bluuebunny/crossref_metadata_2025_split huggingface dataset:
Delayed development of song control nuclei in the zebra finch is related to behavioral development
Authors: Herrmann Kathrin , Bischof Hans‐Joachim 
Published: January 2005

AbstractThe postnatal development of two visual areas (nucleus rotundus and ectostriatum) and two song control areas (hyperstriatum ventrale pars caudale, HVc, and nucleus robustus archistriatalis, RA) of the zebra finch brain was followed from birth to adulthood. The following parameters were investigated: (1) neuron size, (2) volume of the brain nuclei, and (3) myelination of axons. The nucleus rotundus, the diencephalic station of the tectofugal pathway, exhibits the fastest development: rotundal neurons reach their maximum size at 20 days of age; the volume of this structure reaches adult size at the same time. The process of myelination begins between day 5 and day 10 and is completed at 40 days of age. A similar temporal sequence of development is seen in the ectostriatum, except myelination starts some days later. Thus the development of these visual areas is completed at 40 days. In, contrast, the development of the song control nuclei is delayed. Neurons in RA and HVc grow steadily up to 40 days of age, attaining a size larger than that observed in adults. Whereas the volume of HVc increases until day 40 and remains stable thereafter, RA volume increases until day 70 and evidences a decrease thereafter. It is not until postnatal day 20 (RA) and day 40 (HVc) that the myelination process starts in the song control areas. Adult myelin density is achieved by 70 days in RA and by 100 days in HVc. It can be demonstrated that the development of the visual system parallels the development of visual performance of the birds. Delayed growth of song control nuclei coincides with development of song.
A Golgi and ultrastructural analysis of the centromedian nucleus of the cat
Authors: Tseng Guo‐Fang , Royce G. James 
Published: January 2005

AbstractThe morphology of neurons in the centromedian nucleus (CM) was studied in rapid Golgi preparations of the adult cat. The ultrastructure of the nucleus, particularly its synaptic organization, was also studied with electron microscopy.The CM contains three types of neurons referred to as principal neurons, Golgi type II neurons, and bushy neurons. Principal neurons are the most numerous, have long dendrites, which branch infrequently, and are divided into two subgroups: principal‐A neurons with dendrites that arborize radially, whereas principal‐B neurons display horizontal orientations. Both subgroups show a frontal orientation in their dendritic organization and give rise to myelinated axons. Golgi type II neurons with their characteristic sinuous dendrites and unmyelinated axons are thought to be interneurons. The occurrence of bushy neurons in the cat's CM is a new finding. These bushy neurons resemble those of thalamic specific relay nuclei and give rise to myelinated axons. In addition to these three cell types, neurons with intermediate features between these three neuronal types are also described.The ultrastructure of CM neurons resembles, in general, typical central nervous system neurons. Presynaptic profiles are classified into four main categories. SR (small round) boutons are small in size, contain clear, round vesicles, and form asymmetrical synaptic contacts with predominantly small‐diameter dendrites. LR (large round) boutons are relatively large and contain both clear and dense‐cored vesicles. They interdigitate and form multiple, moderately asymmetrical synapses with their postsynaptic targets. Pale profiles are identified by their relatively electron‐light appearance. They contain round vesicles and are thought to be dendritic in origin. The last category of presynaptic profiles is pleomorphic boutons. They contain vesicles of different shapes and are further subdivided into two subtypes: pleomorphic‐I ends on soma and dendritic trunks, whereas pleomorphic‐II contacts small‐diameter dendrites. Both subtypes form symmetrical synapses.The glomeruli of specific thalamic relay nuclei generally contain dendrites, LR boutons, and pale profiles. In addition to these, pleomorphic‐II boutons also participate in the formation of the glomerulus of the cat's CM.
Intracerebral transplants of the rat fascia dentata: A Golgi/electron microscope study of dentate granule cells
Authors: Frotscher Michael , Zimmer Jens 
Published: January 2005

AbstractIn the present study we describe the morphological characteristics of dentate granule cells in intracerebral allografts of the rat fascia dentata. Blocks of hippocampal tissue containing the fascia dentata were taken from late embryonic and newborn rats and transplanted to the hippocampal region of other newborn and young adult rats. After survival periods of several months the recipient brains were fixed by perfusion and serially sectioned on a Vibratome. Some sections were stained with thionin to determine the localization and general histological organization of the transplants, while others were Golgi stained with a modification of the section Golgi technique. Well‐impregnated transplant granule cells were gold‐toned and deimpregnated thus allowing a correlated, light and electron microscopic analysis of identified neurons to be done.At the light microscopic level the morphology of the dentate granule cells in the transplants was very similar to Golgi‐impregnated, gold‐toned granule cells in the fascia dentata of normal rats (controls). A few irregular, more obliquely curved dendrites occurred, but basal dendrites passing into the hilar region were never observed. Following an initial spine‐free segment granule cell dendrites were densely covered with spines. The axon, the mossy fiber, originated as usual from the basal pole of the cell body.In the electron microscope, both small and larger complex spines (v and w types) were seen to emerge from the gold‐toned dendrites of the identified granule cells. The thin unmyelinated granule cell axons gave rise to giant mossy fiber boutons in the dentate hilus, but in addition numerous aberrant mossy fiber terminals were found innermost in the dentate molecular layer just above the granule cell layer.The results demonstrate that dentate granule cells that have gone through the major part of their differentiation‐after transplantation develop characteristic dendritic and axonal elements very similar to those of granule cells in the fascia dentata in situ. The minor changes observed correspond to the redistribution of intrinsic connections that results from the absence of major extrinsic afferents.
Tectal neurons of the frog: Intracellular recording and labeling with cobalt electrodes
Authors: Antal M. , Matsumoto N. , Székely G. 
Published: January 2005

AbstractWith the aid of cobalt‐filled intracellular electrodes, responses evoked by electrical and visual stimulation were recorded from tectal neurons. Diffuse light and “edge” and “spot” stimuli were used for visual stimulation; electrical stimuli were delivered by means of bipolar electrodes to the optic tract. The cells were subsequently filled with cobalt for a correlative histological study. The following types of neurons were distinguished: (1) Pear‐shaped neurons with restricted and broad dendritic fields occurring in tectal layers 8, 6, 4, and 2. In one group, the dendrites bore beads and small protrusions and the short axon arborized within, or close to, the dendritic arbor. They responded mostly with inhibitory postsynaptic potentials to the various stimulations. This type of neuron was interpreted to be a tectal interneuron. In the second group the dendrites were smooth, the dendritic arbor was large, and the axon could be followed to layer 7 in a few cases. Excitatory activities with frequent spike discharges prevailed in their responses. They were regarded as efferent neurons of the tectum. (2) Large ganglionic neurons showed a greater variation in form than has been described in previous Golgi studies. Their responses to the different stimulations were also very variable. The axons of five neurons could be followed to the dorsal part of the thalamus, to the postoptic commissural system, and to the direct and crossed tectobulbar tract. These axons emitted several collaterals to tectal, pretectal, and tegmental structures. (3) A single stellate neuron was impaled in layer 9. It responded only to electrical stimulation with excitation. (4) Deep bipolar neurons were not mentioned in earlier works. Their somata were found in layer 6; the vertically oriented dendrites arborized in plexiform layers 7, 5, and 3, over a distance of more than 1 mm. These cells were sensitive only to electrical stimulation.
Studies on the evolution of multiple somatosensory representations in primates: The organization of anterior parietal cortex in the new world callitrichid, Saguinus
Authors: Carlson Mary , Huerta M. F. , Cusick C. G. , Kaas J. H. 
Published: January 2005

AbstractBecause members of the New World family, Callitrichidae, are generally regarded as the most primitive of monkeys, we studied the organization of somatosensory cortex in the tamarin (Saguinus) in hopes of better understanding differences in the organization of anterior parietal cortex in primates and how these differences relate to phylogeny. In most prosimian primates only one complete representation of cutaneous receptors has been found in the region of primary cortex, S‐I, while in all Old and New World monkeys studied to date, two cutaneous representations exist in distinct architectonic fields, areas 3b and 1. In detailed microelectrode mapping studies in anesthetized tamarins, only one complete representation responsive to low‐threshold cutaneous stimulation was evident in the S‐I region. This topographic representation was in a parietal koniocortical field that architectonically resembles area 3b of other monkeys, and the general somatotopic organization of the field was similar to that of area 3b of other monkeys. Cortex rostral to the single representation was generally unresponsive to somatosensory stimuli, or required more intense stimulation for neural activation. Cortex caudal to the representation, in the region of area 1 of other monkeys, was generally either unresponsive or responded to only high‐threshold stimulation, although some recording sites were activated by low‐threshold tactile stimulation.The present evidence, together with that from previous studies, suggests that the single, complete body surface representation in Saguinus is homologous to the S‐I representation found in some prosimians (Galago, Perodicticus) and the area 3b cutaneous representation found in New World Cebidae (Aotus, Saimiri, and Cebus) and Old World Macaca. Cortex rostral to S‐I in Saguinus has the appearance of areas 3a and 4 of other primates. The cortex caudal to S‐I in Saguinus, while resembling area 1 in some ways, does not have all of the features of area 1 of other monkeys. In particular, the field was not easily activated by low‐threshold cutaneous stimuli, as area 1 is in other monkeys, and therefore a second cutaneous representation of all body parts was not demonstrated. Thus, cortex in the expected location of area 1 of Saguinus was not as responsive as area 1 of other monkeys, and it somewhat resembled the high‐threshold fringe zones found caudal to S‐I in anesthetized prosimians and some nonprimates. The results raise the possibility that the area 1 cutaneous representation that is characteristic of other New World monkeys and Old World monkeys evolved from a less responsive precursor along the caudal border of S‐I in early monkeys.
Organization of spinal inputs to the perihypoglossal complex in the cat
Authors: Stechison Michael T. , Saint‐Cyr Jean A. 
Published: January 2005

AbstractFirst‐ and second‐order spinal afferents to the perihypoglossal complex were sought by using axonal transport of WGA‐HRP. Injections in C1, 2, and 3 dorsal root ganglia resulted in axonal labeling in the nucleus intercalatus and the external cuneate nucleus, with a number of retrogradely labeled cells seen as well in the latter. A similar pattern of axonal labeling in the nucleus intercalatus as well as several retrogradely labeled cells were found after spinal cord injections at levels C1, 2, and 3. A prominent field of labeled axons was also present in the rostral main cuneate nucleus. No labeling was seen in the perihypoglossal nuclei after injections in the spinal cord or dorsal root ganglia at levels caudal to C3. After injections of HRP into the perihypoglossal nucleus we were able to identify labeled neurons within Rexed, s laminae V‐VIII and the central cervical nucleus. Anterograde labeling in the main cuneate nucleus was observed after C1 to C5 ganglion and C1 to C6 cord injections. The pattern and extent of labeling in the perihypoglossal nuclei and adjacent structures seen after cerebellar injections into lobules V and VI were comparable to those previously reported and permitted evaluation of the relay from dorsal root ganglia through the intercalatus to the vermis.Topography of the cervical projections to the nucleus intercalatus is considered with respect to that of the perihypoglossal‐collicular projection. A discussion is offered of the apparent importance of nucleus intercalatus as a relay of cervical and vestibular afferent information to premotor structures involved in neck motor control. The perihypoglossal complex is viewed as being organized in such a fashion as to allow the nuclei intercalatus and prepositus hypoglossi to function as key structures in the integration of inputs related to neck and ocular motor control, respectively.
The synaptic ultrastructure in the outer plexiform layer of the catfish retina: A three‐dimensional study with hvem and conventional em of golgi‐impregnated bipolar and horizontal cells
Authors: Hidaka Soh , Christensen Burgess N. , Naka Ken‐Ichi 
Published: January 2005

AbstractSynaptic structures between receptors and horizontal and bipolar cells in the outer plexiform layer (OPL) of Golgi‐impregnated catfish retina were examined by conventional electron microscopy of serial ultrathin sections and by high‐voltage electron microscopy (HVEM) off thick sections. Cone terminals contained multiple synaptic ribbons and rod terminals contained single synaptic ribbons. This observation was used to identify these two types of photoreceptors. The cone horizontal cell, located in the most distal part of the inner nuclear layer (INL), invaginated only cone terminals, whereas the rod horizontal cell, located in the proximal part of the INL, invaginated only rod terminals. Both lateral elements of the triad in the rod terminal originated from a single rod horizontal cell whereas the same structures in the cone terminal were often derived from several cone horizontal cells. Golgi‐impregnated catfish bipolar cells were classified into two types based on the differences in their axonal arborization as described by Famiglietti et al. ('77). Axonal endings of type a bipolar cells were located in the distal part, sublamina a, of the inner plexiform layer (IPL), and axonal endings of type b cells were located in the proximal part, sublamina b, of the IPL. Dendrites from type a bipolar cells made direct contact with the synaptic ribbons in both rod and cone terminals whereas those from type b cells made indirect contact with the ribbons in both rod and cone terminals, but rare direct contact with the ribbon in rod terminals were also seen. In addition, bipolar cells made basal junctions or superficial contact in both rod and cone terminals. The “lateral” processes of bipolar cells invaginating rods penetrated between the rod terminal and rod horizontal cell processes, and made basal junctions with both rod terminals and rod horizontal cells. There was no definitive morphological feature that could be associated with signconserving and sign‐inverting signal transmission.
Identification of medial preoptic neurons that concentrate estradiol and project to the midbrain in the rat
Authors: Fahrbach Susan E. , Morrell Joan I. , Pfaff Donald W. 
Published: January 2005

AbstractFluorescent dye retrograde tracing was combined with steroid hormone autoradiography to study the midbrain projections of the estrogen‐concentrating neurons in the preoptic region of the rat brain. Microinjections of the dyes DAPI, true blue, or a mixture of DAPI and primuline were made into the ventral tegmental area and into the midbrain central gray of ovariectomized, adrenalectomized 2‐3‐month‐old female rats; 3 or 4 days later these animals were injected with [3H]estradiol; the brains were then processed for autoradiography. After exposures of from 3 to 12 months, the autoradiograms were developed and examined for reduced silver grains under cell nuclei (indicating binding of [3H]estradiol) and retrogradely transported fluorescent dye in the cytoplasm (indicating an efferent projection to the midbrain).Numerous [3H]estradiol‐concentrating neurons in the medial preoptic region were found to send their axons to the medial midbrain. The largest numbers of estrogen target neurons that were afferent to the ventral tegmental area and to the midbrain central gray were found in the medial preoptic nucleus, in the surrounding medial preoptic area, and in the ventral bed nucleus of the stria terminalis. Double‐labeled neurons were also identified in the preoptic suprachiasmatic area, in the lateral preoptic area, and in the rostral anterior hypothalamic area. Thus, a subset of the gonadal steroid target cells of the preoptic region have long projections to the medial midbrain, and a subset of the medial preoptic neurons that project to the ventral tegmental area and to the midbrain central gray concentrate estrogen. Behaviors (for example, maternal behavior, male copulatory behavior, and wheel‐running) that are regulated by estrogen action in the medial preoptic region may be controlled by the direct estrogen‐sensitive pathway to the medial midbrain revealed in this study.
Cell surface changes in the developing optic nerve of mice
Authors: Lund R. D. , Perry V. H. , Lagenaur C. F. 
Published: January 2005

AbstractA recently defined antibody to a cell surface protein, M6, inhibits neurite outgrowth in culture (Lagenaur, Fushiki, and Schachner: Soc Neurosci. Abstr. 10:739, '84). In the developing mouse, the antibody stains all parts of the primary optic pathway at birth. Over the next week, staining is lost from the proximal segment of the optic nerve and a week later from the more central part of the nerve. By contrast staining persists through adulthood in the optic fiber layer of the retina. This means that single axons in the mature optic nerve express the antigen over only the proximal few millimeters of their course and over their terminal region.The results are discussed in relation to the overall maturation of the optic pathway and to the processes of membrane maturation and myelination.
Development of the crossed retinocollicular projection in the mouse
Authors: Edwards M. A. , Schneider G. E. , Caviness V. S. 
Published: January 2005

AbstractChanges in the distribution of axons of the crossed retinal projection within the superior colliculus of the developing mouse were studied by means of normal fiber and Golgi impregnations and by anterograde horseradish peroxidase labelling. Retinal axons advance along the optic tract from gestational days E12 to E14 and first invade the superior colliculus on E15. Over the subsequent days until birth (E19), the retinal axons extend within rostrocaudally oriented fascicles that distribute through the full thickness of the uppermost collicular layer, the stratum superficiale (SS). A dramatic transformation of this fiber stratification pattern into the mature pattern occurs over the first postnatal week. The fiber bundles are progressively cleared from the upper half of SS, identified as the future stratum griseum superficiale (SGS). Concurrently, the fiber bundles in the deep SS, identified as the stratum opticum (SO), give rise to individual, nonfasciculated fibers, which arborize within SGS. The contralateral retinal origin of the transient population of axons in SGS as well as the majority of axons that persist in SO is evident from the observation that they degenerate following neonatal enucleation. The number of fiber bundles lost is estimated to be 40–50% of the total population present in the superficial layers at birth. The combined set of observations indicates that axon elimination plays a major role in shaping the laminar pattern of retinal innervation of the colliculus. Retinal ganglion cell death, and not axon pruning, is proposed as the most probable mechanism by which axon fascicles are eliminated from SGS.
Central afferent connections and origin of efferent projections of the facial nerve in the chicken (Gallus gallus domesticus)
Authors: Ganchrow Donald , Ganchrow Judith R. , Gentle Michael J. 
Published: January 2005

AbstractThe central afferent connections and origin of efferent projections of the facial nerve in the adult domestic chicken were studied by anterograde and retrograde transport of horseradish peroxidase from the geniculate ganglion. Ipsilateral afferent projections were traced caudal to the level of entrance of the facial nerve and into tractus solitarius (TS), located dorsomedial to the spinal trigeminal nuclear complex. At several rostrocaudal levels in the medulla, fibers exited from TS and terminated in n. sensorius N. facialis (SVII), and nn. ventrolateralis anterior (Vla) and intermedius anterior (Ia) solitarii. Some axons were followed to n. presulcalis anterior (Pas) solitarii. A separate component terminated in subnucleus interpolaris (ip) of n. descendens nervi trigemini or its medially adjacent reticular formation either by exiting from TS or coursing caudally through the trigeminal complex from entering facial rootlets. Another diffuse component of facial axons ascended dorsally and rostrally from the level of entrance of the facial nerve; these projections dissipated in the pons–some on the dorsomedial border of n. principalis N. trigemini (PrV).Ipsilateral efferent projections were traced through the main genu of the facial nerve to retrogradely labelled somata of pars dorsalis (FMd), pars intermedia (FMi), and pars ventralis (FMv) of n. motorius nervi facialis. A separate group of smaller, multipolar, and spindle‐shaped cells (8–25 μm) wedged between n. olivarius superioris (OS) and the caudal end of FMv, rostrally, and extending caudally in ventrolateral medulla were labelled. These small cells contrast with the larger (21–45 μm), oval, round, and multipolar somata of FMv and may correspond, in part, to a parasympathetic n. salivatorius (Sal).
Dorsal funicular projections to the dorsal column nucleus in a reptile, Caiman crocodilus
Authors: Pritz Michael B. , Stritzel Mark E. 
Published: January 2005

AbstractProjections to the dorsal column nucleus were investigated in the reptile Caiman crocodilus following application of horseradish peroxidase (HRP) crystals to the cervical spinal cord after dorsal myelotomy. Brains were processed for HRP histochemistry by use of tetramethylbenzidine as the chromogen. Injection of the dorsal funiculus alone labelled axons that terminated solely in the ipsilateral dorsal column nucleus. Application of HRP that extended beyond the dorsal funiculus labelled axons that terminated in brainstem areas in addition to the dorsal column nucleus depending upon the injection site. Retrogradely labelled neurons in the brainstem were seen only after HRP injections that extended beyond the dorsal funiculus and varied depending upon the injection site.Dorsal funiculus fibers travel rostrally and turn laterally to reach more anterior portions of the dorsal column nucleus. Fibers peel off in an oblique ventrolateral fashion to terminate in the posterior part of the nucleus where boutons are intermixed with fibers. The anterior portion of the nucleus contains a greater proportion of axon terminals as compared to fibers than does the posterior part. A graphic reconstruction of the dorsal column nucleus was made by superimposing serial sections to view the nucleus in transverse, sagittal, and horizontal planes.