bluuebunny/crossref_metadata_2025_split huggingface dataset:
The accessory optic system of rodents: A whole‐mount HRP study
Authors: Terubayashi Hirofumi , Fujisawa Hajime 
Published: January 2005

AbstractThe three‐dimensional fiber pathways of the accessory optic system in three species of rodents (rat, golden hamster, guinea pig) were examined on whole‐mounted preparations of the diencephalon and the midbrain, without sectioning, by anterograde labeling of retinal axons with horseradish peroxidase (HRP). HRP histochemical studies on the serial coronal sections were also done. In this study, only the accessory optic system on the side contralateral to the eye injection of HRP was clearly detected. The rat accessory optic system consisted of the inferior fasciculus, the superior fasciculus, the medial terminal nucleus, the lateral terminal nucleus, and the dorsal terminal nucleus. After the inferior fasciculus arrived at the ventromedial border of the cerebral peduncle, some fibers from the inferior fasciculus ran caudally to the medial terminal nucleus. The remaining fibers from the inferior fasciculus further proceeded dorsocaudally on the surface of the cerebral peduncle and left the inferior fasciculus at various levels of the cerebral peduncle to be mixed up with the fibers from the superior faciculus. The golden hamster accessory optic system also consisted of the inferior fasciculus, the superior fasciculus, the medial terminal nucleus, the lateral terminal nucleus, and the dorsal terminal nucleus. However, all fibers of the inferior fasciculus ran caudaily on the lateral surface of the hypothalamus or along the ventromedial border of the cerebral peduncle to terminate at the medial terminal nucleus. The guinea pig accessory optic system and rat accessory optic system were similar, but the posterior fibers of the superior fasciculus decreased in number, and the dorsal terminal nucleus and the posterior portion of the lateral terminal nucleus were not observed in the guinea pig accessory optic system.
Fine structural studies of cholecystokinin‐8‐like immunoreactive neurons and axon terminals in the nucleus of tractus solitarius of the rat
Authors: Takagi Hiroshi , Kubota Yoshiyuki , Mori Shiro , Tateishi Kayoko , Hamaoka Toshiyuki , Tohyama Masaya 
Published: January 2005

AbstractCholecystokinin (CCK)‐8‐like immunoreactive structures in the nucleus of tractus solitarius (NTS) were studied by using the peroxidase‐antiperoxidase (PAP) immunohistochemical method. Immunoreactivity was localized in cell bodies and nerve fibers. The perikarya were oval or fusiform (average length 13 μm) and were mostly located in the dorsal half of the medial subnucleus of the NTS at the level of the area postrema (AP). One to three straight immunoreactive dendritelike processes emerged from the perikarya. Neurons that had first been identified under light microscopy were also studied by electron microscopy. Each neuron had a moderate amount of cytoplasm and an oval or elongated nucleus that was eccentrically located in the soma. A few synaptic inputs were found on the CCK immunoreactive perikarya, while a moderate number were seen on both proximal and distal dendrites. These neurons received both asymmetrical and symmetrical synaptic inputs. The immunoreactive dendrites were most frequently in asymmetrical synaptic contact with nonreactive boutons (max. 2.7 μm in diameter) containing fairly densely packed, small round vesicles.CCK immunoreactive boutons located in the NTS at the level of the AP were analyzed using electron microscopy; these boutons formed asymmetrical synaptic contact with other neuronal elements. Their postsynaptic targets were immunoreactive and nonreactive perikarya and dendrites.These data suggest that CCK‐containing afferents might affect the neurotransmission of heterogenous types of solitary neurons.
Time course of mossy fiber degeneration following pontine ablation in the rat
Authors: Anderson W. A. , Flumerfelt B. A. 
Published: January 2005

AbstractThe normal ultrastructure of mossy fiber terminals within the ansiform lobule of the rat was investigated in parasagittal sections of the cerebellar cortex. Four types of mossy fiber varicosities (simple and complex dispersed, simple and complex clustered) were distinguished on the basis of the presence or absence of clublike excrescences and the concentration of synaptic vesicles within the cortical zone of the terminal.Removal of the pontocerebellar input to the contralateral cerebellar hemisphere was performed electrolytically. Such lesions, when placed in the basilar pontine gray using a dorsal approach, resulted in the degeneration of nearly the entire population of mossy fiber varicosities within the contralateral ansiform lobule. As early as 3 days following pontine ablation, degenerative changes were observed within the synaptic portions of the mossy fibers. Two distinct axonal reactions were apparent within this population of degenerating varicosities. A small population of mossy fiber varicosities (12%) of the simple clustered variety underwent a rapid course of electron‐dense degeneration, which was complete by the fifth day. These mossy fiber varicosities were very susceptible to phagocytosis by reactive glial elements. The second group which consisted of simple (60%) and complex (26%) varieties of dispersed terminals, underwent a very slow course of electron‐dense degeneration. Reactive glial cells were rarely found in association with this second group of degenerating varicosities. As a result, most glomeruli were found to contain debris from degenerating mossy fiber varicosities throughout the first 57 days following pontine lesions. The majority of the cerebellar glomeruli, however, were denervated by 80 days.
The architecture and some of the interconnections of the rat's amygdala and lateral periallocortex
Authors: Turner Blair H. , Zimmer Jens 
Published: January 2005

AbstractThe connections between the cerebral cortex and amygdala were studied in the rat by means of silver degeneration techniques. To help define the sites of origin and termination of cortico‐amygdaloid connections, the architecture of the cortex and the amygdala was studied in sections from normal brains stained for cells, fibers, acetylcholinesterase activity, and heavy metals (Timm staining).The amygdalopetal cortex on the dorsal and lateral surfaces of the rat brain is limited to a narrow strip of periallocortex that forms the dorsal wall and lip of the rhinal sulcus. Histochemical stains indicate that this cortex comprises several stages of cortical differentiation that are intermediate between the ventrally adjacent allocortices and the dorsally adjacent neocortices. The lateral periallocortex consists of two major divisions, the agranular insula (area 13) anteriorly, and a temporal agranular cortex (areas 35 and 36) posteriorly. The principal amygdaloid target for this cortex is the lateral nucleus. Anterior area 13 and posterior area 35 project to the anterior and posterior halves, respectively, of the medial division of this nucleus, while posterior area 13 and anterior area 35 projects to the lateral division of this nucleus. All divisions of periallocortex also send projections to a part of the putamen that surrounds the lateral half of the central nucleus. All of area 13 also sends efferents to the anterior part of the basal nucleus, while the anterior half of area 13 sends an additional projection to the central nucleus.Comparison of these data with those obtained in the cat and monkey suggests that a constant feature of eutherian brains is the existence of a subset of efferents from each of the four neocortical sensory systems that is routed so as to provide subcortical limbic structures with modality‐specific information. The initial sequence in this sensorilimbic system consists of one or more modality‐specific corticocortical relays that originate in the primary sensory cortices and terminate in one of four topographically adjacent, modality‐specific areas of the insular and temporal cortices. These insular and temporal areas then each establish modality‐specific connections within the amygdaloid complex. The final set of relays presumably comprises the connection that each of these amygdaloid areas makes with the autonomic and endocrine nuclei of the brain.
The distribution of glutamic acid decarboxylase immunoreactivity in the diencephalon of the opossum and rabbit
Authors: Penny G. R. , Conley M. , Schmechel D. E. , Diamond I. T. 
Published: January 2005

AbstractWe have examined the distribution of neurons and terminals immunoreactive for glutamic acid decarboxylase (GAD) in the thalamus and adjacent structures of the opossum (Didelphis virginiana) and the rabbit and have compared this distribution with the distributions we described previously for the cat and bushbaby (Galago senegalensis). The significance of these experiments depends, first, on the fact that GAD is the synthetic enzyme for GABA, and therefore that GAD immunoreactivity is a marker for GABAergic inhibitory neurons, and second, on previous findings that suggest that GABAergic neurons in the dorsal thalamus are local circuit neurons.In both cat and Galago, GAD‐immunoreactive neurons are distributed essentially throughout the entire thalamus. In the opossum, GAD neurons are chiefly confined to the dorsal lateral geniculate nucleus and the lateral extremity of the lateral posterior nucleus. The distribution of GAD neurons in the rabbit is intermediate between that found in the opossum on the one hand and cat and Galago on the other. Like opossum, about 25% of the neurons in the lateral geniculate nucleus of rabbit are GAD immunoreactive. Unlike opossum, however, as many as 18% of the cells in the ventral posterior nucleus of the rabbit are GAD immunoreactive, and scattered cells are also labeled in other thalamic areas, such as the medial geniculate and the lateral group.Aside from the findings in the dorsal thalamus, the chief observation is that GAD‐immunoreactive neurons and/or terminals densely fill all principal targets of the optic tract, including the ventral lateral geniculate nucleus; the superficial gray layer of the superior colliculus; the anterior, posterior, and olivary pretectal nuclei; the nucleus of the optic tract; and the medial and lateral terminal nuclei of the accessory optic tract.These results support the idea first put forward by Cajal that local circuit neurons increase in number during the course of the evolution of complex mammalian brains. If we can assume that the conservative opossum retains characteristics reflecting an early stage of mammalian evolution, the results suggest that thalamic local circuit neurons arose first in the visual system and only later in evolution spread throughout the thalamus.
Comparative localization of neurons containing ovine corticotropin releasing factor (CRF)‐like and neurophysin‐like immunoreactivity in the diencephalon of the pigeon (Columba livia domestica)
Authors: Péczely Péter , Antoni Ferenc A. 
Published: January 2005

AbstractNeural elements immunoreactive for ovine corticotropin releasing factor‐like immunoreactivity(oCRF‐LI) were shown to be present in the diencephalon of the pigeon by using peroxidase‐antiperoxidase immunocytochemistry. The external zone of the anterior median eminence contains a rich network of varicose oCRF‐LI fibers in close proximity to the pituitary portal capillaries. Perikarya reactive for oCRF‐LI were found in several regions known to innervate the median eminence and gave rise to axons which joined the hypothalamo‐hypophyseal tract. A close topographical relationship between neurophysin‐containing and oCRF‐LI‐containing neurons was found in anterior periventricular regions. These observations suggest that oCRF‐LI material might be involved in the hypothalmic control of anterior pituitary hormone secretion in birds, and that neurophysin‐ and oCRF‐LI‐producing nerve cells might be functionally coupled.
Developing descending neurons of the early Xenopus tail spinal cord in the caudal spinal cord of early Xenopus
Authors: Nordlander Ruth H. 
Published: January 2005

AbstractThe enzyme horseradish peroxidase (HRP) was used to describe and identify neurons, axons of which initiate the earliest descending pathways of the tail spinal cord of Xenopus embryos and larvae. Spinal cords were pierced at different rostrocaudal levels with fine insect pins coated with HRP. The resulting pattern of cellular labeling indicated that primitive sensory (Rohon‐Beard) axons were at the lead of developing descending tracts followed by axons of primary motor neurons. Axons of these two neuron types travel in widely separated fascicles located dorso‐ and ventrolaterally, respectively. Subsequently, axons of several morphologically distinct intersegmental interneurons establish several additional fascicles positioned dorsal to the descending motor axons. Descending supraspinal axons appear only later. The distinctive morphological characteristics of each of the early descending cell types are illustrated along with some stages in their early differentiation. These observations establish the temporal pattern by which new axons are added to descending pathways beginning with the simplest level of the amphibian spinal cord and determine the identity of neurons to which axons at early stages in this sequence belong.
Genesis of neurons in the dorsal lateral geniculate nucleus of the cat
Authors: Hickey T. L. , Hitchcock Peter F. 
Published: January 2005

AbstractNeurons that will ultimately form the dorsal and ventral lateral geniculate nuclei, the medial interlaminar nucleus, the perigeniculate nucleus, and the nucleus reticularis of the cat undergo their final cell division beginning on, or slightly before, embryonic day 22 (E22) and ending on, or before, E32. Early in this period, neurogenesis proceeds for all of these geniculate nuclei, whereas only in the dorsal lateral geniculate nucleus does cell birth continue until E32. Distinct spatiotemporal gradients of cell birth are not obvious within any of the individual geniculate nuclei. For the dorsal lateral geniculate nucleus in particular, and for the other geniculate nuclei in general, neurons born early in this period exhibit a full range of adult soma sizes, including large and small neurons. Neurons born late in this period exhibit only small adult somas.The location and size of a neuron within the dorsal lateral geniculate nucleus provide clues to that cell's functional properties. On the basis of presently available information regarding the relationship between structure and function of neurons in the cat's dorsal lateral geniculate nucleus, the findings described here suggest that all functional classes of neurons in the dorsal lateral geniculate nucleus are born at the same time throughout most of this period.
Genesis of morphologically identified neurons in the dorsal lateral geniculate nucleus of the cat
Authors: Hitchcock Peter F. , Hickey T. L. , Dunkel Carol G. 
Published: January 2005

AbstractNeurons in the dorsal lateral geniculate nucleus of the cat can be grouped into five morphological classes based on a variety of structural characteristics. These same structural characteristics can serve as morphological signatures for the three physiological classes (X, Y, W) of neurons found in this nucleus. The purpose of this study was to determine if a relationship exists between the birthdate of neurons within the dorsal lateral geniculate nucleus and the adult morphology of those neurons. Seven cats, each of which had received a single injection of 3H‐thymidine, were studied. A total of 2,138 Golgi‐impregnated neurons were identified in the dorsal lateral geniculate nuclei of these seven cats; 1,517 of these neurons were successfully resectioned and recovered, of which 385 (25%) were found to contain the 3H label. Neurons from each of the five morphological classes were labeled in each of the six animals that received a 3H‐thymidine injection between embryonic day 24 (E24) and E28. Class 3 and class 5 neurons were labeled in a cat injected with 3H‐thymidine on E30. These findings demonstrate that the development of the morphological class of a neuron in the dorsal lateral geniculate nucleus is independent of the time of its final cell division. Further, given the relationship that exists in the cat's dorsal lateral geniculate nucleus between neuronal structure and function, the present findings suggest that the different physiological classes of cells found in this nucleus undergo their final cell divisions throughout most of the period of neurogenesis except that the functional role of neurons born late in this period may be more restricted.
Catecholamine‐ and indoleamine‐ containing neurons in the turtle retina
Authors: Witkovsky P. , Eldred W. , Karten H. J. 
Published: January 2005

AbstractWe identified a population of presumed dopaminergic amacrine cells and populations of presumed serotonergic bipolar and amacrine cells in the retina of the turtle Pseudemys scripta elegans by a combination of autoradiographic, fluorescence, and immunocytochemical techniques. Antisera directed against the dopamine‐synthesizing enzyme, tyrosine hydroxylase (TOH), stained perikarya located at the border of inner nuclear (INL) and inner plexiform (IPL) layers. Processes emitted by these cells arborized in sublaminae 1, 3, and 5 of the IPL. Incubation of retinas in 10−6 M 3H‐dopamine yielded a labeling pattern identical to the staining pattern achieved with TOH antisera, but when the concentration of 3H‐dopamine was increased 25‐fold, both amacrine and bipolar cells are labeled. Following intraocular injection of dopamine, fluorescence micrography revealed both stained amacrine and bipolar cells. The bipolar cells had Landolt's clubs, pyriform perikarya located in the distal portion of the INL, and axons that coursed horizontally in the INL, then entered the IPL, and ramified in both its superficial and deeper layers. Although no fluorescent neuronal profiles were revealed following injection of serotonin (5HT), bipolar cells identical to those described were visualized with 5HT antisera. The intensity of bipolar cell staining with 5HT antisera was improved by preinjection of the eye with exogenous 5HT. We suggest that the bipolar cell is serotonergic, but that it also can actively accumulate dopamine. The 5HT antisera also stained a population of large amacrine cells whose processes ramified in IPL sublaminae 1, 4, and 5. The same populations of presumed serotonergic bipolar and amacrine cells were labeled following incubation of the eyecup in 10−6 M 3H‐5HT.
Postembryonic changes in the peripheral electrosensory system of a weakly electric fish: Addition of receptor organs with age
Authors: Zakon Harold H. 
Published: January 2005

AbstractThe organization of the peripheral electrosensory system of the cheek was studied in an age‐graded series of Sternopygus dariensis in Nissl‐stained sections and silver‐stained whole mounts of skin. As in other gymnotoids, both ampullary and tuberous electroreceptors are present. Small fish have only one ampullary organ or tuberous organ per axon, and the number of receptor organs per axon increases with age in both ampullary and tuberous systems. Large fish may have up to ten tuberous organs per axon, although the distribution of tuberous organs per axon is bimodal with one peak occurring at a single receptor organ per axon and the other peak shifting upward in relation to the age of the fish. The ampullary system adds receptor organs at a faster rate and a large fish may have 20 ampullary organs per axon. With increasing size, the number of sensory receptor cells in each organ remains constant for both types of electroreceptors. Evidence is presented for addition of new electroreceptor units by de novo production in small fish and increases in the number of organs in existing electroreceptor units by division of previously formed organs in medium‐sized and large fish. As the surface area of the skin increases with growth, the density of electroreceptor units decreases and, although new receptor organs are still being added to existing receptor units, no generation of new receptor units occurs in medium‐sized to large fish.
Thalamic projections to the somatosensory cortex of the echidna, Tachyglossus aculeatus
Authors: Ulinski Philip S. 
Published: January 2005

AbstractEvoked potential studies (Lende, '64) suggest that echidnas have a single, topographically organized somatosensory area (SMI) that spans a mediolaterally oriented sulcus called sulcus alpha. A motor area (MI) is situated on the prealpha gyrus. This study examines the cytoarchitecture and thalamic afferents of SMI in the echidna, Tachyglossus aculeatus.SMI contains two cytoarchitectonic fields. A caudal field extends across the postalpha gyrus and onto the floor of sulcus alpha. It has a well‐developed layer 4 and a relatively small number of medium‐sized pyramidal cells in layer 5. The rostral field extends from the floor of sulcus alpha onto its rostral bank. It also has a well‐developed layer 4 but has a large number of large pyramidal cells in layer 5. Layer 4 thins as it is followed onto the crown of the prealpha gyrus. The remainder of this gyrus contains a single cytoarchitectonic field with a thin layer 4 and a layer 5 heavily populated with larger pyramidal cells. This field corresponds to the physiologically defined motor area MI.Thalamic afferents to SMI were examined by placing pressure injections of horseradish peroxidase into the two cytoarchitectonic fields. An injection that involved both fields retrogradely labeled neurons throughout the ventral posterior nucleus of the thalamus. An injection restricted to the caudal field labeled a band of neurons that extends rostrocaudally throughout the ventral part of the ventral posterior nucleus. An injection restricted to the rostral field labeled a band of neurons situated dorsally in the ventral posterior nucleus. No other thalamic groups contained labeled neurons comparable to the labeling seen in the intralaminar or posterior nuclei following a horseradish peroxidase injection into SI of marsupial or placental mammals.These results indicate that SMI in Tachyglossus contains two cytoarchitectonic fields that resemble areas 3a and 3b in some placental mammals, suggesting that the constellation of cytoarchitectonic fields corresponding to areas 4, 3a, and 3b is a basic mammalian character which has been modified in marsupial and many placental mammals.