicles.