bluuebunny/crossref_metadata_2025 huggingface dataset:
Parvalbumin‐containing gabaergic interneurons in the rat neostriatum
Authors: Cowan Ronald L. , Wilson Charles J. , Emson Piers C. , Heizmann Claus W.
Published: May 2005

Antibodies to the intracellular calcium binding protein parvalbumin were shown to label specifically a distinct group of neostriatal GABAergic neurons. These neurons corresponded to the intensely staining subclass of neostriatal GABAergic neurons that have previously been shown to be a class of aspiny interneurons in the neostriatum. The parvalbumin neurons were aspiny neurons with varicose dendrites distributed throughout the neostriatum in a pattern identical to the intensely stained GABA neurons, and both populations of neurons showed increased numbers in the lateral part of the neostriatum. Double labeling of single neurons with both the GABA and parvalbumin antisera showed that all parvalbumin neurons were positive for GABA, but some GABA labelled neurons were not immunoreactive for parvalbumin. These parvalbumin‐negative GABAergic neurons were morphologically similar to the spiny projection neurons, which are GABAergic but usually are not so heavily stained. The relationship of the GABA‐containing parvalbumin neurons to the striatal mosaic organization was determined by using immunocytochemistry for another calcium binding protein, calbindin D28K, to label the matrix compartment of the striatum. The distribution of parvalbumin‐positive neurons relative to the calbindin‐positive matrix and calbindin‐poor patches was determined by using pairs of adjacent sections stained with the calbindin and parvalbumin antisera. This analysis showed that the somata of the parvalbumin neurons were present in both patch and matrix compartments, and their axons and dendrites crossed the boundaries between compartments. A quantitative analysis of the number of neurons in each compartment revealed that the neurons showed no preferential distribution in either compartment, but instead were present according to the area occupied by that compartment. Approximately 10% of parvalbumin neurons were in the patch compartment, and in these same sections, the patch compartment occupied approximately 10% of the area of those sections. Staining with parvalbumin antibodies can therefore be used to identify a single class of GABAergic aspiny interneurons that is present in both patch and matrix compartments, and whose processes cross the borders between these compartments.
Phosphorylation‐Dependent epitopes on neurofilament proteins and neurofilament densities differ in axons in the corticospinal and primary sensory dorsal column tracts in the rat spinal cord
Authors: Szaro Ben G. , Whitnall Mark H. , Gainer Harold
Published: May 2005

The highest molecular weight neurofilament protein (NF‐H) is multiply phosphorylated at epitopes which can be distinguished by specific monoclonal antibodies on Western blots. Eight characterized antibodies were used in immunocytochemistry to examine the tissue distributions of phosphorylated variants of NF‐H in axons of the adult rat spinal cord. The most striking difference in staining was found between axons in the cuneate tract and those in the neighboring dorsal corticospinal tract. Axons in the cuneate tract reacted intensely with antibodies to phosphorylated epitopes of NF‐H and poorly with antibodies to dephosphorylated epitopes of NF‐H, whereas the reverse was the case for the axons of the dorsal corticospinal tract. These differences showed that systematic variations in the phosphorylation of NF‐H in long‐tract axons in the central nervous system occur as a function of cell type. When the cytoskeletons of these axons were compared by electron microscopy, the neurofilaments of the cuneate fibers were seen to be more abundant and formed a latticework, more compactly organized than the neurofilaments of the dorsal corticospinal axons. By comparison, the dorsal corticospinal axons were relatively richer in microtubules than the cuneate axons. Although the cuneate fiber tract contained many more large (greater than 2.0 (μm2) in cross section) axons than did the dorsal corticospinal tract, these differences in cytoskeletal organization were apparent even when myelinated axons of similar sizes (0.4 μm2 to 2.0 μm2) were compared. In addition, the number of neurofilaments in cuneate axons in the 0.4 to 2.0 (μm2) size range was significantly better correlated with axon size than was the case for this size range of dorsal corticospinal axons. Thus, the differences seen in the organization of the neurofilament latticework and the phosphorylation of NF‐H between axons found in these two tracts both appeared to be correlated with cell type, and were independent of length or caliber of the axons.
Columnar organisation of the inferior olive projection to the posterior lobe of the rat cerebellum
Authors: Apps Richard
Published: May 2005

The organisation of the olivocerebellar projection to lobules VI, VIII, and IX of the posterior lobe of the rat cerebellum was investigated in detail by using the retrograde tracer wheat germ agglutinin‐horseradish peroxidase. Small, well‐defined rostro‐caudally orientated columns of olive cells were found to project to different parasagittal areas in the posterior lobe. A column of olive cells about 2,000 μm in rostro‐caudal length in subnucleus “c” and nucleus β of the caudal medial accessory olive (MAO) provides climbing fibre input to the most medial part of lobules VI and IX, but this projection is displaced laterally in lobule VIII by a projection from a column of cells about 600 μm in rostro‐caudal length in lateral caudal MAO (subnucleus “a”). It is possible that each of these columns of olivary neurones may be further subdivided in the rostro‐caudal axis so that different sections project to different medio‐lateral parts of the cortex. A fine‐grain ‘sublobular’ localisation may also exist: the projection to midline lobule VIc arises at caudal levels of the olive from a band of cells in the transition region between subnucleus “c” and nucleus β, whilst by comparison the projection from caudal levels of the olive to lobules VIa and VIb arises from cells located more ventrally in nucleus β. Evidence is also presented to confirm that the posterior lobe vermis in the rat extends further laterally than in other mammals and that part of it receives a projection from a column of olive cells, 1,000 μm in rostro‐caudal length, in a newly defined region of caudal MAO, termed subnucleus “b1”.
Central distribution of afferent pathways from the uterus of the cat
Authors: Kawatani M. , Takeshige C. , De Groat W. C.
Published: May 2005

Afferent pathways from the uterus of the cat were labeled by injections of horseradish peroxidase (HRP), wheat germ agglutinin‐HRP, or fluorescent dyes into the uterine cervix and uterine horns. Afferent input to the uterus arises from small to medium size neurons (average size 31 × 28 um) in dorsal root ganglia at many levels of the spinal cord (T12‐S3). The segmental origin correlates with the location of the afferent terminal field in the uterus. Eighty‐seven percent of the dorsal root ganglion cells (average, 822 on one side) innervating the cervix are located in sacral ganglia, whereas 97% of the cells innervating the uterine horn (average 479 on one side) are located in lumbar ganglia. Double dye labeling experiments indicate that, a small percentage (average 15%) of lumbar neurons innervating the uterine cervix also innervate the uterine horn. The majority (70‐80%) of afferent input to the uterine cervix passes through the pelvic nerve and the remainder through the pudendal nerve, whereas afferent input to the uterine horn must travel in sympathetic nerves. Ovariectomy (10‐14 days) did not change significantly the number, sizes, or segmental distribution of uterine afferent neurons. In some cats (25%) injections of WGA‐HRP into the uterine cervix labeled neurons (90‐125 per animal) in lamina VII in the S2 spinal segment in the region of the sacral parasympathetic nucleus.

Central projections of uterine horn afferent neurons were not labeled; however, afferent projections from the cervix were detected in the sacral spinal cord. The most prominent labeling was present in Lissauer's tract and in lamina I and outer lamina II on the lateral edge of the dorsal horn. From this region some labeled axons extended through lamina V into the dorsal gray commissure. Very few afferents were labeled on the medial side of the dorsal horn. These results are discussed in regard to the physiological function of uterine afferents and the possible transmitter role of vasoactive intestinal polypeptide, which is present in a large percentage (70%) of cervical afferent neurons.
Catecholaminergic, GABAergic, and hippocamposeptal innervation of gabaergic “somatospiny” neurons in the rat lateral septal area
Authors: Jakab Robert L. , Leranth Csaba
Published: May 2005

This study deals with the neurochemical characterization of the rat lateral septal area (LSA) somatospiny neurons and their innervation by hippocamposeptal, Catecholaminergic, and GABAergic fibers. Electron microscopic single and double immunostaining methods were used to label Catecholaminergic fibers and GABAergic cells and boutons. Axon terminals originating in the hippocampus were labeled by acute anterograde axon degeneration induced by fimbria‐fornix transection 36 hours before sacrifice. Three types of experiments were performed. The convergent Catecholaminergic and hippocamposeptal innervation of LSA somatospiny neurons was studied by combining immunostaining for tyrosine hydroxylase (TH) with fimbria‐fornix transection. GABAergic neurons and their hippocamposeptal afferents were identified and characterized in colchicine pretreated animals immunostained for glutamic acid decarboxylase (GAD) combined with fimbria‐fornix transection. The third experiment aimed at simultaneously visualizing the relationships between Catecholaminergic boutons, hippocamposeptal excitatory amino acid containing axon terminals and GABAergic profiles by double immunostaining for TH (the PAP technique) and GAD (the immunogold method) combined with fimbria‐fornix transection. The results are summarized as follows: (1) The same LSA somatospiny neurons receive synaptic inputs from the hippocampus and TH immunoreactive fibers which form pericellular baskets around these cells. (2) LSA somatospiny neurons are GABAergic and are postsynaptic targets of GABAergic boutons with unknown origin and hippocamposeptal axon terminals. (3) The double immunostaining experiment, finally, provided direct evidence that the same GABAergic somatospiny neurons are postsynaptic targets of both Catecholaminergic and hippocamposeptal afferents. The synaptic interconnections described in this study provide anatomical basis for a better understanding of the action of catecholamines, excitatory amino acids, and GABA on the activity of LSA neurons.
Substance P‐ and opioid‐immunoreactive structures in olfactory centers of the cat: Adult pattern and postnatal development
Authors: Wahle Petra , Sanides‐Kohlrausch Claudia , Meyer Gundela , Lubke Joachim
Published: May 2005

Substance P (SP)‐ir and opioid‐ir structures were studied in the cat main olfactory bulb (MOB), accessory olfactory bulb (AOB), and olfactory peduncle. In the MOB, the opioid‐ir and the majority of the SP‐ir neurons belong to the granule cell type. SP‐ir granule cells reside in the deeper granule cell layer, whereas opioid‐ir granule cells reside in the superficial granule cell layer, internal plexiform, and mitral cell layer. Many granule cells are observed in the external plexiform and glomerular layer. Other granule cells were found in the bulbar/peduncular white matter, the taenia tecta, and the genu of the corpus callosum. A new substance P‐ir cell type was identified in the glomerular layer. This cell type was also identified by using the technique of intracellular injection of Lucifer Yellow. The cell type corresponds neither to the external tufted type nor to the short axon cell types described so far.

The AOB resembles the MOB with respect to large numbers of SP‐ir and opioid‐ir granule cells. In addition, a few opioid‐ir neurons, probably superficial mitral cells, were found in the glomerular layer. The AOB is surrounded by islands of immunoreactive granule cells, which connect to the granule cell layer by extremely long processes.

Opioid‐ir and SP‐ir beaded axons pass through the olfactory peduncle terminating on granule cells, and ascend as far as the glomerular layer. All subdivisions of the anterior olfactory nucleus (AON) contain immunoreactive terminal fields. Afferent fibers and terminal plexuses derive from a population of immunoreactive neurons located predominantly in the region of the septo‐olfactory junction. They have large somata. Their axons form recurrent collaterals, some of which run rostrally in the peduncular white matter. Others ascend caudally towards the septal region. The fibers seem to remain ipsilaterally, since the olfactory limb of the anterior commissure and the commissure proper are devoid of SP‐ir and opioid‐ir fibers.

During development SP and opioid immunoreactivity were found only in differentiated granule cells. The peptides were not detectable in migrating or immature granule cells, as identified in Golgi‐impregnated material. The granule cell population largely develops during postnatal life. The number of opioid‐ir granule cells increases slowly and continuously, reaching the adult level not before the sixth postnatal month. Strikingly, SP‐ir granule cell number increases fast and reaches a transient peak during the second month. Thereafter it declines (40% decrease) to the adult density, which is similar to that of opioid‐ir granule cells.
Macaque accessory optic system: I. Definition of the medial terminal nucleus
Authors: Cooper Howard M. , Baleydier Christine , Magnin Michel
Published: May 2005

The organization of the accessory optic system (AOS) has been studied in the macaque monkey following intravitreal injections of tritiated amino acids in one eye. Retinal projections to the dorsal (DTN) and the lateral (LTN) terminal nuclei are identical to those previously described in other primate species. We observed an additional group of retinorecipient cells of the AOS, located between the cerebral peduncle and the substantia nigra, which we define as the interstitial nucleus of the superior fasciculus, medial fibers. In this report, we focus our attention on the medial terminal nucleus (MTN). Although a ventral division of this nucleus (MTNv) was not observed in the macaque, the retina projects to a group of cells in the midbrain reticular formation (MRF), which we argue to be homologous to the dorsal division of the MTN (MTNd). To provide evidence in support of this homology, the retinal projection to the MTNv and MTNd was also examined in 21 additional species from 11 orders of mammals including carnivores, marsupials, lagomorphs, rodents, bats, insectivores, tree shrews, hyraxes, pholidotess, edentates, and five additional species of primates. Whereas the retina projects to both ventral and dorsal divisions in all species studied, in haplorhine primates only the projection to the MTNd is conserved. The relative topological position of the MTNd in the MRF, dorsomedial to the substantia nigra and ventrolateral to the red nucleus, remains constant throughout the mammals. The trajectory of fiber paths innervating the MTNd is also similar in all species. In addition, the MTNd has comparable afferent and efferent connections with retina, pretectum, and vestibular nuclei in all species thus far studied. These results support the unequivocal conclusion that the MTNd is an unvarying feature of the mammalian AOS.
Macaque accessory optic system: II. Connections with the pretectum
Authors: Baleydier Christine , Magnin Michel , Cooper Howard M.
Published: May 2005

Connections of the accessory optic system (AOS) with the pretectum are described in the macaque monkey. Injections of tritiated amino acids in the pretectum demonstrate a major contralateral projection to the dorsal (DTN), lateral (LTN), and medial (MTN) terminal nuclei of the AOS and a sparser projection to the ipsilateral LTN. Injections of retrograde tracers, Fast Blue (FB), or wheat germ agglutinin horseradish peroxidase (WGA‐HRP) plus nonconjugated horseradish peroxidase (HRP) in the LTN show that the pretectal‐LTN projection originates from two nuclei. The main source of pretectal efferents to the LTN is from the pretectal olivary nucleus (OPN) and is entirely contralateral. This projection, which appears unique to primates, originates from the large multipolar cells of the OPN. In addition to this projection, the nucleus of the optic tract (NOT) projects to the ipsilateral LTN, as in nonprimates. Injection of WGA‐HRP in the pretectum shows a reciprocal predominantely ipsilateral projection from the LTN to the pretectum.

Retinas were observed after injection of FB in the LTN. The retinal ganglion cells projecting to the AOS are mainly distributed near the fovea and in the nasal region of the contralateral eye, suggesting a nasotemporal pattern of decussation.

The demonstration of a direct connection between LTN and OPN forces to a reconsideration of the functional role of the AOS. Previous descriptions of luminance responsive cells in the LTN support a possible participation of this nucleus in the control of the pupillary light reflex.
Multiple representations of body movements in mesial area 6 and the adjacent cingulate cortex: An intracortical microstimulation study in the macaque monkey
Authors: Luppino G. , Matelli M. , Camarda R. M. , Gallese V. , Rizzolatti G.
Published: May 2005

The mesial agranular frontal cortex that lies rostral to area 4 (F1) is formed by two distinct cytoarchitectonic areas: F3, located caudally, and F6, located rostrally. In the present experiments we investigated the organization of F3 and F6 by observing the motor responses evoked by their intracortical electrical microstimulation. Our main purpose was to find out whether the cytoarchitectonic subdivision of the mesial agranular frontal cortex into two areas has a physiological counterpart.

The result showed that F3 (the caudal area) contains a complete motor representation with hindlimb movements located caudally, forelimb movements located centrally, and orofacial movements located rostrally. The great majority of limb movements involved proximal joints. With respect to F1, F3 showed the following functional characteristics: (1) lack of segregation between proximal and distal movements, (2) larger percentage of complex movements, and (3) higher excitability threshold.

Movements were more difficult to elicit from F6 (the rostral area) than from F3. However, by using a longer stimulus train duration (100 ms) 39.3% of tested sites produced body movements. This percentage increased (50.5%) when the electrical stimulation was applied during monkey natural movements instead of when the monkey was still in its chair. Most of the evoked movements concerned the forelimb. More rarely, neck and upper face movements were observed. Unlike F1 and F3 where most movements were fast, slow movements were frequently observed with stimulation of F6. Many of them mimicked natural movements of the animal. Eye movements were evoked from F7 (superior area 6) but not from F6.

An additional motor representation was found in the dorsocaudal part of area 24 (24d). This area is topographically organized with a forelimb representation located caudally and ventrally and a hindlimb representation located rostrally and dorsally. The excitability threshold of area 24d is higher than that of F1 and F3. Evoked movements were occasionally observed also after stimulation of area 24c.

In conclusion, on the mesial cortical wall rostral to F1, there are at least three independent motor representations. On the basis of somatotopic organization and excitability properties, we propose that the term supplementary motor area (SMA‐proper) should be reserved to F3.
Visuotopic organization of corticocortical connections in the visual system of the cat
Authors: Salin P. A. , Girard P. , Kennedy H. , Bullier J.
Published: May 2005

It has recently been demonstrated that, in contrast with the retinogeniculocortical projection, the corticocortical connections in the cat present a high degree of convergence and divergence. This suggests that some corticocortical connections link nonvisuotopically corresponding regions. Using fine‐grain electrophysiological mapping and anatomical tracing, we have set out to test this possibility by placing a small injection of retrograde tracer in area 17 and by comparing the extent of visual field encoded in the region of area 18 containing labeled cells and that represented in the uptake zone.

The results demonstrate that the size of the labeled region on the surface of area 18 is independent of eccentricity and that, despite its anisotrophy, this region of labeling encodes a broadly circular region of visual field that is larger than that encoded in the uptake zone of the tracer in area 17. For example, in the representation of lower visual field, a virtual point in area 17 that encodes a visual field region 4° in diameter receives afferents from a region of area 18 encoding a region 11° wide. Examination of the density of labeled cells in the labeled zone in area 18 reveals that the highest density is observed in a region in visuotopic correspondence with the injection site. However, high labeling density is also occasionally found in patches that do not represent the same visual field region as the injection site. Many receptive fields of neurons recorded in the labeled zone in area 18 only partially overlap or fail to overlap the visual field region encoded by the injection site.

The results also demonstrate that the extent of visual field encoded in the labeled zone in area 18 is the same as that represented in the region of intrinsic labeling in area 17. It is suggested that cortical afferents coming from several cortical areas and converging on a column of cells in area 17 cover the same extent of visual field and that this cortical network constitutes the structural basis for the modulatory regions of the receptive field as well as the synchronization of neurons in different cortical areas.
Light‐dependent plasticity of the synaptic terminals of Mb bipolar cells in goldfish retina
Authors: Yazulla Stephen , Studholme Keith M.
Published: May 2005

We recently described spine‐like protrusions (spinules) from the synaptic terminals of mixed rod‐cone (Mb) bipolar cells of goldfish retina that invaginated about 5% of the presynaptic amacrine cell processes (Yazulla and Studholme, J Comp Neurol 310:11, 1991). In view of reports of a light/dark dependent‐plasticity on the formation of dendritic spinules on goldfish horizontal cells (Raynauld et al., Science 204:1436, 1979; Wagner, J Neurocytol 9:573, 1980), we investigated the possibility that Mb terminal spinules also might show light/dark‐dependent plasticity. Retinas were obtained at noon time from light‐adapted and 3‐hour dark‐adapted goldfish and processed for electron microscopy using conventional histological procedures and by preembedding immunocytochemistry to detect protein kinase C immunoreactivity. Two effects of light adaptation on Mb terminal morphology were observed. First, the surface of Mb terminals was significantly more irregular after dark adaptation than light adaptation. With dark adaptation, Mb terminals appeared «amoeboid,» with numerous cytoplasmic extensions between the presynaptic processes. Second, spinules were sevenfold more frequent after dark adaptation than light adaptation (8% vs. 1.2% of the presynaptic processes were invaginated by spinules). We suggest that the increased frequency of spinules during dark adaptation is related to an enhancement of synaptic transmission from a minor amacrine cell input when the major input from GABAergic amacrine cells is reduced. Also, the irregular surface of dark‐adapted Mb terminals may be related to the reduction of synaptic input during dark adaptation.
Cingulate input to the primary and supplementary motor cortices in the rhesus monkey: Evidence for somatotopy in areas 24c and 23c
Authors: Morecraft Robert J. , van Hoesen Gary W.
Published: May 2005

We examined the distribution of cingulate projections to the somatotopically related parts of the primary (M1) and supplementary (M2) motor cortices of the monkey by using fluorescent dyes. Labeled neurons were found in layers 3, 5 and 6 of areas 24c and 23c and were heaviest following injections placed in M2.

Projections to analogous somatotopic areas in M1 and M2 arose from similar cingulate regions. In area 24c, neurons projecting to the face area of M1 and M2 were located anteriorly, those to the hindlimb were located posteriorly, and neurons projecting to the forelimb area of M1 and M2 were located in between. In area 23c, neurons projecting to the forelimb area of M1 and M2 were located anteriorly and those to the hindlimb area of M1 and M2 were located posteriorly. The face area of M1 and M2 was not found to receive afferents from area 23c. In contrast to this discreteness, cingulate projections to Woolsey's axial representation of M1 were diffuse.

The results support the presence of a separate and somatotopically organized cingulate motor cortex in area 24c. This is predicated on the facts that: (1) small injections of retrograde tracers placed in analogous somatotopic parts of M1 and M2 resulted in similar patterns of labeling within the electrophysiologically “excitable” portion of the anterior cingulate cortex, and (2) this organized topography infers somatotopy. Our data fail to support a somatotopically organized cingulate motor area in area 23c if the criterion of all body parts is demanded. By virtue of its anatomical location and its connectional relation to the spinal cord and isocortical motor fields on the one hand and to the limbic cortex on the other, area 24c may be considered as M3 and provide limbic influences at several levels of motor control. © 1992 Wiley‐Liss, Inc.
Serotoninergic medullary raphespinal projection to the lumbar spinal cord in the rat: A retrograde immunohistochemical study
Authors: Jones S. L. , Light A. R.
Published: May 2005

Classically the raphespinal system has been regarded as a Serotoninergic system; inhibition of spinal nociceptive transmission produced by stimulation of the medullary raphe nuclei is mediated partially by spinal Serotoninergic receptors. However, recent evidence suggests that the raphe nuclei are not homogeneous populations of Serotoninergic cells. The objective of the present study was to re‐examine, in the rat, the Serotoninergic raphespinal projection to the lumbar spinal cord, and to determine the relative contribution of Serotoninergic raphespinal neurons to the total population of raphespinal neurons.

Microinjections of wheat‐germ agglutinin horseradish peroxidase conjugate coupled to colloidal gold into the lumbar spinal cord resulted in the retrograde labeling of 53% and 59% of the serotoninergic neurons in the raphe nuclei and in the para‐raphe zone, respectively Conversely, 47% and 28% of the retrogradely labeled neurons in the raphe and para‐raphe zone, respectively, demonstrated serotonin‐like immunoreactivity. Thus, contrary to previous reports, the present results suggest (1) that only about half of the serotoninergic neurons in the raphe nuclei and in the surrounding para‐raphe zone project to the lumbar spinal cord, and (2) that a large proportion of the neurons in the raphe nuclei (53%) and in the surrounding para‐raphe zone (72%) that project to the lumbar spinal cord are not serotoninergic. © 1992 Wiley‐Liss, Inc.
Survival and integration of bovine chromaffin cells transplanted into rat central nervous system without exogenous trophic factors
Authors: Ortega John D. , Sagen Jacqueline , Pappas George D.
Published: May 2005

Our previous studies have demonstrated that suspension grafts of isolated bovine chromaffin cells survive in the periaqueductal gray (PAG) of rat midbrain for up to 1 year after transplantation. The current study aimed to determine whether this type of graft could survive transplantation into sites other than the PAG that can benefit from chromaffin cell secretory products.

In this study, electron microscope analysis showed that chromaffin cells implanted into the frontal neocortex, striatum, PAG, or the subarachnoid space overlying the spinal cord survived for at least 8 weeks without evidence of degeneration. Intraparenchymally placed grafts appeared relatively avascular and well integrated within the host parenchyma. When blood vessels were found, they were primarily at the host‐graft border and were of the nonfenestrated central nervous system (CNS) type. Numerous synapses were present between the grafted cells and host neuronal processes. In addition, extensive intercommunication, via gap junction‐like structures, was common in the grafts. Morphologic evidence of granular secretion was most commonly seen in striatal grafts. In contrast, subarachnoid grafts displayed minimal interaction with the host spinal tissue and were heavily vascularized with fenestrated capillaries.

Despite morphologic differences between intra‐ and extraparenchymal grafts, this study demonstrates that isolated suspensions of bovine chromaffin cells survive transplantation into CNS sites without exogenous trophic factors and suggests that these cells are potential candidates for neural transplantation into these regions. © 1992 Wiley‐Liss, Inc.
Nerve growth factor receptor‐immunoreactive neurons within the developing human cortex
Authors: Kordower Jeffrey H. , Mufson Elliott J.
Published: May 2005

A monoclonal antibody recognizing the p75 receptor for nerve growth factor (NGF) was used to assess the immunohistochemical expression of NGF receptors within the developing human neo‐, limbic, and paralimbic cortices as well as the hippocampal complex. Between embryonic weeks 16 and 26, a transient population, of neurons located within the upper and lower subplate zones of the neo‐, limbic, and paralimbic cortices expressed the receptor for NGF. In contrast, NGF receptor‐immunoreactive neurons were only observed in the upper subplate zone of the entorhinal cortex at embryonic week 40 (term), a staining pattern not observed in a 5‐year‐old specimen. The expression of NGF receptor‐immunoreactive neurons within the upper subplate zone between embryonic weeks 16 and 40 was characterized by a dense band of immunoreactive neurons and neuropil. These neurons were bipolar with basal and apically directed neurites. NGF receptor‐immunoreactive neurons were also scattered throughout the lower subplate zone and underlying white matter between embryonic weeks 19 and 26. These neurons were multipolar, with less apically directed neurites. NGF receptor‐immunoreactive subplate neurons displayed a topographic distribution with the heaviest concentration found within limbic and paralimbic cortices as well as association neocortex. In contrast, light to moderate NGF receptor‐immunoreactivity was seen in sensory‐motor cortex. Within the hippocampal complex, only a few lightly stained NGF receptor‐immunoreactive neurons were seen within the fimbria, hilar region of the dentate gyrus, and subiculum. The expression of NGF receptor‐immunoreactivity increased within the subplate zone of the pre‐ and parasubiculum culminating in intense entorhinal cortex staining. As the entorhinal cortex merged with the developing inferior temporal association cortex, there was a marked reduction in staining intensity. In contrast to those in the subplate zone, neurons within the germinal zone and cortical plate were NGF receptor immunonegative at all times examined. The presence of NGF receptors in the subplate zone suggests that neurotrophins such as NGF play an important role in the transient viability of these neurons as well as in the guidance of cortical afferent inputs into topographically organized regions of the cerebral cortex. © 1992 Wiley‐Liss, Inc.
Rapid rearrangement of intrinsic tangential connections in the striate cortex of normal and dark‐reared kittens: Lack of exuberance beyond the second postnatal week
Authors: Lübke J. , Albus K.
Published: May 2005

Clustered intrinsic connections in the kitten striate cortex originate from an unclustered, diffusely organized pattern prevailing during the first postnatal week. We have studied the progress of this reorganization and its dependence on visual input by determining the topographies of the intrinsic tangential connections at various postnatal ages by means of axonal tracing methods. Neurons were labeled either by diffusion of the carbocyanin dye DiI in animals ranging in age between 1 day and 30 days, or by retrograde transport of fluorescent microspheres in animals ranging in age between 7 days and 11 months. Quantitative evaluation of retrogradely labeled neurons revealed that during the first postnatal week, intrinsic tangential connections are organized in an unclustered fashion. During the second postnatal week a rapid rearrangement of connections occurs and is complete around postnatal day 11. The main events taking place during the course of this rearrangement are a decrease in the density of tangential connections and an arrangement of them in a clustered fashion. Once the clusters have been formed, the periodicity of the clustered pattern of connections and the size and distinctness of the clusters do not change. This means that the system of clustered tangential connections is adult‐like at the end of the second postnatal week. Dark rearing affects neither the rapid rearrangement of horizontal connections into an adult‐like system of clusters, nor the integrity of this clustered topography until the end of the first postnatal month. The overall distribution and the lateral extent of the tangential connections remain about the same during the postnatal period and are not affected by dark rearing until the end of the first postnatal month. We conclude that the clustered system of tangential connections in the cat's striate cortex is determined innately. © 1992 Wiley‐Liss, Inc.
Müller cells in vascular and avascular retinae: A survey of seven mammals
Authors: Dreher Zofia , Robinson Stephen R. , Distler Claudia
Published: May 2005

Eight monoclonal antibodies were used to label Müller cells in four mammals that have vascular retinae (cats, dogs, humans, and rats) and in three with avascular retinae (echidnas, guinea pigs, and rabbits). Müller cells were found to have a fairly uniform retinal distribution in seven species, with a mean density of 8,000–13,000 cells mm−2. Müller cells in avascular retinae differ from their vascular counterparts in four respects. First, they are shorter than those in vascular retinae. This difference is mainly due to a reduction in the thickness of the outer nuclear layer. Second, the trunks of Müller cells in avascular retinae tend to be thicker, although those in echidnas are an exception to this trend. Third, Müller cell rootlets in avascular retinae follow a more tortuous course than those in vascular retinae, reflecting the fact that photoreceptor nuclei in the two types of retina have different shapes and stacking patterns. Fourth, due to a reduction in the density of photoreceptors in avascular retinae, there are fewer neurones per Müller cell.

Although these four features may enable Müller cells to assist the nutrition of neurones in the inner layers of avascular retinae, they are unlikely to be morphological specializations that have evolved for that purpose. Rather, these features appear to be a direct consequence of the fact that avascular retinae are thinner and have a differently organised outer nuclear layer. These features aside, Müller cells in avascular retinae closely resemble their counterparts in vascular retinae. © 1992 Wiley‐Liss, Inc.
Prenatal formation of the normal mouse corpus callosum: A quantitative study with carbocyanine dyes
Authors: Ozaki Hiroki S. , Wahlsten Douglas
Published: May 2005

Judgment of abnormalities in fetal cortical axon development is more sensitive when a good standard of normal ontogeny is established. The recent availability of postmortem tract tracing methods has greatly improved the observation of axon extension and growth cone morphology in mouse fetuses, which allows much stronger statements about the timing of crucial steps in the formation of the corpus callosum in particular. The first outgrowth and crossing of midplane by axons of the corpus callosum (CC) were examined in 153 normal mouse embryos and fetuses of the hybrid cross B6D2F2/J with carbocyanine dyes applied to brains fixed by perfusion. In most brains a crystal of DiI was inserted into either frontal, parietal, temporal, or occipital cortex in one hemisphere, and a crystal of DiA was placed into a different site in the opposite hemisphere. Although dye diffusion obscured the emergence of axons, linear regression analysis revealed that the first callosal axons emerged from their cortical cells of origin at about 0.4 g body weight or 15.5 days after conception for all four sites. Subsequent axon growth rate was substantially faster for those from frontal cortex (3.2 mm/day) than occipital cortex (1.8 mm/day). Axons from frontal cortex crossed the cerebral midplane first (0.69 g, E16.3), followed by those from parietal (0.74 g), temporal (0.77 g) and occipital cortex (0.92 g, E16.9). Prior to crossing midplane, the pioneering CC axons were usually 200 μm or less in advance of the main bundle, but when they crossed midplane and encountered CC axons growing from homotopic sites in the opposite hemisphere, the pioneering axons were often 0.5 to 2.5 mm ahead of the main bundle. Growth cones were usually large and complex until they had crossed midplane and were thereafter smaller with simple and flat morphologies. The topography of axons in the CC at midplane was organized according to cortical region of origin from the very beginning, when the CC was only a small cap over the hippocampal commissure and dorsal septum. The quantitative results provide a convenient, standard for normal callosal development in mice and should facilitate comparative studies. © 1992 Wiley‐Liss, Inc.
Time of origin of cortico‐collicular projection neurons in the rat visual cortex
Authors: Contamina P. , Boada E.
Published: May 2005

The time of origin and the radial gradient of neurogenesis of cortico‐collicular neurons have been studied in the rat visual area 17. We used a combined technique for the histochemical detection of the retrogradely transported horseradish peroxidase from the superior colliculus and the autoradiographic detection of the [3H]‐thymidine administered during the gestational period. The cortico‐collicular neurons of visual area 17 are located in layer V and are generated on gestational day (GD) 15 (59.78%), GD 16 (36.21%), and GD 17 (4.01%). This finding reveals that, for the cortico‐collicular neuronal population, the birth date is well‐correlated with the laminar position in the adult animal. To see whether the cortico‐collicular neurons located at various radial levels of layer V are generated concurrently, or whether they follow an “insideout” pattern of positioning, we divided layer V into three (upper, middle and lower) sublaminae. Most cortico‐collicular neurons located in the lower two‐thirds of layer V are generated on GD 15 (65%), whereas the neurons located in the upper third of the layer are generated both on GD 15 and GD 16 in almost equal proportions (52.53% and 44.39%, respectively). © 1992 Wiley‐Liss, Inc.
Projections from the lateral nucleus to the basal nucleus of the amygdala: A light and electron microscopic PHA‐L study in the rat
Authors: Stefanacci Lisa , Farb Claudia R. , Pitkänen Asla , Go Gene , Ledoux Joseph E. , Amaral David G.
Published: May 2005

A recent study, carried out in the monkey brain demonstrated a hitherto undescribed projection from the lateral to the basal nucleus of the amygdaloid complex. In the present study, we used light and electron microscopic techniques to determine whether a similar connection exists in the rat brain and to define what type(s) of synaptic contacts are produced by fibers of this projection. Injections of the lectin tracer Phaseolus vulgaris leucoagglutinin (PHA‐L) were placed into several levels of the lateral nucleus and the distribution of fibers in the basal (basolateral) nucleus was evaluated. All lateral nucleus injections resulted in labeled fibers in the basal nucleus, though the density and distribution of labeled fibers depended on the position of the injection site within the lateral nucleus. In general, the heaviest labeling of the basal nucleus was observed after injections at midrostrocaudal levels of the lateral nucleus, especially when the injection was located ventrally. Fibers originating from cells labeled by these injections were observed throughout much of the rostrocaudal extent of the basal nucleus. Rostrally situated injections resulted in substantially lower levels of labeled fibers in the basal nucleus. Injections placed caudally in the lateral nucleus resulted in light to medium levels of labeled fibers in the basal nucleus; the terminal field in these cases did not extend as far rostrally as after the rostral and midlevel injections. Electron microscopic analysis of PHA‐L labeled fibers revealed that they contributed synapses to the basal nucleus. The majority of PHA‐L labeled terminals formed asymmetric contacts on dendritic spines or shafts; a smaller number of PHA‐L labeled terminals formed symmetrical synapses. © 1992 Wiley‐Liss, Inc.
Contractile proteins in the hyaline cells of the chicken cochlea
Authors: Cotanche Douglas A. , Henson Miriam M. , Henson O. W.
Published: May 2005

Hyaline cells are a single layer of epithelial cells found at the inferior edge of the sensory epithelium in the chick cochlea. They rest directly above a specialized region of the basilar membrane at a point where it connects to the fibrocartilaginous skeleton of the cochlear duct. The basal cytoplasm of the hyaline cells contains a bundle of linearly aligned actin filaments that resemble stress fibers in their organization. The actin filaments are anchored in the basal plasma membranes of the cells, which are, in turn, associated with the underlying basal lamina and the extracellular matrix of the basilar membrane. We have used a combination of transmission electron microscopy, differential‐interference‐contrast and epifluorescence light microscopy, and confocal laser scanning microscopy to study the composition and organization of these actin bundles within the hyaline cells. The bundles are arranged into triangular wedges that are oriented radially across the basilar membrane. Each cell contains one or two actin wedges. Adjacent cells can have them aligned in opposite directions so that in a whole‐mount surface preparation they appear as interdigitations. Immunofluorescent staining of the hyaline cells has shown that smooth muscle myosin and α‐actinin are co‐localized to the actin bundles. Smooth muscle myosin is also found throughout the cytoplasm of the cells. The fact that hyaline cells in the chick cochlea are contacted by efferent nerve fibers suggests that these cells may regulate tension on the basilar membrane via the specialized bundle of actin filaments.
Projections from the commissural subnucleus of the nucleus of the solitary tract: An anterograde tracing study in the cat
Authors: Otake Kazuyoshi , Ezure Kazuhisa , Lipski Janusz , Wongshe Richard B.
Published: May 2005

The commissural subnucleus (COM) of the nucleus of the solitary tract (NTS) is known to receive primary afferents from the lungs and other viscera innervated by the vagus nerve, and thus to participate in central autonomic and respiratory control. The aim of the present study was to identify the areas of terminal arborizations of COM neurons in order to examine brainstem sites which may be involved in reflex responses mediated by these neurons. The projections were studied in cats, using biocytin as an anterograde tracer. Labeled fibers and terminal boutons were visualized by horseradish‐peroxidase histochemistry, 2–3 days after microinjection of the tracers into the COM 1–2 mm caudal to the obex. Labeled axons were examined in the brainstem from the rostral pons to the caudal medulla and were found bilaterally, with an ipsilateral predominance, mainly in the following regions: (1) The dorsolateral rostral pons. Terminal boutons were observed in the lateral and medial parabrachial nuclei, Kölliker‐Fuse nucleus, and around the mesencephalic trigeminal tract. This area corresponds to the pontine respiratory group also known as the “pneumotaxic center.” (2) The pontine area dorsolateral to the superior olivary nucleus. This region contains the A5 noradrenergic cell group; (3) Near the ventral surface, below the facial nucleus. This area overlaps with the ‘retrotrapezoid nucleus.’ (4) Respiration‐related areas of the medulla, including the dorsal and ventral respiratory groups, and the Bötzinger complex. (5) The dorsal motor nucleus of the vagus.

These results suggest that the COM is involved in reflex arcs, which have both respiratory functions and autonomic functions. The pathway to the dorsolateral pons, which has been identified in our recent electrophysiological study is likely to play a role in mediating respiratory responses from pulmonary rapidly adapting receptors. Other pathways may represent additional projections from second‐order neurons receiving input from this group of lung receptors, or projections from as yet unidentified neurons that relay information from different afferents terminating in the COM.
Corticotectal projections in the cat: Anterograde transport studies of twenty‐five cortical areas
Authors: Harting John K. , Updyke Bruce V. , van Lieshout David P.
Published: May 2005

Retrograde transport studies have shown that widespread areas of the cerebral cortex project upon the superior colliculus. In order to explore the organization of these extensive projections, the anterograde autoradiographic method has been used to reveal the distribution and pattern of corticotectal projections arising from 25 cortical areas. In the majority of experiments, electrophysiological recording methods were used to characterize the visual representation and cortical area prior to injection of the tracer.

Our findings reveal that seventeen of the 25 cortical areas project upon some portion of the superficial layers (stratum zonale, stratum griseum superficiale, and stratum opticum, SO). These cortical regions include areas 17, 18, 19, 20a, 20b, 21a, 21b, posterior suprasylvian area (PS), ventral lateral suprasylvian area (VLS), posteromedial lateral suprasylvian area (PMLS), anteromedial lateral suprasylvian area (AMLS), anterolateral lateral suprasylvian area (ALLS), posterolateral lateral suprasylvian area (PLLS), dorsolateral lateral suprasyvian area (DLS), periauditory cortex, cingulate cortex, and the visual portion of the anterior ectosylvian sulcus. While some of these corticotectal projections target all superficial laminae and sublaminae, others are more discretely organized in their laminar‐sublaminar distribution. Only the corticotectal projections arising from areas 17 and 18 are exclusively related to the superficial layers. The remaining 15 pathways innervate both the superficial and intermediate and/or deep layers.

The large intermediate gray layer (stratum griseum intermedium; SGI) receives projections from almost every cortical area; only areas 17 and 18 do not project ventral to SO. All corticotectal projections to SGI vary in their sublaminar distribution and in their specific pattern of termination. The majority of these projections are periodic, or patchy, and there are elaborate (double tier, bridges, or streamers) modes of distribution. We have attempted to place these findings into a conceptual framework that emphasizes that the SGI consists of sensory and motor domains, both of which contain a mosaic of connectionally distinct afferent compartments (Illing and Graybiel, '85, Neuroscience 14:455–482; Harting and Van Lieshout, '91, J. Comp. Neurol. 305:543–558).

Corticotectal projections to the layers ventral to SGI, (stratum album intermediale, stratum griseum profundum, and stratum album profundum) arise from thirteen cortical areas. While an organizational plan of these deeper projections is not readily apparent, the distribution of several corticotectal inputs reveals some connectional parcellation.