bluuebunny/crossref_metadata_2025 huggingface dataset:
Correlation of local changes in cerebral blood flow, capillary density, and cytochrome oxidase during development
Authors: Tuor U. I. , Kurpita G. , Simone C.
Published: January 2005

Although elevations in cerebral metabolic demand during development may induce angiogenesis, the correlation among ontogenic changes in local cerebral blood flow, cytochrome oxidase activity (an index of oxidative capacity) and capillary density have not been examined previously. We measured these parameters in selected regions of the brains of anesthetized rabbits of various ages. Increases in all three parameters occurred postnatally within the cerebral cortex and striatum, whereas in the medulla, values at birth were similar to those in adults. In newborns, the pattern of distribution of blood flow within the parietal cortex was such that levels were maximal in the outer layers and declined in deeper layers. This distribution correlated closely with that of capillary density, whereas cytochrome oxidase activity was maximal at levels deeper in the cortex. By postnatal day 17, the distribution for all three parameters was similar to that of cytochrome oxidase activity in young animals. A regression analysis of the regional values demonstrated a positive correlation between capillary density and blood flow in young (≤ postnatal day 8) and old (≥ postnatal day 17) animals. In contrast, cytochrome oxidase activity and capillary density were poorly correlated in young animals but positively correlated in older animals, with the slopes being markedly different (P < 0.005). The results suggest that early in postnatal development, the pattern of cytochrome oxidase activity is relatively mature compared with that of capillary density. By postnatal day 17, microvascular anatomy is closely associated to oxidative capacity, likely reflecting a steady state regulation of capillary density to metabolic requirements. © 1994 Wiley‐Liss, Inc.
Distribution of choline acetyltransferase immunoreactivity in the pigeon brain
Authors: Medina Loreta , Reiner Anton
Published: January 2005

We have investigated the distribution of cholinergic perikarya and fibers in the brain of the pigeon (Columba livia). With this aim, pigeon brain sections were processed immunohistochemi‐cally by using an antiserum specific for chicken choline acetyltransferase. Our results show cholinergic neurons in the pigeon basal telencephalon, the hypothalamus, the habenula, the pretectum, the midbrain tectum, the dorsal isthmus, the isthmic tegmentum, and the cranial nerve motor nuclei. Cholinergic fibers were prominent in the dorsal telencephalon, the striatum, the thalamus, the tectum, and the interpeduncular nucleus. Comparison of our results with previous studies in birds suggests some major cholinergic pathways in the avian brain and clarifies the possible origin of the cholinergic innervation of some parts of the avian brain. In addition, comparison of our results in birds with those in other vertebrate species shows that the organization of the cholinergic systems in many regions of the avian brain (such as the basal forebrain, the epithalamus, the isthmus, and the hindbrain) is much like that in reptiles and mammals. In contrast, however, birds appear largely to lack intrinsic cholinergic neurons in the dorsal (“neocortex‐like”) parts of the telencephalon. © 1994 Wiley‐Liss, Inc.
Dendritic architecture of hypoglossal motoneurons projecting to extrinsic tongue musculature in the rat
Authors: Altschuler Steven M. , Bao Xinmin , Miselis Richard R.
Published: January 2005

The tracer, cholera toxin‐horseradish peroxidase, was used to determine the dendritic architecture and organization of hypoglossal motoneurons in the rat. In 22 animals, the tracer was injected unilaterally into either the geniohyoid, genioglossus, hyoglossus, or styloglossus muscle. Within the hypoglossal nucleus, motoneurons innervating the extrinsic tongue muscles were functionally organized. Geniohyoid and genioglossus motoneurons were located within the ventrolateral and ventromedial subnuclei, respectively, while hyoglossus and styloglossus motoneurons were located within the dorsal subnucleus.

Motoneurons located in all subnuclear divisions were found to have extensive dendrites that extended laterally into the adjacent reticular formation and medially to the ependyma. Less extensive extranuclear dendritic projections were found in the dorsal vagal complex and median raphe. Prominent rostrocaudal and mediolateral dendritic bundling was evident within the ventral subnuclei and dorsal subnucleus, respectively. Dendritic projections were also found extending inter‐ and intrasubnuclearly with a distinct pattern for each muscle.

These data suggest that the varied and extensive dendritic arborizations of hypoglossal motoneurons provide the potential for a wide range of afferent contacts for, and interactions among, motoneurons that could contribute to the modulation of their activity. Specifically, the prominent dendritic bundling may provide an anatomic substrate whereby motoneurons innervating a specific muscle receive and integrate similar afferent input and are thus modulated as a functional unit. In contrast, the extensive intermingling of both inter‐ and intrasubnuclear dendrites within the hypoglossal nucleus may provide a mechanism for the coordination of different muscles, acting synergistically or antagonistically to produce a tongue movement. © 1994 Wiley‐Liss, Inc.
Intrinsic cortical connections in macaque visual area V2: Evidence for interaction between different functional streams
Authors: Levitt Jonathan B. , Yoshioka Takashi , Lund Jennifer S.
Published: January 2005

Area V2 of macaque visual cortex represents an important but poorly understood stage in visual processing. To provide a better understanding of the region, we studied the organization of its intrinsic cortical connections by making focal (200–300 μm) iontophoretic microinjections of the tracer biocytin. Alternate tissue sections were tested for biocytin, cytochrome oxidase (CO), or Cat‐301 immunoreactivity to localize biocytin label relative to the three stripelike compartments that characterize this area. Biocytin‐labeled pyramidal neurons of layers 2/3, and, to a lesser extent, layer 5, provided laterally spreading axon projections that terminated in discrete patches (250–300 μm diameter), primarily in layers 1–3. Any injected locus in V2 projected to 10–15 similarly sized patches, up to 4 mm from the injection site, and distributed in an elongated field orthogonal to the stripe compartments. We noted prominent patchy connections within, as well as between, individual compartments, perhaps reflecting functional substructures within stripes. Each stripe compartment projected to all three compartments but with different relative frequencies; CO‐rich compartments projected mainly to other CO‐rich compartments (75%), whereas CO‐poor compartments projected equally to CO‐rich and CO‐poor compartments. We therefore emphasize the existence of substantial interconnections among all three V2 compartments. As further evidence for crosstalk between visual channels, we also noted an input to the V2 “thick” CO stripes from V1 cells in layer 4A as a distinct population in addition to the neurons of layer 4B. Thus, the CO stripe architecture may not be a marker for strictly segregated parallel visual pathways through V2. © 1994 Wiley‐Liss, Inc.
Organization of the embryonic and early postnatal murine hippocampus. I. Immunocytochemical characterization of neuronal populations in the subplate and marginal zone
Authors: Soriano Eduardo , Del Río Jose Antonio , Martínez Albert , Supèr Hans
Published: January 2005

Immunocytochemical techniques were used to characterize the neuronal populations in the hippocampal subplate and marginal zone from embryonic day 13 (E13) to postnatal day 5 (P5). Sections were processed for the visualization of microtubule‐associated protein 2 (MAP2) and other antigens such as neurotransmitters, neuropeptides, calcium‐binding proteins and a synaptic antigen (Mab SMI81). At E13–E14, only the ventricular zone and the primitive plexiform layer were recognized. Some cells in the later stratum displayed MAP2‐, γ‐aminobutyric acid (GABA)‐and calretinin immunoreactivities. From E15 onwards, the hippocampal and dentate plates became visible. Neurons in the plexiform layers were immunoreactive at E15–E16, whereas the hippocampal and dentate plates showed immunostaining two or three days later. Between E15 and E19 the following populations were distinguished in the plexiform layers: the subventricular zone displayed small neurons that reacted with MAP2 and GABA antibodies; the subplate (prospective stratum oriens) was poorly populated by MAP2‐ and GABA‐positive cells; the inner marginal zone (future stratum radiatum) was heavily populated by multipolar GABAergic cells; the outer marginal zone (stratum lacunosum‐moleculare) displayed horizontal neurons that showed glutamate‐ and calretinin immunoreactivities, their morphology being reminiscent of neocortical Cajal‐Retzius cells. Thus, each plexiform layer was populated by a characteristic neuronal population whose distribution did not overlap. Similar segregated neuronal populations were also found in the developing dentate gyrus. At perintal stages, small numbers of neurons in the plexiform layers began to express calbindin D‐28K and neuropeptides. During early postnatal stages, neurons in the subplate and inner marginal zones were transformed into resident cells of the stratum oriens and radiatum, respectively. In contrast, calretinin‐positive neurons in the stratum lacunosum‐moleculare disappeared at postnatal stages. At E15–E19, SMI81‐immunoreactive fibers were observed in the developing white matter, subplate and outer marginal zone, which suggests that these layers are sites of early synaptogenesis. At PO‐P5, SMI81 immunoreactivity became homogeneously distributed within the hippocampal layers.

The present results show that neurons in the hippocampal subplate and marginal zones have a more precocious morphological and neurochemical differentiation than the neurons residing in the principal cell layers. It is suggested that these early maturing neurons may have a role in the targeting of hippocampal afferents, as subplate cells do in the developing neocortex. © 1994 Wiley‐Liss, Inc.
Postnatal development of vimentin‐positive cells in the rabbit superior colliculus
Authors: Pulido‐Caballero José , Jiménez‐Sampedro Félix , Echevarría‐Aza Diego , Martínez‐Millán Luis
Published: January 2005

The present study examined the postnatal development of the radial glib in the rabbit superior colliculus during the first 40 postnatal days. An antivimentin monoclonal antibody and the carbocyanine fluorescent tracer DiI were used in order to investigate the development of laminar connectivity in the superior colliculus. We focused our study on the superficial gray layer, the intermediate layer, and the deep layers of the superior colliculus, the periaqueductal gray matter (PAGM), and the medial intercollicular region.

Vimentin‐positive structures of glial lineage consisted of (1) the main radial system, which in the newborn rabbit was made up of wavy fibers that ran from the aqueduct to the glial surface, where they terminated in end‐feet. At postnatal day 15, these fibers diminished to 100–200 μm long wavy tracts, which emanated from the aqueduct, and to a few straight or arched fragments in the superficial gray layer; (2) The median ventricular formation, which extends from mesencephalic aqueduct to the intercollicular sulcus, was characterized by a series of ascending, vimentin‐positive fibers, some of large caliber, which persisted until postnatal day 40; (3) the tangential fiber system, which was made up of fibers that diverged from the median ventricular formation and of a number of short tracts running perpendicular to the periaqueductal radial fibers; these structures may provide support for migrating subpopulations of neurons; (4) immature and mature‐like protoplasmic and fibrous astrocytes, which appeared during the second postnatal week. Thereafter, the number of vimentin‐positive astrocytes decreased sharply. Our findings generally support earlier descriptions of the radial glib, except for the persistence, in superficial layers of the superior colliculus, of straight and curved fragments of fibers, which may participate in the organization of visual afferents at this level. © 1994 Wiley‐Liss, Inc.
Neuronal aromatase expression in preoptic, strial, and amygdaloid regions during late prenatal and early postnatal development in the rat
Authors: Shinoda Koh , Nagano Mamoru , Osawa Yoshio
Published: January 2005

Brain aromatase has been considered to be an important clue in elucidating the actions of androgen on brain sexual differentiation. Using highly specific anti‐P450arom antiserum, the regional and subcellular distributions were immunohistochemically evaluated in the preoptic, strial, and amygdaloid regions of developing rat brains. Aromatase‐immunoreactive (AROM‐I) neurons were classified into three groups. The first, in which immunostaining occurs only during certain pre‐ or neonatal days (E16–P2), included the anterior medial preoptic nucleus, the periventricular preoptic nucleus, neurons associated with the strial part of the preoptic area, and the rostral portion of the medial preoptic nucleus. The second is a striking AROM‐I cell group in the “medial preopticoamygdaloid neuronal arc,” which extends from the medial preoptic nucleus to the principal nucleus of the bed nucleus of the stria terminals and the posterodorsal part of the medial amygdaloid nucleus. The AROM‐I neurons appeared by E16, reaching a peak in staining intensity between E18 and P2 and diminishing after the perinatal stage. After P14, a third group of AROM‐I neurons emerged in the lateral septal nucleus, the oval nucleus of the bed nucleus of the stria terminalis, and the central amygdaloid nucleus. The second group was thought to be the major aromatization center in developing rat brains, while the center might partly shift to the third group of neurons after the late infantile stage. The distribution and developmental patterns were basically similar in males and females, suggesting that the neonatally prominent aromatase is not induced by male‐specific androgen surges occurring around birth. On immunoelectron microscopy, subneuronal aromatase was predominantly localized on the nuclear membrane and endoplasmic reticulum, which appeared to be appropriate for the efficient conversion of androgen into estrogen just prior to blinding to the nuclear receptors. © 1994 Wiley‐Liss, Inc.
A quantitative morphological analysis of the cerebellar nuclei in normal and lurcher mutant mice. II. Volumetric changes in cytological components
Authors: Heckroth John A.
Published: January 2005

In the present study the stereological point counting method has been used to determine volumetric changes in the cytological components of the lurcher cerebellar nuclei. The volume fraction of neuronal somata was estimated, using semithin toludine blue stained sections. Seven categories of profiles were analyzed in electron micrographs: (1) dendrites, (2) boutons on dendrites, (3) boutons on somata (4) myelinated fibers, (5) glial perikarya, (6) vascular elements, and (7) unclassified components. Volume fraction data indicate that the volumetric composition of the wild‐type murine cerebellar nuclei is: 38% myelinated fibers, 8% neuronal somata, 11% dendrites, 10% boutons on dendrites, less than 1% boutons on somata, 2.5% glial somata, and 6% vascular elements. Unclassified elements, consisting primarily of glial processes and intercellular space, comprised 23% of the volume of the wild‐type cerebellar nuclei. In lurcher, the loss of myelinated axons and boutons accounts for 59% of the atrophy of the cerebellar nuclei. Loss of nuclear neurons accounts for 2%, and a reduction in dendritic arbors for another 8.3% of this atrophy. The remaining 30.7% of the lost nuclear volume results from reduced volume of glial processes, vascular elements, and intercellular space. © 1994 Wiley‐Liss, Inc.
Immunolocalization of aromatic L‐amino acid decarboxylase in goldfish (Carassius auratus) brain
Authors: Beltramo M. , Krieger M. , Tillet Y. , Thibault J. , Calas A. , Mazzi V. , Franzoni M. F.
Published: January 2005

The distribution of monoamines (catecholamines and serotonin) in fishes has been previously studied by immunohistochemistry of both the monoamines themselves and their biosynthetic enzymes. But the distribution of neuron containing aromatic L‐amino acid decarboxylase, and enzyme involved in the biosynthesis of both catecholamines and serotonin, has up to now not been investigated. In order to improve knowledge about the localization of aromatic L‐amino acid decarboxylase, neurons containing this enzyme were mapped immunohistochemically in the goldfish brain. Furthermore, neurons bearing aromatic L‐amino acid decarboxylase immunoreactivity have been compared with those containing tyrosine hydroxylase and serotonin immunoreactivities. Our results show that distribution of aromatic L‐amino acid decarboxylase immunoreactivity generally coincides with that of tyrosine hydroxylase and serotonin. Nevertheless, the presence of nine D cell groups (containing aromatic L‐amino acid decarboxylase but lacking both catecholamines and serotonin) and six groups of neurons which are aromatic L‐amino acid decarboxylase‐immunoreactive but contain tyrosine hydroxylase, and might produce L‐DOPA, have been revealed. The occurrence of both D cell groups and presumptive L‐DOPA neurons in goldfish brain is discussed in relation to similar findings in fish and mammalian brain. © 1994 Wiley‐Liss, Inc.
Are there three types of horizontal cell in the human retina?
Authors: Kolb Helga , Fernandez Eduardo , Schouten James , Ahnelt Peter , Linberg Kenneth A. , Fisher Steven K.
Published: January 2005

Golgi‐impregnated horizontal cells (HCs) as viewed in whole mount human retinas have been studies by light microscopic (LM) techniques. Impregnated HCs have been drawn by camera lucida and by the Eutectics neuron tracing method to provide quantitative data on dendritic tree sizes, dendritic tree shapes, and dendritic terminals for statistical treatment and cluster analysis. In addition, fractal analysis of HC dendritic branching patterns have been performed.

Three significantly different HCs can be classified on both subjective and objective morphological criteria in central and peripheral human retina. In the fauves all HCs are so small that it is difficult to achieve a clear separation of the subtypes, although they can be distinguished by the experienced observer. HI types are the classic HCs of Polyak (The Retina, Chicago: University of Chicago Press, 1941) with distinct dendritic terminal clusters going to cones and a fan‐shaped axon terminal consisting of large numbers of rod‐destined terminals. HII cells have profusely branched, overlapping dendrites, with poorly defined terminals going to cones and a short curled axon bearing small terminals also going to cones. The HIII types exhibit larger diameter, more asymmetrically shaped dendritic trees and 30% nire dendritic terminal clusters than HI cells at any location on the retina. Many HIII cells appear to emit a process from the cell body in the inner nuclear layer (INL) that descends into the outer strata of the inner plexiform layer (IPL). The axon of the HIII cell may end in a loosely organized, sprawling arborization.

Fractal dimensions of the horizontal cells also show significant differences between the three groups. HIII cells exhibit the highest fractal dimension followed by HI and HIII cells with lower and lowest fractal dimensions, respectively. The fractal dimension of HII cells of rhesus monkeys, as determined from drawings by other authors in other publication, are the same as HII cells of human retina. © 1994 Wiley‐Liss, Inc.
Parietal, temporal, and occipita projections to cortex of the superior temporal sulcus in the rhesus monkey: A retrograde tracer study
Authors: Seltzer Benjamin , Pandya Deepak N.
Published: January 2005

The afferent cortical connections of individual cytoarchitectonic areas within the superior temporal sucus (STS) of the rhesus monkey were studied by retrograde tracer techniques, including double tracer experiments. Rostral superior temporal polysensory (STP) cortex (area TPO‐1) receives input from the rostral superior temporal gyrus (STG), cortex of the circular sulcus, and parahippocampal gyrus (PHG) (areas 35, TF, and TL). Mid‐STP cortex (areas TPO‐2 and ‐3) has input from the mid‐STG, cortex of the mid‐circular sulcus, caudal inferior parietal lodule (IPL), cingulate gyrus (areas, 23, 24, retrosplenial cortex), and mid‐PHG (areas 28, TF, TH, and TL). Caudal STP cortex (area TPO‐4) has afferent connections with the caudal STG, cortex of the cauda insula and caudal circular sulcus, caudal IPL, lower bank of the intraparietal sulcus (IPS), medial parietal lobe, cingulate gyrus, and mid‐ and caudal PHG (areas TF, TH, TL; prostriate area). The most rostral cortex of the lower bank of the STS (areasTEa and TEm), a presumed visual association area, receives input from the rostal inferotemporal (IT) region; more cauda portions of areas TEa and TEm have afferent connections with the caudal IT region, PHG, preoccipital gyrus, and cortex of the lower bank of the IPS. © 1994 Wiley‐Liss, Inc.

This article is a US Government work and, as such, is in the public domain in the United States of America.
Compartment of brain‐type cretine kinase and ubiquitous mitochondrial cretine kinase in neurons: Evidence for a cretine phosphate energy shuttle in adult rat brain
Authors: Friedman David L. , Roberts Robert
Published: January 2005

Multiple isoforms of cretine kinase (CK) are expressed in specific cell types as part of an energy delivery or shuttle system. To test hypothesis that neurons utilize a cretine phosphate energy shuttle, we examined the pattern of CK isoform expression and localization in adult rat brain. Two isoforms of CK are present in brain extracts, “brain‐type,” or BCK, and the ubiquitin form of the mitochondrial CK (uMtCK), as detected by enzyme activity following nondenaturing electrophoresis and by Western blotting following denaturing electrophorsis. In formalin‐fixed and parafinn‐embedded sections of rat brain, uMtCK immunostaining is detected in the somata of all Golgi type I neurons in the cerebellum, pontine reticular formation, red nucleus, hippocampus, and cerebral cortex. Immunostainig for uMtCK appears throughout the cell body but not in nuclei. BCK immunostaining is also present in somata of Golgi type I neurons in the cerebellum, red nucleus, and pons and is distributed throughout the cell body and within nuclei. BCK immunostaining also appeared in neuronal processes and is concentrated in the molecular layers of the cerebellum and the hippocampus and in cortical pyramidal cell dendrites. These results demonstrate a coordinate pattern of expression and compartmentation of BCK and MtCK isoform in neurons, which provides an anatomic basis for the transfer of metabolic energy via a cretine phosphate energy shuttle. © 1994 Wiley‐Liss, Inc.
The morphological development of the inferior colliculus in a marsupial, the northern quoll (Dasyurus hallucatus)
Authors: Aitkin Lindsay , Nelson John , Farrington Moyra , Swann Sue
Published: January 2005

As a part of a project concerning the development of hearing, some features of the morphological development of the inferior colliculus were studied in a marsuglial, the Northern quall or native cat (Dasyurus hallucatus). Marsuglials are of particular interest in developmental studies because much embryonic development occurs outside the uterus, in the pouch. Nissl‐stained material was prepared from pouch‐young at various ages between 11 and 81 days, and for a number of adults. Four pouch‐young were injected with tritiated thymidine and killed later during pouch life.

The inferior colliculus is first recognizable in pouch‐young aged 23 days, when it is bordered by a cell‐sparse ring of tissue. By this time, the labelling patterns following injections of tritiated thymidine made on days 7–9 suggest that migration of cells to the inferior colliculus from the ventricular germinal zone has been largely completed. At 81 days, close to the time when the young move out of the pouch, the adult cytoarchitecture—a central nucleus flanked by dorsal and lateral cortical regions—is clear.

Cell areas expand monotonically as a function of age. The period of days 45–50 is associated with a large expansion of cell volume and a concomitant decrease in packing density. It is likely that functional connections are forming during this period, which may herald the onset of hearing in the quall.

Total cell numbers increase to a peak at day 36, fall to a minimum at day 50, and rise again to the adult value. The second increase is likely to be a phase of glial proliferation, in part associated with the onset of myelination. This increase correlates with departure of the young from the pouch. © 1994 Wiley‐Liss, Inc.
Anatomy and projection patterns of the superior olivary comlex in the mexican free‐tailed bat, Tadarida brasiliensis mexicana
Authors: Grothe Benedikt , Schweizer Hermann , Pollak George D. , Schuller Gerd , Rosemann Christina
Published: January 2005

The superior olivary complex (SOC) is the first station in the ascending auditory pathway that receives binaural projections. Two of the principal nuclei, the lateral superior olive (LSO) and the medial superior olive (MSO), are major sources of ascending projections to the inferior colliculus. Whereas almost all mammals have an LSO, it has traditionally been thought that only animals that hear low frequencies have an MSO. Recent reports, however, suggest that the medial part of the SOC in bats is highly variable and that at least some bats have a well‐developed MSO. Thus, the main goal of this study was to evaluate the cytoarchitecture and connections of the principal superior olivary nuclei of the Mexican free‐tailed bat, with specific attention directed at the MSO. Cell and fiber stained material revealed that the LSO and the medial nucleus of the trapezoid body (MNTB) are similar to those described for other mammals. There are two medial nuclei we refer to as dorsomedial periolivary nucleus (DMPO) and MSO. Tracer experiments exhibited that the DMPO receives bilateral projections from the cochlear nucleus, and additional projections from the ipsilateral MNTB. The DMPO sends a strong projection to the ipsilateral inferior colliculus. Positive staining for acetylcholinesterase indicates that the DMPO is a part of the olivocochlear system, as it is in other animals. The MSO in the free‐tailed bat meets many of the criteria that traditionally define this nucleus. These include the presence of bipolar and multipolar principal cells, bilateral innervation from the cochlear nucleus, a strong projection from the ipsilateral MNTB, and the absence of cholinergic cells. The major difference from traditional MSO features is that it projects bilaterally to the inferior colliculus. Approximately 30% of its cells provide collateral projections to the colliculi on both sides. Funcional implications of the MSO for the free‐tailed bat are considered in the Discussion. © 1994 Wiley‐Liss, Inc.
Relationship between structure and function of neurons in the rat rostral nucleus tractus solitarii
Authors: King Michael S. , Bradley Robert M.
Published: January 2005

To investigate the relationship between the structure and function of neurons in the rostral (gustatory) nucleus tractus solitarii (rNTS), we analyzed the morphological and biophysical properties of rNTS neurons by performing whole‐cell recordings in a brain slice preparation. Overall, neurons (n=58) had a mean somal diameter of 16 μm, an average dendritic length of 598 μm, an average dendritic thickness of 0.91 μm, and a spine density of 0.037 spines/μm. Neurons were separated into three groups (elongate, miltipolar, and ovoid) on the basis of previously established morphological criteria. The highest percentage (49%) of neurons were classified as ovoid, while 35% were multipolar and only 16% were elongate.

The most frequently ovserved firing pattern, in all three cell types, elicited by a 1,200 ms, 100 pA depolarizing current pulse was a regularly firing spike train. However, the intrinsic firing properties of the remaining neurons were different. Thirty‐one percent of the ovoid neurons responded with a short burst of action potentials and 44% of the elongate neurons showed a delay in the onset of the spike train following a hyperpolarizing prepulse. Less than 16% of the multipolar neurons demonstrated either of these firing characteristics.

Therefore, rNTS neurons with similar morphology do not have unique biophysical properties. However, the data suggest that there may be subpopulations of the three morphological types, each of which displays a different firing pattern. Since the structure and function of the three morphological groups were not strictly correlated, these subpopulations may represent functional groups. © 1994 Wiley‐Liss, Inc.
The organization of the embronic and early postnatal murine hippocampus. II. Development of entorhinal, commissural, and septal connections studied with the lipophilic tracer DiI
Authors: Supèr Hans , Soriano Eduardo
Published: January 2005

We have analyzed the early development of the main hippocampal afferents in the mouse. Following injections of the lipophilic tracer 1–1′‐dioctadecyl‐3, 3, 3′, 3′‐tetramethylindocarbocyanine perchorate (DiI) in the entorhinal cortex, entorhinal axons were observed for the first time inthe hippocampus at E15, in the white matter, At E17, entorhinal fibers arborized within the stratum lacunosum‐moleculare. At subsequent stages entorhinal axons formed dense networks that were restricted to their appropriate termination zone in the lacunosum‐moleculare. The first axons invading the fascia dentata were noticed at E19, their density increasing at later stages. These axons were mainly present in the outer molecular layer. This onset of entorhinohippocampal projections was corroborated by retrograde labeling data after injections in the hippocampus. Commissural fibers first entered the contralateral hippocampus at E18, their number increasing at the following stages. Commissural axons arborized within the stratum oriens and radiatum in the hippocampus proper. In the fascia dentata, the earliest commissural fibers were seen at P2, terminating in the inner zone of the molecular layer and in the hilus. We conclude that developing entorhinal and commissural axons show a high degree of laminar specificity from the earliest stages of formation, which is compatible with the notion that distinct subsets of early maturing neurons populating the hippocampal plexiform layers may attract particular fiber systems.

Hippocamposeptal fibers develop at E15, before the first septal fibers can be detected in the hippocampus. These early hippocamposeptal fibers originated from nonpyramidal neurons and terminated in the medial septal area, which is the main source of septal afferents to the hippocampus. In contrast, septohippocampal fibers were not seen in the hippocampus until E17. At perinatal stages, the hippocamposeptal connection reshapes, sending axons to the dorsolateral septal area as the innervation of the medial septum becomes less conspicuous. This sequence suggests that hippocampal neurons pioneer the formation of septohippocampal connections. © 1994 Wiley‐Liss, Inc.
Pedunculopontine nucleus in the squirrel monkey: Cholinergic and glutamatergic projections to the substantia nigra
Authors: Lavoie Brigitte , Parent André
Published: January 2005

The distribution and chemospecificity of the pedunculonigral neurons have been studied in squirrel monkeys (Saimiri sciureus)with cholera toxin subunit B (CTb) and fluorogold (FG) as retrograde tracers combined with immunohistochemistry for choline acetyltransferase (ChAT), glutamate, and the calcuium binding protein calbindin D‐28k. The injection of either CTb or FG into the substantia nigra produces prominent retrograde cell labeling in the mesopontine tegmentum. Labeled neurons are particularly numerous at the level of the decussation of the superior cerebellar peduncle, where they abound principally in the pars dissipata of the pedunculopontine nucleus (PPN). A significant proportion of retrogradely labeled neurons in the PPN display ChAT immunoreactivity. Whithin the entire PPN, approximately 25% of the retrogradley labeled neurons express ChAT immunoreactivity, but proportions of doubly labeled neurons are about 35%, 25% in the rostral, middle, and caudal thirds of the PPn, respectively. These doubly labeled neurons are scattered among numerous retrogradely labeled neurons that are ChAT‐negative and whose number increases along the rostrocaudal extent of the PPN. Several retrogradely labeled neurons in the PPN display glutamate immunoreactivity, but very few express calbindin. This study provides the first direct evedence for the involvement of cholinergic and glutamatergic neurons in the pedunculonigral projection in primates. Furthermore, the fact that some neurons of the PPN display bothe ChAT and glutamate immunoreactivity indicates that single neurons in the mesopontine tegmentum may exert a two‐fold effect upon dopaminergic neurons of the substantia nigra. This dual cholinergic and glutamatergic pedunculonigral projection may play a crucial role in the functional organization of primate basal ganglia. © 1994 Wiley‐Liss, Inc.
Catecholaminergic systems in the zebrafish. I. Number, morphology, and histochemical characteristics of neurons in the locus coeruleus
Authors: Ma Pokay M.
Published: January 2005

The locus coeruleus is a noradrenergic nucleus located in the isthmal tegmentum. In mammals, it contains several thousand neurons that have diverse projection patterns and contain various neuropentides. In fishes, this nucleus contains few neurons. This study attempts to define and quantify morphological types of locus coeruleus neurons, and search for neurochemical subpopulations in the zebrafish. In this fish, the locus coeruleus contains between 3 and 10neurons, and most nuclei contain between 5 and 8 cells. Nuclei in more inbred lines of fish have a narrower range of neurons. The difference in neuron number between the two sides of the same brain is small, but only 24% of the brains have identical numbers on both sides. These observations suggest that there is a two‐step control of neuron number: the genetic constitution of the fish determines the approximate number of cells, while epigenetic factors determine the final number. Based on dendritic orientation, three types of cells are identified: (1) V type, neurons with only ventrally projecting dendrites; (2) L types, neurons with only laterally projecting dendrites; and (3) VL type, neurons with both ventrally and laterally projecting dendrites. Over 65% of the neurons are of the V type; some nuclei have V type; some nuclei have V type cells only. There is a correlation between the total number of neurons and the ratio of each cell type. In nuclei with five cells or fewer, over 80% of the neurons are V type; higher percentages of the other two types are seen in nuclei with 6 or more neurons. The dendritic morphology and orientation suggest that various types of neurons may receive different inputs. Cholinesterases are not detectable in locus coeruleus neurons. Immunocytochemical staining for a number of neuropeptides also fails to demonstrate detectable levels. Neuropeptide Y is present in some cell abutting the locus coeruleus, but these are probably not catecholamine‐containing neurons. Some neurons contain choline‐acetyltransferase. These observations suggest that locus coeruleus neurons of the zebradish may be morphologically and neurochemically heterogeneous. © 1994 Wiley‐Liss, Inc.
Multiple striatal representation in primate substantia nigra
Authors: Parent André , Hazrati Lili‐Naz
Published: January 2005

The pattern of arborization of the striatonigral fibers in the squirrel monkey (Saimiri Sciureus) was studied with Phaseolus vulgaris‐leucoagglutinin (PHA‐L) and biocytin as anterograde tracers. Single, small injections of PHA‐L or biocytin in either the caudate nucleus or the putamen give rise to at least four distinct, nonoverlapping but interconnected fiber plexuses that are distributed throughout the rostrocaudal extent of the substantia nigra pars reticulata (SNr) according to a strikingly precise and constant sequence. These plexuses, which comprise numerous fibers that closely entwine unlabeled dendrites of SNr neurons (woolly fibers), often lie at the base of dopaminergic cell columns of the substantia nigra pars compacta (SNc). Long and varicose fibers emerge dorsally from SNr plexuses and climb along the ventrally oriented denarites of dopaminergic SNc neurons, as visualized with tyrosine hydroxylase immunohistochemistry. These fibers appear to contact en passant both dendrites and cell bodies of dopaminergic neurons belonging to the ventral tier of SNc. Anterograde double‐labeling experiments involving small deposits of PHA‐L and biocytin in adjacent areas of the caudate nucleus and the putamen reveal that neighboring striatonigral cell populations form two distinct sets of terminal plexuses that remain well segregated throughout SNr. Plexuses from the two sources interdigitate in some parts of SNr, but never intermix. Furthermore, the wooly fibers in these plexuses are composed exclusively of either PHA‐L‐or biocytin‐labeled elements; none of them display both types of labeling. These results reveal that the striatonigral projection in primates is highly divergent and that the striatum has multiple representations at nigral levels. They also indicate that striatal information is conveyed to the substantia nigra in a highly ordered fashion through multiple segregated channels. © 1994 Wiley‐Liss, Inc.
Cobalt accumulation in neurons expressing ionotropic excitatory amino acid receptors in young rat spinal cord: Morphology and distribution
Authors: Nagy István , Woolf Clifford J. , Dray Andy , Urbán László
Published: January 2005

Excitatory amino acids (EAA) acting on N‐methyl‐D‐aspartate (NMDA), α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazole propionic acid (AMPA) and kainate receptors play an important role in synaptic transmission in the spinal cord. Quantitative autordiography and physiological experiments suggest that NMDA receptors are localized mainly in lamina II while kainate and AMPA receptors are found on both dorsal and ventral horn neurons. However the cell types expressing EAA receptors and their laminar distribution is not known. We have used a cobalt uptake mentod to study the morphology and distribution of spinal cord neurons expressing AMPA, kainate, or NMDA excitatory amino acid receptors in the lumbar enlargement of the rat spinal cord. The technique involved superfusion of hemisected spinal cords of 14 day‐old rat pups in vitro with excitatory amino acid receptor ligands in the presence of CoCl2. Cobalt has been shown to enter cells through ligand‐gated ion channels in place of Ca2+. Cells which accumulated cobalt ions following activation by ionotropic excitatory amino acid receptors were visualised histochemically. The cobalt uptake generated receptors‐specific labeling of cells, as the NMDA receptor antagonist D‐(−)‐2‐amino‐(5)‐phosphonovaleric acid (D‐AP‐5) (20 μM) blocked the NMDA, but not kainte‐inducced cobalt uptake. The kainate‐induced cobalt labeling was reduced by the non‐selective excitatory amino acid receptor antagonist kynurenic acid (4 mM). Passive opening of the voltage‐gated Ca2+ ‐channel by KCI (50 mM) did not result in colbalt uptake, indicating that cobalt enters cells through ligand‐gated Ca2+ ‐channels.

AMPA (500 μM), kainate (500 μM), or NMDA (500 μM) each induced cobalt uptake with characteristic patterns and distributions of neuronal staining. Overall, kainate induced cobalt uptake in the greatest number of neuronal perikarya while NMDA‐induced uptake was the lowest. AMPA and kainate, but not NMDA superfusion, resulted in cobalt labeling of glial cells.

Our result show that the cobalt uptake technique is a useful way to study the morphology and distribution of cells expressing receptors with ligand‐gated Ca2+ channels. © 1994 Wiley‐Liss, Inc.
Early‐eye morphogenesis in the zebrafish, Brachydanio rerio
Authors: Schmitt Ellen A. , Dowling John E.
Published: January 2005

Early eye morphogenesis in the zebrafish between 12 and 36 hours postfertilization was studied by light‐ and scanning electron microscopy. Overall, early eye morphogenesis in the zebrafish is similar to that vertebrates even thought the optic primordia evaginate from the forebrain as solid masses of cells. After initial evagination 6–7 somite stage [SS], the optic primordia take on a wing‐like shape (8–9 SS). Subsequently, they bend ventrally and rotate slighlty in an anterior direction (10–12 SS). These changes serve to bring the primordia from a horizontal to a more Vertical orientation in relation to the embryonic neural axis. Invagination commences from the center of each primordium (14 SS) and progresses symmetrically out towards the periphery (14–20 SS). The choroid fissure forms by an involution along the anterior region of the eyecup (18–20 SS). By 24 hours postfertilization (pf), the eyecups are well formed. Between 24 and 36 hours pf, the eyes rotate further in relation to the axis of the embryo, and this repositions the choroid fissue to a typical ventral location by 36 hours pf. Because of the two rotations of the eye during early morphogenesis, particularly the later one, the anterior‐posterior orientation of the emerging optic primordium ultimately becomes the ventral‐dorsal axis of the completed eyecup. © 1994 Wiley‐Liss, Inc.
Long‐range horizontal connections between supragranular pyramidal cells in the extrastriate visual cortex of the rat
Authors: Lohmann H. , Rörig B.
Published: January 2005

In this study, we examined the morphological structure and synaptic physiology of long‐range axon projections among supragranular pyramidal cells in the extrastriate visual cortex of the rat. Intra‐and extracellular recordings form layer II/III pyramidal cells were performed in brain slices of area 18a following extracellular stimulation of either the underlying white matter or within layer II/III. Neurons were injected with biocytin for two‐dimensional reconstruction of their axon arborizations.

The conduction velocity of afferent fibers (0.58 m/s) was twice as high as that of intracortical tangential fibers (0.28 m/s). Layer II/III cells were mainly di‐or polysynaptically driven by afferent activation, but predominantly monosynaptically driven from intracortical stimulation sites. The afferent as well as intracortically as well as intracortically evoked postsynaptic potentials showed a very similar time course and shape. From both stimulation sites, suprathreshold action potentials could be elicited. The current threshold for a postsynaptic response and the slope and width of excitatory postsynaptic potentials (EPSPS) increased with the distance of lateral stimulation. The morphological properties of layer II/III pyramidal cell axon collaterals colsely corresponded to the electrophysiological results. Long‐range intraareal axon collaterals could be followed up to 1 mm within the supragranular layers. Their length‐distance distribution showed an inverse relationship to the threshold currents of EPSPs. Pyramidal cells exhibited regularly spaced patches of horizontal axon collaterals with an interpatch distance of about 250 μm.

We concluded that the supragranular horizontal network in the extrastriate visual cortex of the rat is qualitatively very similar to that of cats and monkeys. However, quantitative differences exist in its spatial extent and physiological characteristics. © 1994 Wiley‐Liss, Inc.
Distribution of TAG‐1/Axonin‐1 in fibre tracts and migratory streams of the developing mouse nervous system
Authors: Wolfer David P. , Henehan‐Beatty Anne , Stoeckli Esther T. , Sonderegger Peter , Lipp Hans‐Peter
Published: January 2005

The axonal cell adhesion molecule, TAG‐1/axonin‐1, stimulates axonal growth and supports neurite fasciculation in vitro. Using a polyclonal antiserum raised against chick axonin‐1, which shares 75% of its sequence with TAG‐1 of the rat, we have mapped the distribution of TAG‐1/axonin‐1 throughout the developing nervous system of the mouse.

Although absent from proliferating neuroepithelia and from non‐neuronal cells, immunoreactivity for TAG‐1/axonin‐1 is expressed by stage‐specific subpopulations of differentiating neurons from embryonic day 10 to postnatal day 15. It stains their axons and the surface of their parent somata during the early phases of axogenesis. In agreement with a putative role of TAG‐1/axonin‐1 as an axon‐bound growth substrate, immunoreactivity is found in developing spinal and cranial nerves, in corticothalamic projections, as well as in subsets of fasciculating long projecting tracts of the central nervous system, such as the dorsal funiculi of the spinal cord, the lateral olfactory and optic tracts, the fasciculus retroflexus, and the predorsal bundle. High levels of immunoreactivity characterise the development of the cerebellar molecular layer, the corpus callosum, anterior and hippocampal commissure, and of crossed projections in the spinal cord and at several levels of the brainstem.

Intense immunoreactivity in fine collaterals of cutaneous afferents, including their growth cones that are in contact with the embryonic skin, suggests a role of TAG‐1/axonin‐1 in target recognition. While staining is weak on the somata of radially migrating neurons such as cortical neurons and cerebellar granule cells, strong immunoreactivity is associated with neural somata and processes of the three tangential migrations that form the precerebellar nuclei, indicating a possible involvement of TAG‐1/axonin‐1 in contacts between these neurons and the processes they migrate upon. © 1994 Wiley‐Liss, Inc.
Cholinergic innervation in the human hippocampal formation including the entorhinal cortex
Authors: De Lacalle Sonsoles , Lim Chun , Sobreviela Teresa , Mufson Elliott J. , Hersh Louis B. , Saper Clifford B.
Published: January 2005

The cholinergic innervation of the hippocampal formation is thought to play an important role in memory processes, but its organization in humans has not been described in detail. We studied the cholinergic innervation of the human hippocampal formation by means of immunohistochemistry with polyclonal antisera directed against acetyleholinesterase (AChE), choline acetyltransferase (ChAT), and the low‐affinity (p75) nerve growth factor receptor (NGFR). The density of ChAT‐like immunoreactive (ChAT‐li) fibers differed substantially among the various regions, in general paralleling the pattern of AChE‐li staining. One notable exception was the presence of AChE‐li cell bodies. In contrast, ChAT immunoreactivity was associated only with fibers and terminals. NGFR‐li staining corresponded closely to the ChAT‐li fiber pattern.

ChAT‐li fibers in the CA fields diffusely filled the stratum pyramidale and extended into the stratum oriens and radiatum as well. The highest density was consistently observed in CA4 and CA3 subfields. Staining decreased from CA4 to CA1 and was substantially less dense in the subicular complex. In the entorhinal cortex, the ChAT‐ and NGFR‐li fiber innervation displayed a laminar pattern, most intense over the nests of cells in layer II.

There was a trend towards an age‐related reduction in the density of ChAT‐ and AChE‐li fibers and terminals. Nonetheless, we also found a surprisingly conserved NGFR‐li innervation and the presence of occasional NGFR‐li pyramidal cells, providing evidence of a plastic response in the brains of the elderly patients.© 1994 Wiley‐Liss, Inc.