bluuebunny/crossref_metadata_2025_split huggingface dataset:
Telencephalic projections from midbrain and isthmal cell groups in the pigeon. II. The nigral complex
Authors: Kitt Cheryl A. , Brauth Steven E. 
Published: January 2005

AbstractThe trajectories and telencephalic terminal fields of neurons within the area ventralis of Tsai (AVT) and nucleus tegmenti pedunculopontinus pars compacta (TPc) were determined in the pigeon by using amino acid autoradiography and horseradish peroxidase histochemistry. Previous histochemical studies have considered these cell groups comparable to the A10 and A9 components of the mammalian nigral complex.The results show the efferents derived from these cell groups ascend to the telencephalon via the medial and lateral forebrain bundles, ansa lenticularis, and quintofrontal and occipitomesencephalic tracts. All projections are bilateral and symmetrical, although projections to the contralateral hemisphere are extremely sparse.Within the telencephalon many cell fields receive projections from the AVT and TPc nuclei; however, the most substantial projections reach structures within the basal telencephalon, especially the paleostriatal complex. Within the paleostriatal complex the paleostriatum augmentatum (PA) receives a very heavy projection from the TPc. AVT projections reach primarily rostromedial portions of PA as well as the lobus parolfactorius. The large‐celled portions of the paleostriatum including the paleostriatum primitivum and nucleus intrapeduncularis do not appear to receive projections from either AVT or TPc neurons.Projections from AVT and TPc neurons terminate within other structures of the basal telencephalon including the lateral and medial septal nuclei, the olfactory tubercle, the ventral paleostriatum and the preoptic area. Pallial derivatives including the hyperstriatum dorsale, hyperstriatum ventrale, dorsal archistriatum, and hippocampus also receive projections from AVT and TPc neurons, although these projections are much sparser than those reaching subpallial structures. Large portions of the telencephalon including the hyperstriatum accessorium, most of the hyperstriatum ventrale, much of the archistriatum, and much of the neostriatum do not receive projections from AVT or TPc neurons. Furthermore, there is substantial overlap between the telencephalic projections of TPc and AVT neurons, as well as considerable overlap between the projections of both these nigral cell groups and the projections of the locus coeruleus complex in the pigeon. This high degree of overlap between locus coeruleus and nigral telencephalic terminal fields is quite different from the condition in mammals and suggests possible functional divergence for some of thesee pathways in contemporary amniote forms.
Co‐Localization of fixative‐modified glutamate and glutaminase in neurons of the spinal trigeminal nucleus of the rat: An immunohistochemical and immunoradiochemical analysis
Authors: Magnusson Kathy R. , Larson Alice A. , Madl James E. , Altschuler Richard A. , Beitz Alvin J. 
Published: January 2005

AbstractThe spinal trigeminal, nucleus (STN) is involved in processing orofacial sensory information, including tactile, thermal and nociceptive input, and relaying this information to higher brain centers, such as the thalamus. Very little information is available regarding the major excitatory neurotransmitters of this nucleus. The amino acid glutamate has been proposed as a major excitatory neurotransmitter in the central nervous system. In the present study, a novel monoclonal antibody, specific for fixative‐modified glutamate, was utilized in conjunction with polyclonal antisera against glutaminase and aspartate aminotransferase (AATase) in an attempt to identify and map the locations of possible glutamatergic neurons in the STN. Co‐localization experiments were performed by radiolabeling our monoclonal antibody and using this antibody in conjunction with the polyclonal antisera against glutaminase and AATase to evaluate the possible coexistence of glutamate with glutaminase or AATase in STN neurons.In all three subnuclei of the STN, immunohistochemically labeled neuronal profiles were observed with both of the polyclonal antisera and with the monoclonal antibody. Subnucleus caudalis contained the greatest number of labeled profiles per coronal section followed by subnucleus interpolaris and subnucleus oralis. The number and the distribution of immunoreactive profiles observed after the use of the glutaminase antiserum was comparable to that obtained with the monoclonal antibody. Co‐localization experiments demonstrated that all glutaminase‐like immunoreactive neurons also contained fixative‐modified glutamate‐like immunoradioactivity. These results suggest that glutamatergic neurons are present in the spinal trigeminal nucleus. The AATase antiserum labeled more neuronal profiles in each of the three subnuclei than did the glutaminase antiserum or the monoclonal antibody. In addition, co‐localization experiments indicated that glutamate like immunoreactivity was present in only two‐thirds of AATase‐like immunoreactive neuronal profiles. These findings suggest that glutaminase may be a more reliable marker of glutamatergic function than AATase.
The growth of muscle nerves in relation to the formation of primary myotubes in the developing chick forelimb
Authors: Noakes Peter G. , Everett Alan W. , Bennett Max R. 
Published: January 2005

AbstractA study has been made of the development of muscle nerves to primary myotube clusters destined to become the flexor carpi ulnaris (fcu) and flexordigitorum profundus (fdp) muscles in the avian forelimb. Myotubes and nerves were identified by immunofluorescent techniques using antibodies to the heavy and light subunits of myosin and neurofilament, respectively. At stage24 the main ventral nerve trunk (the brachialis longus inferior nerve; bli n) had entered the limb before the appearance of myotubes in the limb. At stage 25/26 the bli n within the ventral compartment of the forearm had given rise to the interosseus nerve (in n) and the medial‐ulnar nerve (m‐u n) at the junction of the stylopodium and zeugopodium. The first few myotubes of the fdp and fcu muscles were observed at this level within the ventral premuscle cell mass; however, no nerves projected toward these myotubes from either the in n or the m‐u n at this time. At stage 26/27 the fcu and the fdp muscles each consisted of clusters of 20–40 myotubes; each cluster was clearly delineated within the ventral premuscle cell mass. By this time small groups of axons had left the in n and the m‐u n to grow into the fdp and fcu myotube clusters, respectively; these axons formed the muscle nerves. At stage 28/29 the number of primary myotubes in the clusters composing the fdp and fcu muscles had greatly increased, as did the size of the muscle nerves; each muscle was still clearly identifiable within the ventral muscle mass. By stage 32 the fdp and fcu muscles had clearly separated and the muscle nerves had divided into several well‐spaced branches within each muscle.The present observations show that the main nerve trunks grow into the limb before the formation of myotubes expressing myosin isozymes. When myotubes do form they appear in small clusters at specific sites within the premuscle mass, before muscle nerves appear; a distinct muscle is destined to form from each of these clusters. Muscle nerves first branch from the main limb nerves when the myotube cluster contains more than about ten myotubes.
Laminar distribution of receptors in monkey (Macaca fascicularis) geniculostriate system
Authors: Shaw C. , Cynader M. 
Published: January 2005

AbstractWe have examined the laminar distributions of eight types of receptor in the primary visual cortex (area 17) and the lateral geniculate nucleus (LGN) of the macaque monkey. The receptor populations and subpopulations examined included those selective for γ‐aminobutyric acid (GABA) (using [3H]‐muscimol as ligand), L‐glutamate‐related receptors (using [3H]‐L‐glutamate and [3H]‐AMPA), muscarinic acetylcholine (using [3H]‐quinuclidinyl benzilate–NB and [3H]‐N‐methyl scopolomine–MS), cholecystokinin (CCK) (using [3H] pentagastrin), benzodiazepine (using [3H]‐flunitrazepam), and adenosine (using [3H]‐cyclohexyladenosine–CHA).Each of the receptors examined exhibited characteristic and differing laminar patterns of binding in the striate cortex. Perhaps reflecting the high density of cell bodies and synapses in layer 4C, most receptors, except those labelled by [3H]‐L‐glutamate or [3H]‐AMPA, showed dense concentrations in this layer. Layers 4B and 5, which contain relatively few cell bodies and heavy myelin concentrations, were in general lightly labelled. Layer 6 showed relatively heavy labelling when [3H]‐AMPA (quisqualate) or [3H]pentagastrin (CCK) were used as ligands. The superficial layers of the cortex were zones of relative concentration of GABA, benzodiazepine, acetylcholine, glutamate‐related, and adenosine receptors. In general, the binding patterns resembled those previously described for cat visual cortex, but there were also some clear differences. The distributions of all of these receptors likely reflect the differential input substances to different laminae of the visual cortex.Of the receptors examined, only those for GABA, benzodiazepine, and acetylcholine were found in substantial concentration in the LGN. Of these, GABA and benzodiazepine receptors showed especially dense binding in the magnocellular layers of the LGN compared to the parvicellular layers.
Distribution of γ‐aminobutyric acid‐immunoreactive neurons in the septal region of the rat brain
Authors: Onteniente Brigitte , Tago Hisao , Kimura Hiroshi , Maeda Toshihiro 
Published: January 2005

AbstractThe distribution of γ‐aminobutyric acid‐immunoreactive (GABA‐I) elements was examined in the septal region of the rat brain. The indirect peroxidase‐antiperoxidase technique was used with anti‐GABA antibodies in normal and colchicine‐pretreated rats, with or without use of detergent in the incubation medium.Intraventricular injection of colchicine did not result in any change in the staining of neuronal perikarya. Intraseptal injections increased the intensity of labelling of GABA‐I cell bodies in the lateral septal nucleus and increased the number of labelled cells in the medial septal nucleus and diagonal band of Broca (dbB). Triton X‐100 added to the incubation media decreased the intensity of staining and number of GABA‐I somata in all septal nuclei with a concentration‐dependent effect. No change was observed concerning GABA‐I varicosities.The septal area, including the lateral, medial, and triangular septal nuclei; the anterior rudiment of the hippocampus; the island of Calleja magna; the septofimbrial nucleus; the bed nucleus of the stria terminalis; and the dbB showed a strong reaction to anti‐GABA antibodies with regard to GABA‐containing surrounding structures. GABA‐I axonal varicosities were observed: in all the regions with an uneven distribution. The highest density was found in the dorsal and ventral parts of the lateral septal nucleus and in a band situated between the dbB and the nucleus accumbens. Labelled varicosities were frequently observed surrounding GABA‐I and nonimmunoreactive cell bodies.GABA‐I somata ranged from 10 to 30μm in diameter. Small neurons were present in great number at the ventricular border and in the zona limitans. Medium‐size and large neurons were mostly observed in the medial part of the dorsal lateral nucleus and in the intermediate lateral nucleus. Large, strongly immunoreactive somata were revealed in the medial septum and dbB by intraseptal injections of colchicine.
Posthatching development of synapses in the neuropil of nucleus rotundus of the zebra finch: A quantitative electron microscopic study
Authors: Nixdorf Barbara , Bischof Hans‐Joachim 
Published: January 2005

AbstractThe development and maturation of synapses in the nucleus rotundus of the zebra finch were examined at 1, 5, 10, 20, and 100 days posthatching. Quantitative ultrastructural techniques were applied to investigate synaptic density, size of presynaptic terminals, and length of postsynaptic thickenings. During development there is a steady increase in the number of synapses and an enlargement of the presynaptic terminals. The length of the postsynaptic thickenings, however, decreases significantly during posthatching development. All three parameters reach adult values within 20 days of age. A close relationship was found between the enlargement of the presynaptic terminals and the increase in the number of contact zones up Lv the 20th day. The general feature of this developmental progress is in good agreement with biochemical and, to a certain extent, behavioral studies.
LHRH and catecholamine neuronal systems in the olfactory bulb of the mouse
Authors: Rosser Anne E. , Hökfelt Tomas , Goldstein Menek 
Published: January 2005

AbstractThe luteinizing‐hormone‐releasing hormone (LHRH) components of the mouse olfactory system were studied by using the indirect immunohistofluorescence technique. LHRH‐positive cell bodies were found in both the main olfactory bulb (MOB) and the accessory olfactory bulb (AOB); two distinct cell groups were found—one located adjacent to the AOB in the dorsal part of the MOB and a second in the superficial ventromedial aspect of the MOB. LHRH‐positive fibers were found predominantly in the posterior half of the main olfactory bulb innervating the olfactory nerve layer, the glomerular layer, the external plexiform layer, and the mitral cell layer, and small numbers innervated the AOB. The greatest density of LHRH‐immunoreactive fibers was seen adjacent to the AOB where one group of LHRH‐positive cells was noted.Sections adjacent to those stained with LHRH antibody were analysed for tyrosine hydroxylase (TH) and dopamine β‐hydroxylase (DBH). The TH staining was intense for both cells and fibers in the glomerular layer of the MOB. In the AOB lower numbers of cell bodies and fibers were seen in the glomerular layer. The internal granular layer and internal plexiform layers were both stained, the internal granular layer showing more intensely fluorescent fibers with a higher density. Since no overlapping DBH‐positive fibers were found here, these TH‐positive nerve endings may be dopaminergic. DBH staining was confined to sparse networks of weakly fluorescent fibers with the highest numbers in the internal plexiform layer of the AOB and fewer fibers in the external plexiform, rostral, and granular layers of the MOB. Elution‐restaining experiments revealed that the LHRH‐positive and TH‐positive elements represent different cell populations.
Course of retinogeniculate projection fibers in the cat optic nerve
Authors: Naito Jumpei 
Published: January 2005

AbstractThe fiber courses of the cat optic nerve were studied by using wheat germ agglutinin conjugated to horseadish peroxidase (WGA‐HRP), which was iontophoretically applied to electrophysiologically defined positions in the lateral geniculate nucleus (LGN).Grossly, there were two distinct bends along the legth of the optic nerve. The ventrally flexing anterior bend was located approximately 2 mm from the eyeball, while the dorsally flexing posterior bend was found at some 6 mm distant. The optic nerve fibers showed a tendency to scatter toward the chiasm. At the optic nerve head, the fibers from the different retinal areas maintained the retinal topography in a simpligfied form according to the trajectory of optic fibers surrounding the optic disc. Between the anterior and posterior bends, the fibers from the pericentral, middle‐temporal, and most upper areas of the dorsal retina migrated ventrally and were arranged in the middle of the lateral, middle, and medial parts of the optic nerve, respectively, while fibers from the middle‐temporal area of the ventral retina migrated dorsally and scattered into the lateral half. The fibers from the temporal and nasal horizontal meridian areas tended to hold their respective positions in the lateral and medial halves of the optic nerve. As a result, in this level they displayed a complex retinotopy in that the fibers from each part of the retina were mixed. Passing the posterior bend, as the optic nerve proceeded toward the chiasm, the characteristic pattern became less defined. Near the chiasm, the retinotopy became very scattered, showing a partial dorsoventral inversion of the retinal topography with substantial overlapping.It was noted from the present findings that the fibers from ventral retina scattered more quickly than the fibers from the dorsal retina, which tended to hold their grouping until the anterior bend, but the central or pericentral retinal fibers proceeded without significant scatter as far as the posterior bend. The analysis of labelled ganglion cells suggested that even if fibers that arise from one certain “mode” of ganglion cells are selected, it is unlikely that they maintain their initial fiber topography along the entire length of the optic nerve.
Localization of glutamic‐acid‐decarboxylase‐immunoreactive axon terminals in the inferior olive of the rat, with special emphasis on anatomical relations between GABAergic synapses and dendrodendritic gap junctions
Authors: Sotelo C. , Gotow T. , Wassef M. 
Published: January 2005

AbstractImmunocytochemical and electron microscopic methods were used to examine the GABAergic innervation of the inferior olivary nucleus in adult rats. This neuronal system was visualized with an antibody against glutamic acid decarboxylase (GAD, EC 4.1.1.15), the GABA‐synthesizing enzyme. A GAD‐positive reaction product was encountered only in short segments of preterminal axons and in axon terminals. Their relative number per unit area of neuropil was very similar in all olivary subnuclei. Despite this homogeneity in density, obvious intraregional differences existed. Some regions were strongly immunoreactive (the “c” subgroup, the ß nucleus, and the mediolateral outgrowth of the medial accessory olive), whereas others were weakly labeled (the dorsomedial cell column and the central zones of the medial accessory and principal olives). The strongly immunoreactive areas contained the largest and most intensively labeled axon terminals. Areas of weak labeling were filled with small, weakly immunoreactive nerve terminals. Thus, variations in size and in intensity of labeling create a specific pattern of GABA innervation, revealed by an almost continuous gradient between the above‐mentioned extremes.The GAD‐positive axon terminals established conventional synapses with dendrites (94% of the samples) or with cell bodies (6%). The vast majority of these synapses were type II (84%) and only a small proportion formed type I synaptic contacts (16%), regardless of the nature of the postsynaptic element. Immunoreactive terminals were also involved in the complex synaptic arrangements‐‐‐the glomeruli, which characterize the olivary neuropil. Within these formations, olivary neurons were electrotonically coupled through dendrodendritic gap junctions. There was a constant association between GAD‐positive axon terminals and small dendritic appendages linked by gap junctions. This association was revealed not only by the systematic presence of immunolabeled terminals directly apposed to the dendritic appendages but, more importantly, by the frequent presence of type II synapses straddling both elements. These synapses were in close proximity to the low‐resistance pathways represented by the gap junctions. The strategic location of these GABA synapses is discussed in relation to recent findings indicating the possibility of a synaptic modulation of the electrical coupling: the release of GABA, by increasing nonjunctional membrane conductance, could shunt the coupling between olivary neurons. The functional decoupling of selected gap junctions would be responsible for the spatial organization of the olivary electrotonic coupling.
Morphology of physiologically identified bipolar cells in the retina of the tiger salamander, Ambystoma tigrinum
Authors: Hare William Alan , Lowe Janet S. , Owen Geoffrey 
Published: January 2005

AbstractIntracellular recordings of the light responses of bipolar cells were made in the isolated perfused retina of the larval tiger salamander by microelectrodes filled with a 1% solution of the enzyme horseradish peroxidase (HRP). Two classes of bipolar cell were identified in terms of their responses to luminous spots and annuli centered upon their receptive fields: on‐center cells, which depolarized in response to a centered spot and hyperpolarized in response to a concentric annulus, and off‐center cells, which responded with the opposite polarities. Physiologically identified cells were labelled with HRP by iontophoretic injection and prepared for light microscopy. Examples of each of the three classes of bipolar cell described in Cajal's study of the amphibian retina were found amongst the labelled cells. The only morphological feature found to correlate with the physiological classification was the stratum at which the axon of the cell arborized in the inner plexiform layer. The axons of on‐center cells arborized in the more proximal sublamina b, while those of off‐center cells arborized in the more distal sublamina a. This is consistent with earlier findings in the retinae of the cat and the carp.
The distribution of dopamine immunoreactivity in the forebrain and midbrain of the lizard Gekko gecko: An immunohistochemical study with antibodies against dopamine
Authors: Smeets Wilhelmus J. A. J. , Hoogland Piet V. , Voorn Pieter 
Published: January 2005

AbstractThe distribution of dopamine (DA) immunoreactivity in the forebrain and the midbrain of the lizard Gekko gecko was studied by using recently developed antibodies against DA. Dopamine‐containing cells were found around the glomeruli of the olfactory bulb, in several parts of the periventricular hypothalamic nucleus, in the periventricular organ, the ependymal wall of the infundibular recess, the lateral hypothalamic area and the pretectal posterodorsal nucleus of the diencephalon, and in the ventral tegmental area, the substantia nigra, and the presumed reptilian equivalent of the mammalian A8 cell group of the mesencephalon.Dopaminergic fibers and terminals were observed throughout the whole brain, but particularly in the diencephalon and the telencephalon. The nucleus accumbens appears to have the most dense innervation, but also the striatum, amygdaloid complex, olfactory tubercle, septum, and dorsal ventricular ridge (especially its superficial zone) show numerous DA‐containing fibers and terminals. Except for the lateral cortex, cortical areas are not densely innervated by DA fibers.In several respects DA distribution in the gekkonid brain differs from that in other reptiles studied. For instance, in the Gekko the dorsal ventricular ridge is densely innervated by DA fibers, whereas in turtles and crocodiles the same structure shows only weak catecholaminergic histofluorescence. When compared to the distribution of DA immunoreactivity in mammals, it appers that the DA system in the gekkonid telencephalon resembles the distribution of DA in the limbic forebrain and striatum of mammals. Whether these similarities in distribution of DA also imply similarities in function will be discussed.