bluuebunny/crossref_metadata_2025 huggingface dataset:
Histochemical localization of cytochrome oxidase in the retina and optic tectum of normal goldfish: A combined cytochrome oxidase‐horseradish peroxidase study
Authors: Kageyama Glenn H. , Meyer Ronald L.
Published: January 2005

Cytochrome oxidase (C.O.) was histochemically localized in the normal retina and optic tectum of goldfish in order to examine the laminar and cellular oxidative metabolic organization of these structures. In the optic tectum, C.O. exhibited a distinct laminar, regional, and cellular distribution. The laminae with highest C.O. levels were those that receive optic input, suggesting a dominant role for visual activity in tectal function. This was demonstrated by colocalizing C.O. and HRP‐filled optic fibers in the same section. However, the distribution of C.O. within the optic laminae was not uniform. Within the main optic layers, the SFGS, four metabolically distinct sublaminae were distinguished and designated from superficial to deep as sublaminae a, b, c, and d. The most intense reactivity was localized within SFGSa and SFGSd, followed by SFGSb, then SFGSc. In SFGSd, intense reactivity was found to occur specifically within a class of large diameter axons and terminals that were apparently optic since these were also labeled with HRP and cobaltous lysine applied to the optic nerve. Regional C.O. differences across the tectum were also noted. Low levels were found in neurons and optic terminals along the growing immature medial, lateral, and posterior edges of tectum, but were higher at the more mature anterior pole and central regions of tectum. This suggests that the oxidative metabolic activity is initially low in newly formed tectal neurons and optic axons, but gradually increases with neuronal growth and functional axon terminal maturation. Most C.O. staining was localized within neuropil, whereas the perikarya of most tectal neurons were only lightly reactive. Only a few neuron classes, mostly the relatively larger projection neurons, had darkly reactive perikarya.

In the retina, intense C.O. reactivity was localized within the inner segments of photoreceptors, the inner and outer plexiform layers, and within certain classes of bipolar and ganglion cells. The large ganglion cells in particular were intensely reactive. Like the large diameter optic terminals in SFGSd, the large ganglion cells were preferentially filled with HRP, suggesting that they may project to tectum and are the source of the darkly reactive large diameter axons and terminals in sublamina SFGSd.

We propose a new scheme to describe tectal lamination that integrates laminar differences in C.O. reactivity with classical histological work. We further suggest that these laminar patterns represent a functional substratification of the classically defined tectal laminae and, in particular, suggest that different optic sublaminae may be innervated by different classes of ganglion cells.
Immunohistochemical localization of a membrane‐associated, 4.1‐like protein in the rat visual cortex during postnatal development
Authors: Tsumoto T. , Sato H. , Sobue K.
Published: January 2005

Expression and localization of a membrane‐associated protein, an analog of erythrocyte protein 4.1, in the visual cortex were immunohistochemically studied in the rat, ranging in age from newborn to adult. In the adult, dendrites and somas of layer V pyramidal cells were stained by the antiprotein 4.1 antibody. In most of these immunoreactive neurons, the plasma membrane seemed to be preferentially stained. Neurons located in layers II and III of the cortex were only faintly stained, and those in layers IV and VI were not stained. At birth, the immunoreactivity was already present in pyramidal cells located in the upper part of the cortical subplate. Immature neurons located in the cortical plate were not stained by the antibody, suggesting that the 4.1‐like protein is expressed only in the neurons that have differentiated or are differentiating.

At postnatal days 2–8, immunoreactive neurons were dramatically increased in layers V and VI and intense labeling was seen at the apical dendrites of layer V pyramidal cells. Most of the stained processes of these and other neurons showed a sign of rapid dendritic growth, i.e., growth cones and filopodia. At days 10–17, the basal dendrites of pyramidal cells in layers II and III became detectable, although still slender. At days 20–37, these dendrites in layers II, III, and V became intensely immunoreactive, and dendritic spines were visualized by the antibody. Throughout all the ages, axons of neurons and neuroglia were not stained by the antibody. Also, most of the neurons in layer IV of the cortex were not immunoreactive.

These results suggest that the 4.1‐like protein is abundantly expressed in growing parts of the dendrites and spines. A hypothesis that this protein may play a role in synaptic plasticity in the developing visual cortex is discussed.
Prenatal development of neurons in the human prefrontal cortex: I. A qualitative Golgi study
Authors: Mrzljak Ladislav , Uylings Harry B. M. , Kostovic Ivica , van Eden Corbert G.
Published: January 2005

Golgi‐Stensaas and rapid‐Golgi staining techniques are used to study neuronal differentiation in the developing human prefrontal cortex in fetuses, premature infants, and full‐term newborns from 10.5 to 40 weeks of gestation. Horizontal neurons (Cajal‐Retzius neurons) above the cortical plate (in the marginal zone) and randomly oriented neurons below the cortical plate (in the primordial subplate) are more differentiated than the immature bipolar cortical plate neurons in the 10.5‐week fetus. During 13.5–15 weeks of gestation the fetal subplate zone can be clearly distinguished‐between the cortical plate and the intermediate zone. This subplate zone contains more mature neurons than the cortical plate, especially polymorphous neurons. The basic features of the apical and basal dendrites of pyramidal neurons develop between 17 and 25 weeks of gestation, before the thalamocortical fibres invade the cortical plate. Intensive differentiation of the subplate neurons occurs in this period, when various types of afferent fibres reside in the subplate zone. At least five neuronal types can be distinguished in the subplate, i.e., polymorphous, fusiform, multipolar, normal, and inverted pyramidal neurons. The ingrowth of afferent fibres into the cortical plate between 26 and 34 weeks of gestation coincides with intensive dendritic differentiation and the appearance of spines on dendrites of the prospective layer III and V pyramidal neurons as well as with the differentiation of the double bouquet interneurons in the prospective supragranular layers and layer IV. Multipolar nonpyramidal neurons with the dendritic features of basket neurons are observed between 32 and 34 weeks of gestation in future layer V. They are less differentiated than the double bouquet neurons. The neurons of the subplate zone continue their dendritic differentiation after 26/27 weeks of gestation and are still observed in the full‐term newborn. The axonal pattern of the subplate neurons suggests a possible functional role for them as either interneurons or projection neurons.
Quantitative analysis of the recurrent collaterals derived from Purkinje cells in zone X of the cat's vermis
Authors: Bishop Georgia A.
Published: January 2005

Intracellular electrodes filled with 4% horseradish peroxidase (HRP) were used to impale Purkinje cells in zone x of the cat's cerebellum. Subsequent to recording responses to bilateral stimulation of the ulnar, radial, and sciatic nerves, the cells were injected with HRP. Intracellularly labeled Purkinje cells were located and correlated with the physiological data. Purkinje cells in zone x respond primarily to stimulation of the ipsilateral forelimb. However, they have broad receptive fields in that most also receive inputs from stimulation of the contralateral forelimb or from more than one forelimb nerve; a few respond to activation of the hindlimb.

The distribution of the recurrent collaterals of zone x Purkinje cells has several features that are similar to those from zones a, b, and c: (1) they have a similar number of varicosities within the plexus; (2) they distribute primarily in the sagittal as compared to the transverse plane; and (3) most varicosities in the plexus are located within the Purkinje cell layer. However, several characteristics distinguish the collaterals of zone x Purkinje cells. First, they have a greater transverse extent than those derived from Purkinje cells in zones a, b, and c. Second, they have a higher percentage of collaterals that extend to more superficial aspects of the molecular layer as well as to deep levels of the granule cell layer.

The rostral extent of zone x has not been clearly defined in previous studies. On the basis of anatomical and physiological data derived from the present study it appears that Purkinje cells located in lobule Va have physiological and morphological properties similar to those observed for Purkinje cells in more caudal folia of lobule V. Thus, on the basis of the organization of local circuits, it appears that zone x extends at least to the most rostral folia of lobule V.

In conclusion, these data suggest that Purkinje cells in zone x may not be involved in controlling the movements of specific muscles, as may be the case in other cortical zones. Rather, it could be hypothesized that Purkinje cells in zone x have a more generalized role in coordinating agonist and antagonist muscle groups in one limb or regulating patterns of movement between limbs.
Projections of the cochlear nuclei and nucleus laminaris to the inferior colliculus of the barn owl
Authors: Takahashi Terry T. , Konishi Masakazu
Published: January 2005

The barn owl determines the directions from which sounds emanate by computing the interaural differences in the timing and intensity of sounds. These cues for sound localization are processed in independent channels originating at nucleus magnocellularis (NM) and nucleus angularis (NA), the cochlear nuclei. The cells of NM are specialized for encoding the phase of sounds in the ipsilateral ear. The cells of NA are specialized for encoding the intensity of sounds in the ipsilateral ear.

NM projects solely, bilaterally, and tonotopically to nucleus laminaris (NL). NL and NA project to largely nonoverlapping zones in the central nucleus of the inferior colliculus (ICc), thus forming hodological subdivisions in which time and intensity information may be processed. The terminal field of NL occupies a discrete zone in the rostromedial portion of the contralateral ICc, which we have termed the “core” of ICc. The terminal field of NA surrounds the core of ICc and thus forms a “shell” around it. The projection from NL to the core conserves tonotopy. Low‐frequency regions of NL project to the dorsal portions of the core whereas higher‐frequency regions project to more ventral portions. This innervation pattern is consistent with earlier physiological studies of tonotopy. Physiological studies have also suggested that NL and the core of ICc contain a representation of the location of a sound source along the horizontal axis. Our data suggest that the projection from NL to the core preserves spatiotopy. Thus, the dorsal portion of NL on the left, which contains a representation of eccentric loci in the right hemifield, innervates the area of the right ICc core that represents eccentric right loci. The more ventral portion of the left NL, which represents loci close to the vertical meridian, innervates the more rostral portions of the right core, which also represents loci near the vertical meridian.
Autoradiographic localization of nicotinic acetylcholine receptors in the brain of the zebra finch (Poephila guttata)
Authors: Watson James T. , Adkins‐Regan Elizabeth , Whiting Paul , Lindstrom Jon M. , Podleski Thomas R.
Published: January 2005

We have localized nicotinic acetylcholine receptors in the zebra finch brain by using three 125I‐labelled ligands: alpha bungarotoxin and two monoclonal antibodies to neuronal nicotinic receptors (MAb 35 of Tzardos et al., J. Biol. Chem., 250:8635–8645, ′81; and MAb 270 of Whiting and Lindstrom: J. Neurosci. 6:3061–3069, ′86). Unfixed brains from intact adult male and female zebra finches were prepared for in vitro autoradiography. Lowresolution film autoradiograms and high‐resolution emulsion autoradiograms were prepared for each of the three ligands.

The major brain structures that bind all three of the ligands are hippocampus; hyperstriatum dorsalis; hyperstriatum ventralis; nucleus lentiformis mesencephali; nucleus pretectalis, some layers of the optic tectum; nucleus mesencephalicus lateralis; pars dorsalis; locus ceruleus; and all cranial motor nuclei except nucleus nervi hypoglossi.

The major structures labelled only by [125I]‐alpha bungarotoxin binding included hyperstriatum accessorium and the nuclei: preopticus medialis, medialis hypothalami posterioris, semilunaris, olivarius inferior, and the periventricular organ. Of the song control nuclei, nucleus magnocellularis of the anterior neostriatum; hyperstriatum ventralis, pars caudalis; nucleus intercollicularis; and nucleus hypoglossus were labelled.

The binding patterns of the two antibodies were similar to one another but not identical. Both labelled nucleus spiriformis lateralis and nucleus geniculatus lateralis, pars ventralis especially heavily and also labelled the nucleus habenula medialis; nucleus subpretectalis; nucleus isthmi, pars magnocellularis; nucleus reticularis gigantocellularis; nucleus reticularis lateralis; nucleus tractus solitarii; nucleus vestibularis dorsolateralis; nucleus vestibularis lateralis; nucleus descendens nervi trigemini; and the deep cerebellar nuclei. Lobus parolfactorius and nucleus vestibularis medialis were labelled by only MAb 270, whereas only MAb 35 labelled nucleus laminaris and the medial and lateral pontine nuclei.

These data extend previous reports of cholinergic participation in the song system (Ryan and Arnold: J. Comp. Neurol. 202:211–219, ′81) to suggest that the zebra finch song system may contain several closely related nicotinic receptors. In several brain nuclei it appeared that certain anatomical portions of a nucleus or a certain class of neurons were specifically labelled. Furthermore, in certain cases, the labelling appeared to be clustered around Nissl‐stained cell nuclei, thus suggesting that the receptors are concentrated on or in somata.
Colocalization of fixative‐modified glutamate and glutaminase but not GAD in rubrospinal neurons
Authors: Beitz Alvin J. , Ecklund Lorelei J.
Published: January 2005

In an attempt to identify putative neurotransmitters of rubrospinal neurons, immunocytochemical procedures were utilized in combination with retrograde tracing techniques in 15 adult male rats. Following injections of horseradish peroxidase (HRP) or wheat germ agglutinin conjugated to HRP (WGA‐HRP) into the spinal cord, midbrain sections were processed with a combined procedure that allowed visualization of both the retrograde tracer and one or more antigens including glutamate, glutaminase, and glutamatic acid decarboxylase (GAD). Initial colocalization studies demonstrated that glutamatelike and glutaminaselike immunoreactivities were cocontained within the same neurons. Following injections of HRP or WGA‐HRP into the spinal cord approximately 53% of retrogradely labeled neurons contained glutamate immunoreactivity. Triple‐labeling experiments indicated that glutamatelike immunoreactivity was colocalized with glutaminase immunoreactivity in retrogradely labeled rubrospinal neurons. Retrogradely labeled neurons did not contain GAD immunoreactivity. Moreover, triple labeling experiments verified that glutamatelike immunoreactive retrogradely labeled cells did not cocontain GAD immunoreactivity. These studies demonstrate that glutamate and its synthesizing enzyme, glutaminase, are present in some rubrospinal neurons and raise the possibility that a component of the rubrospinal projection may be glutamatergic. GAD, on the other hand, is not present in rubrospinal neurons. This finding supports the hypothesis that GABAergic neurons play a role as interneurons in the red nucleus.
Mamillary body in the rat: A cytoarchitectonic, golgi, and ultrastructural study
Authors: Allen Gary V. , Hopkins David A.
Published: January 2005

The present study provides a comprehensive light and electron microscopic analysis of the anatomical organization of the rat mamillary body. The cytoarchitecture and morphology of mamillary neurons were investigated with the aid of Nissl‐stained and Golgi‐impregnated sections cut in transverse, horizontal, and sagittal planes. The ultrastructural features of the mamillary nuclei were correlated with observations made on Golgi material. The mamillary body is comprised of a lateral and a medial nucleus, the latter being subdivided into five major subnuclei: pars lateralis, pars basalis, pars medialis, pars medianus, and pars posterior. The perikarya are medium‐sized or small with the proportions of each differing among subnuclei. The largest perikarya are found in the lateral mamillary nucleus (cell area 257.0 μm2) and have 2‐5 radially oriented aspiny dendrites that are often beaded. Small cells predominate in the pars lateralis (cell area 116.3 μm2) and pars basalis (cell area 118.3 μm2), whereas the pars medialis (cell area 196.7 μm2), pars medianus (cell area 136.5 μm2), and pars posterior (cell area 154.6 μm2) contain mainly medium‐sized cells. The dendrites of most cells in the medial nucleus are radially oriented and exhibit a variety of spines including numerous short stubby spines, spines with thin necks that end in spherical swellings, and long thin spines. Neuronal somata are often closely apposed with no intervening glial processes and contain eccentrically located nuclei with one or more invaginations of the nuclear envelope.

Two main classes of axon terminals were identified in the mamillary body. One type contains round vesicles and forms asymmetric synaptic junctions (RA) with dendrites and dendritic spines. RA terminals rarely contact neuronal somata and proximal dendrites in the MB. The second type contains pleomorphic vesicles and forms mainly symmetric synaptic junctions (PS) with neuronal somata as well as dendrites and spinous processes. Dense‐cored vesicles were frequently seen in both types of terminals. Both types of terminals often synapse with two adjacent dendrites and are also found near or adjacent to each other on the same dendrite. A quantitative analysis indicated that the numbers of RA terminals in the medial nucleus almost equals the numbers of PS terminals, whereas the lateral mamillary nucleus contains considerably more PS (64%) than RA terminals (36%).
Nucleus basalis (Ch4) and cortical cholinergic innervation in the human brain: Observations based on the distribution of acetylcholinesterase and choline acetyltransferase
Authors: Mesulam M‐Marsel , Geula Changiz
Published: January 2005

The nucleus basalis (NB) of the human brain is a large, complex, and highly differentiated structure. Many of its neurons are magnocellular, hyperchromic, isodendritic, acetylcholinesterase‐rich, and choline‐acetyltransferase‐positive. Concurrent histochemical and immunological staining demonstrated that all choline‐acetyltransferase‐positive NB neurons in the human brain also contain acetylcholinesterase enzyme activity. Only a small minority of acetylcholinesterase‐rich magnocellular cell bodies in the NB failed to show choline acetyltransferase immunoreactivity. Sections that were counterstained for Nissl substance showed that 80‐90% of all magnocellular neurons in the NB were choline‐acetyltransferase‐positive and therefore cholinergic. These characteristics, which are very similar to those of the NB in the monkey brain, justified the designation of these cholinergic neurons in the human brain as the Ch4 (or NB‐Ch4) complex. On morphological grounds, the compact parts of the human NB‐Ch4 complex were divided into distinct sectors which appeared to show a greater level of differentiation than in the monkey brain. In addition to the compact sectors, interstitial elements of NB‐Ch4 were embedded within adjacent fiber bundles.

The putative cortical projections from NB‐Ch4 were identified in the form of acetylcholinesterase‐rich fibers. These fibers formed a dense plexus in all cortical regions but also displayed laminar and regional variations. Limbic and paralimbic areas had higher concentrations of these fibers than the immediately adjacent neocortical association areas. Alzheimer's disease was associated with a marked depletion of cortical acetylcholinesterase. Two cases of Alzheimer's disease with relatively selective NB‐Ch4 cell loss supported the hypothesis that the corticopetal cholinergic pathways in the human brain may have a topographical organization similar to that in the monkey brain.
Distribution and characterization of neuropeptide Y‐like immunoreactivity in the brain of the crested newt
Authors: Perroteau Isabelle , Danger Jean‐Michel , Biffo Stefano , Pelletier Georges , Vaudry Hubert , Fasolo Aldo
Published: January 2005

The newt brain represents a simplified model for the increasingly complex vertebrate neuronal organization. The localization of neuropeptide Y‐like (NPY‐like) containing neurons in the brain of Triturus cristatus was studied by means of indirect immunofluorescence, peroxidase‐antiperoxidase, and avidin‐biotin techniques using a highly specific antiserum. NPY‐like positive cell bodies were observed in several areas, most notably in the telencephalon (primordium hippocampi and amygdaloid complex), the preoptic and suprachiasmatic areas, the hypothalamus, the dorsal thalamus, the tegmentum, and the rhombencephalon (laterolateral grey column and raphe area). Nerve fibres were particularly abundant in the pallium, striatum, septum, amygdaloid, preoptic neuropils, and pars intercalaris diencephali. Bundles of NPY‐immunoreactive fibres also were visualized in the dorsal thalamus and in the posterior hypothalamus. The pars intermedia lacked any NPY‐like positive fibres. Neuronal processes also were found in the tectum mesencephali and in the body of the cerebellum. A prominent NPY‐like fibre network was observed in the octavolateralis. Concentrations of NPY measured by means of a specific radioimmunoassay were threefold higher in the hypothalamus (15.2 ± 1.3 ng/mg proteins) than in the rhombencephalon (4.9 ± 0.3) and the mesencephalon (4.3 ± 0.2). The concentration found in the telencephalon was 2.1 ± 0.3 ng/mg proteins. Sephadex G‐50 gel chromatography of whole brain extracts indicated the presence of high molecular weight forms of NPY‐like material in addition to the authentic peptide. Both amphibian and mammalian NPY peptides had an apparent molecular weight of 4,000 daltons, as evidenced by immunoblotting analysis. High‐performance liquid chromatography demonstrated, however, that the newt peptide was slightly less hydrophobic than porcine NPY. The present findings indicate that NPY‐immunoreactive neurons are widely distributed in the brain of urodeles. Our data indicate that the NPY molecule has been relatively well preserved during evolution.
Local synaptic organization of cholinergic neurons in the basolateral hypothalamus
Authors: Meeker Rick B. , Swanson Debra J. , Hayward James N.
Published: January 2005

A monoclonal antibody to choline acetyltransferase (ChAT) was utilized for immunocytochemical identification of cholinergic neurons in the basolateral hypothalamus. Light and electron microscopic examination revealed a network of cell bodies, dendrites, and axonal processes dorsolateral to the supraoptic nucleus. Within this region the cells immunoreactive for ChAT receive numerous unlabeled terminals which contact dendrites, cell soma, axons and occasional somatic spines. In a few cases, small ChAT‐immunoreactive terminals were observed contacting a cholinergic cell soma or large dendrite. Many ChAT‐immunoreactive fibers were directed toward the supraoptic nucleus forming a dense local network but very few of these fibers penetrated deeper than approximately 20 μm into the supraoptic nucleus. A total of 63 ChAT‐immunoreactive terminals were mapped within the basal hypothalamus, of which the vast majority contacted unlabeled dendrites immediately dorsolateral to the supraoptic nucleus. Labeled terminals were rare or nonexistent in the medial portions of the hypothalamus or deep within the supraoptic nucleus. This pattern of ChAT terminal densities correlates with the distribution of binding for the muscarinic cholinergic probe, [3H]quinuclidinylbenzilate, but not the binding of the putative nicotinic cholinergic probe, [125I]alpha‐bungarotoxin, which is high within the supraoptic nucleus. Thus, the cholinergic neurons of the basal hypothalamus appear to form a network of intrinsic connections which probably represent input to muscarinic cholinergic receptors. No evidence was found to suggest that cholinergic presynaptic terminals were colocalized with the alpha‐bungarotoxin binding protein within the supraoptic nucleus.
Auditory receptor of the red‐eared turtle: I. General ultrastructure
Authors: Sneary Michael G.
Published: January 2005

The auditory receptor of the red‐eared turtle has been the subject of intensive electrophysiological study within the last decade, yet the details of its ultrastructure have remained uninvestigated. In the present report information is derived from an analysis of specimens prepared for light, scanning electron, and transmission electron microscopy. Attention is focused on the ultrastructure of hair cells, supporting cells, and nerve fibers within the sensory epithelium as well as the basilar membrane upon which it rests. A description of the receptor's relations to surrounding sensory epithelia, the limbus of the cochlear duct, and the basilar membrane is also included. Observations are discussed in the light of similar information from other reptilian auditory receptors and the mammalian organ of Corti.
Ultrastructural characteristics of GD3 ganglioside‐positive immature glia in rat forebrain white matter
Authors: LeVine Steven M. , Goldman James E.
Published: January 2005

Immunocytochemistry and electron microscopy were used to examine the ultrastructural features of immature neuroectodermal cells of the rat forebrain in their early stages of differentiation. We used a monoclonal antibody (AbR24) to GD3 ganglioside, which binds to cells of the subventricular zone (SVZ). R24 also labels immature cells in developing white and gray matter (LeVine and Goldman: J. Neurosci. in press, '88, and accompanying paper). Sections of developing cingulum and white matter adjacent to the cingulum were examined at E18, P4, and P10 by using a preembedding immunocytochemical technique with PAP reagents. Labeled cells seen earliest were large, with high nuclear to cytoplasmic ratios and few cytoplasmic organelles. With time, smaller forms appeared, with prominent Golgi apparatus and processes containing microtubules. Labeled cells with similar characteristics but which contained cytoplasmic vacuoles were also observed. The results indicate a series of ultrastructural transformations that are consistent with oligodendrocyte differentiation.
Effects of increasing ploidy on the lumbar lateral motor column and hindlimb of newly metamorphosed Xenopus laevis: A comparison of diploid and triploid siblings
Authors: Sperry David G.
Published: January 2005

This study was undertaken to determine how increasing ploidy in Xenopus laevis affected the size of the lumbar lateral motor column (L‐LMC) motoneuron population, the size of representative hindlimb muscles, and the relationship between these features in animals at the completion of metamorphosis. Triploids were produced by exposing fertilized diploid eggs to increased hydrostatic pressure. In the triploids, L‐LMC motoneuron number was significantly reduced and motoneuron nuclear cross‐sectional area was significantly increased. Both L‐LMC length and the total L‐LMC size (neuron number × mean nuclear size) were roughly equal in diploids and triploids. No ploidy‐related differences in fiber number were observed in two representative thigh muscles.

In diploid animals, motoneuron number is significantly correlated with both muscle fiber number and with body size. The latter two variables are also significantly correlated with one another, making it possible that a feature related to muscle fiber number or one related to body size or both are significant in determining motoneuron number. In triploid animals, motoneuron number was significantly correlated with body size but not with muscle fiber number. This suggests that the feature significant in determining motoneuron number may be one related to body size rather than to muscle fiber number. If a feature related to muscle fiber number were the primary determinant of motoneuron number, one would have expected in addition similar average changes in the two variables in comparing diploids and triploids. That this was not observed provides further reason to suspect muscle fiber numbers may not be a primary determinant of motoneuron number.

In both diploids and triploids, total L‐LMC size (a value combining neuron number and neuron size) was highly correlated with body size, but again, not with muscle fiber number. The average total L‐LMC size and the average body size were equal in diploids and triploids while average motoneuron number was significantly different. What this suggests is that in discussing possible mechanisms to account for correspondences between central and peripheral sizes, the relevant variable for the former may be total L‐LMC size rather than motoneuron number.
Binding pattern of alpha‐bungarotoxin on horizontal cells of a marine teleost retina
Authors: Deplano Stefania
Published: January 2005

A conjugate of alpha‐bungarotoxin and a fluorescent marker (fluorescein isothiocyanate) has been used to localize “nicotinic” acetylcholine receptors on neurons in the outer plexiform layer of marine teleost retina. Toxin binding was confined to bipolar cell dendrites and to intermediate horizontal cells. The arrangement of labeled horizontal cells appears irregular inthe whole retina, with a peak density in the ventral and dorsal quandrants. Alpha‐bungarotoxin receptors on horizontal cells differ from those on bipolar cells and from those on dendrites in the inner plexiform layer in their sensitivity to agonists and antagonists such as d‐tubocurarine and nicotine. They consistute a different type of “nicotinic” receptor that probably has a different function.
Cell death in suboptic necrotic centers of chick embryo diencephalon and their topographic relationship with the earliest optic fiber fascicles
Authors: Navascuéeas Julio , Martíian‐Partido Gervasio , Alvarez Ignacio S. , Rodríiaguez‐Gallardo Lucíiaa
Published: January 2005

The structural features of suboptic necrotic centers (SONCs) in the floor of the chick embryo diencephalon were studied. These necrotic areas were observed lateral to the prospective zone of the optic chiasm through developmental stages 14 to 24. The relationship between SONCs and the earliest optic fiber fascicles also was studied in an attempt to determine the possible significance of these cell death areas in the mechanism of optic pathway development.

In SONCs, healthy neuroepithelial cells contain primary lysosomes and phagocytose fragments of dead cells. Discrete regions within the cytoplasm of some cells show electron‐transparent vacuoles in contact with dense contents of ruptured lytic bodies. The cytoplasm of dying cells and dead cell fragments are notably electron dense, with numerous secondary lysosomes and electron‐transparent vacuoles. These observations are interpreted on the assumption that after autophagic processes, condensation and fragmentation take place in dying cells of the SONCs.

In the ventricular lumen adjacent to the SONCs, numerous more or less spherical bodies are observed that appear to be shed from the tip of the cells constituting the SONCs. Three different types of intraventricular bodies can be distinguished: loose, moderately dense, and highly dense. The first type appears to originate from apical portions of cells that undergo autolytic processes. Moderately dense fragments are interpreted as originating from dying cells in which the cytoplasm is undergoing condensation. Finally, highly dense intraventricular bodies appear to be fragments of dead cells that are shed into the ventricular lumen.

SONCs separate the prospective area of the optic chiasm from lateral regions of the diencephalic floor. Extracellular spaces are poorly developed within the wall of the SONCs, whereas the neuroepithelium of the presumptive optic chiasm and regions located rostral and caudal to SONCs show abundant and extensive extracellular spaces. These are bounded by long marginal processes of neuroepithelial cells. Sagittal sections of embryonic heads at stages 22–24 reveal optic fiber fascicles penetrating the SONCs asymmetrically, as they are found only in its caudal half. These observations suggest that the SONCs function as doorways made of compact neuroepithelium, to be traversed by the earliest optic fibers before they reach the middle zone of the floor of the diencephalon through which they travel to the contralateral optic tract within large extracellular spaces.
Distribution of glutamate‐decarboxylase‐immunoreactive neurons and synapses in the rat and monkey hippocampus: Light and electron microscopy
Authors: Babb Thomas L. , Pretorius James K. , Kupfer William R. , Brown W. Jann
Published: January 2005

We have studied the distribution of γ‐aminobutyric acid (GABA) neurons, axons, and synapses in the rat and monkey hippocampal formation by using gluta nate decarboxylase (GAD) immunocytochemistry together with Nissl stairs, electron microscopy, and double‐labeled retrograde transport of horseradish peroxidase. The numbers of GAD‐containing (putative GABA) neurons and their percentages compared to all Nissl‐stained neurons were calculated throughout all the various fields and strata of the mammalian hippocampus. Although their numbers are greatest in the polymorph region of the fascia dentata (FD) and in the principal cell layers stratum pyramidale (SP) and stratum granulosum (SG), GAD immunoreactive (GAD‐IR) cells are numerous in other strata that contain mostly dendrites and scattered cells. These GAD‐IR (putative GABA) neurons in dendritic regions may be involved in feedforward dendritic inhibition or may directly inhibit nearby neurons. We used a postmortem delay technique, which resulted in apparent diffusion of GAD into dendrites and axons and allowed better visualization of the extensive dendritic domain of GAD‐IR neurons. Computerized image analysis of GAD‐IR puncta indicated that putative GABA terminals were numerous on apical and basilar dendrites of all pyramidal cells but unexpectedly highest in the monkey presubiculum. In the rat, GAD‐IR neurons projected axons ipsilaterally from every region to the fascia dentata and CA1; however, commissural GAD‐IR axons to the fascia dentata arose from GAD‐IR neurons in only the contralateral fascia dentata and subiculum. Electron microscopy of GADstained hippocampus identified GAD‐IR neurons with non‐GAD‐IR (possibly excitatory) synapses and GAD‐IR terminals on somata and dendrites, 80% being the symmetric type and 20% the asymmetric type. In contrast, non‐GAD‐IR terminals were asymmetric 80% of the time.
Central trajectories of type II spiral ganglion neurons
Authors: Brown M. C. , Berglund A. M. , Kiang N. Y. S. , Ryugo D. K.
Published: January 2005

Previous attempts to trace the central pathways of the thin axons from type II spiral ganglion neurons have been hampered by technical difficulties such as fading of the reaction product as distance increases from the injection site (Ryugo et al.: Soc. Neurosci. Abstr. 12:779, '86; Brown: J. Comp. Neurol. 260:591–604, '87). By using small rodents (gerbils and mice), which have short auditory nerves, we have succeeded in filling the entire central axon and terminals of type II neurons after peripheral injections of horseradish peroxidase. The general course of the type II fibers within the auditory nerve and cochlear nucleus is similar to that of type I fibers except that terminals from type II neurons are often found in regions of the cochlear nucleus that have high densities of granule cells.
Prevention of optic nerve regeneration in the frog Hyla moorei transiently delays the death of some ganglion cells
Authors: Humphrey M. F. , Darby J. E. , Beazley L. D.
Published: January 2005

We have previously reported that a proportion of ganglion cells die during optic nerve regeneration in the adult frog Hyla moorei (Humphrey and Beazley, '85). Here we assess the effect of preventing optic nerve regeneration on this cell loss. The optic nerve was crushed unilaterally and regeneration was allowed to progress unimpeded in one experimental series but was prevented by ligating or capping the nerve in another.

We estimated total cell numbers in the ganglion cell layer from cresylstained wholemounts, comparing each experimental retina with its unoperated partner. At 70–78 days postcrush, mean cell numbers had fallen by 31.5% for frogs with unimpeded regeneration (N = 9), a significantly greater reduction than the 21.5% (N = 8) loss for the impeded regeneration series (p < 0.001). Thereafter, cell numbers were stable for frogs with unimpeded regeneration. Cell death continued in the series with impeded regeneration, and losses exceeded those of frogs with unimpeded regeneration from 110 days postcrush. When regeneration was impeded, ganglion cell somas underwent an intense cell soma reaction and became arranged in rows radiating from the optic nerve head.

Our findings indicate that some ganglion cells are transiently spared when regeneration of their axons is prevented. The abnormally extensive contacts formed between somas may delay ganglion cell loss. However, the eventual death of most ganglion cells shows them to be target‐independent in the long term.
Distribution of reduced‐nicotinamide‐adenine‐dinucleotide‐phosphate diaphorase‐positive cells and fibers in the cat central nervous system
Authors: Mizukawa Kiminao , Vincent Steven R. , McGeer Patrick L. , McGeer Edith G.
Published: January 2005

Previous histochemical studies have suggested that reduced nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase exists in distinct subsets of neurons that neither belong to a single transmitter type nor embrace all the neurons using a single transmitter. As a step toward establishing the role of this enzyme, the distribution of NADPH‐diaphorase‐positive neurons and fibers in the cat central nervous system was mapped by using a direct histochemical method.

Heavily stained NADPH‐diaphorase‐positive neurons with many prominent cell processes were observed in the cerebral cortex, white matter, caudate nucleus, putamen, nucleus accumbens, septal nucleus, amygdala, anterior, lateral and posterior hypothalamic areas, dorsolateral part of the periaqueductal gray, superior colliculus, central tegmental field (Berman) (pedunculopontine tegmental area), dorsal tegmental nucleus, nucleus coeruleus, mesencephalic and pontine reticular formation, gigantocellular and magnocellular tegmental fields, nucleus facialis, and motor nucleus of the vagus. Moderately stained neurons with two or three prominent cell processes were observed in the nucleus of the diagonal band of Broca, globus pallidus, and substantia innominata. Medium‐size, moderately stained neurons that had round large nuclei and no visible cell processes were found in the subthalamic nucleus, pontine gray, trapezoid body, and infratrigeminal, cochlear, and vestibular nuclei. Very dense NADPH‐diaphorase‐positive nerve terminal fields were seen in the olfactory tubercle, cortex, caudate nucleus, putamen, dentate gyrus, and interpeduncular nucleus. Intensely stained NADPH‐diaphorase‐positive nerve fibers were found in the stria terminalis, marginal region of the central tegmental field, dorsal tegmental nucleus, and spinal trigeminal tract as well as around the brachium conjunctivum. Although the staining of neurons and tracts was highly selective, they did not correspond to any single known neuronal or neurotransmitter type. Positive staining occurred in discrete subsets of neurons known to be associated with a variety of peptides and classical neurotransmitters. The functional significance of high NADPH diaphorase activity is unknown.
Neurons of origin and fiber trajectory of amygdalofugal projections to the medial preoptic area in syrian hamsters
Authors: Maragos William F. , Newman Sarah Winans , Lehman Michael N. , Powers J. Bradley
Published: January 2005

The amygdaloid neurons of origin and the trajectory of amygdaloid fibers to the medial preoptic area of the adult male Syrian hamster were identified by using horseradish peroxidase (HRP) histochemistry. After iontophoresis of HRP into the medial preoptic area, retrogradely labeled amygdaloid neurons were located in the dorsal and caudal parts of the medial amygdaloid nucleus and throughout the amygdalohippocampal area. No amygdaloid neurons were labeled after HRP applications confined to the most rostral portion of the medial preoptic area (anterior to the body of the anterior commissure). Following more caudal medial preoptic area injections (body of the anterior commissure to the suprachiasmatic nucleus) the distribution of retrogradely labeled cells in the medial amygdaloid nucleus and the amygdalohippocampal area revealed no topographic organization of the amygdalopreoptic connections. When amygdaloid neurons were labeled, the amygdalohippocampal area contained two to five times as many HRP‐filled cells as the medial amygdaloid nucleus.

Retrogradely transported HRP could be followed from the medial preoptic area to the amygdala through fibers in the dorsomedial quadrant of the stria terminalis. In addition, electrolytic lesions of the stria terminalis prior to iontophoresis of HRP into the medial preoptic area prevented retrograde transport to neurons in both the dorsocaudal medial amygdaloid nucleus and the amygdalohippocampal area.

These results confirm earlier observations describing the location of autoradiographically labeled efferents from the medial amygdaloid nucleus to the medial preoptic area and provide new information about the restricted region within the medial amygdaloid nucleus from which these projections arise. They also suggest that, unlike the projections from the medial amygdaloid nucleus to the bed nucleus of the stria terminalis, the efferents to the medial preoptic area travel entirely in the stria terminalis.
Immunocytochemical study of a temperature‐sensitive choline acetyltransferase mutant of Drosophila melanogaster
Authors: Ikeda Kazuo , Salvaterra Paul M.
Published: January 2005

Using a monoclonal antibody to choline acetyltransferase (ChAT), we have identified immunoreactive synaptic terminals in the neuropil regions of the cephalic ganglion of Drosophila melanogaster. This study demonstrates the distribution of antibody‐labeled structures within the optic lobe, and then investigates the immunoreactivity altered by mutation in two temperature‐sensitive ChAT alleles, chats−1 and chats−2.

The general structure of the optic lobe was first observed by means of the silver impregnation technique. Then the presence of ChAT immunoreactivity was determined by the application of antibody [1G4] conjugated with HRP to frozen sections, followed by the 3,3′‐diamino‐benzidine tetratinct layers, which correspond to the three synaptic layers of the laminarneurons, in the medulla. Also, staining appeared in four distinct layers in the lobula. In addition, weaker staining was observed in the lamina, which corresponds to the retinula cell terminals. Somal layers were not stained.

In Canton‐S (wild‐type), the three medullar layers stain distinctly at both 19°C and 30°C. In chats−1 at 19°C, the stain appeared in the same layers as that of Canton‐S, but with somewhat lower density. In chats−2 at 19°C, the density of the stain was even lower. The densities of the stain in these mutants were further decreased after exposing the flies to 30°C. The decreases were dependent on the length of exposure to the higher temperature. The decrease in stain of the specimens obtained after 24 hours exposure to 30°C was clearly recognizable in both chats−1 and chats−2. The stain was visually unrecognizable after 120 hrs incubation at 30°C in chats−1, and after 80 hrs in chats−2. The stained structures in the medulla are apparently terminals of the laminar neurons. α‐Bungarotoxin (α‐BTX) conjugated with HRP and visualized by the DAB‐H2O2 reaction was also used to stain frozen sections of wild‐type and mutant Drosophila. The three layers of α‐BTX‐HRP stained structures in the medulla overlapped with the layers revealed by 1G4. Exposure to high temperature (30°C) for up to 120 hours did not show any effect on the stain obtained by α‐BTX‐HRP in either allele.

These results show that 1G4, a monoclonal antibody specific for Drosophila ChAT, can be used to identify ChAT‐containing neurons. In the temperature‐ sensitive ChAT mutant, chats, the reduced immunoreactivity paralleled the reduced ChAt activity levels which have been observed in this mutant.
Distribution of mu, delta, and kappa opiate receptor types in the forebrain and midbrain of pigeons
Authors: Reiner Anton , Brauth Steven E. , Kitt Cheryl A. , Quirion Remi
Published: January 2005

Ligands that are highly specific for the mu, delta, and kappa opiate receptor binding sites in mammalian brains have been identified and used to map the distribution of these receptor types in the brains of various mammalian species. In the present study, the selectivity and binding characteristics in the pigeon brain of three such ligands were examined by in vitro receptor binding techniques and found to be similar to those reported in previous studies on mammalian species. These ligands were then used in conjunction with autoradiographic receptor binding techniques to study the distribution of mu, delta, and kappa opiate receptor binding sites in the forebrain and midbrain of pigeons. The autoradiographic results indicated that the three opiate receptor types showed similar but not identical distributions. For example, mu, delta, and kappa receptors were all abundant within several parts of the cortical‐equivalent region of the telencephalon, particularly the hyperstriatum ventrale and the medial neostriatum. In contrast, in other parts of the cortical‐equivalent region of the avian telencephalon, such as the dorsal archistriatum and caudal neostriatum, only kappa receptors appeared to be abundant. Within the basal ganglia, all three types of opiate receptos were abundant in the striatum and low in the pallidum. Within the diencephalon, kappa and delta binding was high in the dorsal and dorsomedial thalamic nuclei, but the levels of all three receptor types were generally low in the specific sensory relay nuclei of the thalamus. Kappa binding and delta binding were high, but mu was low in the hypothalamus. Within the midbrain, all three receptor types were abundant in both the superficial and deep tectal layers, in periventricular areas, and in the tegmental dopaminergic cell groups.

In many cases, the distribution of opiate receptors in the pigeon forebrain generally showed considerable overlap with the distribution of opioid peptide‐containing fiber systems (for example, in the striatal portion of the basal ganglia), but there were some clear examples of receptor‐ligand mismatch. For example, although all three receptor types are very abundant in the hyperstriatum ventrale, opioid peptide‐containing fibers are sparse in this region. Conversely, within the pallidal portion of the basal ganglia, opioid peptide‐containing fibers are abundant, but the levels of opiate receptors appear to be considerably lower than would be expected. Thus, receptorligand mismatches are not restricted to the mammalian brain, since they are a prominent feature of the organization of the brain opiate systems in pigeons. Although the precise functional significance of such mismatches will require further elucidation, it nonetheless appears likely that the endogenous opioid peptides of the avian brain act through the opiate receptors whose distribution is described in the present paper.