bluuebunny/crossref_metadata_2025 huggingface dataset:
Postnatal maturation of the dopaminergic innervation of monkey prefrontal and motor cortices: A tyrosine hydroxylase immunohistochemical analysis
Authors: Rosenberg David R. , Lewis David A.
Published: January 2005

The mature functional architecture of the primate prefrontal cortex arises during a protracted period of postnatal development. Although catecholaminergic afferents arrive in the primate cortex quite early during fetal development, several lines of evidence suggest that substantial changes in the dopaminergic innervation of prefrontal cortex may occur during postnatal development. In this study, we used immunocytochemical techniques and antibodies against tyrosine hydroxylase, the rate‐limiting enzyme in catecholamine biosynthesis, to examine the precise time course from birth to adulthood of the maturational changes of tyrosine hydroxylase‐labeled axons in prefrontal cortical areas 9 and 46 and primary motor cortex (area 4) of rhesus monkeys.

In area 9, the densities of tyrosine hydroxylase‐labeled axons and varicosities in the superficial and deep cortical layers remained relatively constant during postnatal development. In contrast, marked developmental changes in innervation density occurred in the middle cortical layers. For example, in deep layer III, the density of tyrosine hydroxylase‐positive varicosities was relatively low and uniform in animals under 1 month of age but then increased by a factor of three in animals 2–3 months of age. The density of labeled varicosities continued to increase, reaching a peak (sixfold greater than in the youngest animals) in aninuds 2–3 years of age before declining to stable adult levels. Similar laminar‐specific patterns of change also occurred in areas 46 and 4, although regional differences were present in the magnitude and precise time course of these developmental changes.

These findings demonstrate that the innervation of monkey frontal cortex by tyrosine hydroxylase‐immunoreactive axons undergoes a protracted, laminar‐specific pattern of change during postnatal development that continues through adolescence and into early adulthood. These developmental refinements may interact with other modifications of cortical circuitry that underlie the functional maturation of these regions. © 1995 Wiley‐Liss, Inc.
Raphe nuclei in three cartilaginous fishes, Hydrolagus colliei, Heterodontus francisci, and Squalus acanthias
Authors: Stuesse Sherry L. , Stuesse David C. , Cruce William L. R.
Published: January 2005

The vertebrate reticular formation, containing over 30 nuclei in mammals, is a core brainstem area with a long evolutionary history. However, not all reticular nuclei are equally old. Nuclei that are widespread among the vertebrate classes are probably ones that evolved early. We describe raphe nuclei in the reticular formation of three cartilaginous fishes that diverged from a common ancestor over 350 million years ago. These fishes are Hydrolagus colliei, a holocephalan, Squalus acanthias, a small‐brained shark, and Heterodontus francisci, a large‐brained shark. Nuclear identification was based on immunohistochemical localization of serotonin and leu‐enkephalin, on brainstem location, and on cytoarchitectonics. Raphe nuclei are clustered in inferior and superior cell groups, but within these groups individual nuclei can be identified: raphe pallidus, raphe obscurus, and raphe magnus in the inferior group and raphe pontis, raphe dorsalis, raphe centralis superior, and raphe linearis in the superior group. Hydrolagus lacked a dorsal raphe, nucleus, but the nucleus was present in the sharks. The majority of immunoreactive cells are found in the superior group, especially in raphe centralis superior, but immunoreactive cells are present from spinal cord to caudal mesencephalon. The distribution and cytoarchitectonics of serotoninergic and enkephalinergic cells are Similar to each other, but raphe nuclei contain fewer enkephalinergic than serotoninergic cells. The cytoarchitectonics of immunoreactive raphe cells in cartilaginous fishes are remarkably Similar to those described for raphe nuclei in mammals; however, the lack of a raphe dorsalis in Hydrolagus indicates that either it evolved later than the other raphe nuclei or it was lost in holocephalan fishes. © 1995 Wiley‐Liss, Inc.
Architecture of individual dendrites from intracellularly labeled thalamocortical projection neurons in the ventral posterolateral and ventral posteromedial nuclei of cat
Authors: Ohara P. T. , Ralston H. J. , Havton L. A.
Published: January 2005

This study provides quantitative descriptions of individual dendrites from electrophysiologically characterized and intracellularly labeled thalamocortical projection (TCP) neurons of the cat ventrobasal complex. One hundred nine dendrites from six ventral posterolateral (VPL) neurons and six ventral posteromedial (VPM) neurons were examined. Measurement of several parameters showed that the individual dendrites were very similar to each other in overall architecture even though they varied greatly in total length and number of dendritic branches. The mean path distance (length from soma to a dendritic tip) was very similar for a dendrites in each group (VPL or VPM) regardless of the number of branches found along the path distance. However, VPL dendrites had a longer mean path distance (VPL = 206 ± 36 μm; n = 51) than VPM dendrites (VPM = 182 ± 29 μm; n = 58; P < 0.001). For all dendrites there was a strong correlation between the stem dendrite diameter and the dendritic length, which allows the estimation of dendritic length from dendrite diameter. Analysis of dendritic scaling shows that branches higher than first order do not follow Rall's ½ power rule, so these neurons cannot be modeled using the equivalent cylinder approximation.

The data add to the qualitative descriptions of cat ventrobasal (VB) TCP dendrites currently available and provide a basis for future comparative, developmental, and plasticity studies. Analysis shows that many parameters of cat VB TCP dendrites fall within a narrow range, suggesting that, regardless of differences in length or superficial appearance, these dendrites share a stable underlying architecture. © 1995 Wiley‐Liss, Inc.
Projections from the anterodorsal and anteroveniral nucleus of the thalamus to the limbic cortex in the rat
Authors: Van Groen Thomas , Wyss J. Michael
Published: January 2005

The present study characterized the projections of the anterodorsal (AD) and the anteroventral (AV) thalamic nuclei to the limbic cortex. Both AD and AV project to the full extent of the retrosplenial granular cortex in a topographic pattern. Neurons in caudal parts of both nuclei project to rostral retrosplenial cortex, and neurons in rostral parts of both nuclei project to caudal retrosplenial cortpx. Within AV, the magnocellular neurons project primarily to the retrosplenial granular a cortex, whereas the parvicellular neurons project mainly to the retrosplenial granular b cortex. AD projections to retrosplenial cortex terminate in very different patternsthan do AV projections: The AD projection terminates with equal density in layers I, III, and IV of the retrosplenial granular cortex, whereas, in contrast, the AV projections terminate very densely in layer Ia and less densely in layer IV. Further, both AD and AV project densely to the postsubicular, presubicular, and parasubicular cortices and lightly to the entorhinal (only the most caudal part) cortex and to the subiculum proper (only the most septal part). Rostral parts of AD project equally to all three subicular cortices, whereas neurons in caudal AD project primarily to the postsubicular cortex. Compared to AD, neurons in AV have a less extensive projection to the subicular cortex, and this projection terminates primarily in the postsubicular and presubicular cortices. Further, the AD projection terminates in layers I, II/III, and V of postsubiculum, whereas the AV projection terminates only in layers I and V. © 1995 Wiley‐Liss, Inc.
Intrinsic circuit organization of the major layers and sublayers of the dorsolateral prefrontal cortex in the rhesus monkey
Authors: Kritzer M. F. , Goldman‐Rakic P. S.
Published: January 2005

Intrinsic connections are likely to play important roles in cognitive information processing to in the prefrontal association cortex. To gain insight into the organization of these circuits, intracortical connections of major laminar and sublaminar divisions were retrogradely labeled in Walker's area 9 and 46 in rhesus monkeys by using cholera toxin (B‐subunit) conjugated to colloidal gold. Microinjections placed within particular cortical laminae produced unique patterns of retrograde labeling. Injections in layers II/III yielded labeling which was laterally widespread (2–7 mm) in supragranular layers, and more narrowly focused, i.e., conforming to a column, in layers IV–VI. In contrast, local circuits associated with layers IV and Vb displayed a regular, cylindrical organization, whereas intrinsic connections of layer Va were laterally extensive (3–5 mm) in layers III and Va. Finally, injections in layer VI gave rise to a narrow column of cell labeling traversing all layers, augmented by laterally extensive labeling (∼ 7 mm) in layer VI. The intrinsic connections of the prefrontal cortex were arrayed within mediolaterally elongated stripes which were often distributed asymmetrically in either the medial or lateral direction. In addition, labsled cells within these mediolaterally oriented fields were frequently grouped within discrete clusters or narrow bands. The intrinsic connections identified in this study differ from the local circuits of corresponding layers reported for primary visual cortex; the unique intrinsic wiring diagram of the prefrontal cortex may be related to its specialized cognitive and mnemonic functions. © 1995 Wiley‐Liss, Inc.
Developing mossy fiber terminal fields in the rat cerebellar cortex may segregate because of Purkinje cell compartmentation and not competition
Authors: Ji Zhongqi , Hawkes Richard
Published: January 2005

Many mossy fiber afferent projections to the rat cerebellar cortex terminate in parasagittal bands. In particular, the anterior lobe ver‐mis of the cerebellum contains alternating bands of mossy fibers from the spinal cord and external cuneate nuclei. The cerebellar cortical efferents, the Purkiwe cells, are also organized in parasagittal bands. These can be revealed by immurkochemical staining for the antigen zebrin II, which is selectively expressed by bands of Purkinie cells. In some cases, the boundaries between mossy fiber terminal fields align with identified transitions between zebrin+/− sets of Purkinie cells, whereas others are located within apparently homogeneous Purkinie cell compartments. Two theories can explain the terminal‐field topography: In one view, mossy fiber terminals segregate during development, because growth cones from different sources compete for common territory. Alternatively, mossy fiber growth cones directly recognize chemically distinct target territories, and activitydependent mechanisms play only minor roles. To explore these issues, two sets of experiments were performed. First, the terminal‐field map of the neonatal spinocerebellar projection was compared to the Purkinie cell compartmentation as revealed by anticalbindin immunocytochemistry. Second, subsets of spinocerebellar mossy fiber afferents were ablated early in postnatal development, and the consequences for the neighboring cuneocerebellar terminal fields were mapped in the adult with reference to the zebrin II+/− compartments. These experiments revealed no evidence that competitive interactions constrain the mossy fiber terminal‐field distribution but, rather, suggest that the organization of the mossy fiber projections follows the oompartmentation of the Purkinie cells. © 1995 Wiley‐Liss, Inc.
Ultrastructural evidence for a paucity of projections from the lumbosacral cord to the pontine micturition center or M‐region in the cat: A new concept for the organization of the micturition reflex with the periaqueductal gray as central relay
Authors: Blok Bertil F. M. , De Weerd Henk , Holstege Gert
Published: January 2005

Information concerning the rate of bladder filling is determined by receptors in the bladder wall and conveyed via afferent fibers in the pelvic nerve to sensory neurons in the lumbosacral cord. It was assumed that this information is relayed from the lumbosacral cord to a medial cell group in the dorsolateral pontine tegmentum, called the M‐region, the pontine micturition center, or Barrington's nucleus. The M‐region, in turn, projects via long descending pathways to the sacral parasympathetic motoneurons. In the present electron microscopic study, it was investigated in cats whether monosynaptic projections from lumbosacral neurons to the M‐region indeed exist. Wheat‐germ agglutinin‐horseradish peroxidase injections were made into the lumbosacral cord. Many retrogradely labeled dendrites and somata were found in the M‐region, but no labeled terminals were found on retrogradely labeled dendrites or somata. Only a small number of anterogradely labeled terminals, which were filled with mainly round vesicles, contacted unlabeled dendrites in the M‐region. In contrast, many more anterogradely labeled terminals, which were filled with mainly round and, to a limited extent, dense core vesicles and with asymmetrical synapses, were found on dendrites in the lateral part of the periaqueductal gray (PAG). Previously (Blok and Holstege [1994] Neurosci. Lett. 166:93–96), it was demonstrated that the lateral part of the PAG contains neurons projecting to the M‐region.

A concept for the central organization of the micturition reflex is presented in which ascending projections from the lumbosacral cord convey information on bladder filling to the PAG. When the bladder contains so much urine that voiding is necessary, the PAG, in turn, triggers the M‐region. The M‐region, however, also receives afferents from the preoptic area, which might be involved in phe final decision to start micturition. © 1995 Wiley‐Liss, Inc.
Thyrotropin‐releasing hormone‐immunoreactive varicosities synapse on rat phrenic motoneurons
Authors: Murphy Susan M. , Pilowsky Paul M. , Sun Qi‐Jian , Llewellyn‐Smith Ida J.
Published: January 2005

The relationship between retrogradely labelled or intracellularly filled phrenic motoneurons and varicosities containing thyrotropin‐releasing hormone immunoreactivity was investigated in rats by light and electron microscopy. Phrenic motoneurons were identified via retrograde tracing from the dirphragm with cholera toxin B subunit, which was followed by immunocytochemistry to visualise retrogradely labelled motoneurons and thyrotropinrpleasing hormone‐immunoreactive nerve fibres in their vicinity. At the light microscopic level, varicose thyrotropin‐releasing hormone‐immunoreactive nerve fibres were distributed sparsely in the phrenic motor nucleus, with some axons surrounding retrogradely labelled motoneurons. In separate intracellular experiments, four phrenic motoneurons identified by antidromic activation from the C5 phrenic nerve root were subsequently filled with Neurobiotin, and nerve fibres that contained thyrotropin‐releasing hormone immunoreactivity were identified by immunocytochemistry. The numbers and locations of thyrotropin‐releasing hormone‐immunoreactive varicosities that were closely apposed to the intracellularly labelled motoneurons were mapped using a camera lucida technique. Close appositions by thyrotropin‐releasing hormone‐immunoreactive varicosities were seen on somata as well as on proximal and distal dendrites. The closely apposed varicosities were usually present in tight clusters, which were formed by single varicose axons. However, the distribution was nonuniform, in that some dendrites did not receive any close appositions. Ultrastructural analysis of random ultrathin sections through retrogradely labelled neurons showed that varicosities with thyrotropin releasing hormone immunoreactivity made 1.8% of all synapses and direct contacts on somata and 2.3% of synapses and contacts with dendrites of the retrogradely labelled phrenic motoneurons. The results of these experiments suggest that thyrotropin‐releasing hormoneimmunoreactive varicosities provide similar numbers of inputs to both the somata and dendrites of phrenic motoheurons. These thyrotropin‐releasing hormone‐containing inputs seen via light and electron microscopy could modulate the excitability of phrenic motoneurons. © 1995 Wiley‐Liss, Inc.
Distribution of acidic fibroblast growth factor mRNA‐expressing neurons in the adult mouse central nervous system
Authors: Kresse Adelheid , Pettersson Ralf , Hökfelt Tomas
Published: January 2005

The distribution of acidic fibroblast growth factor (aFGF) mRNA‐expressing neurons was studied throughout the adult mouse central nervous system (CNS) with in situ hybridization histochemistry using a radiolabelled synthetic oligodeoxynucleotide probe complementary to the mRNA of human aFGF. We report here a widespread distribution of aFGF mRNA in several defined functional systems of the adult mouse brain, whereby the highest levels of aFGF mRNA were found in large somatomotor neurons in the nuclei of the oculomotor, trochlear, abducens, and hypoglossal nerves; in the motoneurons of the ventral spinal cord and the special visceromotor neurons in the motor nucleus of the trigeminal nerve; and in the facial and ambigaus nuclei. Labelled perikarya were also detected in all central structures of the auditory pathway including the level of the inferior colliculus, i.e., the lateral and medial superior nuclei; the trapezoid, cochlear, and lateral lemniscal nuclei; and parts of the anterior colliculus. Furthermore, many aFGF‐positive cell bodies were found in the vestibular system and other structures projecting to the cerebellum, in the deep cerebellar nuclei, in somatosensory structures of the medulla (i.e., in the gracile, cuneate, and external cuneate nuclei), as well as in the spinal nucleus of the trigeminal nerve. The findings that aFGF mRNA is expressed in all components of several well‐defined systems (i.e., in sensory structures) as Well as in central neurons that process sensory information and, finally, in some efferent projections point towards a concept of aFGF expression primarily within certain neuronal circuitries. © 1995 Wiley‐Liss, Inc.
Histological identification of premotor neurons for horizontal saccades in monkey and man by parvalbumin immunostaining
Authors: Horn Anja K. E. , Büttner‐Ennever Jean A. , Suzuki Yasuo , Henn Volker
Published: January 2005

The premotor excitatory and inhibitory burst neurons are essential for horizontal saccades. In the monkey, excitatory burst neurons lie in the ipsilateral paramedian pontine reticular formation, and the inhibitory burst neurons lie more caudally in the contralateral nucleus paragigantocellularis dorsalis. For a neuropathological analysis of degenerative changes in saccadic disorders of patients, the histological identification of the burst neuron areas in man is important. Here, we show that this is possible with parvalbumin immunostaining as a histological marker. First, in monkeys, the premotor burst neurons were backlabeled by injections of wheat germ agglutinin‐horseradish peroxidase or cholera toxin subunit B into the abducens nucleus or tetanus toxin fragment C into the lateral rectus muscle and shown by double labeling to contain parvalbumin. Then, human brainstein sections were immunoreacted for parvalbumin, and, by comparing the resulting staining pattern to that in the monkey, the homologous burst neuron areas were defined in man. In the monkey, excitatory burst neurons were confined to the nucleus reticularis pontis caudalis and did not extend farther rostrally into the nucleus reticularis pontis oralis. All retrogradely labeled cells in both burst neuron areas were parvalbumir. positive, and approximately 70% of the parvalbumin‐positive cells were retrogradely labeled. Both burst neuron areas were highlighted by their parvalbumin taining pattern and could be outlined in man as well. The putative excitatory burst neuron area in man is in the medial part of the nucleus reticularis pontis caudalis (extending 2.5 mm mediolaterally), immediately rostral (250 μm) to the omnipause neurons and extending 2.2 mm rostrally, and the putative inhibitory burst neuron area lies in the medial part of the paragigantocellular nucleus caudal to the abducqns nucleus, extending 1.8 mm caudally. The location of the burst neuron areas, including the burst neurons themselves, via parvalbuinin immunostaining will help in the analysis of clinical cases with slow saccades. © 1995 Wiley‐Liss, Inc.
Central nervous system neurons infected by pseudorabies virus injected into the rat urinary bladder following unilateral transection of the pelvic nerve
Authors: Nadelhaft Irving , Vera Pedro L.
Published: January 2005

Following the transection of one pelvic nerve and both hypogastric nerves, the urinary bladder of male Sprague‐Dawley rats was injected with pseudorabies virus (PRV; Bartha strain). The central stump of the transected pelvic nerve was labelled with fast blue (FB), and rats were maintained for 2, 2. 5, and 3 days following viral infection. Tissue was processed with antisera against PRV and choline acetyltransferase (CAT). In the L6‐S1 spinal cord, neurons in the ipsilateral intermediolateral area (IML) were labelled after 2 days. After 2. 5 days, labelled neurons were also found in the dorsal gray commissure (DGC), the ipsilateral superficial dorsal horn, and the contralateral IML area. After 3 days, many labelled neurons appeared in the superficiai dorsal horns and, bilaterally, in the L6‐S1 dorsal root ganglia. In both IMLs, two groups of PRV‐labelled neurons were found: (1) CAT‐positive preganglionic cells and (2) smaller, CAT‐negative cells located slightly dorsal to the preganglionic neurons. No other doubly stained neurons were found in the spinal cord. Contralateral DRG neurons stained for either PRV or FB or both. Ipsilateral DRG neurons stained only for PRV. PRV‐immunoreactive (IR) neurons appeared in the brainstem only after 3 days. These were located primarily in the pontine micturition centers (equal numbers), the ventral locus coeruleus, and the raphe and lateral reticular areas. © 1995 Wiley‐Liss, Inc.
Effect of sensory deafferentation on immunoreactivity of GABAergic cells and on GABA receptors in the adult cat visual cortex
Authors: Rosier A. M. , Arckens L. , Demeulemeester H. , Orban G. A. , Eysel U. T. , Wu Y.‐J. , Vandesande F.
Published: January 2005

To investigate the effects of sensory deafferentation on the cortical GABAergic circuitry in adult cats, glutamic acid decarboxylase (GAD) and gamma‐aminobutyric acid (GABA) immunoreactivity and GABA receptor binding were studied in the visual cortex of normal cats and compared with cats that had received restricted binocular central lesions of the retina and had survived for 2 weeks postlesion in a normal visual environment.

In the visual cortex of lesioned cats, two changes were observed in the number of GAD‐immunoreactive elements in the regions affected by the retinal lesions: the number of GAD‐positive puncta decreased, whereas that of GAD‐immunoreactive somata increased. In contrast, no detectable changes were measured in the number of GABA‐immunopositive somata or puncta. At the receptor level, we observed no differences in either the laminar distribution or the affinity of cortical GABAA and GABAB receptors labeled with [3H]‐muscimol and [3H]‐baclofen, respectively, in the lesioned versus normal cats.

We present the hypothesis that sensory deafferentation in these adult cats (1) leads to a reduction of cortical GABAergic inhibition in the deafferented region, and (2) that this decreased inhibition may permit changes in efficiency of synapses and (3) that these changes may represent a first stage of events underlying the retinotopic reorganization preceeding the structural changes. © 1995 Wiley‐Liss, Inc.
Human cingulate cortex: Surface features, flat maps, and cytoarchitecture
Authors: Vogt Brent A. , Nimchinsky Esther A. , Vogt Leslie J. , Hof Patrick R.
Published: January 2005

The surface morphology land cytoarchitecture of human cingulate cortex was evaluated in the brains of 27 neurologically intact individuals. Variations in surface features included a single cingulate sulcus (CS) with or without segmentation or double parallel sulci with or without segmentation. The single CS was deeper (9.7 ± 0.81 mm) than in cases with double parallel sulci (7.5 ± 0.48 mm). There were dimples parallel to the CS in anterior cingulate cortex (ACC) and anastomoses between the CS and the superior CS. Flat maps of the medial cortical surface were made in a two‐stage reconstruction process and used to plot areas. The ACC is agranular and has a prominent layer V. Areas 33 and 25 have poor laminar differentiation, and there are three parts of area 24: area 24a adjacent to area 33 and partially within the callosal sulcus has homogeneous layers II and III, area 24b on the gyral surface has the most prominent layer Va of any cingulate area and distinct layers IIIa‐b and IIIc, and area 24c in the ventral bank of the CS has thin layers II–III and no differentiation of layer V. There are four caudal divisions of area 24. Areas 24a′ and 24b′ have a thinner layer Va and layer III is thicker and less dense than in areas 24a and 24b. Area 24c′ is caudal to area 24c and has densely packed, large pyramids throughout layer V. Area 24c'g is caudal to area 24c′ and has the largest layer Vb pyramidal neurons in cingulate cortex. Area 32 is a cingulofrontal transition cortex with large layer IIIc pyramidal neurons and a dysgranular layer IV. Area 32′ is caudal to area 32 and has an indistinct layer IV, larger layer IIIc pyramids, and fewer neurons in layer Va. Posterior cingulate cortex has medial and lateral parts of area 29, a dysgranular area 30, and three divisions of area 23: area 23a has a thin layer IIIc and moderate‐sized pyramids in layer Va, area 23b has large and prominent pyramids in layers IIIc and Va, and area 23c has the thinnest layers V and VI in cingulate cortex. Area 31 is the cinguloparietal transition area in the parasplenial lobules and has very large layer IIIc pyramids. Finally, variations in architecture between cases were assessed in neuron perikarya counts in area 23a. There was an age‐related decrease in neuron density in layer IV (r = −0.63; ages 45–102), but not in other layers. These observations provide structural underpinnings for interpreting functional imaging studies of the human medial surface. © 1995 Wiley‐Liss, Inc.
Development of the chiasm of a marsupial, the quokka wallaby
Authors: Harman Alison M. , Jeffery Glen
Published: January 2005

We have previously shown that the mature optic chiasm of a marsupial is divided morphologically into three regions, two lateral regions in which ipsilaterally projecting axons are confined and a central region containing only contralaterally projecting axons. By contrast, in the chiasms of eutherian (placental) mammals studied to date, there is no tripartite configuration. Ipsilaterally and contralaterally projecting axons from each eye are mixed in the caudal nerve and in each hemichiasm and encounter axons from the opposite eye near the midline of the chiasm. Here, we show that, unlike eutherians, marsupials have astrocytic processes in high concentrations in lateral regions of the nerve and rostral chiasm. Early in development, during the period when optic axons are growing through the chiasm, many intrachiasmatic cells are seen with densities five to eight times higher in lateral than in central chiasmatic regions. Such cells continue to be added to all chiasmatic regions; later in development, considerably more are added centrally, as the chiasm increases in volume. In the mature chiasm, cell densities are similar in all regions. By contrast to the marsupial, cell addition in the chiasm of a placental mammal, the ferret, is almost entirely restricted to later developmental stages, after axons have grown through the chiasm, and there are no obvious spatial variations in the distribution of cells during the period examined. During development, similar to the adult marsupial, ipsilaterally projecting axons do not approach the chiasmatic midline but remain confined laterally. We propose that the cells generated early and seen in high densities in the lateral chiasmatic regions of the marsupial may play a role in guiding retinal axons through this region of pathway selection. These data suggest that there is not a common pattern of developmental mechanisms that control the path of axons through the chiasm of different mammals. © 1995 Wiley‐Liss, Inc.
Nerve growth factor prevents apoptotic cell death in injured central cholinergic neurons
Authors: Wilcox Barbara J. , Applegate Michael D. , Portera‐Cailliau Carlos , Koliatsos Vassilis E.
Published: January 2005

Experimental lesions have been widely used to induce neuronal degeneration and to test the ability of trophic molecules to prevent lesion‐induced alterations, but these studies have not demonstrated unequivocally that afflicted neurons die as a result of these manipulations. The documentation of neuronal death in the above‐described models and the time when it occurs after injury are crucial for the interpretation of trophic effects. In the present study, we combined multiple approaches to investigate the nature of retrograde neuronal changes in holinargic neurons of the medial septal nucleus (MSN) after complete, unilateral transection of the fimbria‐fornix (F‐F). Projection neurons of the MSN were prelabeled with the fluorescent tracer Fluoro‐gold (FG) 1 week prior to lesion. By counting both FG‐labeled and choline acetyltransferase (ChAT)‐immunoreactive neurons in the MSN at multiple time points postaxotomy, we differentiated the phenotypic response to injury from the degenerative process and established a critical time between the third and fourth weeks postaxotomy, during which ∼ 50% of fluorescent perikarya disappear. Working in the previous time window, we identified dying cells by electron microscopy (EM) and terminal transferase‐mediated (TdT) deoxyuridine triphosphate (d‐UTP)‐biotin nick end labeling (TUNEL) and showed that MSN neurons die via apoptosis, beginning at 16 days postaxotomy. An additional group of animals was allowed to survive for 1 month (i.e., 10 days after cell death has been completed); during this period, animals were treated with intraventricular nerve growth factor (NGF). Quantitative analysis of surviving cholinergic perikarya showed that NGF prevented retrograde degeneration of the majority of neurons. In concert, the results of the present study establish that NGF does not merely protect the phenotype but also prevents cell death in lesioned central cholinergic neurons. © 1995 Wiley‐Liss, Inc.
Development of catecholamine systems in the central nervous system of the newt Pleurodeles waltlii as revealed by tyrosine hydroxylase immunohistochemistry
Authors: González Agustín , Marín Oscar , Smeets Wilhelmus J. A. J.
Published: January 2005

The aim of the present study was to extend our knowledge of the development of catecholamine (CA) systems in the class of amphibians to the order of urodeles. In contrast to previous studies of urodeles, the present study with antisera against tyrosine hydroxylase (TH) and dopamine revealed that CA systems are already present at early embryonic stages of the newt, Pleurodeles waltlii. Although the development from fertilized egg to juvenile in the urodele Pleurodeles lasts twice as long as that in the anuran, Xenopus laevis, and shows less dramatic changes in external morphology, the spatiotemporal sequence of appearance of TH‐immunoreactive cell groups is rather similar. An early appearance of TH‐immunoreactive cell bodies occurs in the olfactory bulb, the posterior tubercle, the accompanying cell group of the hypothalamic periventricular organ, the suprachiasmatic nucleus, the locus codruleus, an area immediately ventral to the central canal of the spinal cord, and in the retina.

The presence of CA systems at early embryonic stages of both anurans and urodeles suggests that these systems are already of functional significance early in development. The maturation of CA neuronal structures in the olfactory and retinal circuitries, which takes place during development earlier in amphibians than in mammals, supports that notion. © 1995 Wiley‐Liss, Inc.
Dendritic morphology of CA1 pyramidal neurones from the rat hippocampus: I. Branching patterns
Authors: Bannister N. J. , Larkman A. U.
Published: January 2005

The aim of this study was to provide quantitative descriptions of the dendritic branching patterns of pyramidal neurones in the CA1 region of the rat hippocampus. Thirteen adult cells were filled with biocytin and reconstructed by using the light microscope.

The number of basal trees arising from the soma of each cell ranged from two to eight. There was wide variation in the number of terminal segments per tree. Six cells had single apical trunks, and seven had trunks that bifurcated in stratum radiatum. The number of apical oblique trees ranged from nine to 30, with each tree usually showing a lower degree of branching than basal trees. Basal and oblique trees had similar branching patterns, with the majority of branch points occurring close to the origin of the tree. Both basal and oblique terminal segments were generally much longer than intermediate segments and constituted up to 90% of the combined dendritic length of the tree. The branching pattern of the apical tuft was different, with many relatively long intermediate segments; terminal segments contributed only some 66% of the combined dendritic length of these trees. The mean total combined dendritic length for six adult cells reconstructed and measured completely was 11,900 ± 1,000 μm (standard deviation).

The relative proportions of the different parts of the dendritic system, although not the total dendritic length, were correlated with the location of the soma relative, to the cell body layer. Cells with somata close to the stratum pyramidale/stratum radiatum border had more dendrites terminating in stratum radiatum and fewer in stratum oriens than cells with somata further from it. © 1995 Wiley‐Liss, Inc.
NGF mRNA is expressed by GABAergic but not cholinergic neurons in rat basal forebrain
Authors: Lauterborn Julie C. , Bizon Jennifer L. , Tran Tien M. D. , Gall Christine M.
Published: January 2005

Nerve growth factor (NGF) supports the survival and biosynthetic activities of basal forebrain cholinergic neurons and is expressed by neurons within lateral aspects of this system including the horizontal limb of the diagonal bands and magnocellular preoptic areas. In the present study, colormetric and isotopic in situ hybridization techniques were combined to identify the neurotransmitter phenotype of the NGF‐producing cells in these two areas. Adult rat forebrain tissue was processed for the colocalization of mRNA for NGF with mRNA for either choline acetyltransferase, a cholinergic cell marker, or glutamic acid decarboxylase, a GABAergic cell marker. In both regions, many neurons were single‐labeled for choline acetyltransferase mRNA, but cells containing both choline acetyltransferase and NGF mRNA were not detected. In these fields, virtually all NGF mRNA‐positive neurons contained glutamic acid decarboxylase mRNA. The double‐labeled cells comprised a subpopulation of GABAergic neurons; numerous cells labeled with glutamic acid decarboxylase cRNA alone were codistributed with the double‐labeled neurons. These data demonstrate that in basal forebrain GABAergic neurons are the principal source of locally produced NGF. © 1995 Wiley‐Liss, Inc.
Immunohistological localization of tenascin‐c in the developing and regenerating retinotectal system of two amphibian species
Authors: Becker Thomas , Becker Catherina G. , Niemann Ulrike , Naujoks‐Manteuffel Christiane , Bartsch Udo , Schachner Melitta , Roth Gerhard
Published: January 2005

The expression pattern of the extracellular matrix molecule tenascin‐C was investigated in the retinotectal system of the frog Discoglossus pictus and the salamander Pleurodeles waltl during development and optic nerve regeneration in the adult. In both species, the retina was devoid of tenascin‐C immunoreactivity at all ages studied. During development, tenascin‐C was distributed in a gradient in the optic nerve, with the highest immunoreactivity in the eye near part of the optic nerve. The myelin‐associated glycoprotein was distributed in a gradient with opposite polarity. In Discoglossus, but not Pleurodeles, tenascin‐C was detected in the anterior chiasm. In the tectum of both species, tenascin‐C was observed in deep cellular and fiber layers but not in the layers receiving optic fibers or proliferative zones. The distribution patterns of tenascin‐C were the same during development and in the adult, except for a disappearance of the molecule from the intraocular part of the optic nerve. After lesioning the optic nerve of adult animals, tenascin‐C was strongly reexpressed in the intraocular part of the optic nerve but was only weakly upregulated in the distal optic nerve stump. In contrast, a chondroitin sulfate epitope was strongly upregulated in the distal optic nerve stump.

These observations suggest that during development, tenascin‐C serves as an attenuating barrier for myelinating cells in the optic nerve and contributes to the guidance of growing retinal ganglion cell axons. Due to its sustained expression in the adult, tenascin‐C may have similar functions during regeneration of the lesioned adult retinotectal system. © 1995 Wiley‐Liss, Inc.
Brain‐derived neurotrophic factor mRNA is expressed in the developing taste bud‐bearing tongue papillae of rat
Authors: Nosrat C. A. , Olson L.
Published: January 2005

Brain‐derived neurotrophic factor (BDNF) and nerve growth factor (NGF) are expressed in many areas of the nervous system and its target tissues. Using in situ hybridization we have investigated the possible presence of NGF mRNA and BDNF mRNA in the developing fungiform and circumvallate papillae of the rat tongue. BDNF mRNA is present in the epithelium of the developing fungiform papillae in E15, E16, and E17 rat embryos with peak concentration at E16. It starts to diminish after E17 and is almost absent at E21. There is a specific temporospatial change in the expression of BDNF mRNA in developing circumvallate papillae. It is expressed in the epithelium of the superior and posterior surfaces of the papillae at E15, E16, and E17. Already at E17 the BDNF mRNA labeling has started to decrease in the superior epithelium. At E19 and E21, BDNF mRNA is exclusively present in the epithelium of the inner and outer walls of the trench, surrounding the papilla at the posterior and lateral surfaces where the taste buds are located later in life. BDNF mRNA was also detected in the developing palatal taste buds. NGF mRNA was below detection level in the developing papillae. The highly localized expression of BDNF mRNA in areas where taste buds are to be formed suggests that BDNF may be one crucial factor in the formation of the epithelial innervation prior to taste bud formation. It might also participate in the formation and/or maintenance of the papillary and/or taste bud innervation apparatus. We conclude that the neurotrophin BDNF is expressed in early development of taste bud‐bearing papillae in the rat tongue in a temporally and spatially controlled manner, presumably to act as a target‐derived chemoat tractant for the early nerve fibers. © 1995 Wiley‐Liss, Inc.
Two histological markers reveal a similar photoperiodic difference in the volume of the high vocal center in male European starlings
Authors: Bernard Daniel J. , Ball Gregory F.
Published: January 2005

Most studies of seasonal changes in the avian song control system have used Nissl stains to characterize the nuclei. More recent work has indicated that changes in nucleus volume evident in Nissl‐stained tissue are not always apparent when investigated with other histochemical criteria. In this experiment, we used two different markers (Nissl stain and α2‐adrenergic receptor autoradiography) to characterize changes in the song system of European starlings (Sturnus vulgaris). Fluctuating levels of circulating testosterone (T) appear to be causally related to seasonal changes in the song system. Therefore, we used photoperiod manipulations to place male starlings into different physiological conditions. Photosensitive male starlings were placed on 11L:13D or 16L:8D photoperiods for at least 5 months. Birds on 11L:13D have enlarged gonads and circulating T. In contrast, starlings maintained on 16L:8D initially show marked gonadal growth. However, after about 6–8 weeks the birds are photorefractory (i.e., the gonads are regressed and T falls to undetectable levels). The volume of the high vocal center (HVC) was 44% larger in the 11L:13D than in 16L:8D birds in Nissl‐stained tissue. The density of α2‐adrenergic receptors as determined by in vitro receptor autoradiography with [3H]p‐amino‐lonidine (PAC) is higher in HVC than in the surrounding neostriatum, clearly delineating the boundaries of the nucleus. We reconstructed the volume of HVC using PAC autoradiography on adjacent sections. The results were identical to those from the Nissl‐stained tissue. Thus, two histochemical markers indicate a photoperiodic difference in HVC volume of male starlings. © 1995 Wiley‐Liss, Inc.
Morphology of thalamocortical neurons projecting to the primary somatosensory cortex and their relationship to spinothalamic terminals in the squirrel monkey
Authors: Shi Ting , Apkarian A. Vania
Published: January 2005

This study examined the morphology of thalamocortical neurons projecting to the primary somatosensory cortex (SI; hand region of areas 3a, 3b, 1, and 2) and their relationship to the spinothalamic (STT) terminals in the squirrel monkey. Retrogradely labeled thalamocortical neurons were intracellularly filled with Lucifer yellow (LY), and the STT terminals were anterogradely labeled with biotinylated dextran. Both filled neurons and labeled terminals were differentially visualized in the same field by a dual immunocytochemical staining method. SI‐projecting neurons appeared at the light level to be in contact with STT terminal boutons in the ventroposterior lateral (VPL), ventroposterior inferior (VPI), and centrolateral (CL) nuclei and the posterior complex (PO). The analyses of the neuronal morphology revealed that somatic and dendritic morphologies of SI‐projecting neurons in these thalamic nuclei, as well as in the anterior pulvinlar (Pub), centromedial (CM), and ventrolateral (VL) nuclei, were generally comparable with some exceptions: VPL neurons had the largest soma sizes, the most primary dendrites, and the longest total dendritic length among all neurons studied; VPI neurons had the smallest soma sizes; VPL SI‐projecting neurons were different from those in VPI in their soma sizes, shape factors, and orientations; in VPL the cells projecting to the superficial layers of SI were smaller than those projecting to the deeper layers, but in VPI the two groups of neurons were similar in soma sizes. In general, the SI‐projecting neurons in VPL, VPI, and CL were similar in their dendritic morphologies and branching patterns, and varied from those in Pub, PO, CM, and VL. © 1995 Wiley‐Liss, Inc.
Dopamine receptor mRNA expression patterns by opioid peptide cells in the nucleus accumbens of the rat: A double in situ hybridization study
Authors: Curran Eileen J. , Watson Stanley J.
Published: January 2005

Colocalization of proenkephalin and prodynorphin mRNAs with each other as well as with D1, D2, and D3 dopamine receptor mRNAs was analyzed in the nucleus accumbens of the rat. Distinct combinations were detected in the rostral pole, core, and shell subdivisions of the nucleus accumbens. Proenkephalin and prodynorphin mRNAs were principally localized in separate cells in the core. All detectable prodynor cells in the core expressed D1 mRNA but not D2 mRNA. Conversely, approximately 95% of the proenkephalin‐positive cells in this region expressed D2 mRNA but not D1 mRNA. This pattern was identical to that observed in the caudate putamen. In the rostral pole and the shell, embedded in a background of this “typical” colocalization pattern, clusters of cells expressing a distinct configuration were found. In these clusters, proenkephalin‐positive cells expressed both prodynorphin and D1 mRNAs, but they did not express D2 mRNA.

D3 and prodynorphin mRNAs were colocalized in “limbic” striatal areas, including the ventromedial caudate putamen, the rostral pole, and the medial shell. In contrast, D3 mRNA was not detected in any proenkephalin‐positive cells. Together with the prodynorphin/D1 data, this suggests that a subset of prodynorphin cells expresses both D1 and D3 mRNAs.

It is concluded that (1) clusters of cells that coexpress proenkephalin, prodynorphin, and D1 mRNAs overlap extensively with previously defined cytoarchitectural cell clusters in the nucleus accumbens and (2) a subset of the prodynorphin cells in the ventromedial caudate putamen and the nucleus accumbens contains both D1 and D3 mRNAs. © 1995 Wiley‐Liss, Inc.
Topographical organization in the early postnatal projection: A carbocyanine dye and 3‐D computer reconstruction study in the rat
Authors: Leergaard Trygve B. , Lakke Egbert A. J. F. , Bjaalie Jan G.
Published: January 2005

We have explored basic rules guiding the early development of topographically organized projections, employing the rat corticopontine projection as a model system. Using anterograde in vivo tracing with 1,1′, dioctadecyl‐3,3,3′,3′ ‐tetramethylindocarbocyanine perchiorate (DiI), we studied the distribution of labelled fibers in the pontine nuclei in relation to cortical site of origin during the first postnatal week.

Labelled corticopontine fibers enter the pontine nuclei in distinct, sharply defined zones. The putative terminal fibers typically occupy lamella‐like subspaces. Related to changes in cortical site of origin, we describe mediolateral, internal to external, and caudorostral distribution gradients in the pontine nuclei. Fibers originating in the anterolateral cortex occupy an internal central core, while implantations at increasing distance from the anterolateral cortex produce (1) more externally located lamellae, and (2) a caudal to rostral shift in fiber location. Previous investigations have shown that pontocerebellar neurons migrate into the ventral pons in a temporal sequence (Altman and Bayer [1987] J. Comp. Neurol. 257:529). The earliest arriving neurons occupy the central core and later arriving neurons settle in more externally and rostrally located subspaces. We hypothesize that the earliest arriving corticopon tine fibers grow into the then only available zone of pontocerebellar neurons (central core), attracted by a diffusible chemotropic cue. Later arriving fibers grow into correspondingly later and more externally and rostrally located contingents of pontocerebellar neurons. Thus, we propose that the topographical organization in the early postnatal corticopontine projections determined by simple temporal and spatial gradients operative within source cerebra cortex and target region (pontine nuclei). © 1995 Wiley‐Liss, Inc.