bluuebunny/crossref_metadata_2025 huggingface dataset:
Demonstration of initial axon collaterals of cells of origin of the ventral spinocerebellar tract in the cat
Authors: Bras H. , Cavallari P. , Jankowska E.
Published: May 2005

Neurones of origin of the ventral spinocerebellar tract were stained with intracellularly applied horseradish peroxidase to investigate whether they give off any initial axon collaterals. The neurones were located in the fourth and fifth lumbar segments and were identified by their antidromic activation following stimulation in the contralateral superior cerebellar peduncle. Nine of the 23 neurones with well‐stained axons were found to give off axon collaterals soon after the axons crossed the midline. The collaterals entered the contralateral ventral horn and branched within lamina VII and the dorsal part of lamina VIII. Collaterals were found arising only from neurones located in the middle of lamina VII and from axons which took a mediorostral direction. In all of these neurones excitatory postsynaptic potentials were evoked from group Ia afferents of at least some nerves, in addition to such potentials from Ib or unidentified group I afferents, and inhibitory postsynaptic potentials were evoked from group I and II afferents. The area of terminal branching of the collaterals suggests that they may supply contralateral ventral spinocerebellar neurones with information from muscles and/or mediate crossed reflexes from group I afferents.
Distribution of glycine receptor immunoreactivity in the spinal cord of the rat: Cytochemical evidence for a differential glycinergic control of lamina I and V nociceptive neurons
Authors: Basbaum Allan I.
Published: May 2005

In this study we characterized the distribution of glycine receptor immunoreactivity in the spinal cord of the rat by using monoclonal antisera directed against the purified glycine receptor. There was dense, punctate glycine receptor immunoreactive staining in all regions of the gray matter ventral to the substantia gelatinosa. The densest staining was found in laminae III and IV of the dorsal horn. There were also distinct, tributarylike bands of punctate staining that extended well into the white matter of the lateral and ventral funiculi. The only consistent cell body staining was found in small neurons of the ventral horn. The labelled neurons were distributed among larger, unlabelled motoneurons.

In general, the pattern of glycine receptor immunoreactivity was similar at all levels of the spinal cord and was comparable to that seen with binding of a tritiated glycine receptor antagonist, strychnine, to sections of rat spinal cord (Zarbin et al.: J. Neurosci. 1:532–547, '81). Two important exceptions, however, were observed. In contrast to the high levels of strychnine binding reported in the substantia gelatinosa, we found almost no glycine receptor immunoreactivity in laminae I and II of the superficial dorsal horn of the spinal cord or of the trigeminal nucleus caudalis. There was also a notable absence of antibody staining in the intermediolateral cell column of the thoracic cord.

The presence of dense glycine receptor immunoreactivity in the region of lamina V and its absence in the superficial dorsal horn are discussed in terms of a possible differential glycinergic control of nociceptive neurons of laminae I and V.
Neurocytology of the cerebral ganglion of Fasciola hepatica (Platyhelminthes)
Authors: Sukhdeo Suzanne C. , Sukhdeo Michael V. K. , Mettrick David F.
Published: May 2005

An ultrastructural study of the organization and fine structure of the nervous system of the parasitic flatworm Fasciola hepatica was undertaken. The brain consists of paired cerebral ganglia, located just posterior to the oral sucker, that are connected by a transverse commissure which crosses over the dorsal surface of the pharynx. The cell bodies of the cerebral ganglia are not organized into a clearly defined rind around the neuropile but are loosely scattered around and within the neuropile area. The neuropile consists of two morphologically distinct types of unmyelinated nerve processes. The small nerve processes, with smooth cell membranes, are less than 2 μ in diameter, whereas the “giant” processes are greater than 12 μ in diameter and have extensively invaginated cell membranes. Giant processes make up the bulk of the nerve fibers in the transverse commissure and longitudinal nerve cords. Four morphological types of vesicles are present in the small processes; small clear vesicles (which were found associated with synapses), spheroidal and ellipsoidal dense vesicles, and dense‐core vesicles. Two types of synapses are found in the neuropile: simple synapses characterized by pre‐ and postsynaptic membrane densities, clusters of small clear vesicles, and a clear synaptic cleft; and wedge‐shaped synapses or divergent diads each having one presynaptic process synapsing onto two postsynaptic processes. Synaptic contacts were observed only between small processes; no synapses were observed on the cell bodies or on giant processes.
Three‐dimensional counting: An accurate and direct method to estimate numbers of cells in sectioned material
Authors: Williams Robert W. , Rakic Pasko
Published: May 2005

We introduce a way to count and measure cells in an optically defined volume of tissue called a counting box. This method—direct three‐dimensional counting (3DC)—eliminates the need for correction factors, such as that introduced by Abercrombie (Anat. Rec. 94:239–247, '46), to determine the number of cells per unit volume (Nv). Problems caused by irregular cell shape and cell size, nonrandom orientation, and splitting of cells by the knife during sectioning are overcome. Furthermore, 3DC is insensitive to large variations in section thickness.

The innovative feature of 3DC is the definition of a counting box with top and bottom sides located inside the section a precise distance away from the cut surfaces of the tissue. The positions of the top and bottom sides of the counting box are delimited by using a digital length gauge and a Z‐axis control unit.

Sections of tissue between 8 and 100 μ thick are examined with a high numerical aperture objective in combination with video‐enhanced differential interference contrast optics (DIC). Cells are marked on a television screen while the microscopist scans systematically from the top to the bottom of the counting box. Cells that are located completely inside the box and cells that only cross through its top, right, or back sides are counted. All cells that cross the planes that define the bottom, left, and front sides of the counting box are not counted.

Direct 3DC provides an accurate, simple, and reliable way to count cells, nuclei, nucleoli, or other objects in sectioned material. To build the counting system requires a standard transmitted light microscope equipped with DIC optics, a video camera, a position sensor, and a Z‐axis control unit.
A Golgi analysis of the gustatory zone of the nucleus of the solitary tract in the adult hamster
Authors: Davis Barry J. , Jang Taichang
Published: May 2005

The somal shapes, dendritic features, and orientations of the neurons within the gustatory zone of the nucleus of the solitary tract were studied with the rapid Golgi method in the adult hamster. These Golgi studies complement previous quantitative morphometric analyses of the distributions of large and small neurons within the gustatory zone. Class 1 neurons are usually fusiform and possess long, relatively unbranched dendrites that often extend beyond the cytoarchitectonic boundaries of the gustatory zone. Class II neurons are multipolar and possess more dendrites that are significantly shorter than those of class I neurons. Both classes of neurons are spine poor. Computer‐generated three‐dimensional rotational analyses demonstrate that the dendritic arborizations of neurons of the gustatory zone are oriented preferentially in the horizontal plane. Dendrites extend in parallel or perpendicular to the solitary tract, the source of peripheral gustatory inputs, and appear to be positioned spatially to maximize synaptic interactions with these peripheral fibers. These Golgi studies also suggest that individual gustatory neurons may be influenced by incoming gustatory fibers that innervate separate populations of taste buds, a finding that is not predictable from the topographical organization of the gustatory zone.
Numbers of synapses in laminae I–IV of the rat dorsal horn
Authors: McNeill D. L. , Chung K. , Hulsebosch C. E. , Bolender R. P. , Coggeshall R. E.
Published: May 2005

The present study determines numerical densities (NVsyn) and total numbers of synaptic discs in laminae I‐IV of the rat S2 dorsal horn. Previous methods for NVsyn have the advantage of being relatively simple, but these assume that the discs are round, flat, and of uniform size. In our material, serial reconstructions indicate that these assumptions are not met. Accordingly we use a stereological method that is not as dependent on these assumptions. This method is to divide the surface density of the discs by the mean surface area of a disc (NVsyn = SVsyn/Ssyn). We refer to this as a reconstruction method because synaptic discs are reconstructed from serial sections. We also calculate numerical densities by several previously used standard methods, and the findings are similar but not identical. We find that numerical density and total synaptic numbers are smallest in lamina I, and densities and total numbers are not significantly different when lamina II is compared to laminae III and IV. Thus the intense labeling of terminals with certain compounds that characterize lamina I and II does not imply an increase in total synaptic numbers or in synaptic density. In addition there is a general increase in synaptic densities and numbers as one proceeds from lamina I to lamina IV. Another point is that the numerical density of synapses in the dorsal horn is approximately that of the cerebral cortex. These data will serve as a basis from which to judge the effects of denervations and other manipulations that purportedly change synaptic numbers.
Early differentiation of ganglion, amacrine, bipolar, and muller cells in the developing fovea of human retina
Authors: van Driel Diana , Provis Jan M. , Billson Francis A.
Published: May 2005

We examined the differntiation and maturation of neurons and glia of the inner nuclear layer (INL) and ganglion cell layer (GCL) in the retina of a human fetus of 15 weeks gestation. Serial, ultrathin sections were cut from a resinembedded specimen from the posterior pole of the retina. The region of the putative fovea was defined by the absence of rod photoreceptors from the outer nuclear layer; only sections through the putative fovea were studied. Cell somata were classified on the basis of morphological criteria and, through the analysis of serial sections, morphological characteristics of the cell processes were established. In the inner plexiform layer (IPL), the types of synapses were analysed. The majority of cells in the INL and GCL were differentiated and could be identified. Ganglion cell somata were observed in the GCL and INL. Of 186 somata analysed in the INL, 66 were Muller cells, 21 amacrine cells, and 2 ganglion cells; a further 7 cells were classified as either amacrine or ganglion. Bipolar cells were thought to comprise the majority of the remaining 90 somata, but these could not be positively identified, as it was not possible to trace bipolar cell axons to their cell bodies deep in the INL. A detailed description of the morphological characteristics of the identified cells and their processes, and of the axonal processes of bipolar cells, is provided. Puncta adherentia and other simple intercellular junctions were commonly seen in the IPL and involved all cell types. Amacrine cell synapses and immature, monad bipolar cell synapses were common within the IPL. Dyad bipolar synapses were uncommon at this stage of development. A possible sequence of synaptogenesis in the IPL is discussed.
Inhibin β, somatostatin, and enkephalin immunoreactivities coexist in caudal medullary neurons that project to the paraventricular nucleus of the hypothalamus
Authors: Sawchenko P. E. , Arias C. , Bittencourt J. C.
Published: May 2005

Concurrent and sequential dual immunohistochemical labeling methods were used in combination, along with retrograde tracing techniques, to determine the extent to which inhibin < (Iβ), somatostatin‐28 (SS‐28), and enkephalin (ENK) immunoreactivity (IR) might be jointly expressed in neurons centered in the caudal part of the nucleus of the solitary tract )NTS( that project to the paraventricular nucleus of the hypothalamus (PVH). The results indicate that at least 65% of Iβ‐stained neurons in the NTS also express SS‐28 IR, and at least 33% are ENK‐positive. At least 25% of the Iβ IR population stains positively for all three peptides. A substantial number of cells stained with markers for two, or all three, peptide families, could be retrogradely labeled following tracer deposits centered in the PVH. Prominent Iβ and SS‐28 IR projections from the caudal medulla to the hypothalamus have been described and include a preferential input to oxytocinergic (OT) compartments of the magnocellular neurosecretory system. The present results suggest that these arise in large measure from a common pool of neurons, a subset of which also shows ENK IR. Implications for the control of OT secretion, and for the processing of sensory information through the NTS, are discussed.
Tyrosine hydroxylase‐like immunoreactivity in the brain of fifth instar Rhodnius prolixus stål (hemiptera: Reduviidae)
Authors: Nyhof‐Young Joyce , Orchard Ian
Published: May 2005

The distribution of tyrosine hydroxylase‐like immunoreactivity was mapped in whole‐mount preparations of the brain of fifth instar Rhodnius prolixus Stål. Immunoreactivity was limited to neuronal cell bodies and processes, which were distributed over both ventral and dorsal surfaces of the CNS. The brain, excluding the optic lobes, contained about 160 tyrosine hydroxylase‐like immunoreactive cells. Each optic lobe contained two groups of small round cell bodies, which were too numerous to count. The wide distribution of immunoreactivity suggests that tyrosine hydroxylase is present in neurons with diverse central functions. Tyrosine hydroxylase is the rate‐limiting enzyme in catecholamine synthesis in vertebrates. A comparison of a map of the distribution of catecholamine‐induced fluorescence obtained using the glyoxylic‐acid technique (Flanagan; J. Insect Physiol. 30(9):697‐704, 1984) with that generated for tyrosine hydroxylase reveals considerable overlap between the two systems, suggesting that tyrosine hydroxylase is used in the catecholamine pathway in this insect. The mapping of these reactive neurons is an important step for identification of unique tyrosine hydroxylase‐containing neurons, and is our initial step in the analysis of identified catecholamine‐containing neurons in R. prolixus.
Contribution of brainstem GABAergic circuitry to descending antinociceptive controls: I. GABA‐immunoreactive projection neurons in the periaqueductal gray and nucleus raphe magnus
Authors: Reichling David B. , Basbaum Allan I.
Published: May 2005

The fact that GABA receptor agonists and antagonists influence nociceptive thresholds when microinjected into the rostroventral medulla or in the spinal cord may reflect the involvement of GABAergic neuronal elements in endogenous antinociceptive pathways. In the present study we used immunocytochemistry and retrograde tract tracing to investigate the contribution of GABAergic projection neurons to the antinociceptive network linking the midbrain periaqueductal gray matter (PAG), the nucleus raphe magnus (NRM), and the spinal cord dorsal horn. The tracer, WGAapoHRP‐Au was injected into either the NRM or the spinal cord and the distribution of labeled neurons in sections of the PAG and medulla, respectively, was studied. The same sections were immunostained to demonstrate GABA‐immunoreactive neurons. Although GABA‐immunoreactive neurons were abundant in the PAG, only 1.5% were retrogradely labeled from the NRM. Similarly, very few GABA‐immunoreactive neurons within the cytoarchitectural boundaries of the NRM were retrogradely labeled from the spinal cord. A much higher proportion of GABA‐immunoreactive neurons in the region lateral to the NRM, however, were retrogradely labeled from the spinal cord. Eighteen percent of GABA‐immunoreactive neurons were retrogradely labeled in the nucleus reticularis paragigantocellularis; conversely, 15% of the retrogradely labeled neurons in this region were GABA‐immunoreactive. These results indicate that GABAergic projections constitute a very minor component of the PAG‐NRM‐spinal cord pathway; however, there is a significant contribution of GABAergic neurons to the spinal projections that originate lateral to the NRM. The majority of GABAergic neurons in the PAG and NRM are presumed to be inhibitory interneurons that directly or indirectly regulate activity in efferent pathways from these regions.
Generation patterns of immunocytochemically identified cholinergic neurons at autonomic levels of the rat spinal cord
Authors: Barber Robert P. , Phelps Patricia E. , Vaughn James E.
Published: May 2005

The time at which a neuron is “born” appears to have significant consequences for the cell's subsequent differentiation. As part of a continuing investigation of cholinergic neuronal development, we have combined ChAT immunocytochemistry and [3H]thymidine autoradiography to determine the generation patterns of somatic and autonomic motor neurons at upper thoracic (T1‐3), upper lumbar (L1‐3), and lumbosacral (L6‐S1) levels of the rat spinal cord. Additionally, the generation patterns of two subsets of cholinergic interneurons (partition cells and central canal cluster cells) were compared with those of somatic and autonomic motor neurons. Embryonic day 11 (E11) was the first day of cholinergic neuronal generation at each of the three spinal levels studied, and it also was the peak generation day for somatic and autonomic neurons in the upper thoracic spinal cord. The peak generation of homologous neurons at upper lumbar and lumbosacral spinal levels occurred at E12 and E13, respectively. Somatic and autonomic motor neurons were generated synchronously, and their production at each rostrocaudal level was virtually completed within a 2‐day period. Cholinergic interneurons were generated 1 or 2 days later than motor neurons at the same rostrocaudal level. In summary, the birthdays of all spinal cholinergic neurons studied followed the general rostrocaudal spatiotemporal gradient of spinal neurogenesis. In addition, the generation of cholinergic interneurons also followed the general ventrodorsal gradient. In contrast, however, autonomic motor neurons disobeyed the rule of a ventral‐to‐dorsal progression of spinal neuronal generation, thus adding another example in which autonomic motor neurons display unusual developmental patterns.
The size and dendritic structure of HRP‐labeled gamma motoneurons in the cat spinal cord
Authors: Moschovakis A. K. , Burke R. E. , Fyffe R. E. W.
Published: May 2005

We report quantitative data obtained from 60 fully reconstructed dendritic trees belonging to eight γ‐motoneurons (γ‐MNs) and six additional γ‐MNs that were not completely reconstructed. The cells were labeled intracellularly with horseradish peroxidase (HRP). These data are compared to measurements from 79 reconstructed dendrites belonging to seven documented α‐motoneurons (α‐MNs), supplemented by a larger sample of α‐MNs labeled intracellularly or by retrograde transport with HRP. As expected from earlier studies, the soma dimensions and total membrane area of γ‐MNs were smaller than those of α‐MNs. Although γ‐MN dendrites were, on average, slightly but significantly longer than those of α‐MNs, the former had, on average, smaller diameter stem dendrites, less membrane area, and less profuse branching, and they tended to branch closer to the soma and to terminate farther from the soma. These differences were evident even when subsets of dendrites with similar stem diameters were compared. Some of the anatomical distinctions suggest that γ‐MNs are qualitatively as well as quantitatively different from α‐MNs, even though the distributions of many of the morphological variables examined showed no abrupt discontinuities between the two motoneuron groups.
Ascending general visceral pathways within the brainstems of two teleost fishes: Ictalurus punctatus and Carassius auratus
Authors: Finger Thomas E. , Kanwal Jagmeet S.
Published: May 2005

The primary general visceral nucleus in goldfish. (Carassius auratus) and catfish (Ictalurus punctatus) is located at the ventroposterior boundary of the vagal gustatory lobe and receives coelomic visceral, but not gustatory inputs. The neuronal tracer horseradish peroxidase (HRP) was employed to visualize sources of input to and/ascending projections from the primary general visceral nucleus in these species. In addition, immunocytochemical techniques were utilized to define the cytological divisions within the pontine gustatory‐visceral complex. The pontine secondary visceral nuclei in both catfish and goldfish contains numerous somata and fibers immunoreactive for calcitonin gene‐related peptide (CGRP). In contrast, the secondary gustatory nuclei are devoid of fibers and cells immunoreactive for CGRP.

In both the goldfish and the channel catfish, the primary general visceral nucleus receives input from the vagal gustatory lobe, as well as the medullary reticular formation. In the channel catfish, the primary general visceral nucleus projects bilaterally to the secondary visceral nucleus, which lies rostrolateral to the secondary gustatory nucleus in the dorsal pons. Fibers cross the midline via the rostral part of the isthmic commissure. Injection of HRP into the primary general visceral nucleus of a goldfish labels ascending fibers that project to a secondary visceral nucleus situated ventral, lateral, and rostral to the secondary gustatory complex. In general, the results indicate that general visceral systems ascend in parallel to gustatory systems within the brainstem, and that general visceral but not gustatory nuclei are immunoreactive for the peptide CGRP.
Selective vulnerability of the hippocampal pyramidal neurons to hypothyroidism in male and female rats
Authors: Madeira M. D. , Sousa N. , Lima‐Andrade M. T. , Calheiros F. , Cadete‐Leite A. , Paula‐Barbosa M. M.
Published: May 2005

Thyroid hormone deficiency has long been considered to affect profoundly such cognitive functions as learning and memory, which are known to depend on the structural integrity of the hippocampal formation. Since we previously found that the number of granule cells of the dentate gyrus is reduced in hypothyroid animals, we decided to extend our observations to the pyramidal cells of the hippocampus in order to gain further insight into the effects of hypothyroidism upon the other neuronal links of the hippocampal trisynaptic circuitry, inasmuch as CA1 neurons are known to be particularly vulnerable to aggressive agents.

Groups of 6 male and 6 female rats aged 30 and 180 days were analysed separately after being treated as follows: (1) hypothyroid from day 0 until day 30 (30‐day‐old hypothyroid group); (2) respective 30‐day‐old control; (3) hypothyroid from day 0 until day 180 (180‐day‐old hypothyroid group); (4) hypothyroid until day 30 and thenceforth maintained euthyroid (recovery group); (5) hypothyroid since day 30 (adult hypothyroid group); and (6) respective 180‐day‐old control. The volume of the pyramidal cell layer of the CA1 and CA3 regions and the numerical density of the respective neurons were evaluated, thereby allowing us to estimate the total number of pyramidal cells in each hippocampal region. The areal density and the mean nuclear volume of CA1 and CA3 pyramidal cells were also estimated.

In the CA3 region, we found that hypothyroidism, whatever its duration and time of onset, induces a reduction in the volume of the pyramidal cell layer and a parallel increase in the numerical density of its neurons, without interfering with the total number of pyramidal cells. Conversely, in the CA1 region, thyroid hormone deficiency started either neonatally or during maturity was found to lead to a decrease in the total number of pyramidal cells. Reductions ranging between 14.2 and 22.5% were found in 30 and 180‐day‐old hypothyroid groups. The reestablishment of a euthyroid state did not ameliorate the referred neuronal loss.

The present results support the view that hypothyroidism induces small alterations in the structural organization of the hippocampal CA3 region, contrary to what happens in CA1 in which neuronal death occurs. Furthermore, the data presented herein demonstrate that the total number of CA1 pyramidal cells displays sexual dimorphism that is not affected by thyroid hormone manipulations. These findings allow us to admit that hypothyroidism induces anatomical changes in the hippocampus which are in line with those reported for the dentate gyrus, thereby providing additional morphological basis for the cognitive alterations described in this condition. © 1992 Wiley‐Liss, Inc.
Vasopressin innervation of sexually dimorphic structures of the gerbil forebrain under various hormonal conditions
Authors: Crenshaw Bradley J. , de Vries Geert J. , Yahr Pauline
Published: May 2005

The distribution of vasopressin‐immunoreactive fibers in the forebrain of male and female gerbils was studied, focusing on the lateral septum and the sexually dimorphic area (SDA) found at the border between the medial preoptic area and the anterior hypothalamus. To study hormonal influences on the densities of these fibers, some animals of each sex were gonadectomized or gonadectomized and given testosterone. Others were given sham operations. High densities of vasopressin‐immunoreactive fibers were found in the lateral septum. In the SDA, the densities of these fibers varied considerably. Many were found in the medial half of the medial SDA, but few in the lateral SDA. Vasopressin‐immunoreactive fibers were also sparse in the lateral half of the medial SDA, except for a dense cluster in the SDA pars compacta of males. Similar but smaller clusters were seen in the same location in females although the SDA pars compacta could not be detected in Nissl‐stained sections from the female brains. Fiber densities in two areas, the lateral septum and the lateral SDA, were sensitive to gonadal steroids. In both cases, castration reduced fiber density and testosterone enhanced it. In addition, fiber densities in two areas, the lateral septum and the medial SDA, were sexually dimorphic. In each case, fiber density was greater in males. There was no hormonal effect, however, on the fiber densities in the medial SDA. The fact that the fiber plexuses in the lateral septum and the medial SDA respond differently to gonadal steroids suggests that they arise from different cells and possibly from different areas of the brain. The vasopressin‐immunoreactive fibers in the lateral septum probably come from steroid‐sensitive vasopressin neurons in the bed nucleus of the stria terminalis. Those in the medial SDA may originate in the dorsal aspect of the suprachiasmatic nucleus where vasopressin‐immunoreactive cell bodies were seen. © 1992 Wiley‐Liss, Inc.
Localization of 3H‐nicotine, 125I‐kappa‐bungarotoxin, and 125I‐alpha‐bungarotoxin binding to nicotinic sites in the chicken forebrain and midbrain
Authors: Sorenson Eva M. , Chiappinelli Vincent A.
Published: May 2005

We have previously localized cholinergic cell bodies and fibers within the midbrain of the chicken with choline acetyltransferase immunohistochemistry. In a continuing effort to characterize the central cholinergic system, the present study examines the distribution of various nicotinic acetylcholine receptors in the forebrain and midbrain of the chicken. The binding of 3H‐nicotine, 125I‐kappa‐bungarotoxin, and 125I‐α‐bungarotoxin was localized by film autoradiography in adjacent sections of the adult chicken brain, allowing a comparison of the distribution of different classes of nicotinic binding sites within the brain.

Although all three ligands were often co‐localized, there were areas that bound 3H‐nicotine but not the 125I‐neurotoxins, or vice versa. Very high densities of all three ligands were found in the hyperstriatum ventrale; the nucleus geniculatus lateralis, pars ventralis; the griseum tectale; the nucleus dorsolateralis anterior thalami; the nucleus lentiformis mesencephali, pars lateralis and pars medialis; the periventricular organ; and the stratum griseum et fibrosum superficial, layer f of the optic tectum. The nucleus spiriformis lateralis had the highest levels of 3H‐nicotine binding in the chicken brain, but it did not bind either of the two snake neurotoxins. On the other hand, high levels of both 125I‐α‐bungarotoxin and 125I‐kappa‐bungarotoxin binding were found in the nucleus semilunaris and the nucleus ovoidalis, but these areas contained little or no 3H‐nicotine binding. No unique 125I‐kappa‐bungarotoxin sites, unrecognized by 125I‐α‐bungarotoxin, were identified by the low resolution autoradiography performed in this study.

In general, nicotinic receptors were found in areas that have been reported to contain cholinergic cell bodies or fibers. Comparison of our results with the expression of neuronal nicotinic receptor subunits, as determined by in situ hybridization, suggests that many of the high affinity 3H‐nicotine sites are localized presynaptically, as, for example, in the retinorecipient nuclei and the nucleus interpeduncularis. The lack of 125I‐kappa‐bungarotoxin binding in the presence of α‐bungarotoxin indicates that the chicken brain has only very low levels of a unique kappa‐bungarotoxin site. This is in marked contrast to chicken, frog, and rat autonomic ganglia, where a unique kappa‐neurotoxin‐sensitive receptor has been identified and shown to mediate nicotinic neurotransmission. © 1992 Wiley‐Liss, Inc.
Distribution of corticotropin‐releasing factor‐like immunoreactivity in squirrel monkey (Saimiri sciureus) amygdala
Authors: Bassett J. L. , Foote S. L.
Published: May 2005

Previous anatomical studies of corticotropin‐releasing factor (CRF)‐like immunoreactivity in rat brain have reported prominent clustering of neuronal elements containing this peptide within the amygdala. The highest concentrations of both CRF‐positive cells and fibers were evident in the central nucleus, an observation consistent with the putative role of this peptide in autonomic and endocrine regulation. In addition, lower densities of CRF‐positive somata and processes have boon noted in other amygdaloid nuclei. However, the distribution of CRF‐like immunoreactivity in the amygdala has not been described for any primate species. Such a description would be of interest since substantial differences in the distribution of CRF in rodent and primate have been reported for other brain regions.

The present study uses immunohistochemical methods, with a polyclonal antiserum directed against the human form of CRF, to determine the distribution of this peptide in non‐colchicine‐treated monkeys (Saimiri sciureus). Within the amygdaloid complex, the most numerous and concentrated collections of CRF‐positive neurons were seen in the basal and lateral nuclei. The highest densities of CRF‐positive fibers and terminals were seen in the lateral and central amygdaloid nuclei. Moderately dense plexuses of CRF‐positive fibers also were seen in layer Ia of the periamygdaloid cortex, nucleus of the lateral olfactory tract, anterior and posterior cortical nuclei, and the medial nucleus. Thus, the distribution of CRF‐like immunoreactivity differs substantially in monkey and rat amygdala. Since CRF‐positive perikarya in monkey are most prominent in nuclei with pronounced interconnections with neocortex, these differences may be an integral component of the increased cortical development that characterizes the primate brain. © 1992 Wiley‐Liss, Inc.
Novel developmental boundary in the cerebellum revealed by zebrin expression in the Lurcher (Lc/+) mutant mouse
Authors: Tano David , Napieralski Julie A. , Eisenman Leonard M. , Messer Anne , Plummer Julie , Hawkes Richard
Published: May 2005

The cerebellar cortex contains at least two classes of Purkinje cells, which are organized into alternating arrays of parasagittal bands. The clearest demonstration of this compartmentation is the pattern of expression of a family of polypeptide antigens, the zebrins, which are expressed selectively by Purkinje cell subsets. Furthermore, anterograde tracing experiments show that the zebrin compartments are closely correlated with both afferent and efferent projection maps. The further subdivision of long parasagittal bands into smaller modules may occur through several different mechanisms, including the intrinsic cerebellar lobulation and the selective distribution of afferent terminal fields. However, while the longitudinal subdivisions are straightforwardly shown, the mediolateral boundaries are more subtle. In this report we describe a novel mediolateral and anteroposterior compartmentation boundary in mice, running across lobule VIII, that is revealed by the consequences of the lurcher (Lc/+) allele for zebrin expression. In normal mice zebrin compartmentation develops in several discrete stages: until postnatal day 5 (PD5) there is no zebrin expression; from PD5–PD7 zebrin is found only in the posterior lobe vermis, with immunoreactive Purkinje cells in lobules X, IX, and VIII but not elsewhere; from PD7–PD12 most Purkinje cells in the vermis become zebrin+ from PD12–PD15 immunoreactivity also appears in the hemispheres so that almost all Purkinje cells now are zebrin+ and finally, from PD15–PD25 zebrin is gradually suppressed in those Purkinje cells that are zebrin‐ in the adult until the mature pattern of parasagittal compartments is revealed. In the Lc/+ mutant the normal developmental progression is interrupted at around PD7. As a result, the pattern of zebrin expression becomes frozen at that stage when immunoreactive Purkinje cells are confined exclusively to the posterior lobe vermis. A reproducible boundary between expressing and nonexpressing zones runs mediolaterally across the dorsal surface of lobule VIII. Apart from zebrin expression itself, there are no obvious structural correlates of this transition. This mediolateral boundary identifies a developmental unit in the posterior lobe vermis of the cerebellum, and provides further evidence that the cerebellum is a highly heterogeneous structure. © 1992 Wiley‐Liss, Inc.
Development of the olivocerebellar projection in the rat: I. Transient biochemical compartmentation of the inferior olive
Authors: Wassef Marion , Chedotal Alain , Cholley Béatrice , Thomasset Monique , Heizmann Claus W. , Sotelo Constantino
Published: May 2005

In the present study the early phases of the development of the inferior olive were examined by using immunocytochemical techniques. We observed that, from embryonic day 16 onward, antibodies against the calcium binding proteins parvalbumin and calbindin and the calcitonin gene related peptide stain partially overlapping territories of the inferior olive. This staining delimits a biochemical zonation of the inferior olive which is combinatory and transient. We have previously observed a biochemical parcellation of the cerebellar Purkinje cells which, like that of the inferior olive, is first observed, at E16, involves the combined expression of marker proteins and is also transient. In order to know whether the biochemical compartmentations of the cerebellum and inferior olive arise independently, the time course of the development of the olivocerebellar projection was studied by anterograde and retrograde in vitro axonal tracing by using the fluorescent carbocyanine dye DiI. The olivocerebellar axons were found to reach the limit of the cerebellar plate at E16 and to enter it at E17. Even at this age the great majority of the climbing fibers are tightly fasciculated, which minimizes their interactions with the PC clusters. These observations indicate that the topographical heterogeneity of Purkinje cells and inferior olive neurons arise independently. The transient biochemical individualization of subgroups of neurons during development could contribute to recognition mechanisms. © 1992 Wiley‐Liss, Inc.
Myelin‐Axon relationships in the rat phrenic nerve: Longitudinal variation and lateral asymmetry
Authors: Fraher John P.
Published: May 2005

It is known that the myelin sheath thickness‐axon perimeter relationship varies between peripheral nerves. This study examines the possibility that that relationship may vary between levels along a given nerve or between corresponding levels of the right and left examples of the same nerve. The relationship is examined for large and small fibre classes at well separated upper and lower intrathoracic levels in the rat phrenic nerve. The study shows that the myelin‐axon relationship differs between levels along the same nerve bundle in the same (intrathoracic) environment. Thus, for a given increase in the perimeter of large axons, sheath thickness increases significantly more at lower than at upper levels. In addition, myelin sheath thickness shows a statistically significant lateral asymmetry in favour of the left side for the large fibre class at the upper thoracic level. The setting of the myelin sheath thickness‐axon perimeter relationship also differs between the large and small fibre classes at each level examined. Large fibres have proportionately thicker sheaths than small fibres and this difference is reflected in the significantly smaller g‐ratio of the former. Systematic differences in the setting of the myelin sheath thickness‐axon perimeter relationship between large and small fibre classes may be a widely occurring phenomenon. It may be concluded that the myelin‐axon relationship varies significantly both within and between nerves and also between fibre classes. Accordingly, morphometric studies of normal or pathological nerves should take into account possible consistent longitudinal variation or lateral asymmetry in fibre parameters and myelin‐axon relationships within a given nerve bundle or fibre class, in order to avoid introducing systematic bias and to minimize variance between samples. © 1992 Wiley‐Liss, Inc.
Effects of sex and androgen treatment on dendritic dimensions of neurons in the sexually dimorphic preoptic/anterior hypothalamic area of male and female ferrets
Authors: Cherry James A. , Tobet Stuart A. , DeVood Timothy J. , Baum Michael J.
Published: May 2005

A sexually dimorphic group of cells at the dorsal border of the preoptic/anterior hypothalamic area (POA/AH) of ferrets has been previously identified in Nissl‐stained tissue. In this study, Golgi‐stained tissue was examined in order (1) to determine whether sex differences exist in dendritic dimensions of neurons from this region, and (2) to assess the effects of adult androgen treatment on dendritic morphology in ferrets of both sexes. Brains from adult ferrets given daily injections of testosterone propionate (5 mg/kg body weight) or oil vehicle for 5 weeks after gonadectomy were impregnated by Golgi‐Cox procedures. After sectioning at 120 μm, 78 multipolar neurons were selected from the sexually dimorphic POA/AH of 12 ferrets and reconstructed in three dimensions with the aid of a computer‐assisted neuron tracing system. Large sex differences were observed in somal area and most aspects of dendritic morphology, including total length, number of branches, and total dendritic surface area. Androgen also appeared to accentuate dendritic arborization in both sexes, but this effect was weaker than the sex effect, more apparent in males than females, and restricted to fewer variables. The most statistically significant effects of adult androgen treatment in males were found for total dendritic surface area and percentage of fourth order dendrites, and in females, average dendritic thickness. These data show that strong sex differences exist in dendritic structure of neurons in the POA/AH, and suggest that alterations in levels of gonadal steroids in adulthood may promote synaptic remodeling in a region of the brain involved in the control of sexually dimorphic behaviors. © 1992 Wiley‐Liss, Inc.
Time of ganglion cell genesis in relation to the chiasmatic pathway choice of retinofugal axons
Authors: Reese B. E. , Guillery R. W. , Mallarino C.
Published: May 2005

The time of generation of retinal ganglion cells in fetal cats has been related to the course taken later by their axons in the optic chiasm. The ganglion cells were labelled with tritiated thymidine either on embryonic day (E) 26 or on E‐301. When the cats were mature, ganglion cells were retrogradely labelled with horseradish peroxidase injected into one optic tract. The distribution of double‐labelled cells showed that cells in the temporal retina generated on E‐26 all have axons that take an uncrossed course in the chiasm, whereas, of the cells generated on E‐30 in the temporal retina, some take a crossed course and others take an uncrossed course. The uncrossed axons of the E‐26 cohort come from cells having a central distribution on the retina. For the E‐30 cohort, the uncrossed axons come from cells having a relatively peripheral distribution, whereas the crossed axons come from more central cells.

The present results suggest that the mechanism which serves to direct temporal retinal axons into the ipsilateral optic tract weakens as development proceeds. In principle, the change may occur in either a chiasmatic signal, read by temporal but not nasal optic axons, or in a retinal label, carried by temporal but not nasal cells and their processes. Since temporal retinal cells born concurrently at different places can project to opposite optic tracts, a retinal signal that deteriorates with time in a centroperipheral fashion is favored by the present results.
Topography of ganglion cells in the dog and wolf retina
Authors: Peichlcu Leo
Published: May 2005

The topographical distribution of retinal ganglion cells in seven breeds of dog (Canis lupus f. familiaris) and in the wolf (Canis lupus) was studied in retinal wholemounts stained with cresyl violet or with a reduced silver method. A prominent feature of all wolf retinae was a pronounced “visual streak” of high ganglion cell density, extending from the central area far into both temporal and nasal retina. By contrast, either a pronounced or a moderate visual streak was found in dog retinae. It is hypothesized that a pronounced streak is an archetypal feature of Canis lupus, and that the moderate streak in some dogs is a corollary of breeding during domestication.

Irrespective of the differences in streak form and retinal area, the estimated total number of ganglion cells was about 200,000 cells in the wolf and 115,000 in the dog. Ganglion cell density maxima in the central area of the wolf were about 12,000–14,000/mm2, and in the dog they ranged from 6,400/mm2 to 14,400/mm2. This implies individual differences in visual acuity. Alpha ganglion cells constituted 3–14% of all ganglion cells in the dog and 1–18% in the wolf, depending on retinal location. A distinct feature of all dogs and wolves was the absence of alpha cells in a substantial region of temporal peripheral retina. This has not been found in any other mammalian species and suggests corresponding functional deficits.
Heterogeneity of sensory hair cells in a fish ear
Authors: Chang Janet S.Y. , Popper Arthur N. , Saidel William M.
Published: May 2005

The ultrastructure of sensory hair cells in the utricle of the cichlid fish, Astronotus ocellatus, the oscar, was studied by transmission electron microscopy of serial ultrathin sections from different regions of the epithelium. Two distinctly different types of hair cell were found, one located in the striolar region of the epithelium and the other in the extrastriolar region. Striolar hair cells have a well‐defined perinuclear cisterna located just below the nucleus, and large perinuclear mitochondria, Synapuc bodies.of striolar cells are small and located in clusters, while those in extrastriolar cells are relatively large and individually dispersed. The extrastriolar hair cell closely resembles the amniote type II hair cell. On the basis of these data, and consistent with earlier studies, it appears that the striolar hair cells closely resemble amniote type I hair cells in many significant ways. Thus we have called them type I‐like cells. The extrastriolar hair cells appear to be typical of eighth nerve mechanorecep‐tors commonly described for fish and closely resemble the amniote type II hair cell.
Topography and collateralization of the dopaminergic projections to motor and lateral prefrontal cortex in owl monkeys
Authors: Gaspar P. , Stepniewska I. , Kaas J. H.
Published: May 2005

The sources and histochemical characteristics of dopaminergic projections to motor and premotor areas of cortex were investigated in owl monkeys in which information from related studies was used to subdivide cortex into motor fields. Brainstem projections to frontal cortex were identified by injections of different fluorescent dyes in the primary motor cortex (M1) and the supplementary motor area (SMA), first identified by microstimulation. Injections were also placed in dorsal premotor cortex and lateral prefrontal cortex. The distribution of retrogradely labeled neurons was related to the location of tyrosine hydroxylase immunolabeled neurons on the same or alternate brain sections to identify the dopamine (DA) neurons. All DA cortically projecting neurons were located in the A8–A10 complex, largely in its dorsal components, including the parabrachial pigmented n. of the ventral tegmental area (VTA), pars gamma of the substantia nigra compacta, and the dorsal part of the retrorubral area (A8). Fewer cells were in the midline groups of VTA (n. linearis rostralis and caudalis) and in the n. paranigralis. DA neurons projecting to M1, SMA, and prefrontal cortex were largely intermixed, and some of these neurons were double or triple labeled by the fluorescent dyes, indicating Collateralization to two or three fields; DA cells projecting to M1 were more numerous than to the other locations. The dorsal components of the A8–A10 complex from which arose the DA mesocortical projection were also characterized by the presence of calbindin‐immunoreactive neurons and by a dense neurotensin and noradrenergic terminal innervation.

Compared to rodents or felines, the DA neurons projecting to the lateral frontal lobe of primates appear to be shifted dorsally and laterally in the nigral complex. The topographic overlap, partial Collateralization, and common histochemical characteristics of the DA mesocortical neurons projecting to different fields of the lateral frontal lobe suggest that some degree of functional unity exists within this projection. © 1992 Wiley‐Liss, Inc.