bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantitative analyses of neuronal development in the lateral motor column of mouse spinal cord. II. Development of motor neuronal organelles
Authors: Holley John A. , Wimer Cynthia C. , Vaughn James E. 
Published: January 2005

AbstractThe development of organelles within presumptive alpha motor neuronal somata was studied by electron microscopic morphometric analysis. Cells with large nuclei were selected for sampling from the lateral motor column of the brachial spinal cord of mouse embryos ranging in age from embryonic day 11 (E11) through E16. The first objective was to compare the cytodifferentiation of alpha motor neuronal somata among three genetically different strains of mice that differ in the development of forelimb reflex behavior and associated pathway synaptogenesis (Vaughn et al., ′75). On the basis of multiple linear regression analyses, no significant differences were found among strains for either the initial levels or rates of cytodifferentiation. As a result, the data were combined for all three strains to analyze organelle changes during early neuronal development. The average areas of perikaryal cytoplasm and nuclei increased significantly. In addition, the relative areas of nucleoli, mitochondria, Golgi complexes, and rough endoplasmic reticulum increased, while the relative areas of heterochromatin and “free” ribosomes decreased. There were significant increases in the number of mitochondria and Golgi complexes per unit area of perikaryal cytoplasm. The average size of mitochondria appeared to increase during development, but was significantly smaller in adult alpha motor neurons than in embryonic specimens. In contrast, the average size of individual Golgi complexes was relatively constant throughout embryonic development, as well as in the adult. In general, the cytodifferentiation of alpha motor neurons appeared to progress in a relatively constant, linear fashion between E11 and E16.
Sources of olfactory inputs to opossum mediodorsal nucleus identified by horseradish peroxidase and autoradiographic methods
Authors: Benjamin Robert M. , Jackson Jan C. , Golden Gregory T. , West Charles H. K. 
Published: January 2005

AbstractSome sources of olfactory input to the opossum mediodorsal thalamic nucleus (MD) were identified by retrograde horserdish peroxidase and anterograde autoradiographic methods. One major source originated from the olfactorytubercle and a narrow strip of piriform cortex bordering the tubercle. The tubercle‐MD projection exhibited a definite spatial organization and included all except the most medial part of MD. The fact that the projection reached the most lateral and ventral extent of MD abutting the intralaminar complex suggests that the entire opossum MD may correspond to only the medial, magnocellular division in the primate and that the equivalents of both the parvocellular and paralamellar divisions may be absent.
Basal ganglia pathways to the tectum: The afferent and efferent connections of the lateral spiriform nucleus of pigeon
Authors: Reiner Anton , Brecha Nicholas C. , Karten Harvey J. 
Published: January 2005

AbstractPrevious studies have demonstrated that the lateral spiriform nucleus (SpL) of the avian pretectum receives a major input from the ipsilateral basal ganglia (Karten and Dubbeldam, 1973) and projects to the ipsilateral optic tectum (Brecha et al., 1976). The present study has further detailed the anatomical organization of the afferent and efferent connections of SpL, with particular reference to (1) the sources of afferent inputs to SpL, (2) the projection targets of SpL, and (3) the laminar termination pattern of the SpL projection to the tectum.The SpL was found to receive clear‐cut major inputs from only three nuclei: (1) the ipsilateral paleostriatum primitivum (PP) of the basal ganglia (the avian homologue of the mammalian globus pallidus), (2) the ipsilateral anterior nucleus of the ansa lenticularis (ALa) of the diencephalon, and (3) the ipsilateral nucleus tegmentipedunculopontinus (TPc) of the mesencephalon. Both TPc and ALa have previously been noted themselves to receive major inputs from the ipsilateral PP (Karten and Dubbeldam, 1973). Two other cell groups may give rise to a slight projection to the ipsilateral SpL: (1) the posterior nucleus of the ansa lenticularis (ALp) of the diencephalon and (2) the nucleus semilunaris (SLu) of the isthmic brainstem. The ALp also receives a major input from PP (Karten and Dubbeldam, 1973), while SLu receives a major tectal projection (Hunt and Kunzle, 1976a).The ipsilateral tectum was found to be the only projection target of SpL. The present data suggest that the SpL projection to the tectum is restricted to layers 8–13, with layers 11–13 receiving the heaviest projection from SpL. Among layers 8–10, layer 9 receives the lightest projection from SpL.The present results indicate that SpL receives only a limited number of inputs, which in all likelihood relay largely basal ganglia input to SpL. Since SpL projects only to the tectum, the sole function of SpL apparently is the transmission of ipsilateral basal ganglia influences to the avian optic tectum. Tectal layers 8–15 have been previously found to represent the layers of origin of the descending pathways of the avian tectum to hindbrain motor and “premotor” cell groups (Reiner and Karten, 1982). In view of the purported involvement of the basal ganglia in motor functions, the basal ganglia pathway to the ipsilateral tectum via SpL may represent a major route by which the avian basal ganglia exert influences over motor functions.
Raphespinal projections in the north american opossum: Evidence for connectional heterogeneity
Authors: Martin G. F. , Cabana T. , Ditirro F. J. , Ho R. H. , Humbertson A. O. 
Published: January 2005

AbstractRetrograde transport studies revealed that the nuclei pallidus, obscurus, and magnus raphae as well as the adjacent reticular formation innervate the spinal cord in the opossum. HRP‐lesion experiments showed that a relatively large number of neurons within the nucleus obscurus raphae and closely adjacent areas of the nucleus reticularis gigantocellularis project through the ventrolateral white matter and that many cells within the nucleus magnus raphae, the nucleus reticularis gigantocellularis pars ventralis, and the nucleus reticularis pontis pars ventralis contribute axons to the dorsal half of the lateral funiculi. Neurons within the rostral pole of the nucleus magnus raphae and the adjacent nucleus reticularis pontis pars ventralis may project exclusively through the latter route.Each of the above‐mentioned raphe and reticular nuclei contain nonindolaminergic as well as indolaminergic neurons (Crutcher and Humbertson, 1978). When True‐Blue was injected into the spinal cord and the brain processed for monoamine histofluorescence evidence for True‐Blue was found in neurons of both types.Injections of 3H‐leucine centered within the nuclei pallidus and obscurus raphae and/or the closely adjacent nucleus reticularis gigantocellularis labeled axons within autonomic nuclei and laminae IV‐X. Labeled axons were particularly numerous within the intermediolateral cell column and within laminae IX and X. Injections of the caudoventral part of the nucleus magnus raphae or the adjacent nucleus reticualris gigantocellularis pars ventralis labeled axons in the same areas as well as within laminae I‐III. When the injection was placed within the rostal part of the nucleus magnus raphae or the adjacent nucleus reticularis pontis pars ventralis axons were labeled within laminae I‐III and external zones of laminae IV‐VII, but not within lamina IX. The immunohistofluorescence method revealed evidence for indolaminergic axons in each of the spinal areas labeled by injections of 3H‐leucine into the raphe and adjacent reticular formation. They were particularly abundant within the intermediolateral cell column and within laminae IX and X. These data indicate that raphe spinal systems are chemically and connectionally heterogeneous.
Electron microscopical observations on the indoleamine‐accumulating neurons and their synaptic connections in the retina of the cat
Authors: Holmgren‐Taylor Ingrid 
Published: January 2005

AbstractThe distribution of indoleamine‐accumulating amacrine cells and their synaptic connections in the retina of the cat were analyzed in the fluorescence, phase‐contrast, and electron microscopes. The findings were compared to recently characterized morphological subclasses of amacrine cells.The indoleamine‐accumulating neurons were visualized after labeling with an exogenous indoleamine, 5, 6‐dihydroxytryptamine. The intravitreal injection of the labeling drug was preceded by treatment with the neurotoxic dopamine‐analogue, 6‐hydroxydopamine, in order to destroy the otherwise interfering dopaminergic processes.The analysis in the fluorescence and phase‐contrast microscopes confirmed earlier reports that the indoleamine‐accumulating cell bodies and processes have a distribution consistent with that of amacrine cells. A stratified branching pattern of the indoleamine‐accumulating processes in the outer half of the inner plexiform layer was discovered. In the inner half of that layer the branching pattern is diffuse.In the electron microscope the indoleamine‐accumulating neurons were seen to have synapses of the conventional type. Their main synaptic contacts are reciprocal synapses with rod bipolar terminals in sublamina b of the inner plexiform layer. They also have synapses with flat cone bipolar terminals in sublamina a, and occasionally with amacrine cells and ganglion cells throughout the inner plexiform layer. Synapses with invaginating cone bipolar terminals, in sublamina b, appear to be rare. The synaptic arrangement with reciprocal synapses with rod bipolar terminals is similar to that of the recently reported AI amacrine cells. It is also similar to that of the indoleamine‐accumulating neurons in the retinae of other mammals investigated earlier.
Quantitative studies of retinal ganglion cells in a turtle, Pseudemys scripta elegans: II. Size spectrum of ganglion cells and its regional variation
Authors: Peterson Ellengene H. , Ulinski P. S. 
Published: January 2005

AbstractRecent evidence suggests that ganglion cell size and its regional variation may be an important feature of vertebrate retinas. Accordingly, we have examined Nissl‐stained, whole‐mounted Pseudemys scripta retinas to determine the soma size spectrum of ganglion cells at different retinal loci. Cell size histograms reveal that at any given point on the retina, a majority of ganglion cells are small (6–10 μm), and in peripheral samples there is some evidence for a second, larger size class (12–15 μm). Comparison of samples along the dorsoventral and nasotemporal axes suggests that there are two major trends in soma size variation. Along the dorsoventral axis, ganglion cell diameter increases sharply from the visual streak (6–7 μm, cf. Peterson and Ulinski, 1979) to the dorsal and ventral periphery (9–10 μm). These changes reflect a tendency towards increased size for the entire distribution as well as a relative decrease in the frequency of small ganglion cells. This soma size variation is significantly correlated with changes in ganglion cell density. Along the nasotemporal axis, temporal ganglion cells are significantly larger than those at more nasal retinal loci. This differences reflects an overall increase in the size of ganglion cells in temporal retina and a small but significant increase in the percentage of neurons larger than 15 μm.
Identified motor neurons in the cockroach exhibit stereotypic peripheral branching and nerve terminal structure
Authors: Denburg Jeffrey L. 
Published: January 2005

AbstractThe peripheral branching of the identified motor neurons Df and Ds which innervate the coxal depressor muscles in the legs of cockroaches was examined using the anterograde transport of a cobaltic ‐lysine complex and the retrograde transport of cobaltous ion or horseradish peroxidase. In all animals the axons of these motor neurons leave the ganglion in the dorsal portion of nerve root 5 and undergo a 180° spiral that brings them directly to the first branch. They leave the nerve root at this branch to innervate the muscles. The pattern of branching of Df within muscles 178 and 179 was highly stereotyped with little variability being observed among identical and homologous muscles within the same and different individuals. The great extent of the neuronal branching within the muscles suggests that a relatively large percentage of the surface area of the muscle fibers is involved in intercellular interactions with the motor neurons. The two motor neurons could also be distinguished by the structure of their axon terminals. Those of Df were beaded and extended either parallel or perpendicular to the muscle fiber. Those of Ds were thinner, wavy, less regular, and appeared with a greater frequency. Identified neurons may therefore be further characterized by their stereotypical peripheral branching and axon terminal structure.
Ultrastructure of the paraphysis cerebri of the water snake Natrix maura L
Authors: Fernández‐Llebrez Pedro , Becerra José , Marín‐Girón Fernando 
Published: January 2005

AbstractParaphyseal epithelial cells of Natrix maura have been studied with light and electron microscopy. They showed a clear polarity apically related to the third ventricle and, basally, to a connective tissue layer which surrounded the whole organ. The apical surface of the cells, attached by junctional complexes, showed many microvilli, scarce cilia, and some pinocytotic coated vesicles. In their apical cytoplasm many mitochondria and a well developed Golgi apparatus and endoplasmic reticulum were observed. Whereas lamellar bodies were abundant and closely related with mitochondria, glycogen particles were absent. Basal cell membrane showed infoldings where pinocytotic coated vesicles were detected. In the connective tissue layer, fenestrated sinusoids and fibrocytes, as well as rare unmyelinated nerve fibers engulfed by Schwann cells, were present. The possible active role of paraphyseal cells in exchanging substances between cerebrospinal fluid and blood is discussed.
Afferent and efferent connections of small nuclei in the posterolateral hypothalamus of the cat
Authors: Fujii Masako 
Published: January 2005

AbstractFour separate neuronal groups, termed the anterior, dorsal, vental, and posterior nuclei of the juxtamamillary complex, were labeled retrogradely form the thalamic lateral posterior nucleus with horseradish peroxidase. The retrograde labeling was predominantly ipsilateral in the anterior, dorsal, and ventral nuclei, while it was predominantly contralateral in the posterior nucleus. The anterior, dorsal, and posterior nuclei could be detected clearly in Nissl sections; the ventral nucleus was only identified by horseradish peroxidase transport. The distribution of afferents to the juxtamamillary nuclei was investigated with the Fink‐Heimer technique. Following lesions of the olfactory tubercle and underlying structures, degenerating fibers in the medial forebrain bundle terminated discretely in the juxtamamillary nuclei. The dense terminal pattern conformed to the borders of the nuclei and was sometimes visible macroscopically. This pattern resembles that of medial forebrain bundle afferents to nuclei gemini in the rabbit and rat. Since the anatomical portions of these nuclei are also similar, it was concluded that the nuclei of the cat are comparable with the nuclei gemini in the rabbit and rat.
Organization of nucleus rotundus, a tectofugal thalamic nucleus in turtles. II. Ultrastructural analyses
Authors: Rainey W. T. , Ulinski P. S. 
Published: January 2005

AbstractNucleus rotundus is a large, tectorecipient nucleus in the dorsal thalamus of the pond turtles Pseudemys scripta and Chrysemys picta. Rotundal neurons form a single, morphologically homogeneous population (Rainey, '79) that projects to the dorsal ventricular ridge in the telencephalon. The present paper examines the morphology of and the distribution of synapses upon rotundal neurons.Astrocytes, oligodendrocytes, and neurons can be identified in both 1‐μm sections stained with toluidine blue and electron micrographs of nucleus rotundus. Rotundal neurons contain euchromatic nuclei and the usual complement of mitochondria, rough endoplasmic reticulum, and free ribosomes in their cytoplasm. They are morphologically homogeneous. Two types of terminal boutons can be defined in rotundus. RA boutons contain round synaptic vesicles and form asymmetric synaptic junctions with rotundal dendrites. FS boutons contain small, flattened or pleomorphic vesicles and form nearly symmetric synaptic junctions with rotundal dendrites and somata. RA boutons occasionally form clusters of contiguous boutons that are presynaptic to one or more thin, central profiles. These profiles are probably the dendritic appendages observed on peripheral dendrites in Golgi material. The distribution of RA and FS boutons along dendrites was investigated by a two‐step procedure. First, rotundal neurons were retrogradely solid‐filled with horseradish peroxidase reaction product. Dendritic diameters were measured at 20‐μm intervals along dendritic shafts to produce a plot of dendritic diameter as a function of distance from the soma. Second, the percentage of membrane on dendritic profiles of different diameters that was contacted by RA and FS terminals was determined from electron micrographs. Comparison of the two plots indicates that both bouton types are distributed along the full extent of the dendritic tree, but RA boutons are much more common on the distal two‐thirds of rotundal dendrites.This analysis suggests that rotundal neurons form a single population of cells that are morphologically homogeneous and project to the forebrain. There is no indication of interaction between neurons in nucleus rotundus, either via axonal collaterals or presynaptic dendrites. Boutons are distributed on rotundal neurons such that FS boutons are prevalent on the somata and most proximal segments of the dendritic shafts, while RA boutons are most common on the more distal dendritic shafts. RA boutons also contribute to synaptic clusters that may center around complex dendritic appendages.
Influence of neonatal cochlear removal on the development of mouse cochlear nucleus: II. Dendritic morphometry of its neurons
Authors: Trune Dennis R. 
Published: January 2005

AbstractRight cochleae were aspirated from 6‐day‐old mice to determine the influence of cochlear integrity on the dendritic development of neurons within cochlear nucleus (CN). At 45 days of age, cochlear destruction was confirmed histologically and the brains were stained by the Golgi‐Cox method to permit dendritic morphometry in CN ipsilateral (deafferented) and contralateral (normal) to the neonatally lesioned cochleae. The dendritic field cross‐sectional area of ventral CN bushy cells was reduced on the deafferented side, as was the total dendritic length of stellate cells throughout ventral and dorsal CN. The neonatal deafferentation had no statistically significant effect on the total dendritic length of those dorsal CN fusiform cells that developed. These dendritic changes are interpreted as lack of development due to the loss of auditory nerve afferents during a critical period of development and indicate that any congenital pathology that compromises the cochlear sensorineural structures may lead to central auditory abnormalities as well.
A Comparison of dendritic spine number and type on pyramidal neurons of the visual cortex of old adult rats from social or isolated environments
Authors: Connor James R. , Diamond Marian C. 
Published: January 2005

AbstractThe present study determined the effect of the housing condition experienced by old adult male rats on the appearance and number of dendritic spines. Specifically, 20‐month‐old rats were killed following 6 months of living in either a social environment (three to a cage) or living alone. The total number of dendritic spines per unit length was examined along segments of oblique, basal, and apical dendritic branches of pyramidal cells from layers II, III, Va, and Vb of the visual cortex. In addition to determining the total spine number, the spines were differentiated into two topographical categories: those with a lollipop configuration (type L) and those with a nubbin configuration (type N). Out results show that neither the total spine density nor the type L spine density were generally influenced by the two housing conditions. However, the density of type N spines was almost always greater on neurons from rats which had been living alone irrespective of the cortical layer or the dendritic segment counted.Some differences in total spine density and type L spine density were noted when neurons from the same environment but different cortical layers were compared, and these findings are discussed. However, the major focus of this paper was to extend our previous report of a selective increase in type N spines with age. We now show that in addition to increasing with age, type N spine density is also selectively increased by the condition of social deprivation.
Ultrastructural observations of the migration and early development of trigeminal motoneurons in chick embryos
Authors: Moody Sally A. , Heaton Marieta B. 
Published: January 2005

AbstractThe migration of immature chick trigeminal (V) motoneurons from a miclline medial column to a lateral nucleus was studied between days 3 and 7 of incubation. The somatic translocation of these cells is preceded by the lateral outgrowth of their axons. At days 3–4 the axons grow within extracellular spaces dorsal to pial end feet at the external limiting membrane. At later ages the axons grow deeper within the intermediate zone. Upon reaching the medial border of the V sensory tract the axons turn ventrally, exit from the neural tube, and grow toward the mandibular arch. The medial column somas rotate from their original radial orientation to lie parallel to the pial surface. They migrate laterally in close association with fiber bundles composed of axonal and trailing processes of medial column and other migrating V motoneurons. Several punctate contacts are made between the migrating cells and the axon bundles; these contacts may stabilize the somas while the growing tips of their axons elongate. During migration the cytoplasm of the V motoneuron matures, acquiring rough endoplasmic retic‐ulum, lysosomes, and multivesicular bodies. Immature synapses contact premigratory, migratory, and postmigratory cells on day 4. Their maturation on day 5 coincides with the onset of active jaw movements.Some V motoneurons secondarily migrate dorsally from the lateral nucleus while their trailing axons are in the head mesenchyme. Few punctate contacts are observed between these cells and their substrate, the longitudinal fibers of the lateral longitudinal fasciculus. Postmigratory dorsal V motoneurons are organelle poor and have few synaptic contacts by day 7. This undifferentiated state may reflect a later onset of the spontaneous movement of their target, the levator palpebrae muscle.