bluuebunny/crossref_metadata_2025 huggingface dataset:
Premotor descending neurons responding selectively to local visual stimuli in flies
Authors: Gronenberg Wulfila , Strausfeld Nicholas J.
Published: January 2005

The responses of dorsal descending neurons suggest great versatility of the visual system in detecting features of the visual world. Although wide‐field motion‐sensitive neurons respond to symmetric visual flow fields presented to both eyes, other neurons are known to respond selectively to asymmetric movement of the visual surround. The present account distinguishes yet a third class of descending neurons (DNs) that is selectively activated by local presentation of moving gratings or small contrasting objects. Excitation of these DNs in response to local motion contrasts with their inhibitory responses to wide‐field motion. The described DNs invade dorsal neuropil of the pro‐ and mesothoracic ganglia where they converge with other morphologically and physiologically characterized descending elements. Axon collaterals of DNs visit thoracic neuropil containing the dendrites of motor neurons supplying indirect neck and flight muscles. The present results are discussed with respect to the organization of small‐field retinotopic outputs from the lobula, and with respect to the parallel projection of many information channels from the brain to the neck and flight motors.
Trigeminocerebellar projections to the posterior lobe in the cat, as studied by anterograde transport of wheat germ agglutinin‐horseradish peroxidase
Authors: Ikeda Michiko , Matsushita Matsuo
Published: January 2005

Cerebellar projections of the nucleus interpolaris and oralis of the spinal trigeminal nucleus were studied in the cat by anterograde transport of wheat germ agglutinin conjugated to horseradish peroxidase (WGA‐HRP). Injections of WGA‐HRP into these nuclei labeled many mossy fiber terminals mainly ipsilaterally in the rostral folium of lobule IX (IXa or IXa + b), the simple lobule, the anterior part (sublobule A) of the paramedian lobule and the posterior part of crus II. Labeled terminals were also seen in the anterior lobe, lobules VI and VII, the anterior part of crus I, and the paraflocculus dorsalis.

Projection fields in the horizontal plane of lobules were reconstructed from a series of transverse sections through each folium of lobule IX, the paramedian lobule, and the posterior part of crus II on the ipsilateral side. In sublobule IXa + b, labeled terminals were distributed in five longitudinal areas extending along the apicobasal axis of the sublobule. These five areas were located in the apical two‐thirds of the ipsilateral half of the sublobule. Labeled terminals were distributed in five longitudinal areas in sublobule A (the rostral part) of the paramedian lobule. In the posterior part of crus II, four aggregations of labeled terminals were present in cross sections through a lobule. They were distributed in the apicobasal extent of the lobules.

The present study indicates that the projection fields of trigeminocerebellar fibers are longitudinally arranged along the apicobasal axis of the cerebellar lobules.
Prenatal development of neurons in the human prefrontal cortex. II. A quantitative Golgi study
Authors: Mrzljak Ladislav , Uylings Harry B. M. , Kostovic Ivica , van Eden Corbert G.
Published: January 2005

The quantitative development of neurons in the human dorsolateral and lateral prefrontal cortex was studied in Golgi‐impregnated tissue from postmortem brains ranging from 13.5 weeks of gestation up to the second postnatal month. Pyramidal neurons in the future layers III and V of the cortical plate, as well as different types of neurons in the transient subplate zone, were studied. The basal dendrites of the future layer III and V pyramidal neurons show a slow increase during the first two‐thirds of the period of gestation. From 27–32 weeks of gestation on, there is a rapid increase in the length of basal dendrites of layer III and V pyramidal neurons, while the number of basal dendrites per pyramidal neuron appears to stabilize at 26/27 weeks of gestation. The increase in total length of basal dendrites per pyramidal neuron is mainly due to an increase in the number of bifurcations and the growth of terminal segments. Throughout the whole period studied, the size of the layer III pyramidal basal dendritic tree was smaller than that of layer V pyramidal neurons. Thus, not until postnatal life do the layer III pyramidal basal dendrites become larger than those of layer V. No statistically significant differences were found for data of the pyramidal neurons between the superior and middle frontal gyri. The dendritic size of subplate neurons, except for the subplate inverted pyramidal neurons, significantly exceeds the size of the basal dendrites of the pyramidal neurons up to the seventh gestational month, which indicates an earlier maturation of these subplate neurons. During the period examined, no clear decrease in the size of the subplate neurons was observed. The present study shows that the dendritic parameters of either subplate or cortical plate pyramidal neurons rapidly increase during the periods of ingrowth of afferent fibers into the subplate zone and cortical plate, respectively. In the Golgi preparations of the prefrontal cortex, the size of the subplate neurons does not show any clearly regressive changes at the end of the prenatal period.
Transmitter diversity in ganglion cells of the guinea pig gallbladder: An immunohistochemical study
Authors: Talmage Erin K. , Pouliot Wendy A. , Cornbrooks Ellen B. , Mawe Gary M.
Published: January 2005

Several neurotransmitters have been reported to exist in the ganglionated plexus of the guinea pig gallbladder. These include substance P, neuropeptide Y (NPY), calcitonin gene‐related peptide, vasoactive intestinal peptide (VIP), acetylcholine, norepinephrine, serotonin and dopamine. To determine which neuropeptides are intrinsic to gallbladder ganglia, we performed immunohistochemistry on colchicine‐treated preparations. In separate, single‐labeled preparations, a majority of neurons contained substance P‐, NPY‐, or somatostatin‐like immunoreactivity. In double‐labeled preparations, a large majority of the neurons that contained substance P‐like immunoreactivity also contained NPY‐like immunoreactivity and somatostatin‐like immunoreactivity. Immunoreactivity for VIP was present in a small percentage of the gallbladder neurons which did not contain substance P‐like immunoreactivity. Additional experiments were done to test for the presence of other compounds, known to exist in the neurons of the gut. Although immunoreactivity was found in control preparations of small intestine, the ganglionated plexus of the gallbladder lacked immunoreactivity for galanin, dynorphin, enkephalin, gastrin‐releasing peptide, or gamma‐aminobutyric acid. We conclude that ganglia of the guinea pig gallbladder contain at least two populations of neurons, based on transmitter phenotype. One of these populations appears to contain substance P, NPY, and somatostatin. Another population, which represents a small contingent of the total population of neurons, contains VIP.
Morphological and neurochemical features of cultured primary skin fibroblasts of fischer 344 rats following striatal implantation
Authors: Kawaja Michael D. , Gage Fred H.
Published: January 2005

In order to assess the feasibility of using primary skin fibroblasts as a donor population for genetic modification and subsequent intracerebral grafting, the present study examines the structural and neurochemical characteristics of intrastriatal grafts of isogeneic primary fibroblasts over a period of 6 months. In culture, primary skin fibroblasts obtained from a female Fischer 344 rat display robust growth, but once confluent these cells exhibit contact inhibition. Following the implantation of cultured primary cells within the striatum of other adult rats from the same inbred strain, isologous grafts stain immunohistochemically for fibronectin at 1 week, and this immunostaining persists up to 6 months. Immunoreactivity for laminin is intense within the grafts from 1 to 8 weeks, but decreases by 6 months. Astrocytes within the striatum respond dramatically to the implantation of primary fibroblasts, such that immunohistochemical staining for glial fibrillary acidic protein increases markedly from 1 to 8 weeks after implantation. Although the intensity of immunostaining for glial fibrillary acidic protein diminishes among striatal astrocytes between 8 weeks and 6 months, the astrocytic border between the grafts and striatal neuropil remains intensely immunoreactive. Capillaries within the grafts stain immunohistochemically for glucose transporter (a facilitated glucose uptake carrier) as early as 3 weeks after implantation. Following intravenous infusions of peroxidase, capillaries within fibroblast grafts do not permit the extravasation of this macromolecule at 8 weeks and 6 months. Thus, capillaries formed within intracerebral grafts of primary skin fibroblasts exhibit a functional impermeable barrier to macromolecules similar to those capillaries of the host striatum. At the ultrastructural level, grafts possess numerous fibroblasts and have an extracellular matrix filled with collagen. Reactive astrocytic processes filled with intermediate filaments are found throughout the grafts. Hypertrophied astrocytes and their processes also appear to form a continuous border between the grafts and striatal neuropil. Grafts of primary fibroblasts also possess an extensive vasculature that is composed of capillaries with nonfenestrated endothelial cells; the occurrence of reactive astrocytic processes closely associated with or enveloping capillaries is variable. These results provide direct morphological and neurochemical evidence for the long‐term survival of isologous fibroblasts after implantation within the rat striatum. From these data, we propose that isologous skin fibroblasts can be considered as donor candidates for successful intracerebral grafting following gene transfer.
Visual factors in sound localization in mammals
Authors: Heffner Rickye S. , Heffner Henry E.
Published: January 2005

The ability of mammals to localize sound varies widely among species. During the past decade, evidence has accumulated that this variation cannot be accounted for simply on the basis of the availability of the physical cues for locus. Evidence is presented that a major factor in sound localization is the need to direct the field of best vision to a sound source for further scrutiny. Thus, species with broad fields of best vision (such as visual streaks) require less accurate information regarding the location of a sound source than do species with very narrow fields of best vision (such as foveae). To support this suggestion, data are reported for the width of the field of best vision in the form of retinal ganglion cell isodensity contours for thirteen species of mammals. The possible contribution of other factors including binocular fields, visual acuity, and the degree to which a species is predatory in lifestyle, is also examined.
Organizational and morphological features of cat sacrocaudal motoneurons
Authors: Ritz Louis A. , Bailey Steven M. , Murray Constance R. , Sparkes Mary L.
Published: January 2005

We have investigated the organizational and morphological features of motoneurons from cat sacrocaudal spinal cord, the portion of the neuraxis that innervates the tail. This information is pertinent for development of a new model of spinal cord injury. An understanding of sacrocaudal circuitry is essential for physiological and behavioral assessment of the effects of sacrocaudal lesions.

Observations from Nissl‐stained sections corroborated Rexed's cytoarchitectural scheme. Putative motoneurons were located within two regions of the ventral horn: the ventromedial nucleus (lamina IX) and the nucleus commissuralis. To map motoneuron pools, choleratoxin‐horseradish peroxidase conjugate was injected into each dorsal tail muscle. The dorsomedial muscle was innervated by ipsilateral nucleus commissuralis motoneurons. The dorsolateral and intertransversarius muscles were innervated by ipsilateral lamina IX and nucleus commissuralis motoneurons. Cell bodies of retrogradely labeled sacrocaudal motoneurons ranged from 22 to 82 μm in diameter; the unimodal distributions peaked between 45 and 50 μm.

Dendritic trees of motoneurons, revealed by retrograde labeling or by intracellular injection with horseradish peroxidase, were extensive. Five to eight primary dendrites originated from the cell body. Dendritic branches extended throughout the ipsilateral ventral gray matter, with processes spreading into the surrounding white matter and the base of the dorsal horn. Dendrites from motoneurons with their soma in the lateral portion of lamina IX formed a longitudinal plexus at the gray/white border. Medial dendrites from motoneurons in the nucleus commissuralis formed bundles in the ventral gray commissure and spread throughout the contralateral ventral horn. It is speculated that contralateral dendrites subserve synchronized co‐contraction of medial muscles from both sides of the tail.
Regional distribution of DARPP‐32 (Dopamine‐ 0Mr = 32,000) mRNA in mouse brain
Authors: Perez Ruth G. , Lewis Robert M.
Published: January 2005

DARPP‐32 (dopamine‐ and adenosine 3′,5′‐mbnophosphate‐regulated phosphoprotein of Mr = 32,000) mRNA distribution was examined in adult mouse central nervous system by in situ hybridization. In general, DARPP‐32 mRNA was found in regions of brain where cells express the dopamine D1 subtype receptor. Cells of the olfactory tubercle, caudate‐putamen, and nucleus accumbens had the highest levels of DARPP‐32 mRNA, as did choroid plexus and Purkinje cells. Relatively high levels were found in medial habenula and lateral piriform cortex. Moderate levels were seen in cerebral cortex layer VI, medial piriform cortex, lateral entorhinal cortex, tenia tecta, anterior olfactory nucleus, and lateral bed nucleus of the stria terminalis. Low levels were observed in hippocampus, cerebral cortex layers II and III, olfactory bulb, and the nucleus of the lateral olfactory tract. DARPP‐32 mRNA levels in the amygdaloid nuclei varied greatly.
The nigral projection to predorsal bundle cells in the superior colliculus of the rat
Authors: Bickford M. E. , Hall W. C.
Published: January 2005

Predorsal bundle cells give rise to the major efferent pathway from the superior colliculus to the premotor centers of the brainstem and spinal cord responsible for initiating orienting movements. The activity of predorsal bundle cells is profoundly influenced by an inhibitory pathway from substantia nigra pars reticulata that uses gamma aminobutyric acid (GABA) as a neurotransmitter. The present study examines the morphological basis for this influence of substantia nigra on predorsal bundle cells in the rat. In the first experiments, the laminar distributions of the nigrotectal tract terminals and the predorsal bundle cells were compared. The predorsal bundle cells were labeled by the retrograde axonal transport of horseradish peroxidase from either the decussation of the predorsal bundle or the cervical spinal cord, while the terminations of the pathway from substantia nigra pars reticulata were labeled by anterograde axonal transport from the substantia nigra. Either horseradish peroxidase, wheat germ agglutinin conjugated to horseradish peroxidase, or Phaseolus vulgaris leucoagglutinin were used as anterograde tracers. The results showed that the distributions of both the predorsal bundle cells and the nigrotectal terminals are restricted almost entirely to the intermediate grey layer and that they overlap extensively. Predorsal bundle cells varied in size. Within the areas of maximum overlap, the majority, regardless of size, was closely apposed by nigrotectal terminals. In a second series of experiments, the synaptic contacts between nigrotectal terminals and the tectospinal component of the predorsal bundle were examined in tissue in which both the terminals and the tectospinal cells were labeled for electron microscopy. In the final experiments, the distribution and fine structure of the nigrotectal terminals were compared to those of terminals that had been labeled immunocytochemically with an antibody to glutamic acid decarboxylase, the synthesizing enzyme for GABA. The results showed that nigrotectal terminals contain large numbers of mitochondria and pleomorphic vesicles, and form synaptic contacts with the somas and proximal dendrites of tectospinal cells. These synapses have modest postsynaptic densities. In both their distribution and fine structure, these terminations resemble the glutamic acid decarboxylase immunoreactive terminals that contact tectospinal cells. Taken together, these results support the view that the nigrotectal tract is an important source of GABAergic input to most, if not all, predorsal bundle cells. © 1992 Wiley‐Liss, Inc.
Dendritic organization of class II (inter)neurons in the dorsal lateral geniculate nucleus of the tree shrew: Observations based on Golgi, immunocytochemical, and biocytin methods
Authors: Conley Michael , Wilson Kristin F.
Published: January 2005

In this report we examine the dendritic organization of putative interneurons (class II cells) in different layers of the dorsal lateral geniculate nucleus of the tree shrew. The results show that there is considerable morphological diversity within this class, but that two broad groups can be identified: neurons whose dendrites remain within a layer or its adjacent interlaminar zones (intralaminar class II cells); and neurons whose dendrites cross into an adjacent layer(s) (interlaminar class II cells). The majority of class II cells in every layer have intralaminar dendrites, some of which are oriented along a particular axis, and others that are organized radially. The paired layers (1 and 2, 4 and 5) contain a particular group of intralaminar class II cells that have radially organized dendrites and elaborate claw‐like appendages. The dendrites of interlaminar class II cells are organized along lines of projection and extend across as many as four layers. These cells often reside close to or within the interlaminar zones. Overall, the organization of class II cells seems to follow a pattern similar to the class I (relay) cells identified previously. Most have intralaminar dendrites, which presumably underlie the fidelity of signals transmitted from the retina to a particular layer. However, there are also a number of other cells whose processes cross laminar borders, presumably to affect integrative functions within the nucleus. © 1992 Wiley‐Liss, Inc.
5B4‐CAM expression parallels neurite outgrowth and synaptogenesis in the developing rat brain
Authors: Alcantara Adriana A. , Pfenninger Karl H. , Greenough William T.
Published: January 2005

In order to study whether 5B4‐CAM expression parallels neurite outgrowth and synaptogenesis, a monoclonal antibody, 5B4, was used, which recognizes both fetal (185–250 kD) and adult (140 kD, 180 kD) forms of the neural cell adhesion molecule (N—CAM), to identify and localize the antigen in rat tissue during developmental ages P1 through P31 and in adults between P60 and 2 years of age. A ubiquitous pattern of intense immunolabelling was detected during the earliest stages of development. 5B4‐CAM expression paralleled process outgrowth and the early stages of synaptogenesis in the cerebral cortex, hippocampal formation, and cerebellum. In the adult, immunoreactivity was generally less intense, but the cerebral cortex and hippocampal and cerebellar molecular layers, all areas implicated in learning—associated plasticity, retained substantial immunoreactivity. The inner one–third of the dentate gyrus molecular layer, an area implicated in axonal sprouting and reactive synaptogenesis, was particularly intensely labelled. Evidence from this work suggests that 5B4‐CAM expression may be useful in monitoring neurite outgrowth and the early stages of synapse formation during development and possibly axonal sprouting and reactive synaptogenesis in the adult. © 1992 Wiley‐Liss, Inc.
A crustacean neuronal cytoskeletal protein with characteristics of neurofilaments and microtubule‐associated proteins
Authors: Weaver Debora J. , Viancour Terry A.
Published: January 2005

The purpose of this study was to characterize further a unique protein that is a component of the cytoskeleton of crayfish neurons. This protein, referred to as P600, is unique because it is unusually large (Mr > 600 kD), and because it has characteristics in common with both mammalian microtubule‐associated proteins and neurofilaments. Immunohistochemical techniques have shown that P600 colocalizes with microtubules and is a component of the fibrous side‐arms that extend from microtubules (Weaver and Viancour, Brain Res. 544:49, 1991). We have developed a method for obtaining purified P600 by using gel nitration techniques. When viewed by negative staining electron microscopy, P600 obtained by that method produced 11 nm‐wide beaded filaments. The number of filaments was strictly related to the P600 concentration in a column fraction. A small amount of P600 consistently copurified with taxol‐stabilized microtubules. The proportion copurifying with microtubules was increased by using apyrase to deplete ATP, or by using a nonhydrolyzable ATP analogue to compete with ATP. Immunogold labeling localized P600 near the ends of a subset of the fibrous side‐arms extending from endogenous axonal microtubules. Several polyclonal antibodies against mammalian microtubule‐associated proteins were tested for P600 labeling on immunoblots, and positive labeling was obtained with an antiserum directed against a region of microtubule‐associated protein 1B that has microtubule binding activity. Epitope homology between P600, mammalian microtubule‐associated protein 1B, and the mammalian mid‐molecular weight neurofilament subunit is discussed in the context of possible evolutionary relationships among these cytoskeletal proteins.
Development and birthdates of vasoactive intestinal peptide immunoreactive neurons in the chick proventriculus
Authors: Epstein Miles L. , Saffrey M. Jill , Poulsen Kristian T.
Published: January 2005

To gain insight into the mechanisms regulating expression of transmitter phenotypes in the enteric nervous system, we have studied the development and birthdate of vasoactive intestinal peptide immunoreactive (VIP‐IR) myenteric neurons in the chicken proventriculus (secretory portion of the avian stomach) by a combination of immunocytochemistry and radioautography. The appearance and numbers of VIP‐IR neurons in whole mounts of the myenteric plexus from chick embryos and chickens were examined. We found that VIP‐IR neurons first appeared at embryonic day (E) 5.5–6.5 in the distal part of the proventriculus. At E7.5, VIP‐IR neurons were found singly, in pairs, or in small groups, which together with unlabeled cells formed primitive myenteric ganglia. VIP‐IR fibers were found within the developing fiber tracts which connected the ganglia. The number of VIP‐IR neurons was found to be maximum in the E15.5 embryo and to decline to 68% of maximum in the 4 week old chicken.

Birthdate studies were performed by application of either single pulses or cumulative doses of [3H]‐thymidine to embryos between E3 and E14. Whole mounts of the myenteric plexus from the proventriculus of these embryos were immunostained for VIP at E10 or E17. The whole mounts were subsequently sectioned and processed for radioautography. We found that VIP‐IR myenteric neurons were born between E3 and E10 with a peak at E7. Most cells underwent terminal division between E5 and E9. These data will be useful in determining the time and conditions when cells make decisions about transmitter phenotypes. © 1992 Wiley‐Liss, Inc.
A dopaminergic projection to the rat mammillary nuclei demonstrated by retrograde transport of wheat germ agglutinin–horseradish peroxidase and tyrosine hydroxylase immunohistochemistry
Authors: Gonzalo‐Ruiz A. , Alonso A. , Sanz J. M. , Llinás R. R.
Published: January 2005

The presence and distribution of dopaminergic neurons and terminals in the hypothalamus of the rat were studied by tyrosine hydroxylase (TH) immunohistochemistry.

Strongly labelled TH‐immunoreactive neurons were seen in the dorsomedial hypothalamic nucleus, periventricular region, zona incerta, arcuate nucleus, and supramammillary nucleus. A few TH‐positive neurons were also identified in the dorsal and ventral premammillary nucleus, as well as the lateral hypothalamic area. TH‐immunoreactive fibres and terminals were unevenly distributed in the mammillary nuclei; small, weakly labelled terminals were scattered in the medial mammillary nucleus, while large, strongly labelled, varicose terminals were densely concentrated in the internal part of the lateral mammillary nucleus. A few dorsoventrally oriented TH‐positive axon bundles were also identified in the lateral mammillary nucleus.

A dopaminergic projection to the mammillary nuclei from the supramammillary nucleus and lateral hypothalamic area was identified by double labelling with retrograde transport of wheat germ agglutinin‐horseradish peroxidase and TH‐immunohistochemistry. The lateral mammillary nucleus receives a weak dopaminergic projection from the medial, and stronger projections from the lateral, caudal supramammillary nucleus. The double‐labelled neurons in the lateral supramammillary nucleus appear to encapsulate the caudal end of the mammillary nuclei. The medial mammillary nucleus receives a very light dopaminergic projection from the caudal lateral hypothalamic area.

These results suggest that the supramammillary nucleus is the principal source of the dopaminergic input to the mammillary nuclei, establishing a local TH‐pathway in the mammillary complex. The supramammillary cell groups are able to modulate the limbic system through its dopaminergic input to the mammillary nuclei as well as through its extensive dopaminergic projection to the lateral septal nucleus. © 1992 Wiley‐Liss, Inc.
Pathway from the zona incerta to the superior colliculus in the rat
Authors: Kim Uhnoh , Gregory E. , Hall William C.
Published: January 2005

In order to test the proposal that the zona incerta contributes to the generation of orienting movements, we examined the synaptic relationships between the incertotectal pathway and the cells of origin of the predorsal bundle. The predorsal bundle cells give rise to the major premotor pathway from the superior colliculus to the brainstem gaze centers. First, cytochrome oxidase histochemistry, gamma‐aminobutyric acid (GABA), and glutamic acid decarboxylase (GAD) immunocytochemistry, and the axonal transport of markers were used to define the borders of a ventral subdivision of the zona incerta. This subdivision projects topographically to the same sublamina of the intermediate grey layer of the superior colliculus that contains the vast majority of the predorsal bundle cells. Experiments in which incertotectal cells were labeled by both retrograde transport and immunocytochemistry showed that this pathway is GABAergic. Retrograde and anterograde experiments also showed that this pathway is reciprocated by a pathway from the intermediate grey layer of the superior colliculus to the same ventral subdivision of the zona incerta. Finally, experiments combining axonal transport and electron microscopic methods showed that the incertotectal pathway is the source of a monosynaptic GABAergic input to the cells of origin of the predorsal bundle. The ventral subdivision of the zona incerta is contrasted with a second source of GABAergic input to the predorsal bundle cells, the substantia nigra pars reticulata. © 1992 Wiley‐Liss, Inc.
Progressive morphological abnormalities observed in rat spinal motor neurons at extended intervals after axonal regeneration
Authors: Bowe Constance M. , Evans Nyle H. , Vlacha Vasoliki
Published: January 2005

It is generally accepted that mammalian spinal motor neurons return to normal after axotomy if their regenerated axons successfully reinnervate appropriate peripheral targets. However, morphological abnormalities, recently observed in spinal motor neurons examined 1 year after nerve crush injury, raise the possibility that delayed perikaryal changes occur after regeneration is complete. In order to distinguish between chronic and progressive alterations in neurons with long‐term regenerated axons, rat spinal motor neurons and dorsal root ganglion cells were examined at 5 and 10 months following unilateral sciatic nerve crush. Neurons with regenerated axons were identified by retrograde labelling with horseradish peroxidase. The structural properties of neurons ipsilateral to nerve injury were compared to those of neurons from the spinal cord and dorsal root ganglia on the contralateral side and from age‐matched control rats.

At 5 months postcrush, the morphology of motor and sensory neurons ipsilateral to injury was comparable to that of control cells. However, several features of the motor neurons with regenerated axons distinguished them from control motor neurons at 10 months postcrush. Mean perikaryal area of ipsilateral spinal motor neurons was larger than the means for control motor neurons (p < 0.001). Ipsilateral spinal motor neurons also appeared clustered within the spinal cord and had thicker dendrites. Dorsal root ganglion cells with regenerated axons were slightly larger than control cells at 10 months postcrush but they exhibited no other morphological changes. The present findings indicate that spinal motor neurons are progressively altered after their regenerated axons have reestablished functional synapses with their peripheral targets. © 1992 Wiley‐Liss, Inc.
Substance P‐containing pyramidal neurons in the cat somatic sensory cortex
Authors: Conti Fiorenzo , de Biasi Silvia , Fabri Mara , Abdullah Lubna , Manzoni Tullio , Petrusz Peter
Published: January 2005

Light and electron microscopic immunocytochemical methods were used to verify the possibility that neocortical pyramidal neurons in the first somatic sensory cortex of cats contain substance P.

At the light microscopic level, substance P‐positive neurons accounted for about 3% of all cortical neurons, and the vast majority were nonpyramidal cells. However, 10% of substance P‐positive neurons had a large conical cell body, a prominent apical dendrite directed toward the pia, and basal dendrites, thus suggesting they are pyramidal neurons. These neurons were in layers III and V. At the electron microscopic level, the majority of immunoreactive axon terminals formed symmetric synapses, but some substance P‐positive axon terminals made asymmetric synapses. Labelled dendritic spines were also present.

Combined retrograde transport‐immunocytochemical experiments were also carried out to study whether substance P‐positive neurons are projection neurons. Colloidal gold‐labelled wheat germ agglutinin conjugated to enzymatically inactive horseradish peroxidase was injected either in the first somatic sensory cortex or in the dorsal column nuclei. In the somatic sensory cortex contralateral to the injection sites, a few substance P‐positive neurons in layers III and V also contained black granules, indicative of retrograde transport. This indicates that some substance P‐positive neurons project to cortical and subcortical targets.

We have therefore identified a subpopulation of substance P‐positive neurons that have most of the features of pyramidal neurons, are the probable source of immunoreactive axon terminals forming asymmetric synapses on dendritic spines, and project to the contralateral somatic sensory cortex and dorsal column nuclei. These characteristics fulfill the criteria required for classifying a cortical neuron as pyramidal. © 1992 Wiley‐Liss, Inc.
Quantitative autoradiographic distribution of calcitonin gene‐related peptide (hCGRPα) binding sites in the rat and monkey spinal cord
Authors: Yashpal K. , Kar S. , Dennis T. , Quirion R.
Published: January 2005

Calcitonin gene‐related peptide (CGRP) has been implicated in various spinal functions on the basis of its presence in the substantia gelatinosa and motoneurons and the biological effects induced by intrathecal CGRP injections. We investigated here the comparative distribution of [125I]hCGRPα binding sites in various segments of the rat and monkey spinal cord. The immunocytochemical localization of CGRP‐like material in rat spinal cord was also evaluated for comparison. In the rat spinal cord, high densities of [125I]hCGRPα binding sites were observed in lamina I, in a U‐shaped band that included lamina X and the medial parts of laminae III‐IV and in the intermediolateral and intermediomedial nuclei. The substantia gelatinosa (lamina II) contained relatively lower, but still significant, densities of [125I]hCGRPα binding sites, while the ventral horn showed low amounts of specific labeling. CGRP‐like immunoreactive fibers, on the other hand, were heavily concentrated in laminae I–II and in the reticulated portion of lamina V of the dorsal horn. Immunoreactivity to CGRP antiserum was also noted in fibers around the central canal and in a number of motoneurons of the ventral horn. In the monkey spinal cord, [125I]hCGRPα binding sites were present in lamina I in a U‐shaped band that included lamina X and the medial portions of laminae V–VI. Relatively low levels of [125I]hCGRPα binding were detected in laminae II to IV of the dorsal horn, while the ventral horn was more enriched with specific [125I]hCGRPα binding sites. Thus, it appears that the autoradiographic distribution of [125I]hCGRPα sites is species dependent in the spinal cord. Additionally, some differences are observed between the localization of [125I]hCGRPα binding sites and immunoreactive material in the rat spinal cord. These differences may be relevant to the purported roles of CGRP‐like peptides in spinal functions such as nociception, control of sympathetic output, and motor control. © 1992 Wiley‐Liss, Inc.
An aromatase‐associated cytoplasmic inclusion, the “stigmoid body”, in the rat brain: I. Distribution in the forebrain
Authors: Shinoda Koh , Mori Shiro , Ohtsuki Tsukasa , Osawa Yoshio
Published: January 2005

An aromatase‐containing neural system was examined in the rat forebrain, using a polyclonal antibody against aromatase‐associated human placental antigen X‐P2 (hPAX‐P2).

Numerous dot‐like structures, which we have called stigmoid bodies, were immunostained in the preoptico‐hypothalamic region, the bed nucleus of the stria terminalis, the medial amygdala, the arcuate nucleus, the subfornical organ, and the area extending from the hypothalamic area to the central gray through the medial forebrain bundle and the periventricular fiber system of the posterior diencephalon. The stigmoid bodies were always found as inclusions in the neuronal cytoplasm. Their diameter was usually 1–3 μm, but exceptionally large forms, over 3 μm, were found in some brain regions, including the area extending from the median preoptic nucleus surrounding the organosum vasculosum laminae terminalis to the anterior medial preoptic nucleus, the periventricular nucleus of the preoptic area, and some parts of the medial preoptic nucleus. Most of these nuclei show sexual dimorphism. The distribution pattern of the hPAX‐P2 immunoreactive stigmoid bodies agreed well with that of aromatase activity previously reported in many biochemical studies. Brain regions where the stigmoid bodies were prominent largely coincide with steroid binding locations common to both androgen and estrogen, or regions where both sex steroid receptors are present. Although it still remains to be determined whether aromatase is localized within these stigmoid bodies, it appears likely that they are closely associated with the function of sex steroids at their target sites in the brain. © 1992 Wiley‐Liss, Inc.
The organization of the thalamocortical connections of the mediodorsal thalamic nucleus in the rat, related to the ventral forebrain–prefrontal cortex topography
Authors: Ray James P. , Price Joseph L.
Published: January 2005

The medial and central segments of the mediodorsal nucleus of the thalamus (MD) receive afferents from the ventral forebrain, including the piriform cortex, the ventral pallidum, and the amygdaloid complex. Because MD is reciprocally interconnected with prefrontal and agranular insular cortical areas, it provides a relay of ventral forebrain activity to these cortical areas. However, there are also direct projections from the piriform cortex and the amygdala to the prefrontal and agranular insular cortices.

This study addresses whether this system has a “triangular” organization, such that structures in the ventral forebrain project to interconnected areas in MD and the prefrontal/insular cortex. The thalamocortical projections of MD have been studied in experiments with injections of retrograde tracers into prefrontal or agranular insular cortical areas. In many of the same experiments, projections from the ventral forebrain to MD and to the prefrontal/insular cortex have been demonstrated with anterograde axonal tracers.

The connections of the piriform cortex (PC) with MD and the prefrontal/insular cortex form an organized triangular system. The PC projections to the central and medial segments of MD and to the lateral orbital cortex (LO) and the ventral and posterior agranular insular cortices (AIv and AIp) are topographically organized, such that more caudal parts of PC tend to project more medially in MD and more caudally within the orbital/insular cortex. The central and medial portions of MD also send matching, topographically organized projections to LO, AIv and AIp, with more medial parts of MD projecting further caudally. The anterior cortical nucleus of the amygdala (COa) also projects to the dorsal part of the medial segment of MD and to its cortical targets, the medial orbital area (MO) and AIp.

The projections of the basal/accessory basal amygdaloid nuclei to MD and to prefrontal cortex, and from MD to amygdaloceptive parts of prefrontal cortex, are not as tightly organized. Amygdalothalamic afferents in MD are concentrated in the dorsal half of the medial segment. Cells in this part of the nucleus project to the amygdaloceptive prelimbic area (PL) and AIp. However, other amygdaloceptive prefrontal areas are connected to parts of MD that do not receive fibers from the amygdala.

Ventral pallidal afferents are distributed to all parts of the central and medial segments of MD, overlapping with the fibers from the amygdala and piriform cortex. Fibers from other parts of the pallidum, or related areas such as the substantia nigra, pars reticulata, terminate in the lateral and ventral parts of MD, where they overlap with inputs from the superior colliculus and other brainstem structures. Thus, pallidal or pallidum‐related inputs overlap with other afferents in all parts of MD. © 1992 Wiley‐Liss, Inc.
Physiology and morphology of neurons in the dorsal motor nucleus of the vagus and the nucleus of the solitary tract that are sensitive to distension of the small intestine
Authors: Zhang Xueguo , Fogel Ronald , Renehan William E.
Published: January 2005

We have recently shown that distension‐sensitive vagal afferents are part of a neural circuit affecting absorption of water in the rat small intestine. Our results indicated that vagal afferent activity directly or indirectly influences the activity of neurons in the dorsal motor nucleus of the vagus (DMNV). In the present study we pursued this interaction by examining the structure and function of neurons in the DMNV and nucleus of the solitary tract (NST) that responded to moderate distension of the small intestine. Distension‐sensitive cells were filled by intracellular iontophoretic injection of horseradish peroxidase. A total of 43 distension‐sensitive brainstem neurons were successfully characterized and labeled. Sixteen of the 17 NST neurons were excited by distension of the small intestine. Ten of the seventeen were restricted to the ipsilateral NST. Only two NST neurons possessed axons that terminated in the subjacent DMNV. In contrast to the response profile of the NST neurons, 24 of 26 DMNV neurons were inhibited by intestinal distension. Fourteen of the DMNV neurons appeared to contribute to the vagus nerve and 15 extended dendrites into the overlying NST. We propose that distension‐induced inhibition of DMNV activity is accomplished by inhibitory NST neurons, which synapse on the dendrites of DMNV neurons in the NST. © 1992 Wiley‐Liss, Inc.
Design and control of the head retractor muscle in a turtle, Pseudemys (trachemys) scripta: I. Architecture and histochemistry of single muscle fibers
Authors: Callister R. J. , Callister R. , Peterson E. H.
Published: January 2005

We are using the head retractor muscle (RCCQ) of a turtle, Pseudemys scripta, to analyze the neuromuscular mechanisms by which organisms vary the force and timing of muscle contraction. Previously we demonstrated that RCCQ comprises three histochemically defined fiber types: fast glycolytic (Fg), fast oxidative glycolytic (FOG), and slow oxidative (SO). In the present paper we report the 1) architectural features of single muscle fibers in RCCQ, including their lengths, diameters, and taper characteristics, 2) histochemical profiles of single muscle fibers, and 3) quantitative relations between our architectural and histochemical variables.

Single fibers in RCCQ exhibit an order of magnitude variation in length (4–60 mm). Approximately 40% span the full muscle. The remaining fibers generally attach to bone or tendon at one end, and the other end tapers intramuscularly; rarely a fiber may taper at both ends. The maximum (untapering) diameters of single fibers are bimodally distributed, forming two diameter classes. Fibers also vary in the percentage of their total length that tapers and in the shape of the tapering region. Large diameter muscle fibers generally are longer and have shorter, more blunted tapers than small diameter fibers. The large diameter fibers are almost all Fg types; these fibers have a median diameter of 59.3 m̈m, and they account for approximately 60% of total fibers in RCCQ. FOG and SO fibers generally have small diameters (median: 32.5 m̈m and 35.8 m̈m), and they typically account for 30% and 10% of total fibers. We use these relations to draw inferences about the attachments and architecture of glycolytic (Fg) and oxidative (FOG, SO) fiber types.

Taken together, our data suggest that single muscle fibers in RCCQ may be architecturally as well as histochemically specialized to perform different roles in head retraction. In the accompanying paper we report the efferent innervation of these fibers and consider some of the neural control problems posed by these diverse fiber types. © 1992 Wiley‐Liss, Inc.
Variation in form and axonal termination in the nucleus of the optic tract of the rat: The medial terminal nucleus input on neurons projecting to the inferior olive
Authors: Van Der Togt Chris , Van Der Want Johannes
Published: January 2005

The nucleus of the optic tract (NOT) and the medial terminal nucleus (MTN) are two primary visual nuclei that take part in circuits sustaining the optokinetic reflex, The morphology of rat NOT cells projecting to the inferior olive (NOT‐IO neurons) and their terminal input, specifically terminals originating from the MTN, have been studied in the rat at the light and electron microscopical level. This has been done by means of combined retrograde tracing from the inferior olive and anterograde tracing from the MTN to the NOT. The area containing MTN terminal fibers and the area occupied by NOT‐IO neurons has been found to match. This matched distribution provides a more detailed description of the NOT, with possible functional implications. Identified NOT‐IO neurons demonstrate considerable variability in their dendritic branching pattern and have been found to include all neuronal cell types described for the NOT. The dendritic branching pattern of NOT‐IO cells could be related to the orientation and distribution of the NOT's major afferent fiber systems. NOT‐IO neurons receive a variable MTN and retinal input onto their somata, comparable to other cells in the NOT. With exception of the superficial part of the NOT, NOT‐IO neurons with the most MTN terminals were found dorsally in areas containing large numbers of MTN terminals. In conclusion, although NOT‐IO neurons are uniform with respect to their receptive field properties, they vary considerably with respect to the shape of the cell body, dendritic branching pattern, and terminal input. This means that morphological characteristics of NOT‐IO neurons have no predictive value with regard to their receptive field properties. © 1992 Wiley‐Liss, Inc.
Immunohistochemical study on development of serotonin‐, substance P‐, and enkephalin‐positive fibers in the rat spinal motor nucleus
Authors: Ozaki Shigeru , Kudo Norio , Okado Nobuo
Published: January 2005

Developmental changes in the coexistence of serotonin and substance P/enkephalin within single fibers of lamina IX of the rat lumbar spinal cord were examined by the use of a double‐labelling immunohistochemical technique. On postnatal day (P) 0, 65.0% of immunoreactive varicosities contained only serotonin, and 21.3% of them had both serotonin and substance P. The coexistent ratio of serotonin and substance P in single fibers increased with development: 61.9% of serotonin positive varicosities co‐contained substance P on P28, similar to the ratio found in adult animals (67.4%). The ratios of varicosities containing only substance P remained the same from PO to adult stage (about 15%). Enkephalin positive immunoreactivity was not co‐localized with serotonin positive varicosities at any stage of development.

Although numerous serotonin positive fibers were found in lamina IX, only a few substance P and enkephalin positive fibers were observed in the same area on P0. The density of serotonin positive varicosities increased slightly by P28, whereas substance P and enkephalin positive fibers increased considerably by this age. Between P28 and the adult stage, the density of serotonin positive fibers decreased by about 50%.

The cross sectional area of axonal varicosities containing serotonin‐ and substance P‐like immunoreactivity was similar in both P0 and adult animals, whereas that of enkephalin positive fibers was different.

We also examined the coexistence of serotonin and substance P within single neurons of the caudal raphe nuclei in P7 and adult animals, and found that the coexistent ratio significantly increased with development. © 1992 Wiley‐Liss, Inc.