bluuebunny/crossref_metadata_2025_split huggingface dataset:
Projection of septal organ receptor neurons to the main olfactory bulb in rats
Authors: Pedersen Patricia E. , Benson Thane E. 
Published: January 2005

AbstractThe septal organ of Masera is a distinct patch of olfactory epithelium on the septal wall of the nasal cavity. It lies ventral to the main olfactory receptor sheet. Central projections of the septal organ to the main and/or accessory olfactory bulb were studies with puncate HRP injections into the posterior dorsomedial olfactory bulb of rat pups. Injection sites encompassed 2‐‐8% of the main olfactory bulb glomeruli and some injection sites were confined to the accessory olfactory bulb glomeruli. The distribution of receptor neurons in the septal organ that were labeled as a result of retrograde transport from the injection sites was determined.Olfactory receptor neurons were labeled in septal organs of those animals with injection sites confined to the main olfactory bulb. Subsequent to the posterior dorsomedial bulbar injections of this study, labeled receptor neurons were preferentially located in the posterior portion of the septal organ and were clustered about a plane dorsal to the plane bisecting the organ. Injections confined to the accessory olfactory bulb only labeled vomeronsal organ receptor neurons. Thus it is likely that the main olfactory bulb and not the accessory olfactory bulb is the bulbar terminus of septal organ receptor neurons. To date, experimental evidence suggests that the septal organ system may comprise an anatomically and functionally unique chemosensory pathway for odor detection.
Functional organization of crayfish abdominal ganglia: I. The flexor systems
Authors: Leise Esther M. , Hall Wendy M. , Mulloney Brian 
Published: January 2005

AbstractFor insect ganglia, Altman (A dvances in Physiological Science, Vol. 23. Neurobiology of Invertebrates. New York: Pergamon Press, pp. 537–555, '81) proposed that individual neuropils control different motor activities. A corollary of this hypothesis is that motor neurons involved in many behavioral functions should branch in more neuropils than those active in fewer behaviors. In crayfish, the abdominal fast‐flexor muscles are active only during the generation of the powerstroke for tailflips, whereas the slow‐flexor muscles are involved in the maintenance of body posture. The slow flexors are thus active in many of the crayfish's behavioral activities. To test the generality of Altman's idea, we filled groups of crayfish fast‐flexor and slow‐flexors were motor neurons with cobalt chloride and described their shapes with respect to the ganglionic structures through which they pass. Individual fast flexors were also filled intracellularly with HRP. Ganglia containing well‐filled neurons were osmicated, embedded in plastec, and sectioned. Unstained sections were examined by light microscopy and pertinent sections were photographed. We found that the paths of the larger neurites were invariant, that the dendritic domains of fast and slow motor neurons occupied distinctive sets of neuropils, and that dendrites of slow motor neurons branched in more ganglionic structures than did those of fast motor neurons. These results are consistent with Altman's hypothesis.
Immunohistochemical study on the development of serotoninergic neurons in the chick: I. Distribution of cell bodies and fibers in the brain
Authors: Sako Hiroko , Kojima Tokuzo , Okado Nobuo 
Published: January 2005

AbstractThe ontogenetic development of the serotoninergic system in the embryonic as well as in posthatching chick brain was studied with an indirect immunohistochemical technique with the aid of a specific antibody to serotonin (5‐hydroxytryptamine).By embryonic day 4, rostral and caudal groups of serotonin‐immunoreactive cell populations appeared in the mesencephalon and rostral and caudal rhombencephalon. At this stage, the rostral group had a considerable number of labelled cells that sent axons toward more rostral parts of brain, whereas the caudal group consisted of a small number of scattered serotonin‐immunoreactive cells. The number of serotonin‐positive cells increased with development, such that by embryonic day 8 almost all the serotoninergic cell groups found in the adult chick were already present. Serotoninergic‐positive cells appeared in the paraventricular organ of the diencephalon as early as embryonic day 10. Judging from the cytoarchitectural organization of serotonin‐immunoreactive cells, all of the serotoninergic cell groups in the chick brain seemed to be fully developed by embryonic day 16.On embryonic day 4, serotonin‐immunoreactive fibers were found to enter into the marginal layer of the mesencephalon. Subsequently, serotonin‐positive fibers ascended in the marginal layer of the brainstem up to the levels of the diencephalon and to the telencephalon on embryonic day 6 and 8, respectively. Serotonin‐positive fibers, which first began to penetrate into the mantle layer on embryonic day 8, reached to the rostral pole of the telencephalon by embryonic day 10. In general, serotonin fibers were found in almost all brain regions by embryonic day 16. However, “terminal formation” in some nuclei did not seem to begin until the late embryonic or posthatching period.These observations indicate that the initial development of serotoninergic cell groups occurs during the first half of the 20th day of the incubation period of the chick. However, a longer time, ranging from early embryonic to posthatching stages, is necessary for the complete development of the serotoninergic projections.
Immunohistochemical study on the development of serotoninergic neurons in the chick: II. Distribution of cell bodies and fibers in the spinal cord
Authors: Sako Hiroko , Kojima Tokuzo , Okado Nobuo 
Published: January 2005

AbstractDevelopmental changes of serotonin (5‐hydroxytryptamine) neurons and fibers in the spinal cord of the embryo and posthatching chick were studied with immunohistochemical techniques with the aid of an antibody against serotonin.The first serotonin‐immunoreactive fibers were found in the marginal layer of the cervical and lumbar spinal cord on embryonic days 6 and 8, respectively. There was a time lag of a few days between the first appearance of serotonin fibers in the marginal layer (embryonic days 6–8) and the time of penetration of serotonin fibers into the mantle layer (embryonic day 8 or older). The developments of serotonin innervation in the rostral parts of the spinal cord precedes that of caudal regions.Serotonin fibers penetrating into the mantle layer of the lumbar spinal cord were first found in lamina VII on embryonic day 8, whereas there were no serotonin‐immunoreactive fibers in lamina IX by embryonic day 10.Large differences were found between embryonic day 16 and posthatching day 5 with regard to the density of serotonin varicosities and fibers in lamina IX, where profiles of soma and large‐sized dendrites were heavily covered with varicosities. Laminae I and II first received serotonin fibers on embryonic day 16 and had a much denser innervation by posthatching day 5. There were no traces of serotonin fibers in lamina III in the stages examined up to posthatching day 5.Serotonin fibers were located in the lateral and ventral marginal layers in all specimens examined; only a few fibers were found in the dorsal marginal layer.Although few, serotonin‐immunoreactive cell bodies were found in an area around the central canal of all animals from embryonic day 8 to adult. Some of these were located in the ependymal layer and sent processes toward the central canal; there were a small number of cells with long, fine processes. Serotonin‐immunoreactive fibers in the spinal cord were not altered in regions rostral to the spinal transection, whereas all the serotoninergic fibers of the supraspinal origin were eliminated in the spinal cord caudal to the gap.
Morphological features of spiking and nonspiking cells in the paratracheal ganglion of the ferret
Authors: Coburn Ronald F. , Kalia Madhu P. 
Published: January 2005

AbstractThe present series of experiments was designed to study details of the morphology and connectivity of functionally identified cells located in the paratracheal ganglia of the ferret. The morphology of 11 spiking (AH cells) and seven nonspiking (type B cells) ganglion cells was examined. Intraaxonally injected horseradish peroxidase (HRP) was used as the label. Each spiking and nonspiking cell was identified by intracellular recording prior to the HRP injection. “Whole mount preparations” were processed for HRP histochemistry with diaminobenzidine as the chromogen. HRP‐labeled cell bodies of both the spiking AH and nonspiking type B neurons demonstrated similar morphological features. Both types of ganglion cells showed (1) axons arising from a small, ill‐defined axon hillock which exited from the cell as single or multiple branches of equal diameter and coursed unidirectionally through the interganglionic nerve trunk to an adjacent ganglion; (2) short, fine, tapering processes (presumptive dendrites) in the immediate vicinity of the injected cell; and (3) processes extending out of the ganglion cell perpendicular to the interganglionic nerve trunk which could be followed into the smooth muscle. Extraperikaryal injections of HRP into a ganglion retrogradely labeled perikarya in the adjacent ganglia. These results demonstrate that in airway ganglia the morphology of spiking and nonspiking neurons is remarkably similar despite electrophysiological differences. In addition it appears that ganglion cells project to adjacent ganglia and to smooth muscle by means of independent axonal processes. These morphological features of the ganglion cells in airways and the trajectories of their axons correspond to known features of their physiology: i.e., (1) the axon of a ganglion cell travels unidirectionally toward the adjacent ganglion and arborizes there, providing anatomical evidence of communication between ganglia via the interganglionic nerve trunk; and (2) the spiking and nonspiking neurons possess similar morphological features that are typical of ganglion cells described in other systems, such as in the myenteric plexus.
Distribution of cholecystokinin‐immunoreactive cell bodies in the male and female rat: I. Hypothalamus
Authors: Micevych Paul E. , Park Sow Shim , Akesson Thomas R. , Elde Robert 
Published: January 2005

AbstractThe hypothalamic distribution of cholecystokinin‐immunoreactive (CCKI) cell bodies in colchicine‐treated male and female rats was studied. Immunoreactive neurons were visualized along the anterior two‐thirds of the third ventricle but were especially numerous in the preoptic periventricular nucleus. Dense aggregations of CCKI cells were found in the anterior magnocellular, posterior magnocellular, medial parvicellular, and posterior parvicellular divisions of the paraventricular nucleus. Both the supraoptic nucleus and the central, cell‐dense part of the dorsomedial nucleus contained large numbers of CCKI cells.CCKI cells in the preoptic periventricular nucleus were more numerous in the female, as was a population of labeled cells in the dorsal medial preoptic area. However, CCKI cell bodies in this part of the medial preoptic area were larger in males than in females. Males had more CCKI cells in the central part, of the medial preoptic nucleus and in the posterior magnocellular subdivision of the paraventricular nucleus. Both males and females had similar numbers of immunoreactive cells in the anterior magnocellular and the parvicellular divisions of the paraventricular nucleus as well as in the anterior hypothalamus, dorsal areas, dorsomedial nucleus, and supramammillary region. These data provide morphological evidence for a sexually differentiated hypothalamic CCKI system.
Synaptic organization of cholinergic neurons in the monkey neostriatum
Authors: Difiglia Marian 
Published: January 2005

AbstractCholinergic neurons in the monkey neostriatum were examined at the light and electron microscopic level by immunohistochemical methods in order to localize choline acetyltransferase (ChAT), the synthesizing enzyme for acetylcholine. At the light microscopic level a sparse distribution of cholinergic neurons was identified throughout the caudate nucleus. Neurons had large (25–30 μm) somata, eccentric invaginated nuclei, primary dendrites of unequal diameters, and varicosities on distal dendritic branches. Ultrastructural study showed that the cholinergic cells had a cytoplasm abundant in organelles. Within dendritic branches, mitochondria and cisternae were localized primarily to varicosities, Synaptic inputs were distributed mostly to the dendrites and at least four types that formed symmetric or asymmetric synapses were observed.Immunoreactive fibers were relatively numerous within the neuropil and exhibited small diameters (0.1–0.15 μm) and swellings at frequent intervals. Cholinergic boutons that formed synapses were compared to unlabeled terminals making asymmetric synapses with dendritic spines. Results showed that ChAT‐positive axons had significantly smaller cross‐sectional areas, shorter synaptic junctions, and a higher density and surface area of mitochondria than the unlabeled boutons. Cholinergic axons formed symmetric synapses mostly with dendritic spines (53%) and the shafts of unlabeled primary and distal dendrites (37%). A relatively small proportion of the boutons contacted axon initial segments (1%) and cell bodies (9%) that included medium‐sized neurons with unindented (spiny) and indented (aspiny) nuclei. The majority of dendritic spines contacted by cholinergic axons were also postsynaptic to unlabeled boutons forming asymmetric synapses.The results suggest that cholinergic neurons in the primate neostriatum belong to a single morphological class corresponding to the large aspiny (type II) interneuron identified in previous Golgi studies. Present results along with earlier Golgi‐electron microscopic observations from this laboratory suggest that neostriatal cholinergic cells integrate many sources of intrinsic and extrinsic inputs. The observed convergence of ChAT‐immunoreactive boutons and unlabeled axons onto the same dendritic spines suggests that intrinsic cholinergic axons modulate extrinsic inputs onto neostriatal spiny neurons at postsynaptic sites close to the site of afferent input.
Immunocytochemical and autoradiographic localization of GABAergic neurons in the goldfish retina
Authors: Ball Alexander K. 
Published: January 2005

AbstractThe putative neurotransmitter gamma‐aminobutyric acid (GABA) was localized in goldfish retina by using an antiserum directed against GABA itself. The same types of cells were stained with this antibody as were labelled with an antiserum directed against the synthesizing enzyme for GABA, glutamic acid decarboxylase. Stained neurites of these cells were located throughout the inner plexiform layer (IPL) but staining was more intense in the proximal IPL. The GABA‐immunoreactive staining could be reduced or completely abolished by preabsorbing the primary antibody with GABA. Uptake of [3H]‐GABA or the GABA agonist [3H]‐muscimol was localized in GABA‐stained retinas using light microscope autoradiography. These experiments demonstrated that all types of GABA‐immunoreactive amacrine cells had high‐affinity uptake mechanisms for both [3H]‐GABA and ‐muscimol. Thirty percent of proximal inner nuclear layer (INL) and some cells in the ganglion cell layer (GCL) were labelled by all three GABAergic markers. Most GABA‐immunoreactive amacrine cells were lightly labelled due to [3H] ‐ GABA uptake but a few amacrines (Ab) were heavily labelled. These findings demonstrate that the autoradiographic localization of [3H]‐GABA or [3H]‐muscimol uptake and the immunocytochemical localization of GAD or GABA are appropriate methods for localizing GABAergic neurons in the retina. Few GABA‐immunoreactive amacrine cells accumulated the putative amino acid transmitter [3H]‐glycine, verifying that the goldfish retina contains distinct subpopulations of glycinergic and GABAergic amacrine cells.
Tests of the regenerative capacity of tectal efferent axons in the frog, Rana pipiens
Authors: Lyon Michael J. , Stelzner Dennis J. 
Published: January 2005

AbstractExperiments were designed to determine if neurons of the ranid optic tectum, a major target of the optic nerve, possess the same regenerative potential as optic axons. Normal tectal efferent (TE) projections were reexamined by using the anterograde transport of 3H‐proline and autoradiography (n = 18), bulk‐filling damaged TE axons with horseradish peroxidase (HRP; n = 18) and anterogradely transporting wheat germ agglutinin‐HRP (n = 8) to label TE axons. Results were similar to reports that used degeneration methods (Rubinson: Brain Behav. Evol. 1:529–561, '68; Lazar: Acta. Biol. Hung. 20:171–183, '69). Following a brainstem hemisection just caudal to the nucleus isthmi (1–20 weeks), the ipsilateral descending TE pathway was autoradiographically examined (n = 20). While all other TE projections appeared normal, there was no detectable ipsilateral descending projection beyond the lesion site. Ascending TE axons were cut at the anterior tectal border by hemisecting the left diencephalon (LDH)–a lesion that also cuts optic axons projecting to the left tectum. There was no indication of TE axonal regeneration with the aid of autoradiography or HRP histochemistry 1–30 weeks postlesion (n = 48) even when the medial diencephalon was intentionally left intact (n = 4). However, in all four cases examined, optic axons regenerated following the same LDH where TE axonal regeneration failed (also see Stelzner, Lyon, and Strauss: Anat. Rec. 205:191A–192A, '83). Local effects of LDH should be similar for both the cut optic and cut TE axons. Other factors were tested that may contribute to the lack of TE axonal regeneration. Our results indicate that optic regeneration itself (n = 8), postaxotomy retrograde cell death of TE neurons (n = 6), deafferentation of the tectum of optic axons, and potential sprouting within tectal targets by intact contralateral TE axons (n = 10) are not critical factors aborting TE axonal regeneration. TE axons filled with HRP at chronic periods after LDH (n = 4) terminate anomalously near the LDH border. Many of these endings are similar to reactive endings or terminal clubs seen after axonal injury in the mammalian CNS. Our results suggest that this disparity in regenerative ability of optic and TE axons may be related to a difference in the responsive ability of these cell types to initiate or maintain axonal elongation after axotomy within the amphibian CNS environment.
Interhemispheric connections in the visual cortex of the squirrel monkey (Saimiri sciureus)
Authors: Gould Harry J. , Weber Joseph T. , Rieck Richard W. 
Published: January 2005

AbstractThe callosal connections within the posterior parietal and occipital cortices were studied in the squirrel monkey with horseradish peroxidase tracing techniques. The data were evaluated with particular emphasis on the relationship of major callosal connections along the 17–18 border. The overall pattern of callosal connections in the squirrel monkey also was compared with callosal patterns in other New World simians. Our results show that the dense band of callosal connections along the 17–18 border in the squirrel monkey differs from the connections observed in other New World monkeys in that it is virtually confined to area 18 and avoids area 17. In addition to a continuous band of callosal connections in area 18 that parallels the 17–18 border, rostral extensions of the band are oriented perpendicular to the 17–18 border and present an obvious periodicity. The remaining parieto‐occipital cortex contains a complex pattern of callosal connections that is strikingly similar to patterns reported for other New World monkeys. Thus, it is likely that the dorsolateral extrastriate visual cortex in the squirrel monkey is organized in a manner similar to that found within other New World monkeys.
Area postrema of the goldfish, Carassius auratus: Ultrastructure, fiber connections, and immunocytochemistry
Authors: Morita Yasuhiro , Finger Thomas E. 
Published: January 2005

AbstractThe area postrema in goldfish is a dorsal midline structure in the caudal medulla spanning the level of the obex. As in other vertebrates, the sinus capillaries of the area postrema in goldfish are fenestrated. In goldfish, however, the area postrema is organized in a unique laminar fashion; from superficial to deep: meninx, vasculature, palisade layer, cell body layer, and ventral neuropil layer.Virtually all of the neurons of the area postrema exhibit tyrosine hydroxylase‐like immunoreactivity. Each immunoreactive neuron is essentially bipolar, with a short apical dendrite extending dorsally to reach the external basal lamina of the capillaries and a basal dendrite reaching into the subjacent layer of neuropil. The apical dendrites have no synaptic specializations and probably function as interoceptors detecting blood‐borne chemicals that leak out of the fenestrated capillaries. The basal dendrites receive synaptic input both within the neuropil of the area postrema and in the commissural nucleus of Cajal into which they extend. Primary afferent fibers of the subdiaphragmatic branches of the vagus nerve terminate within the area postrema and commissural nucleus. Thus the neurons of the area postrema may serve not only as direct chemoreceptive interoceptors but may also receive input from other visceral afferent systems.
The combined effects of unilateral enucleation and rearing in a “dim” red light on synapse‐to‐neuron ratios in the rat superior colliculus
Authors: Mackay D. , Bedi K. S. 
Published: January 2005

AbstractRats whose right eyes were enucleated on day 1 after birth and nonenucleated rats were raised in either “light” or “dark” (red light) conditions from birth until 39 days of age. This resulted in 4 groups of animals: light‐reared nonenucleated, light‐reared enucleated, dark‐reared nonenucleated, and dark‐reared enucleated. At 39 days of age, the animals were killed by perfusion with 2.5% sodium cacodylate buffered glutaraldehyde. The superior colliculi were dissected out and processed for embedding in resin. Stereological procedures at the light and electron microscopical levels were used to estimate the synapse‐to‐neuron ratios in the superficial layers of these colliculi.Light‐reared, nonenucleated rats had about 1,850 synapses‐per‐neuron in both the right and left superior colliculi. Rearing nonenucleated rats in the dark reduced this value to about 1,200.Enucleated rats reared in the light showed a differential response in the 2 colliculi. Thus, the contralateral (to the enucleated eye) colliculi showed a decrease, whereas the ipsilateral colliculi showed an increase in the synapse‐to‐neuron ratio compared with light‐reared, nonenucleated rats.When enucleated rats were reared in the red light, there was a decrease in the ratio in both colliculi, although the extent of this decrease was more marked in the contralateral than the ipsilateral colliculi. However, the decrease in the contralateral colliculi was not significantly greater than that observed in the corresponding colliculi from dark‐reared, nonenucleated rats.These results provide useful information on the combined and separate effects of unilateral enucleation at around birth and dark (red light) rearing during early life on the interneuronal connectivity of both the ipsi‐ and contralateral superior colliculi of rats. They also show the vast importance of visual stimulation for the normal development of the subcortical visual centers.