bluuebunny/crossref_metadata_2025 huggingface dataset:
A comparison of the Eimer's organs of three north american moles: The hairy‐tailed mole (Parascalops breweri), the star‐nosed mole (Condylura cristata), and the eastern mole (Scalopus aquaticus)
Authors: Catania Kenneth C.
Published: January 2005

Eimer's organ is a tactile sensory structure found predominantly on the snouts of moles. It consists of a raised papilla of epidermis containing a column of cells associated with sensory receptors. This study compares the Eimer's organs of the hairy‐tailed mole, Parascalops breweri, the star‐nosed mole, Condylura cristata, and the eastern mole, Scalopus aquaticus, by using scanning electron microscopy and light microscopy. Eimer's organs are visible on the snout of the hairy‐tailed and the star‐nosed moles, but not the eastern mole. The Eimer's organs of the hairy‐tailed mole are similar in external appearance, distribution, and internal structure to those found in most species examined. The Eimer's organs of the star‐nosed mole and the eastern mole diverge from this basic form in seemingly opposite directions. The Eim&'s organs of the star‐nosed mole are more numerous, smaller, and highly organized units with a consistent pattern of neuronal terminal swellings within a cell column, below a thin keratinized epidermis. By contrast, the Eimer's organs ofthe eastern mole lie below a thick keratinized epidermis, are less organized in structure, and have no central cell column. The extreme differences between the Eimer's organs of the star‐nosed mole and those of the eastern mole may be the result of the habitat of each species, saturated mud allowing a more elaborate and delicate sensory apparatus in the star‐nosed mole and drier soil requiring a thick keratinized epidermis over the organ in the eastern mole. © 1995 Wiley‐Liss, Inc.
Metabolic mapping of visual areas in the behaving cat: A[14C]2‐deoxyglucose study
Authors: Vanduffel W. , Vandenbussche E. , Singer W. , Orban G. A.
Published: January 2005

Visually responsive cortical areas and subcortical nuclei were studied in the awake cat using the 2‐deoxyglucose technique. Visual input was confined to one hemisphere by unilaterally sectioning the optic tract, the corpus callosum and the commissura anterior. Within the intact hemisphere, numerous cortical regions were distinguishable in the autoradiographs due to differential labelling. Comparison of the intact with the visually deafferented hemisphere confirmed the visual character of eighteen cortical areas (areas 17, 18, 19, 20a, 20b, 21a, 21b, the posteromedial lateral, posterolateral lateral, anteromedial lateral, anterolateral lateral, dorsal lateral, ventral lateral, and posterior suprasylvian areas, the splenial and anterior ectosylvian sylvian areas, insular visual area and posterior area 7) and revealed the visual nature of an area in the posterior cingulate gyrus which had not been described previously. We refer to this area as cingulate visual area (CVA). This area exhibits a gradient in interhemispheric differences along a caudorostral axis similar to that observed in posterior area 7 which is in keeping with the strong and topographic connections between CVA and posterior area 7. These results support the validity of metabolic mapping for the characterisation of cortical areas. © 1995 Wiley‐Liss, Inc.
Abnormal ipsilateral visual field representation in areas 17 and 18 of hypopigmented cats
Authors: Ault Steven J. , Leventhal Audie G. , Vitek Dagmar J. , Creel Donnell J.
Published: January 2005

We compared the central projections of retinal ganglion cells in temporal retina and the cortical representation of visual fields in areas 17 and 18 in cats with various hypopigmentation phenotypes (albino, heterozygous albino, Siamese, and heterozygous Siamese). In all cats studied, we found that the extent of abnormal ipsilateral visual field representation varied widely, and more of the ipsilateral visual field was represented in area 18 than in area 17. The greatest degree of ipsilateral visual field representation was found in albino cats, followed by Siamese, heterozygous albino and heterozygote Siamese cats, respectively. Additionally, in the different groups there was wide variation in the numbers of contralaterally projecting alpha and beta ganglion cells in temporal retina. In all cases, however, contralaterally projecting alpha cells were found to extend further into temporal retina than beta cells. We found that in each cat studied, the maximum extent of the abnormal ipsilateral visual field representation in areas 18 and 17 corresponded to the location of the 50% decussation line (i. e., the point where 50% of the ganglion cells in temporal retina project to the contralateral hemisphere) for alpha and beta cells, respectively, for that cat. Our results suggest that the extent of the abnormal visual field representations in visual cortex of hypopigmented cats reflects the extent of contralaterally projecting retinal ganglion cells in temporal retina. © 1995 Wiley‐Liss, Inc.
Synapses on axons of sympathetic preganglionic neurons in rat and rabbit thoracic spinal cord
Authors: Llewellyn‐Smith Ida J. , Pilowsky Paul , Minson Jane B. , Chalmers John
Published: January 2005

Axosomatic and axodendritic synapses occur on sympathetic preganglionic neurons, but it is not yet known whether their axons receive synaptic input, which could be particularly effective at regulating sympathetic outflow. Here, we examined retrogradely labelled sympathetic preganglionic axons to see if they received synapses. Cholera toxin B subunit (CTB) or CTB conjugated to horseradish peroxidase (CTB‐HRP) was used to label neurons projecting to the rat or rabbit superior cervical ganglion, the rat adrenal medulla, or the rabbit stellate ganglion. At the light microscopic level, small groups of CTB‐immunoreactive axons travelled through the ventral horn near its lateral boundary, with occasional axons taking a more medial course. The axons passed through the ventrolateral funiculus to exit at the ventral roots. In parasagittal section, a few axons branched within the ventral horn, sending processes rostrally and caudally for short distances before they turned ventrally to exit the spinal cord. At the ultrastructural level, CTB‐immunoreactive rat and rabbit sympathetic preganglionic axons were almost exclusively unmyelinated. In contrast, labelling with CTB‐HRP revealed both myelinated and unmyelinated axons in the ventral horn, the ventrolateral white matter, and the ventral roots. CTB‐HRP also allowed the detection of the initial segment of a sympathetic preganglionic axon. Synapses, with vesicles clustered presynaptically and membrane specializations postsynaptically, were found on some unmyelinated CTB‐immunoreactive axons. Occasional axons received several synapses. Synapses were most common on CTB‐containing axons just ventral to the intermediolateral cell column. One synapse was found on an axon within 2 μm of its origin from a proximal dendrite. Rare synapses were found several hundred micrometers ventral to the intermediolateral cell column. One branching axon had synapses just below the branch point on both the main axon and the axonal branch. These findings indicate an extensive synaptic input to the axons of at least some sympathetic preganglionic neurons. These axoaxonic synapses could have a profound effect on sympathetic activity. © 1995 Wiley‐Liss, Inc.
Regenerative axonal sprouting in the cat trochlear nerve
Authors: Iannuzzelli Pasquale G. , Murray Marion , Murphy E. Hazel
Published: January 2005

Following peripheral trochlear nerve axotomy in the cat, the normal number of myelinated axons is restored despite significant motor neuron death, suggesting regulation of the number of myelinated axons in the regenerated nerve. In this study we used light and electron microscopy to examine the production and maintenance of axonal sprouts at different locations in the nerve and at different postoperative intervals. Despite proliferative sprouting and an overproduction of nonmyelinated axons in the regenerating trochlear nerve, the number of myelinated axons was strictly regulated. Only ∼1,000 regenerated axons were eventually remyelinated, but many nonmyelinated axons were still present 6–8 months postaxotomy. Regenerated axons were remyelinated in a proximal‐to‐distal direction between 3 and 4 weeks postaxotomy.

We also examined the maturation of regenerated myelinated axons by measuring axon diameter and myelin index (an expression of myelin thickness). Mean myelinated axon diameter remained significantly below normal in long‐term regenerated nerves. Mean myelin index was not different from normal at 4 weeks postaxotomy but was significantly decreased at long postoperative intervals, reflecting a slightly thicker myelin sheath relative to the axon diameter. This relative increase in mean myehn thickness could serve to restore normal conduction velocity despite the decrease in mean axon diameter.

We suggest that the regulation of the number of myelinated axons at the normal number despite cell death and the increase in mean myelin thickness may both be compensatory mechanisms that function to restore preoperative conditions and maximize functional recovery. © 1995 Wiley‐Liss, Inc.
Somatostatin‐like immunoreactivity in primary afferents of the medial articular nerve and colocalization with substance P in the cat
Authors: Hanesch U. , Heppelmann B. , Schmidt R. F.
Published: January 2005

The proportion of somatostatin‐containing dorsal root ganglion cells innervating the knee joint of the cat via the medial articular nerve was determined by using retrograde labeling with fast blue and immunohistochemistry. Immunoreactivity was found in 8.6% of labeled cell bodies. In colchicine‐treated ganglia, the proportion increased to 16.8%.

Only small and intermediate‐sized perikarya showed somatostatin‐like immunoreactivity, indicating that this neuropeptide is synthesized predominantly in primary afferent units with unmyelinated sensory axons but may also be present in primary afferents with thinly myelinated sensory fibers. Colchicine treatment had no influence on the cell size distribution.

Colocalization of somatostatin with substance P was determined by comparing the proportions of immunopositive dorsal root ganglion cells after incubation with antibodies against substance P or somatostatin or with a mixture of both. Substance P‐like immunoreactivity was found in 18.1% (untreated ganglia) and 19.6% (colchicine treated ganglia) of the labeled neurons. After incubation with a mixed antibody solution, 18.2% of joint afferents in untreated and 19.9% of the cells in colchicine‐treated ganglia were immunopositive. Comparing this result with the results obtained using somatostatin and substance P antibodies alone, one can calculate that both neuropeptides are colocalized in about 17% of the cat's knee joint afferents. About 3% of the neurons contain only substance P, whereas almost none of the neurons contain only somatostatin. Based on this fact, one can assume that both neuropeptides are coreleased in peripheral tissue as well as in the central nervous system. © 1995 Wiley‐Liss, Inc.
Noxious heat‐evoked Fos–like immunoreactivity in the rat medulla, with emphasis on the catecholamine cell groups
Authors: Jones S. L. , Blair R. W.
Published: January 2005

The objectives of the present study were 1) to utilize Fos immunohistochemistry as a marker for neuronal activity in order to examine the population of neurons in the medulla that is engaged by activation of nociceptive peripheral afferents and 2) to determine whether catecholamine‐containing neurons in the medulla also express noxious heat‐evoked Fos‐like immunoreactivity. Noxious heating of the hindpaw evoked specific patterns of Fos‐like immunoreactivity in the medulla in regions known to be involved in both nociceptive processing and cardiovascular regulation. Noxious heating of the hindpaw significantly increased the mean number of neurons expressing Fos‐like immunoreactivity in the contralateral ventrolateral medulla. Increased numbers of Fos‐positive neurons also were observed in both the ipsilateral and the contralateral A1 catecholamine cell groups. Similarly, in the contralateral medullary dorsal reticular fields, noxious heating of the hindpaw significantly increased the mean number of neurons expressing Fos‐like immunoreactivity. In contrast, in the paramedian reticular nucleus, noxious heating of the hindpaw resulted in a significant decrease in the mean number of neurons expressing Fos‐like immunoreactivity. No significant differences in the mean numbers of neurons expressing Fos‐like immunoreactivity were noted in the A2, C1, or C2/C3 medullary catecholamine cell groups. These results suggest that noxious stimuli affect pools of neurons in the medulla with multiple physiological functions. © 1995 Wiley‐Liss, Inc.
Relationship of the time of origin and death of neurons in rat somatosensory cortex: Barrel versus septal cortex and projection versus local circuit neurons
Authors: Miller Michael W.
Published: January 2005

The birth of a neuron initiates a series of ontogenetic events, e. g., neuronal migration and differentiation. The outcomes of these events are neurons that successfully integrate into the cortical circuitry and neurons that are unsuccessful and ultimately die. The present study determined whether there is a relationship between the generation and death of cortical neurons.

The decrease in the density of postmigratory neurons (heavily labeled by a single injection of [3H]thymidine) during normal development was used as an index of neuronal death. The survival indices of neurons varied with their times of origin. Neurons born from gestational day (G) 15 to G18 had the highest rates of survival. In contrast, the earliest and latest generated neurons (i. e., those born on G12‐G13 and those born on G19‐G21, respectively) had the lowest survival rates.

The role of neuronal death in the formation of cortical patterns was determined by assessing the survival of neurons in the barrels and septa of somatosensory cortex. No differences in the survival index were determined for neurons in the C‐row barrels and adjacent septa with a particular time of origin.

The survival rate of projection and local circuit neurons was determined with a doublelabeling technique. One label, [3H]thymidine, was used to determine the time of origin of the neurons. The second label was used to identify the chemical or hodological characteristics of a neuron; projection neurons were labeled either by retrograde transport of horseradish peroxidase or by glutamate immunohistochemistry, and local circuit neurons were immunohistochemically identified with an antibody directed against gamma‐aminobutyric acid (GABA) antibody. The survival rate for projection neurons (labeled by either technique) was as much as twice that for GABA‐immunoreactive local circuit neurons.

Thus, the death of cortical neurons is related to their time of origin. Although neuronal death is not important for sculpting cortical patterns, death does selectively affect neurons with a specific hodological phenotype.
Cholinergin innervation of the primate hippocampal formation. I. Distribution of choline acetyltransferasse immunoreactivity in the Macaca fascicularis and Macaca mulatta monkeys
Authors: Alonso José R. , Amaral David G.
Published: January 2005

The cholinergic innervation of the hippocampal formation of Macaca fascicularis (cynomolgus) and Macaca mulatta(rhesus) monkeys was investigated by immunohistochemical procedures using a monoclonal antibody directed agaist choline acetyltransferase. The distribution of choline acetyltransferase in the monkey demonstrated both similarities and differences with the staining patterns observed in the rat or with acetylcholinesterase in the monkey. While both of these latter preparations demonstrated labeled cells, for example, no choline acetyltransferase labeled neurons were observed in the monkey observed in the monkey hippocampal formation. Choline acetyltransferase activity was restricted to fibers which varied in thickness and number of varicosities and in their regional and laminar distribution. The highest densities of labeled fibers were observed in the unacal protion of the hippocampus, in the parasubiculum, and in the entorhinal cortex; the lowest densities of labeled fibers were observed in CA1 and in midrostrocaudal levels of the dentate gyrus. In the dentate gyrus, immunoreactive fibers were densely distributed in the molecular layer and in an infragranular plexus. One of the few striking noticeable interspecies differences was observed in the dentate gyrus. In the rhesus monkey, labeled fibers in the molecular layer were divided into a superficial denser and an inner lighter lamina, whereas in M. fascicularis, the cholinergic fibers were distributed more homogeneously throughout the molecular layer. In the hippocampus proper, there was a progressive decrease in the density of ChAT‐immunoreactive fibers from CA3/CA2 into CA1. The subiculum also demonstrated modest labeling which was nonetheless higher than in CA1; the border of these fields demonstrated increased fiber labeling. The density of choline acetyltransferase staining was high in the presubiculum and parasubiculum. In the entorhinal cortex, a relatively clear boundary was observed between the more heavily stained superficial layers (I, II, and III) and the more weakly labeled deep layers (V and VI), especially in the intermediate and caudal fields. A transverse decreasing gradient was observed with the densest plexus of cholinergic fibers found in the medially situated olfactory field of the entorhinal cortex and the lowest density in the laterally located caudal and lateral fields.
The human entorhinal cortex: A cytoarchitectonic analysis
Authors: Insausti R. , Tuñón T. , Sobreviela T. , Insausti A. M. , Gonzalo L. M.
Published: January 2005

The entorhinal cortex of man is in the medial aspect of the temporal lobe. As in other mammalian species, it constitutes an essential component of the hippocampal formation and the route through which the neocortex interacts with the hippocampus. The importance of knowing its architecture in detail arises from the possibility of extrapolating it to experimental findings, notably in the nonhuman primate. We have investigated the cytoarchitectonic features of the human entorhinal cortex by using as a base our previous study (D. G. Amaral, R. Insausti, and W. M. Cowan [1987] J. Comp. Neurol. 264:326–355) of the nonhuman primate entorhinal cortex. We prepared serial sections of the temporal lobe from 35 normal brains. Thionin‐ and myelin‐stained series were made of all cases. Sections spaced 500 μm apart through the full rostrocaudal extent of the entorhinal cortex were analyzed. The human entorhinal cortex is made up of six layers, of which layer IV does not appear throughout all subfields of the entorhinal cortex. The overall appearance resembles that of the adjacent neocortex in lateral and caudal portions. In harmony with general structural principles in the nonhuman primate entorhinal cortex, our analysis supports the partitioning of the human entorhinal cortex into eight different subfields. (1) The olfactory subfield (EO), the rostralmost field, is little laminated. (2) The lateral rostral subfield (ELr), laterally located, merges with the laterally adjacent perirhinal cortex. (3) The rostral subfield (ER) is between EO and ELr, with better differentiation of layers II and III than EO. (4) The medial intermediate subfield (EMI) is located at the medial border. (5) The intermediate field (EI) is a lateral continuation of EMI; lamina dissecans (layer IV) can be best appreciated in this field. (6) The lateral caudal subfield (ELc) laterally borders on EI as a continuation of ELr. (7) The caudal subfield (EC) lies caudal to the beginning of the hippocampal fissure, with a distinctive, clear space (Vc) between layers V and VI. (8) The caudal limiting field (ECL) forms the caudal termination of the entorhinal cortex. Thus our parcellation of the entorhinal cortex in man is largely parallel to that arrived at in the monkey. This close homology provides a rational basis for the application to clinical problems of anatomical and functional information obtained in experimental work in nonhuman primates.
Synaptic connectivity of local circuit neurons in laminae III and IV of hamster spinal cord
Authors: Schneider S. P. , Sandiford D. R. , Kavookjian A. M. , Johnson B. D.
Published: January 2005

The present study was undertaken to examine the morphological bases of local synaptic interactions between dorsal horn interneurons. Seven interneurons responding to innocuous mechanical stimuli were intracellularly recorded in lamina III/IV of an isolated preparation of hamster spinal cord with partially intact innervation from an excised patch of hairy skin. Axonal arborizations were stained with horseradish peroxidase (HRP) and examined with an electron microscope. Five cells had extensive synaptic terminations (375‐1, 785 boutons/axon) with localized distributions (rostrocaudal distance, 425‐1,251 μm) overlapping the dendritic trees. Two cells gave rise to deep stem axons that bifurcated into rostrocaudal daughter branches with collaterals ventral to the parent cell bodies (79‐661 boutons/axon). Axons of local interneurons were thinly myelinated and formed terminal and en passant enlargements (mean [±S. D.] diameter = 0.88 ± 0.24 μm, n = 157) containing clear, round vesicles 20‐60 nm in diameter. Collateral branches of deep axon cells produced round, vesicle‐containing boutons comparable in diameter (0.93 ± 0.22 μm, n = 31) to local axon cells. Both types of interneurons formed asymmetric synaptic contacts with dendritic profiles, but not with cell bodies or axon terminals. Postsynaptic profiles contained sparse ribosomes and had a mean diameter of 1.0 ± 0.5 μm (n = 49), significantly smaller than a population of identified proximal dendrites (2.3 ± 0.9 μm, n = 47). HRP‐labeled boutons were rarely (5/45 or 11%) in synaptic contact with more than one profile. We conclude that lamina III/IV interneurons make axodendritic synapses predominantly with distal dendrites. Thus, terminations of deep dorsal horn interneurons appear to have a postsynaptic distribution overlapping with axodendritic contacts formed by several functional classes of cutaneous sensory fibers signaling innocuous mechanical stimuli. Such overlap suggests that local spinal networks selectively and strongly influence afferent signals at initial stages of somatosensory integration.
Anatomical localisation of preproatrial natriuretic peptide mRNA in the rat brain by in situ hybridisation histochemistry: Novel identification in olfactory regions
Authors: Ryan Mary C. , Gundlach Andrew L.
Published: January 2005

Atrial natriuretic peptide (ANP) is one of three structurally homologous natriuretic peptides present in heart and brain, which is thought to be involved in the regulation of water and salt intake, blood pressure, and hormone secretion. In the present study, the distribution of preproatrial natriuretic peptide (ppANP) mRNA in the central nervous system of the rat was examined by in situ hybridisation histochemistry by using [35S]‐labelled oligonucleotides. Cells expressing ppANP mRNA were apparent in several major neuronal systems, being present in hypothalamic, limbic, pontine and forebrain olfactory regions. Relatively high densities of ppANP mRNA‐positive neurones were found in the anterior medial preoptic hypothalamic nucleus, medial habenular nucleus, and in Barrington's nucleus in the pons. Moderate numbers of ppANP mRNA‐positive cells were present in a number of amygdaloid nuclei, including the posterolateral and anterior cortical nuclei, in the zona incerta, and the pedunculopontine tegmental nucleus. Other areas, including the ventromedial hypothalamic nucleus and the laterodorsal tegmental nucleus, displayed only low densities of ppANP mRNA‐positive neurones. A number of structures in which ppANP mRNA (or ANP‐like immunoreactivity) has not previously been reported were found to contain moderate to high numbers of ppANP mRNA‐positive neurones including several nuclei associated with the olfactory system, such as the anterior olfactory nucleus and neurones of the tenia tecta and ventrolateral orbital cortex. Although ppANP mRNA in CA1 pyramidal cells of the hippocampus has been described, we also detected labelling in CA2 and ventral CA3 regions of the hippocampus. Conversely, nuclei such as the bed nucleus of the stria terminalis and the nucleus of the solitary tract, which are reported to possess ANP‐like immunoreactivity, were found not to contain ppANP mRNA. Overall, these results demonstrate the presence of ANP gene expression in discrete neuronal populations of the rat central nervous system and provide additional evidence to support a putative role for this peptide in regulating and integrating hypothalamic, olfactory, limbic, and neuroendocrine systems. © 1995 Wiley‐Liss, Inc.
Localization of nicotinamide adenine dinucleotide phosphate‐diaphorase activity in electrosensory and electromotor systems of a gymnotiform teleost, Apteronotus leptorhynchus
Authors: Turner Ray W. , Moroz Leonid L.
Published: January 2005

The distribution of nicotinamide adenine dinucleotide phosphate‐diaphorase (NADPH‐d) activity was determined in electrosensory and electromotor systems of the weakly electric gymnotiform teleost Apteronotus leptorhynchus as an indicator of putative nitric oxide synthase‐containing cells. NADPH‐d activity was detected in electroreceptors and in afferent nerves of both ampullary and type I and type II tuberous organs. All cell bodies within the anterior lateral line nerve ganglion were positive for NADPH‐d activity, as were the primary afferent axons and termination fields in the medullary electrosensory lateral line lobe. In the corpus cerebelli and valvula cerebelli, NADPH‐d label was present in Purkinje cell somata, mossy fiber synaptic glomeruli, granule cells, and parallel fibers. In the midbrain, NADPH‐d activity was apparent in layer VIIIB of the torus semicircularis dorsalis and in electrosensory laminae of the optic tectum. NADPH‐d was particularly associated with diencephalic electrosensory and electromotor nuclei, including the prepacemaker nucleus, the nucleus subelectrosensorius, and the central posterior nucleus of the thalamus. Intense NADPH‐d activity was present in pacemaker and relay cells of the medullary pacemaker nucleus but was absent from a novel class of smaller cells in this structure. Relay cell axons and spinal electromotor neurons and their axons within the electric organ were positive for NADPH‐d activity. These results indicate that putative nitric oxide synthase‐containing neurons in Apteronotus are localized preferentially to electrosensory and electromotor structures, suggesting a role for nitric oxide in determining the activity of cells involved in detecting or generating weakly electric fields. © 1995 Wiley‐Liss, Inc.
Developmental changes in the distribution of NADPH‐diaphorase‐containing neurons in telencephalic nuclei of the zebra finch song system
Authors: Wallhäusser‐Franke E. , Collins C. E. , Devoogd T. J.
Published: January 2005

Extensive recent research has focused on the potential role of nitric oxide (NO) in synaptic plasticity. Could the capacity to synthesize NO be associated with neural and behavioral plasticity in the song system? The timing of song learning and of major developmental changes in song system anatomy are known. We searched for an association between NO and these developmental events by observing the distribution of neurons staining for NADPH‐diaphorase, an enzyme used in the synthesis of NO, in the brains of zebra finches. Both male and female brains were taken at different developmental ages from day 21 to adulthood. We found that the incidence of stained neurons in the song system nuclei is lower than in surrounding areas. The incidence of staining decreases with development, with most of the decrease occurring prior to the auditory learning phase of song learning. The developmental changes were quantified for area X and found to be highly significant, with a 56% decrease in staining frequency from day 21 to adulthood in males and a 23% decrease in females for the equivalent region. We also found a sexual dimorphism in the song system of adult birds, consisting of a reduced incidence of stained neurons in song system nuclei area X, high vocal center (HVC), and nucleus robustus (RA) archistrialis in males compared with females. These findings suggest that NO is less involved in the plasticity underlying song acquisition than in the earlier formation of the song system. © 1995 Wiley‐Liss, Inc.
Distribution of fos‐like immunoreactivity in the caudal brainstem of the rat following noxious chemical stimulation of the temporomandibular joint
Authors: Hathaway Charles B. , Hu James W. , Bereiter David A.
Published: January 2005

Central expression of the protooncogene c‐fos was used to examine areas receiving noxious sensory input from the rat temporomandibular joint (TMJ). Fos‐like immunoreactivity (Fos‐LI) in the caudal brainstem was visualized 2 hours after unilateral injection of the small‐fiber‐specific excitant /inflammatory irritant mustard oil into the TMJ region. Control animals received injection of either mustard oil into the subcutaneous fascia overlying the masseter muscle or mineral oil vehicle into the TMJ region. In all groups, Fos‐LI was consistently observed ipsilaterally in the spinal trigeminal nucleus and cervical dorsal horn and, bilaterally, in the nucleus of the solitary tract and. the ventrolateral medulla. The expression of Fos‐LI ipsilaterally in the paratrigeminal nucleus was variable. Within the trigeminal sensory complex, Fos‐LI was restricted to subnucleus caudalis and the caudal portions of subnucleus interpolaris near the level of the obex. Approximately 12% of Fos‐LI cells in subnucleus caudalis and in the cervical dorsal horn were found in laminae III‐VI. Compared to TMJ mustard oil injection, mineral oil injection produced less Fos‐LI at all rostrocaudal levels, whereas subcutaneous mustard oil injection produced less Fos‐LI in caudal subnucleus caudalis but similar amounts in the cervical dorsal horn. Neither of these injections yielded significant ipsilateral responses in subnucleus caudalis, indicating that Fos‐LI in this region following TMJ mustard oil injection could be ascribed solely to small‐fiber stimulation in the deep TMJ region. The wide rostrocaudal distribution of Fos‐LI within the caudal brainstem reflects the distribution of TMJ‐responsive nociceptive neurons that may underlie the spread and referral of pain from the TMJ region. © 1995 Wiley‐Liss, Inc.
Neuropeptide tyrosine in the brain of the African lungfish, Protopterus annectens: Immunohistochemical localization and biochemical characterization
Authors: Vallarino Mauro , Tranchand‐Bunel Denis , Thoumas Jean‐Louis , Masini Maria Angela , Conlon J. Michael , Fournier Alain , Pelletier Georges , Vaudry Hubert
Published: January 2005

Lungfishes, which share similarities with both fishes and amphibians, represent an interesting group in which to investigate the evolutionary transition from fishes to tetrapods. In the present study, we have investigated the localization and biochemical characteristics of neuropeptide Y (NPY)‐immunoreactive material in the central nervous system of the African lungfish, Protopterus annectens. NPY‐immunoreactive cell bodies were found in various regions of the brain, most notably in the telencephalon (septal area, ventral striatum, and nucleus accumbens), in the diencephalon (preoptic nucleus, periventricular region of the hypothalamus, and ventral thalamus), and in the tegmentum of the mesencephalon. A strong immunoreaction was also detected in cell bodies of the nervus terminalis. Immunoreactive nerve fibers were particularly abundant in the ventral striatum, the nucleus accumbens, the diagonal band of Broca, the hypothalamus, and the mesencephalic tegmentum. Positive fibers were also seen in the median eminence and in the neural lobe of the pituitary. The NPY‐immunoreactive material localized in the brain and pituitary was characterized by combining high‐performance liquid chromatography (HPLC) analysis and radioimmunological quantitation. The displacement curves obtained with synthetic porcine and frog NPY and serial dilutions of brain and pituitary extracts were parallel. Reversed‐phase HPLC analysis of telencephalon, diencephalon, and pituitary extracts resolved a major NPY‐immunoreactive peak that coeluted with frog NPY. The similarity between the distribution of NPY‐containing neurons and the biochemical characteristics of the immunoreactive peptide in the brain of lungfish and frog strongly favors a close phylogenetic relationship between dipnoans and amphibians. © 1995 Wiley‐Liss, Inc.
Morphometric and electrical properties of reconstructed hippocampal CA3 neurons recorded in vivo
Authors: Turner D. A. , Li X.‐G. , Pyapali G. K. , Ylinen A. , Buzsaki G.
Published: January 2005

CA3 pyramidal neurons were stained with biocytin during intracellular recording in rat hippocampus in vivo and reconstructed using a computer‐based system. The in vivo CA3 neurons were characterized primarily according to their proximity to the hilus and secondarily with respect to the septotemporal location. Neurons measured in CA3a (n = 4), in CA3b (n = 4), and in posterior/ventral locations (n = 3) had the greatest dendritic lengths (19.8, 19.1, and 26.8 mm on average, respectively). Cells closer to the hilus showed much shorter dendritic lengths, averaging 10.4 mm for CA3c neurons (n = 4) and 11.6 mm for zone 3 neurons (n = 2). Half of the cells showed more than one major apical dendrite, and dendritic trees were highly variable even within CA3 subregions. The mean electrotonic length for these cell groups averaged between 0.30 λ (CA3c) and 0.45 λ (posterior /ventral), assuming a constant specificmembrane resistivity of 60 KΩ‐CM2. These CA3 neurons form a database of reconstructed neurons for further morphometric and electrical modelling studies. The large degree of variability between individual CA3 neurons indicates that both dendritic and electrical properties should be specifically calculated for each cell rather than assuming a “typical” morphology. © 1995 Wiley‐Liss, Inc.
Stunted morphologies of cerebellar Purkinje cells in lurcher and staggerer mice are cell‐lntrinsic effects of the mutant genes
Authors: Soha James M. , Herrup Karl
Published: January 2005

Purkinje cells in the neurological mutants lurcher and staggerer exhibit a number of abnormal properties; mutant ↔ wild‐type chimeras have shown that these properties are direct effects of the mutant gene. What has remained unexplored are the numerous dendritic abnormalities that the two mutant Purkinje cells exhibit. In staggerer, Purkinje cells have rudimentary, unbranched dendrites that lack tertiary branchlet spines, In lurcher, before the Purkinje cells die, their dendrites remain short and underdeveloped. To determine whether or not a system of healthy afferents (or other environmental factors) would alter either of these phenotypes, we examined young lurcher and adult staggerer mouse chimeras using Golgi impregnation. In postnatal day 20 (P20) lurcher chimeras, we found two distinct morphological classes of Purkinje cells. One, inferred to be wild type, had a dendritic structure similar to normal Purkinje cells in age‐matched controls. The other consised of cells with small somata, reduced dendritic arbors, and multiple dendritic processes, making them indistinguishable from Purkinje cells in P20 lurcher mutants. We also examined mature staggerer chimeras. We found no evidence that the stunted morphology of staggerer Purkinje cells is rescued in mosaic animals but observed numerous examples of medium to large neurons resembling atrophic Purkinje cells of staggerer mutants. These results suggest that the dendritic abnormalities described in both mutants reflect cell autonomous, developmental genetic blocks in the cytological maturation of the cerebellar Purkinje cell. The implication is that the action of the wild‐type alleles at these two loci are required to execute a normal program of dendritic development. © 1995 Wiley‐Liss, Inc.
Laminar organization of frequency‐defined local axons within and between the inferior colliculi of the guinea pig
Authors: Malmierca Manuel S. , Rees Adrian , Le Beau Fiona E. N. , Bjaalie Jan G.
Published: January 2005

We present a comprehensive description of the local (intrinsic and commissural) connections in the central nucleus of the inferior colliculi (CNICs) in guinea pig. Focal injections of the anterograde tracer biocytin were made into physiologically identified loci of the CNIC and the spatial organisation of the labeled fibres was revealed with computer‐assisted threedimensional (3‐D) reconstruction.

The intrinsic fibres form a series of V‐shaped laminar plexuses composed of fibres bearing both terminal and en passant boutons. Each laminar plexus has a central wing located in the CNIC that extends into the dorsal cortex and an external wing located in the external cortex. The edge where the two wings intersect delimits the lateral border of the central nucleus with the external cortex. The density of labeled terminals was consistently lower in the cortices than in the CNIC. The laminar plexus connects points of similar frequency within the CNIC. Seen in 3‐D, the location, orientation, shape, and area of the laminar plexus vary as a function of best frequency. The commissural fibres ending in the contralateral IC to the injection also form a laminar plexus which is symmetrical to the ipsilateral plexus. Electrolytic lesions placed in the contralateral IC at sites with best frequencies corresponding to those of the injection coincided with the terminals of the commissural fibres in most instances. Possible patterns for the organisation of these connections (point‐to‐point and diverging) are discussed.

Three systems of peripheral axons to the laminar plexus are described: parallel, oblique, and perpendicular to the central wing. The novel parallel system has terminals in both ICs that run parallel to the central wing. It might constitute the anatomical basis for across‐frequency interactions. The oblique and perpendicular systems are fibres of passage projecting to the commissure and brachium of the IC, respectively. © 1995 Wiley‐Liss, Inc.
Glutamate receptor subunits at mossy fiber‐unipolar brush cell synapses: Light and electron microscopic immunocytochemical study in cerebellar cortex of rat and cat
Authors: Jaarsma Dick , Wenthold Robert J. , Mugnaini Enrico
Published: January 2005

The present study provides a survey of the immunolocalization of ionotropic glutamate receptor subunits throughout the rat and cat cerebellar cortex, with emphasis on the unipolar brush cell (UBC), a hitherto neglected cerebellar cell that is densely concentrated in the granular layer of the vestibulocerebellum and that forms giant synapses with mossy fibers. An array of nine previously characterized antibodies has been used, each of which stained a characteristic profile of cerebellar cells. The UBCs of both rat and cat were strongly immunostained by an antibody against the α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazoleproprionate (AMPA) receptor subunits, GluR2 and GluR3; were moderately immunostained by a monoclonal antibody to kainate receptor subunits, GluR5/6/7; were weakly immunostained by antibodies to NR1 subunits; and were not stained by antibodies to GluR1, GluR4, GluR6/7, KA‐2, and NR2A/B. Postsynaptic densities of the giant mossy fiber‐UBC synapses were GluR2/3, GluR5/6/7, and NR1 immunoreactive. The other cerebellar neurons were all immunolabeled to some extent with the GluR2/3 and NR1 antibodies. In addition, Purkinje cells were immunopositive for GluRl and GluR5/6/7; granule cells were immunopositive for GluR5/6/7, GluR6/7, KA‐2, and NR2A/B. The Golgi‐Bergmann glia was densely stained by GluRl and GluR4 antibodies, whereas astrocytes of the granular layer were stained by the GluR4 antiserum. Data provided herein may guide further electrophysiological and pharmacological studies of cerebellar cells in general and the UBCs in particular. © 1995 Wiley‐Liss, Inc.
Sensory neuroanatomy of a skin‐penetrating nematode parasite: Strongyloides stercoralis. I. Amphidial neurons
Authors: Ashton F. T. , Bhopale V. M. , Fine A. E. , Schad G. A.
Published: January 2005

The Strongyloides stercoralis infective larva resumes feeding and development on receipt of signals, presumably chemical, from a host. Only two of the anterior sense organs of this larva are open to the external environment. These large, paired goblet‐shaped sensilla, known as amphids, are presumably, therefore, the only chemoreceptors. Using three‐dimensional reconstructions made from serial electron micrographs, amphidial structure was investigated. In each amphid, cilialike dendritic processes of 11 neurons extend nearly to the amphidial pore; a twelfth terminates at the base of the amphidial channel, behind an array of lateral projections on the other processes. A specialized dendritic process leaves the amphidial channel and forms a complex of lamellae that interdigitate with lamellae of the amphidial sheath cell. This “lamellar cell” is similar to one of the “wing cells” or possibly the “finger cell” of Caenorhabditis elegans. Each of the 13 amphidial neurons was traced to its cell body. Ten neurons, including the lamellar cell, connect to cell bodies in the lateral ganglion, posterior to the nerve ring. The positions of these cell bodies were similar to those of the amphidial cell bodies in C. elegans. Therefore, they were named by using C. elegans nomenclature. Three other amphidial processes connect to cell bodies anterior to the nerve ring; these have no homologs in C. elegans. A map allowing identification of the aimphidial cell bodies in the living worm was prepared. Consequently, laser ablation studies can be conducted to determine which neurons are involved in the infective process. © 1995 Wiley‐Liss, Inc.
Effect of a very early monocular enucleation upon the development of the uncrossed retinofugal pathway in ferrets
Authors: Taylor J. S. H. , Guillery R. W.
Published: January 2005

Monocular enucleations were done in ferret embryos before or during the earliest stages of development of the retinofugal pathway (E23‐E26). The effects on the development of the uncrossed pathway from the surviving eye were assessed on embryonic day 30. This stage was chosen for two reasons: (1) we show that in normal development a substantial uncrossed component from the temporal crescent has developed by E30; and (2) the pathway cannot yet have been affected by the cell death that normally occurs in the retina in the perinatal period. Using DiI labelling from either the temporal crescent or the optic nerve head, we have shown that such early enucleations prevent the formation of the uncrossed pathway from the temporal crescent of the surviving eye. Enucleation at E23/24, before or during the period when the first axons reach the chiasm, prevents the formation of the uncrossed projection. The axons that would normally take an uncrossed course stall lateral to the midline of the optic chiasm. At E26, when many axons have reached the optic chiasm, but none yet come from the temporal crescent, enucleation causes a dramatic reduction in the uncrossed projection, and the complete abolition of the normal uncrossed pathway from the temporal crescent. This demonstrates that there is a requirement for an interaction between the axons of the two eyes at the optic chiasm to establish the normal formation of the uncrossed pathway at the optic chiasm. © 1995 Wiley‐Liss, Inc.
Development of the olfactory and accessory lobes in the american lobster: An allometric analysis and its implications for the deutocerebral structure of decapods
Authors: Helluy Simone M. , Ruchhoeft Maureen L. , Beltz Barbara S.
Published: January 2005

The allometric changes characterizing the growth of the deutocerebrum (midbrain) of the American lobster (Homarus americanus) are studied using computerized three‐dimensional reconstructions of serial brain sections. During the embryogenesis of the midbrain, the paired accessory lobes (higher order processing areas) appear later than the paired olfactory lobes (primary olfactory centers), but the former grow faster from their emergence until metamorphosis. The accessory lobes, as they enlarge, shift progressively from a medial to a posterior position in the lateral deutocerebrum. In early juvenile stages the accessory lobes are one of the largest neuropils of the brain. However, these lobes stop growing in adult animals, whereas the brain and olfactory lobes continue to enlarge, albeit at a slow rate.

The overall shape of the brain and the relative proportions and locations of the deutocerebral neuropils and associated cell clusters of various lobster ontogenetic stages are similar to those of selected adult decapods. In addition, the relation between deutocerebral organization and brain size seem parallel during lobster development and across crustacean species. Measurements of the brains of 13 species of decapods (illustrated in Sandeman et al. [1993] J. Exp. Zool. 265:112, plus Homarus) indicate the following trends: Small brains possess olfactory lobes but no accessory lobes, larger brains possess accessory lobes that are medial and small relative to the olfactory lobes, and the largest brains contain relatively voluminous posterior accessory lobes. These observations indicate that some differences in the organization of the deutocerebrum are related to absolute brain size in crustaceans and suggest that ontogenetic scaling of proportions may apply to the deutocerebral neuropils of decapods. Peramorphosis and paedomorphosis in the evolution of the decapod brain are considered. © 1995 Wiley‐Liss, Inc.
Distribution of chicken‐II gonadotropin‐releasing hormone in mammalian brain
Authors: Rissman Emilie F. , Alones Vinessa E. , Craig‐Veit Chris B. , Millam James R.
Published: January 2005

Brains of nonmammalian vertebrates typically contain multiple forms of gonadotropinreleasing hormone (GnRH). Until recently, only the mammalian form of GnRH (mGnRH) had been isolated in placental mammals. Biochemical and histological data show that both mGnRH and chicken‐II GnRH (cGnRH‐II) are present in a primitive placental mammal, the musk shrew (Suncus murinus). Similar to the case in nonmammalian species, in the musk shrew, neurons that express cGnRH‐Il are located in a discrete cluster in the midbrain. We have used a combination of radioimmunoassay and immunocytochemistry, analyzed at the light level and with electron microscopy, to describe the distribution of cGnRH‐II cell bodies and fibers in the musk shrew brain. All cGnRH‐II‐immunoreactive (ir) neurons reside in the midbrain, and this area contains the greatest concentration of cGnRH‐II peptide in the brain, At the light and electron micrographic levels, we have identified synaptic terminals containing dense core vesicles that are immunoreactive for cGnRH‐II in the medhd habenula. Radioimmunoassay reveals that this region contains the second greatest concentration of cGnRH‐II in the brain. Widely scattered cGnRH‐II‐ir fibers are present throughout the forebrain, particularly in the medial septum, hypothalamus, and midbrain central gray. Scant cGnRH‐II fibers are present in the median eminence, arcuate nucleus, and infundibular stem, and only low concentrations of the peptide are detected in these areas. Finally, intravenous administration of mGnRH is ten times more effective than cGnRH‐II in promoting ovulation. Taken together, the results suggest that cGnRH‐II is likely to act as a neuromodulator or neurotransmitter in mammals and that the medial habenula is the major site of cGnRH‐II action in mammalian brain. © 1995 Wiley‐Liss, Inc.