bluuebunny/crossref_metadata_2025 huggingface dataset:
Sex differences in neuron number in the binocular area of the rat visual cortex
Authors: Reid Silvia N. M. , Juraska Janice M.
Published: January 2005

We have previously shown that the thickness of the binocular area of the primary visual cortex is sexually dimorphic in rats. In the present study, sex differences in the number of neurons in this cortical area were examined in nine littermate pairs of 90‐day‐old Long‐Evans hooded rats. Cytoarchitectonic characteristics were used to define the binocular visual cortex, and its volume was estimated through three‐dimensional reconstruction of serial coronal sections for each hemisphere. Neuronal and glial density as well as neuronal soma size were estimated from semithin sections through a stereological technique, the disector, in the same animals that were used to estimate volume. The volume of the binocular area was 19% greater in males than in females. While there were no sex differences in soma size or in neuronal density, the differences in the volume of the binocular area resulted in significant sex differences (male > female) in the number of neurons overall and in every layer, except layer IV. Glial density was not different between the sexes, but the total number of glial cells was higher in males than in females. These results demonstrate that the binocular visual cortex of the rat is sexually dimorphic in its volume and much of the difference is due to sex differences in the number of neurons and glial cells. © 1992 Wiley‐Liss, Inc.
Transneuronal labeling of cochlear nucleus neurons by HRP‐labeled auditory nerve fibers and olivocochlear branches in mice
Authors: Brown M. C. , Benson T. E.
Published: January 2005

Auditory nerve fibers were labeled by extracellular injections of horseradish peroxidase into the spiral ganglion in mice. The labeled fibers were traced in an anterograde direction through the auditory nerve into the cochlear nucleus. In almost half of the injections, the labeled endings of auditory nerve fibers contacted cochlear nucleus neurons that were also labeled with horseradish peroxidase and were presumably transneuronally labeled. Only darkly labeled endings were associated with transneuronally labeled neurons, but not all darkly labeled endings had targets that were transneuronally labeled. Transneuronal labeling occurred almost exclusively in the ventral cochlear nucleus, often between endbulbs and bushy cells. Both “modified” endbulbs and the larger endbulbs of Held transneuronally labeled the bushy cells that they contacted. At the ultrastructural level, transneuronal labeling was evident as a darkening of ribosomes and the membrane surfaces of mitochondria, endoplasmic reticulum, and the nucleus. Transneuronal labeling occurred rarely in octopus, small, and stellate cells, and in neurons of the dorsal cochlear nucleus. Spiral ganglion injections also label olivocochlear fibers, efferent fibers that pass through the ganglion en route to the hair cells. These fibers give off branches to the cochlear nucleus that were rarely associated with transneuronal labeling. In eight instances, the targets of olivocochlear branches were stellate cells or small cells. We suggest that in our mouse preparation, horseradish peroxidase is effective as a transneuronal marker because the short distance from injection site to the cochlear nucleus results in a high concentration of horseradish peroxidase in the endings of the auditory nerve fibers. © 1992 Wiley‐Liss, Inc.
Projections of leg proprioceptors within the CNS of the fly Phormia in relation to the generalized insect ganglion
Authors: Merritt D. J. , Murphey R. K.
Published: January 2005

We previously reported a modality‐specific layering of leg sensory axons in the CNS of the flies Phormia regina and Drosophila melanogaster with tactile and gustatory axons projecting into a ventral layer and the proprioceptive hair plate axons into an intermediate layer. Here the description is expanded to include the afferent projections of campaniform sensilla on the legs and wings of Phormia. The leg campaniform sensilla produce a number of patterns of projections within an intermediate layer of their ganglion, some of which project intersegmentally into the other thoracic ganglia. One of these patterns is shared by the hair plate sense organs. Selected wing campaniform sensilla were also stained and showed that there is little or no overlap between the projections of leg and wing campaniform sensilla. Similarities with the arrangement of campaniform sensilla and their central processes in Drosophila melanogaster are discussed. To apply the results of this study to a broader range of insects we provide an atlas of the fly CNS and compare it with the locust, which has been the model for much insect neuroanatomy and neurophysiology. © 1992 Wiley‐Liss, Inc.
All indoleamine‐accumulating cells in the rabbit retina contain GABA
Authors: Massey Stephen C. , Mills Stephen L. , Marc Robert E.
Published: January 2005

The indoleamine‐accumulating amacrine cells of the rabbit retina are wide‐field and numerous. They form a dense plexus in sublamina 5 of the inner plexiform layer where they make reciprocal synapses with rod bipolar cells. To provide a quantitative test for the colocalization of serotonin (5‐HT) and γ‐aminobutyric acid (GABA) in the rabbit retina, we designed two parallel double‐label experiments. In the first series, the indoleamine‐accumulating cells were labeled with 5,7‐dihydroxytryptamine (5,7‐DHT), which was subsequently visualized by photooxidation in the presence of diaminobenzidine. This was combined with autoradiography for 3H‐muscimol. In the second and complementary series, 3H‐5‐HT uptake was combined with postembedding GABA immunocytochemistry. These two experiments provided essentially identical results: over 98% of the indoleamine‐accumulating amacrine cells were double‐labeled. This means that, within the limit of experimental error, all the indoleamine‐accumulating amacrine cells are GABAergic. The indoleamine‐accumulating amacrine cells account for 15–20% of a large diverse group of GABA amacrine cells. In addition, the rare type 3 indoleamine‐accumulating cells and fine processes running in the optic fiber layer were double‐labeled. If there is insufficient 5‐HT to support a transmitter role in the rabbit retina, our results suggest that the indoleamine‐accumulating cells may use GABA as a neurotransmitter. Thus, rod bipolar cells, in common with other bipolar cell types, receive extensive negative feedback at GABA‐mediated reciprocal synapses. © 1992 Wiley‐Liss, Inc.
Distribution and characterization of cyclooxygenase immunoreactivity in the ovine brain
Authors: Breder Christopher D. , Smith William L. , Raz Amiram , Masferrer Jamie , Seibert Karen , Needleman Phillip , Saper Clifford B.
Published: January 2005

Evidence from tissue culture studies suggests that glial cells are the principal source of prostaglandins in the brain. We have used immunohistochemistry, Western blot analysis, and enzyme activity assays to localize cyclooxygenase (COX), the enzyme responsible for the conversion of arachidonic acid to prostaglandins, in situ in the normal ovine brain. We observed very few immunoreactive glial cells. In contrast, an extensive distribution of COX‐like immunoreactive (ir) neuronal cell bodies and dendrites and a corresponding pattern of COX enzyme activity were observed. COXir neurons were most abundant in forebrain sites involved in complex, integrative functions and autonomic regulation such as the cerebral cortex, hippocampus, amygdala, bed nucleus of the stria terminalis, substantia innominata, dorsomedial nucleus of the hypothalamus, and tuberomammillary nucleus. Moderate populations were observed in other regions of the central nervous system implicated in sensory afferent processing, including the dorsal column nuclei, spinal trigeminal nucleus, and superior colliculus, and in structures involved in autonomic regulation, such as the nucleus of the solitary tract, parabrachial nucleus, and the periaqueductal gray matter. We did not observe COXir axons or terminal fields, however. Our results suggest that neurons may use prostaglandins as intracellular or perhaps paracrine, but probably not synaptic, mediators in the normal brain. © 1992 Wiley‐Liss, Inc.
Position of growth cones within the retinal nerve fibre layer of fetal ferrets
Authors: Fitzgibbon T. , Reese B. E.
Published: January 2005

Optic axons are added to the retinal nerve fibre layer of fish along its vitreal border in a chronotopic manner. Likewise, the optic tract of all vertebrate species acquires axons preferentially along the superficial surface of the pathway. We have examined the developing retina of fetal ferrets (Mustela putorius furo) aged between embryonic day 27 (E27) and E34 to see whether a similar segregation of growth cones is apparent within the mammalian retinal nerve fibre layer. The distributions of growth cone, “wrist” (thick trailing portion of the growth cone), axonal, and glial profiles were determined from electron micrographs, and expressed as a percentage of neural profiles for several retinal locations.

The retinal nerve fibre layer of fetal ferrets contains radially elongated bundles of fibres composed of axonal, wrist, and growth cone profiles. Glial processes of varying density divide the adjacent bundles, occasionally subdividing them in the plane of the retina, and give rise to endfeet lining the basal lamina and separating the optic axons from the latter. Growth cones within the developing fibre layer represented about 2.4% of profiles at E28, while at later developmental stages (E34), this value fell to about 0.6%. During this period of axonal outgrowth, growth cones were not preferentially segregated toward the vitreal basal lamina or the glial endfeet within the nerve fibre layer. Rather, they were found scattered throughout the axon bundles of the fibre layer. While there were differences in the proportion of immature profiles found within the vitreal half compared to the scleral half of the fibre layer, such that more growth cones and wrists were found vitreally, there was no clear accumulation of them in association with features of the vitreal margin.

The present results show that young and old optic axons course together throughout the depth of the nerve fibre layer. A chronotopic mode of pathway genesis such as seen in the optic fibre layer of fish or in the optic tract of mammals is not present in the nerve fibre layer of ferrets. Differences in growth cone behaviour in the optic fibre layer and tract indicate that the mechanisms governing pathway formation differ along its course. © 1992 Wiley‐Liss, Inc.
Immunocytochemical localization of DARPP‐32, a dopamine and cyclic‐ AMP‐regulated phosphoprotein, in the primate brain
Authors: Ouimet Charles C. , Lamantia Anthony S. , Goldman‐Rakic Patricia , Rakic Pasko , Greengard Paul
Published: January 2005

The localization of DARPP‐32, a dopamine and cAMP‐regulated phosphoprotein, has been studied in monkey brain by immunocytochemistry. This study indicates that DARPP‐32 is enriched in neurons in regions receiving a dense dopamine input from the substantia nigra and ventral tegmental area. Thus, the majority of somata in the anterior olfactory area, nucleus accumbens, caudate nucleus, and putamen are immunoreactive for DARPP‐32. In the caudate nucleus, immunoreactive spines receive asymmetric contacts from unlabeled axon terminals. Immunoreactive somata have diameters of 10–15 μm. In regions known to receive projections from these nuclei, immunoreactivity is confined to small puncta that represent axons and axon terminals. Regions in which immunoreactivity is present in puncta include the ventral pallidum, globus pallidus, and substantia nigra pars reticulata. Dopaminergic neurons themselves are not immunoreactive.

Neurons containing moderate to weak immunoreactivity for DARPP‐32 are observed in portions of the cerebral cortex, particularly in the temporal cortex (layer VI). DARPP‐32‐positive neurons are also present in the cerebellum, in the medial habenula, and in portions of the bed nucleus of the stria terminalis and amygdaloid complex. DARPP‐32 immunoreactivity is also present in astrocytes in the subcortical white matter and in tanycytes in the arcuate nucleus and median eminence.

DARPP‐32 may be an effective marker for dopaminoceptive neurons in which the actions of dopamine on the D‐1 dopamine receptor are mediated through cAMP and its associated protein kinase. © 1992 Wiley‐Liss, Inc.
Tyrosine hydroxylase‐immunoreactive neurons in the nucleus basalis of the common marmoset (Callithrix jacchus)
Authors: Wisniowski L. , Ridley R. M. , Baker H. F. , Fine A.
Published: January 2005

In the course of characterizing the distribution of putative catecholaminergic neurons in the brain of the common marmoset, we encountered a population of such cells in the basal forebrain. Tyrosine hydroxylase‐immunoreactive neurons are abundant within the nucleus basalis magnocellularis throughout its entire rostrocaudal extent, but not in other cholinergic basal forebrain nuclei. Most tyrosine hydroxylase‐immunoreactive cells are large and multipolar. Double staining with antibodies to choline acetyltransferase or nerve growth factor receptor confirmed that these tyrosine hydroxylase‐immunoreactive neurons are cholinergic, and compose at least 40% of the nucleus basalis cholinergic cells. The presence of a catecholamine‐synthesizing enzyme in the neurons that provide the major cholinergic input to the neocortex may have important consequences for cortical function, and may be relevant to the vulnerability of the nucleus basalis in certain neurodegenerative disorders. © 1992 Wiley‐Liss, Inc.
Giant neurons in the caudal pontine reticular formation receive short latency acoustic input: An intracellular recording and HRP‐study in the rat
Authors: Lingenhöhl Kurt , Friauf Eckhard
Published: January 2005

The reticular formation is composed of heterogeneous cell populations with multiple functions. Among these multiple functions is the processing of sensory information in the context of behavior. The purpose of the present study was to identify and characterize neurons in the reticular formation of the rat that receive auditory input. In order to do so, we combined intracellular electrophysiology in vivo with intracellular injection of horseradish peroxidase, enabling us to correlate electrophysiology unequivocally with anatomy at the single cell level.

We found that many neurons in the caudal pontine reticular nucleus (PnC), which we analyzed intracellularly, responded to acoustic stimuli and were excited at short latency (mean EPSP latency: 2.6 ms; mean spike latency: 5.2 ms). This short latency suggests a direct input from the cochlear nucleus, the first central nucleus of the auditory pathway. The morphology revealed that the acoustically driven PnC neurons have very large somata (mean diameter: 44.0 m̈m). They can therefore be referred to as “giant PnC neurons.” Complex dendritic arbors extended from these neurons into the reticular formation and thus formed a large membrane surface for the integration of multimodal inputs. Most of the giant PnC neurons sent their axons caudally into the medial longitudinal fasciculus and can therefore be regarded as reticulospinal neurons.

The results demonstrate that the giant reticulospinal PnC neurons are in a position to transmit acoustic information very quickly to spinal cord neurons and to receive converging input from other parts of the brain. They are thus good candidates for participation in the mediation and modulation of acoustically elicited behaviors, such as the short latency acoustic startle response. © 1992 Wiley‐Liss, Inc.
Neuronal associations in the rat suprachiasmatic nucleus demonstrated by immunoelectron microscopy
Authors: Daikoku Shigeo , Hisano Setsuji , Kagotani Yasuaki
Published: January 2005

The synaptic associations of neurons in the suprachiasmatic nucleus (SCN) of rats were examined by single immunolabeling for somatostatin (SRIH) and arginine vasopressin (AVP), and double immunolabeling for SRIH plus AVP and vasoactive intestinal polypeptide (VIP) plus AVP. Single immunolabeling showed that SRIH neurons, which displayed some somatic and dendritic spines, formed synaptic contacts with immunonegative and positive axon terminals. AVP neurons also formed synaptic contacts with both immunonegative and positive axon terminals. The immunonegative terminals contained small, spherical clear vesicles or flattened clear vesicles. A few immunopositive AVP fibers made synapses with immunonegative somatic or dendritic spines. Double immunolabeling showed synaptic associations between SRIH axons and AVP cell bodies or dendritic processes, and between AVP axons and the somata or dendrites of SRIH neurons. These findings suggest a reciprocal relation between the two types of neurons. Synaptic contacts between AVP neurons and VIP axon terminals were also demonstrated. Previously, we found synapses between SRIH axons and VIP neurons. Thus SRIH neurons appeared to regulate AVP and VIP neurons. On the basis of these findings, two possible oscillation systems of the SCN are proposed. © 1992 Wiley‐Liss, Inc.
Biphasic retinal neurogenesis in the brush‐tailed possum, Trichosurus vulpecula: Further evidence for the mechanisms involved in formation of ganglion cell density gradients
Authors: Harman Alison M. , Sanderson Ken J. , Beazley Lyn D.
Published: January 2005

We investigated cell generation in the retina of the brush‐tailed possum (Trichosurus vulpecula) by using tritiated (3H)‐thymidine labelling of newly generated cells. Animals aged between postnatal day (P) 5 and 85 each received a single injection of 3H‐thymidine. Following autoradiographic processing, maps of labelled cells were constructed from retinal sections. Retinal cell generation takes place in two phases, the first is concluding in the retinal periphery at P53 as the second is seen to commence in midtemporal retina. In the first phase, cells in central retina are generated earlier than those in peripheral regions. In the second phase, cells complete their final division in midtemporal retina first and in the periphery last. Cells generated in the first phase comprise virtually all cells in the ganglion cell layer, amacrine cells, horizontal cells, and cones.

Ganglion cells are produced at a slightly earlier stage than displaced amacrine cells, horizontal cells, or cones. Amacrine cells in the inner nuclear layer are the final cells produced in the first phase. When ganglion cells and amacrine cells are pooled, their combined rate of production matches that of the other cell types. These data indicate that the ratio of displaced amacrine cells: horizontal cells: cones: combined ganglion cells and amacrine cells does not change throughout development. However, the ratio of ganglion cells:amacrines changes steadily as development proceeds to favour amacrine cells. In the second phase, sparse numbers of nonganglion cells in the ganglion cell layer and large numbers of bipolar and Müller cells are produced along with all rods.

The two phases in the possum are similar to those seen in the wallaby, the quokka. However, fewer cells are added in central retina in the possum than in the quokka and cell addition continues for a more extended period in the periphery in the possum. We suggest that this difference in cell addition could account for the development of a more pronounced visual streak of retinal ganglion cells in the possum than in the quokka. A comparison of possum retinal cell generation with that of other marsupials adds support for the “homochrony theory.” © 1992 Wiley‐Liss, Inc.
Enkephalin‐immunoreactive neurons in the parvicellular subdivisions of the paraventricular nucleus project to the external zone of the median eminence
Authors: Merchenthaler Istváan
Published: January 2005

The enkephalin‐immunoreactive neurons that project to the external zone of the median eminence were identified on thin paraffin and thick vibratome sections using a combination of retrograde labeling with peripherally administered Fluoro‐Gold and immunocytochemistry. The vast majority of the enkephalin‐immunoreactive neurons that project to the external zone of the median eminence (ME) reside in the paraventricular nucleus (PVN) of the hypothalamus. Within the PVN, the majority of these hypophysiotropic neurons are located in the medial parvicellular subdivision. while a smaller number can be detected in the anterior and the periventricular subdivisions. Although many enkephalin‐immunoreactive neurons are present in other hypophysiotropic areas of the hypothalamus, such as the medial preoptic area, the anterior periventricular area, and the arcuate nucleus, only a few of these can be retrogradely labeled from the ME. These results provide morphological evidence for the key role of paraventricular enkephalin‐immunoreactive neurons in the regulation of neuroendocrine functions. © 1992 Wiley‐Liss, Inc.
Vasoactive intestinal peptide (VIP) in magnocellular neurons of the hypothalamo‐neurohypophysial system of the mink (Mustela vision) is co‐localized with vasopressin or oxytocin
Authors: Larsen Philip J. , Mikkelsen Jens D.
Published: January 2005

The distribution of vasoactive intestinal peptide (VIP) was analysed in perikarya of the mink hypothalamus with immunohistochemistry and, surprisingly, a large population of magnocellular VIP‐immunoreactive neurons was present in the paraventricular and supraoptic nuclei as well as in accessory hypothalamic nuclei. From perikarya in the paraventricular as well as supraoptic nuclei, a large number of VIP immunoreactive nerve fibers was observed to enter the hypothalamo‐neurohypophysial tract. Within the median eminence, a high density of VIP‐immunoreactive nerve fibers was present in the external and internal zones. Fibers in the external zone of the median eminence were endowed with varicosities and perivascular terminals, while fibers in the internal zone were smooth and without terminal specializations. From the internal zone of the median eminence, fibers coursed via the infundibular stalk to terminate in perivascularly situated terminals in the neurohypophysis. In addition, a substantial number of small VIP‐immunoreactive perikarya was observed within the suprachiasmatic nucleus. These perikarya were immunoreactive to neither vasopressin nor neurophysin. To elucidate the co‐existence of VIP‐immunoreactivity with vasopressin, oxytocin or neurophysin, a sequential double immunoperoxidase procedure to localize antigens with diaminobenzidine and benzidine dihydrochloride as chromagens was performed. From these experiments it was evident that VIP in nearly all magnocellular hypothalamo‐neurohypophysial neurons co‐existed with neurophysin. Based on a semi‐quantitative estimate, half the VIP‐immunoreactive magnocellular perikarya co‐stored vasopressin, while another half co‐stored oxytoxin.

The present study describes the presence of a large population of VIP‐containing neurons in the hypothalamo‐neurohypophysial system of the mink. These findings raise evidence that within the mink, VIP may be involved in neurohypophysial physiology. © 1992 Wiley‐Liss, Inc.
Electron microscopic localization of photoaffinity‐labelled delta opioid receptors in the neostriatum of the rat
Authors: Pasquini F. , Bochet P. , Garbay‐Jaureguiberry C. , Roques B. P. , Rossier J. , Beaudet A.
Published: January 2005

The distribution of delta opioid receptors, selectively labelled in vitro with the photoaffinity probe monoiodo azido‐DTLET ([D‐Thr2, pN3Phe4, Leu5] enkephalyl‐Thr6), was analyzed by light and electron micrsocopic radioautography in sections from rat neostriatum. Preliminary experiments indicated that up to 65% of specific 125I‐azido‐DTLET binding to rat striatal sections was still detectable following prefixation of the brain with 0.5% glutaraldehyde. These experiments also showed that up to 20–30% of the specifically bound radioactivity was covalently linked following ultraviolet irradiation and was thereby retained in tissue during subsequent postfixation and dehydration steps. Accordingly, the topographic distribution of the covalently attached azido‐DTLET molecules was similar to that seen in fresh frozen sections and characteristic of that previously described for delta sites. Light and electron microscopic examination of the label in prefixed, striatal sections irradiated with ultraviolet light revealed that a significant proportion of specifically bound 125I‐azido‐DTLET molecules was intraneuronal. Specifically, 16% of the labelled binding sites were found in dendrites, 12% in perikarya and 4% in axon terminals. These results suggest that an important proportion of delta opioid binding sites labelled in the neostriatum correspond to receptors that are undergoing synthesis, transport and/or recycling. They also imply that a major fraction of delta sites are associated with intrastriatal neurons, as opposed to afferent axons. Approximately 44% of the labelled binding sites were associated with neuronal plasma membranes. Although most of these were found at the level of axodendritic (20%) and dendrodendritic (7%) appositions, comparison of the labelling incidence of these two compartments with their frequency of occurrence in tissue suggested that delta sites are fairly widely dispersed along neuronal plasma membranes. Only a small proportion (smaller than that of mu or kappa sites labelled in the same region) was associated with synaptic specializations. These results support the concept that delta receptors correspond to molecular entities that are distinct from mu and kappa sites and suggest that delta ligands act primarily nonjunctionally on the plasma membrane of striatal neurons. © 1992 Wiley‐Liss, Inc.
Axonal trajectories and distribution of GABAergic spinal neurons in wildtype and mutant zebrafish lacking floor plate cells
Authors: Bernhardt Robert R. , Patel Chetan K. , Wilson Stephen W. , Kuwada John Y.
Published: January 2005

The role of the midline floor plate cells in the neuronal differentiation of the spinal cord was examined by comparing putative GABAergic neurons in wildtype zebrafish embryos with those in cyc‐1 mutant embryos. The mutation produces a pleiotropic recessive lethal phenotype and is severe in rostral brain regions, but its direct effect in the caudal hindbrain and the spinal cord is apparently restricted to the depletion of the midline floor plate cells. In wildtype embryos, an antibody against the neurotransmitter GABA labeled the cell bodies, axons, and growth cones of three classes of previously identified neurons; dorsal longitudinal neurons (DoLA), commissural secondary ascending neurons (CoSA), and ventral longitudinal neurons (VeLD). A novel ventral cell type, Kolmer‐Agduhr (KA) neurons, was also labeled. In the cyc‐1 mutant, abnormalities were observed in some, but not all, of the GABAreactive CoSA, VeLD, and KA axons, while the axonal trajectories of DoLA neurons were not affected. Furthermore, the number of KA cells was reduced in the mutant while the numbers of the other GABAreactive cells were unperturbed. These observations corroborate our earlier hypothesis that the floor plate cells are one of several guidance cues that direct axonal outgrowth near the ventral midline of the spinal cord. They also suggest that the floor plate cells may play a role in the cellular differentiation of the spinal cord of zebrafish embryos. © 1992 Wiley‐Liss, Inc.
Immunofluorescent analysis of creatine kinase in cultured astrocytes by conventional and confocal microscopy: A nuclear localization
Authors: Manos Patricia , Edmond John
Published: January 2005

The subcellular localization of creatine kinase (CK) was examined in primary cultures of astrocytes with immunofluorescent labeling methods and detection by both standard fluorescence microscopy and confocal laser‐scanning microscopy. With conventional microscopy, the pattern of CK staining was uniform throughout the cell cytoplasm and appeared to stain the nuclear region intensely. Staining of CK in the nuclear region co‐localized with the DNA‐specific Hoechst nuclear stain. CK produced a diffuse cytoplasmic staining pattern that was different from the staining pattern produced by the cytoskeletal proteins glial fibrillary acidic protein and tubulin, both of which showed a filamentous cytoskeletal network that excluded the nucleus. To examine the structural details of CK in the nuclear region, serial optical sections were taken through the cell monolayer with a confocal microscope. The cells were immunostained for CK, and the CK‐staining pattern was compared with the staining pattern produced by propidium iodide, which is specific for DNA in RNase‐treated samples and stains total nucleic acid in untreated samples. CK staining was present within the nucleus in each section taken through the monolayer. The nucleolus did not stain for CK. The pattern of CK staining in the nucleus (and cytoplasm) was distinctly different from the staining pattern of either DNA or total nucleic acid. Nuclear CK appeared to have a granular, particulate pattern, which is suggestive of a nucleoplasmic distribution. © 1992 Wiley‐Liss, Inc.
Postnatal development of tyrosine hydroxylase immunoreactive amacrine cells in the rabbit retina: I. Morphological characterization
Authors: Casini Giovanni , Brecha Nicholas C.
Published: January 2005

The present and accompanying (Casini, G., and N.C. Brecha, J. Comp. Neurol. 326:302–313, 1992) papers investigate the postnatal development of tyrosine hydroxylase (TH)‐immunoreactive (IR) amacrine cells in the rabbit retina. This study is focused on a detailed analysis of the patterns of cellular growth and differentiation of TH‐IR amacrine cells, which serve as a model to gain insights into the mechanisms underlying developmental changes associated with the maturation of amacrine cells. Faintly staining TH‐IR neurons are present in the proximal inner nuclear layer of newborn retinas. They are characterized by a large nucleus and usually a single primary process lacking varicosities. At postnatal day (PND) 6, TH‐IR processes display more complex morphological characteristics, including a few varicosities, and second‐ and third‐order ramifications. Growth cones are often seen. At PNDs 10 and 12 (eye opening), TH‐IR cells have general morphological characteristics similar to adult TH‐IR amacrines. They display 2–5 primary processes, which start forming a complex network of fibers in lamina 1 of the inner plexiform layer (IPL). TH‐IR processes are also present in lamina 3 and rarely in lamina 5 of the IPL. Many fibers ending in growth cones are observed. In addition, very rare, thin TH‐IR fibers are present in the outer plexiform layer. At PND 19, TH‐IR fibers form a complex, dense network in lamina 1 of the IPL, and loose networks in laminae 3 and 5. Growth cones are not observed at this age. At PND 26, a few “ring‐like” structures formed by TH‐IR fibers in lamina 1 of the IPL are observed for the first time. In adult retinas, the “ring‐like” structures are more numerous than at PND 26. A second, rare type of TH‐IR cell (“type B”) is encountered in all retinal regions beginning at PND 10. These cells are characterized by weak immunostaining and a small soma size.

The present findings show that a significant differentiation of TH‐IR neurons occurs during the first 10–12 PNDs. Eye opening is an important period for the maturation of TH‐IR amacrines and, more generally, for the maturation of the IPL. © 1992 Wiley‐Liss, Inc.
Morphological response of extending spinal neuritic growth cones to peripheral target tissue
Authors: Somasekhar Thummala , Pollack Emanuel D.
Published: January 2005

Nerve fibers extend from spinal cord explants of larval frog in an enhanced and directed manner when cocultured with limb mesenchyme target tissue. In order to gain a better understanding of the events involved in target directed neurite extension, a detailed examination of the nerve growth cone was undertaken. The growth cones of spinal neurites that had elongated in the presence or absence of target tissue were examined by light and electron microscopy. Scanning electron microscopy revealed that growth cones of cord + limb cultures were elaborate in form with numerous and long filopodia, while those cultured in the absence of the target tissue appeared relatively simple with few, short filopodia. A morphological parallel existed between those growth cones that were cultured without the target and those in cord + limb cultures but which grew from the side of the cord explant away from the mesenchyme tissue. When examined with the transmission electron microscope, growth cones under target influence were organelle‐rich in contrast to target‐deprived growth cones, which lacked the extensive array of vesicles, endoplasmic reticulum, and filaments. When the attachment substratum of polylysine was substituted by collagen, the dramatic differences in growth cones were not realized, although enhanced, oriented growth still occurred in the presence of limb target tissue. It appears that growth cone morphology is a dynamic reflection of the growth effects elicited by a target tissue factor that in turn may be mediated by the nature of the extracellular environment. © 1992 Wiley‐Liss, Inc.
Selective retrograde transport of nipecotic acid, a GABA analog, labels a subpopulation of gerbil olivocochlear neurons
Authors: Ryan Allen F. , Keithley Elizabeth M. , Schwartz Ilsa R. , Wang Zhi‐Xian
Published: January 2005

Perfusion of the gerbil cochlea with micromolar quantities of 3H‐γ‐aminobutyric acid (GABA) results in rapid, selective labeling of 50–60% of the olivocochlear (OC) efferent terminals on afferent dendrites beneath the inner hair cells, and all of the efferent terminals beneath the outer hair cells. In order to identify the neurons from which these GABA‐accumulating terminals originate, the cell bodies were localized by using retrograde transport of 3H‐nipecotic acid, a metabolically inert GABA analog. With survival times of 6–30 hours after cochlear injection, myelinated OC efferent fibers and cell bodies were well labeled, with the greatest number being labeled at 12‐18 hours. All of the labeled neurons belonged to the medial OC system, and no lateral OC neurons were labeled. It is concluded that the GABA‐accumulating endings in the gerbil cochlea arise from medial OC neurons, and therfore that medial OC efferent neurons in this species project to both inner and outer hair cell regions. © 1992 Wiley‐Liss, Inc.
Distribution, of [3H]quinuclidinyl benzilate, [3H]nicotine, and [125I]alpha‐bungarotoxin binding sites in the nucleus tractus solitarii of the cat
Authors: Maley Bruce E. , Seybold Virginia S.
Published: January 2005

The distribution of muscarinic and nicotinic cholinergic binding sites in the cat nucleus tractus solitarii was studied by the technique of in vitro autoradiography. Using the antagonist [3H]quinuclidinyl benzilate, muscarinic binding sites were differentially located in subdivisions of the nucleus tractus solitarii. The majority of muscarinic binding sites were located predominantly in the caudal half of the nucleus, reaching their greatest amounts at the mid levels of the nucleus tractus solitarii. The medial, dorsolateral, intermediate, and interstitial subdivisions contained the highest densities of quinuclidinyl benzilate binding sites. Nicotinic cholinergic binding sites, using [3H]nicotine and [125I]alpha‐bungarotoxin, had unique patterns of distribution. With [3H]nicotine the majority of binding sites were located in rostral levels of the nucleus with very few binding sites present in the caudal half. In contrast, [125I]alpha‐bungarotoxin binding sites were present mainly in subdivisions located in the caudal half of the nucleus, i.e., commissural, ventrolateral, dorsolateral, medial, and intermediate subdivisions, and dropped off precipitously at more rostral levels. The differential distribution of [3H]nicotine and [125I]alpha‐bungarotoxin suggests the two ligands may be labeling different types of nicotinic binding sites in the nucleus tractus solitarii. The unique distribution of muscarinic and nicotinic cholinergic binding sites in the various subdivisions of the nucleus solitarii suggests that muscarinic and nicotine mechanisms may play an active role in the regulation of the diverse autonomic functions at the level of the nucleus tractus solitarii. © 1993 Wiley‐Liss, Inc.
Regional distribution of neural cell adhesion molecule (N‐CAM) and L1 in human and rodent hippocampus
Authors: Miller P. D. , Chung W.‐W. , Lagenaur C. F. , DeKosky S. T.
Published: January 2005

Cell surface adhesion molecules N‐CAM and L 1 are implicated in central nervous system (CNS) cell migration and axon outgrowth in in vitro and in vivo developmental studies. These molecules show a differential distribution during CNS development, thus suggesting that they subserve different roles in process outgrowth and tissue organization. A variety of N‐CAM isoforms are known, and individual N‐CAMs undergo posttranslational modification. Such changes and the potential for generating numerous molecules may mediate development of specific neural cell contacts and circuitry. We evaluated immunohistochemical staining of polyclonal antibodies to L 1 and N‐CAM, as well as monoclonal antibodies directed against embryonic N‐CAM and the 140 and 180 kDa species of N‐CAM in human, rat, and mouse hippocampus. Staining patterns in the three species were qualitatively similar, but staining in the mouse hippocampus was quantitatively greater for some epitopes. A distinctive pattern of staining was found, corresponding to the known anatomy of the structure. Total N‐CAM staining was intense in the hilus and inner molecular layer (ML) of the dentate gyrus with lighter staining in the dentate outer ML. The mossy fiber tract (MFT), comprising axons traveling from the dentate granule cells to CA3 pyramidal cells, was strongly stained by polyclonal antibody to N‐CAM. There was abundant staining of the stratum radiatum (SR) and stratum oriens (SO) of CA1, but stratum lacunosum moleculare (LM) showed very little staining. The monoclonal antibody 12F11, which recognizes the 140 and 180 kDa forms of N‐CAM, intensely stained the MFT, hilus, and inner ML. With 12F11, SO and SR stained uniformly throughout CA1, with much reduced staining in CA2 and CA3. There was little staining in LM. L1 staining was more evenly distributed throughout the hippocampus and dentate, with light hilar and MFT staining, and even staining through the SR and SO. Stratum LM stained intensely for L1, with a narrow clear zone between SR and LM. The ML of the dentate gyrus stained intensely with anti‐L1, with a discrete clear zone separating the inner and outer ML. Embryonic N‐CAM had little staining in CA1 but strong hilar and MFT staining; thus, this “embryonic” determinant continues to be expressed in limited regions in the adult. In contrast to the adult rodent hippocampus, human hippocampus exhibited embryonic N‐CAM in the outer two‐thirds of the ML, but showed very little staining in the hilar region. These distinctive patterns suggest that the distribution of the N‐CAM and L1 molecular species have clear‐cut structural and functional roles in the laminated circuitry of the hippocampus. (c) 1993 Wiley‐Liss, Inc.
Developmental study of the gene expression for α and γ subunits of enolase in the rat brain by in situ hybridization histochemistry
Authors: Watanabe Masahiko , Nagamine Tomoaki , Sakimura Kenji , Takahashi Yasuo , Kondo Hisatake
Published: January 2005

The gene expression for α and γ subunits of enolase, a dimeric enzyme in the glycolytic pathway, was examined in the developing brain of rats by in situ hybridization. The expression for the γ subunit of enolase was first detected in post‐mitotic neurons settled in the mantle zone at E13, and it increased progressively until the adult stage. Expression signals for the α subunit were discerned in two discrete regions showing different developmental changes: the signals in the proliferative ventricular zone were intense at E13 and decreased and eventually disappeared around birth, whereas the signals in the mantle zone persisted until the adult stage. In the adult brain, mRNAs for the α and γ subunits were expressed widely in neurons, resulting in almost similar temporal patterns in the brain except for the cerebellum. Expression levels of the α subunit in adult glial cells were below the detection threshold of the in situ hybridization analysis. These findings suggest that both α and γ enolase subunits participate in energy production in neurons of the mature brain and that marked changes in the subunit composition of enolase occur according to both neuron type and maturation. (c) 1993 Wiley‐Liss, Inc.
Distribution of proneuropeptide Y‐derived peptides in the brain of Rana esculenta and Xenopus laevis
Authors: Lázár Gyula , Maderdrut Jerome L. , Trasti Scott L. , Liposits Zsolt , Tóth Pál , Kozicz Tamás , Merchenthaler István
Published: January 2005

The distribution ofproneuropeptide Y‐containing perikarya and nerve fibers in the brain of Rana esculenta and Xenopus lavis was determined with antisera directed toward neuropeptide Y and the carboxyl terminal flanking peptide.

The distribution of proneuropeptide Y‐like immunoreactivity was similar in both anurans. In the telencephalon, immunoreactive perikarya were found in the olfactory bulb, all subdivisions of the pallium, the septum, pars lateralis of the amygdala, the nucleus accumbens, and the anterior preoptic area. In the diencephalon, labelled perikarya were detected in the ventromedial, ventrolateral and central thalamic nuclei, the magnocellular preoptic nucleus, the suprachiasmatic nucleus, the posterior tuberculum, and the infundibulum. Amacrine‐like cells were stained in the retina. In the pretectal area, posterior thalamic neurons showed intense, Golgi‐like immunostaining. In the mesencephalon, immunoreactive cells were found in the reticular nucleus, the anteroventral tegmental nucleus, the optic tectum, the interpeduncular nucleus, and the torus semicircularis. In the rhombencephalon, labelled perikarya were detected in the secondary visceral nucleus, the central gray, the nucleus of the solitary tract, the dorsal column nuclei, and the spinal nucleus of the trigeminal nerve.

Immunoreactive nerve fibers were observed in all areas of the brain that contained labelled perikarya. The densest accumulations were found in the accessory olfactory bulb, pars lateralis of the amygdala, the ventral habenula, the posterior pituitary, the optic tectum, the interpeduncular nucleus, and the saccular nucleus.

The distribution of proneuropeptide Y‐like immunoreactivity in the anuran brain showed many similarities to the distribution described for the amniote brain. © 1993 Wiley‐Liss, Inc.
Distribution of the neurons containing inositol 1,4,5‐trisphosphate 3‐kinase and its messenger RNA in the developing rat brain
Authors: Mailleux Pierre , Takazawa Kazunaga , Erneux Christophe , Vanderhaeghen Jean‐Jacques
Published: January 2005

As a result of its interaction with a specific receptor, inositol 1,4,5‐trisphosphate (InsP3) mobilizes intracellular calcium. The metabolism of InsP3 is rather complex: InsP3 3‐kinase produces Inositol 1,3,4,5‐tetrakisphosphate (InsP4), a putative second messenger also involved in the intraneuronal calcium homeostasis.

The distribution of the messenger RNA coding for the recently cloned InsP3 3‐kinase was studied in the developing rat brain by using oligonucleotides derived from the rat cDNA sequence and in situ hybridization combined with Northern blot analysis. In addition, the locations of the enzyme were determined by immunohistochemistry in combination with Western blot analysis.

By Northern blot and Western blot analyses on rat brain, the kinase was not detected in the embryo, was first found slightly at birth, and reached adult levels around 2–3 postnatal weeks. These findings were confirmed in the different positive regions by in situ hybridization conducted at the macroscopic level. At the cellular level, the mRNA was found exclusively in the neuronal populations previously demonstrated in the adult. The levels of transcripts per neuron were however higher in the adult than in the neonate brain. The enzyme mRNA could be detected first at postnatal day 0, (birth, PO) in the perikarya of the cerebellar Purkinje cells, followed at P4 by the hippocampal CA1 pyramidal cells and granule cells of the dentate gyrus and finally, at P9, by a majority of the neurons in the cortical layers II‐III and V, especially in the frontal cortex and cingulate cortex; claustrum; caudate, putamen, accumbens, olfactory tubercle and calleja islets; anterior olfactory nucleus; taenia tecta; piriform cortex; dorsolateral septum; bed nucleus stria terminalis; amygdala; hippocampal CA2‐4 sectors and subiculum. By immunohistochemistry, the enzyme was initially found in the periphery of the cell bodies of the neonatal neurons; was progressively enriched in the developing dendritic arborization during the first postnatal weeks where it remained exclusively localized in the adult.

In conclusion, in the developing brain, InsP3 3‐kinase was first detected at birth, and thereafter its concentrations increased to reach adult levels around 2–3 postnatal weeks. At the cellular level, the kinase was exclusively found in the neurons. The small amounts of transcripts found per neuron in the neonate increase during synaptogenesis and the protein became progressively enriched in the developing dendritic arborization, where it is localized in the adult. © 1993 Wiley‐Liss, Inc.
Two visual systems in one brain: Neuropils serving the secondary eyes of the spider Cupiennius salei
Authors: Strausfeld Nicholas J. , Barth Friedrich G.
Published: January 2005

Like other araneans, the wandering spider Cupiennius salei is equipped with one pair of principal eyes and three pairs of secondary eyes. Primary and secondary eyes serve two distinct sets of visual neuropils in the brain. This paper describes cellular organization in neuropils supplied by the secondary eyes, which individually send axons into three laminas resembling their namesakes serving insect superposition eyes. Secondary eye photoreceptors send axons to small‐field projection neurons (L‐cells) which extend from each lamina to supply three separate medullas. Each medulla is a vault of neuropil comprising only a few morphological types of neurons. These can be compared to a subset of retinotopic neurons in the medullas of calliphorid Diptera supplying giant motion‐sensitive neurons in the lobula plate. In Cupiennius, neurons from secondary eye medullas converge at a single target neuropil called the “mushroom body.” This region contains giant output neurons which, like their counterparts in the calliphorid lobula plate, lead to descending pathways that supply thoracic motor circuits. It is suggested that the cellular arrangements serving Cupiennius's secondary eyes are color independent pathways specialized for detecting horizontal motion. The present results do not support the classical view that the spider “mushroom body” is phylogenetically homologous or functionally analogous to its namesake in insects. © 1993 Wiley‐Liss, Inc.