bluuebunny/crossref_metadata_2025 huggingface dataset:
Afferent projections to the cholinergic pedunculopontine tegmental nucleus and adjacent midbrain extrapyramidal area in the albino rat. I. Retrograde tracing studies
Authors: Steininger Teresa L. , Rye David B. , Wainer Bruce H.
Published: January 2005

The afferent connections of the pedunculopontine tegmental nucleus (PPT) and the adjacent midbrain extrapyramidal area (MEA) were examined by retrograde tracing with wheat germ agglutinin‐conjugated horseradish peroxidase (WGA‐HRP). Major afferents to the PPT originate in the periaqueductal gray, central tegmental field, lateral hypothalamic area, dorsal raphe nucleus, superior colliculus, and pontine and medullary reticular fields. Other putative inputs originate in the paraventricular and preoptic hypothalamic nuclei, the zona incerta, nucleus of the solitary tract, central superior raphe nucleus, substantia innominata, posterior hypothalamic area, and thalamic parafascicular nucleus. The major afferent to the medially adjacent MEA originates in the lateral habenula, while other putative afferents include the perifornical and lateral hypothalamic area, periaqueductal gray, superior colliculus, pontine reticular formation, and dorsal raphe nucleus. MEA inputs from basal ganglia nuclei include moderate projections from the substantia nigra pars reticulata, entopeduncular nucleus, and a small projection from the globus pallidus, but not the subthalamic nucleus. Dense anterograde labeling was observed in the substantia nigra pars compacta, entopeduncular nucleus, subthalamic nucleus, globus pallidus, and caudate‐putamen only following WGA‐HRP injections involving the MEA.

The results of this study demonstrate that the PPT and MEA share many potential afferents. Remarkable differences were found that support distinguishing between these two nuclei in future studies regarding the functional organization of the midbrain and pons. The results, for example, confirm our previous observations that the largely reciprocal connections between the midbrain and basal ganglia distinguish the MEA from the PPT. Afferents from the lateral habenula and contralateral superior colliculus represent extensions of more traditional basal ganglion circuitry which further delineate the MEA from the PPT. The results are discussed with respect to the important role of the midbrain and pons in behavioral state control and locomotor mechanisms. © 1992 Wiley‐Liss, Inc.
Cytoarchitectonic heterogeneities in the thalamic reticular nucleus of cats and ferrets
Authors: Clemence Annemarie E. , Mitrofanis John
Published: January 2005

The thalamic reticular nucleus has been classically defined as a group of cells surrounding most of the rostral and lateral surfaces of the dorsal thalamus, lateral to the fibres of the external medullary lamina and medial to those of the internal capsule. With the use of Nissl staining and antibodies to γ‐aminobutyric acid (GABA), somatostatin, and parvalbumin, this study describes the cytoarchitecture of the thalamic reticular nucleus of cats and ferrets. In cats, three subdivisions of the nucleus are distinguished, two of which are distinct in ferrets also.

First, the main body of the reticular nucleus lies lateral to the fibres of the external medullary lamina (except ventrally) and medial to those of the internal capsule. In both cats and ferrets, this structure is heterogeneous, consisting of distinct layers, the details of which vary along the dorsoventral axis. A prominent rostroventral portion of comparatively small rounded cells is also apparent within the main body. Most reticular cells in all areas of the main body are labelled with all of the above mentioned antibodies.

Second, the inner small‐celled region is a group pf small cells located between the external medullary lamina (ventrally) and the medial margin of the ventral regions of the main body of the reticular nucleus: the inner small‐celled region is clearly differentiated in cats only. Previous studies have referred to this area as being part of the main body of the reticular nucleus, but we suggest that it may form a separate subnucleus. For example, the inner small‐celled region stands in striking contrast to the main body of the reticular nucleus in that none of its cells are GABA immunoreactive and only a small caudal subpopulation are parvalbumin immunoreactive. A very similar pattern of immunostaining is apparent for the cells in the zona incerta, although the latter contains a small rostral subpopulation of GABA immunoreactive cells. Furthermore, although morphologically distinct from the zona incerta, the inner small‐celled region fuses with it ventrocaudally. We suggest that the inner small‐celled region may constitute a previously undescribed dorsal extension of the zona incerta, rather than a subdivision of the reticular nucleus.

Third, the perireticular nucleus, hitherto unidentified, is a discrete group of small cells lateral to the main body of the reticular nucleus and medial to the corpus striatum (globus pallidus and caudate‐putamen). It is apparent throughout most of the dorsoventral extent of the main body of the reticular nucleus of cats and ferrets. Although continuous with the latter ventrocaudally, the perireticular nucleus is otherwise clearly separated from it, forming a sheet around the main body of the reticular nucleus. There are no immunocytochemical differences between the perireticular and reticular cells with the antibodies used to date. © 1992 Wiley‐Liss, Inc.
The rat's postero‐orbital sinus hair: II. Normal morphology and the increase in peripheral innervation with adjacent nerve section
Authors: Williams J. B. , de Permentier P. , Waite P. M. E.
Published: January 2005

The morphology and innervation of the postero‐orbital (PO) sinus hair has been studied in normal rats and in adult animals in which an adjacent nerve, the infraorbital nerve, was sectioned on postnatal day 0 or day 7. The normal morphology of the follicle was similar to that of mystacial sinus hairs. However, the normal innervation differed from mystacial follicles in three respects: (1) instead of a separate innervation, the deep vibrissal nerve (DVN) and dermal plexus were supplied by a common follicle and skin nerve, named here the postero‐orbital cutaneous nerve, a branch of the zygomaticofacial nerve; (2) the entry of the DVN through the capsule was highly variable; in some cases fascicles entered in close proximity, but in others they were widely distributed around the capsule; and (3) two or three small nerves, called here anastomosing nerves, were found to leave the PO follicle. These arose from the DVN after it had passed through the capsule to the cavernous sinus. The anastomosing nerves passed back through the capsule and ascended on the outer surface of the follicle to join the dermal plexus. Each nerve contained 1–4 myelinated fibres and 11–35 unmyelinated fibres.

Infraorbital (IO) nerve section on day 0 caused a 19% (P < 0.001, n = 8) increase in numbers of fibres to the DVN on the lesioned side. Most of the increase was due to unmyelinated fibres with no significant change in myelinated axons. No change in axon numbers in the DVN occurred after day 7 lesions. Labelling of the mystacial pad and the PO follicle did not result in any double labelling of cells in the trigeminal ganglion, in either normal or lesioned animals, making it improbable that the increased numbers of unmyelinated axons arose from rerouting of infraorbital fibres. It is suggested that the increased innervation of the PO follicle may arise by the rescue of ganglion cells from developmentally programmed cell death. © 1992 Wiley‐Liss, Inc.
Morphology of single vestibulospinal collaterals in the upper cervical spinal cord of the cat. II. Collaterals originating from axons outside the ventral funiculi
Authors: Donevan A. H. , MacDonald J. A. , Brennan P. A. , Rose P. K.
Published: January 2005

Recent studies have shown that vestibulospinal axons reach the upper cervical spinal cord of the cat via several different funicular routes. The purpose of this study was to describe the projections of those axons travelling outside the well‐recognized pathways in the ventral funiculi. These axons are located in the dorsal columns, dorsolateral funiculi, and lateral funiculi. Collaterals of these axons were stained following extracellular injections of Phaseolus vulgaris leucoagglutinin in the medial and descending vestibular nuclei. The trajectories of individual collaterals were reconstructed from serial histological sections.

Collaterals arising from axons in the same funiculus usually had the same characteristic appearance. Axons in the lateral funiculi, ipsilateral or contralateral to their cells of origin, gave rise to collaterals that had a simple structure and usually followed a horizontal trajectory across laminae VII and VIII. The boutons of these collaterals were distributed throughout the mediolateral extent of laminae VI and VII and the dorsal half of lamina VIII. In contrast, axons in the dorsolateral funiculi, ipsilateral or contralateral to their cells of origin, terminated primarily in laminae IV and V. Many collaterals of these axons projected either rostrally or caudally and had a narrow mediolateral distribution. The combined distribution of boutons from collaterals originating from axons in the dorsal columns included the dorsal horn and intermediate zone. Although these collaterals were less common and formed a heterogeneous group, they were easily distinguished from collaterals originating from axons travelling in other funiculi.

These results indicate that vestibulospinal axons travelling outside the ventral funiculi comprise several distinct systems. Each system travels by a different funicular route and is distinguished by differences in collateral morphology and termination zones. Compared to vestibulospinal axons travelling in the ventromedial funiculus, vestibulospinal axons in lateral and dorsal funiculi have a more dorsal termination zone. Vestibulospinal projections to the upper cervical spinal cord appear to consist of several functional subdivisions that correspond to different funicular pathways. © 1992 Wiley‐Liss, Inc.
A comparison of glycogen phosphorylase a and cytochrome oxidase histochemical staining in rat brain
Authors: Harley Carolyn A. , Bielajew Catherine H.
Published: January 2005

The utility of metabolic markers that index functional neuronal circuits is widely appreciated. The present study asks whether patterns of the metabolic enzyme, active glycogen phosphorylase, parallel those of the neuronal marker, cytochrome oxidase. Fresh frozen rat brain sections (30 μm) were processed for either active glycogen phosphorylase or cytochrome oxidase at each often levels of the neuraxis. Although these metabolic markers predominate in different cellular compartments–glycogen phosphorylase in the astrocytic compartment and cytochrome oxidase in the neuronal compartment–the patterns of high, moderate, and low levels of activity for both enzymes were generally parallel. These similarities extended to detailed patterns of heterogeneous staining within structures, in particular, to laminated and modular distribution within cerebral and cerebellar cortical structures. The modular distribution was evident in barrel structures in the cerebral cortex and in parasagittal compartments in the vermis of the cerebellum.

Conspicuous differences between the two patterns occurred in white matter, in subcortical grey matter regions such as the nucleus accumbens, diagonal band, amygdala, and globus pallidus, and in the superior olivary nuclei of the brainstem as well as in nonneural structures such as the choroid plexus and ependyma. Discrete patchiness was characteristic of active glycogen phosphorylase distribution in the limbic neuropil of the dentate gyrus and entorhinal cortex.

The strong parallels between active glycogen phosphorylase and cytochrome oxidase distribution support the view that glycogen phosphorylase, despite its glial localization, can reflect neuronal metabolic demands. © 1992 Wiley‐Liss, Inc.
Somatostatin‐ and neuropeptide Y‐like immunoreactivity in the dentate area, hippocampus, and subiculum of the domestic pig
Authors: Holm Ida E. , Geneser Finn A. , Zimmer Jens
Published: January 2005

With the principal aim of providing baseline observations for future experimental studies, the distribution of somatostatin‐like and neuropeptide Y‐like immunoreactivities is described in the dentate area, hippocampus, and subiculum of the domestic pig (Sus scrofa domesticus) and compared with the distribution described in other mammals.

Intensely stained somatostatin‐like immunoreactive nerve cell bodies were present throughout the region, with highest densities in the dentate hilus, stratum radiatum and stratum oriens of the hippocampal regio inferior, stratum oriens of the hippocampal regio superior, and in the subicular cell layer. Somatostatin‐like immunoreactive terminals were represented by both stained fibers and stained puncta. Scattered somatostatin‐like immunoreactive nerve fibers were seen in most areas, but regular fiber plexuses were present in the dentate molecular layer and dentate hilus, stratum moleculare of the hippocampus, and in the subicular plexiform layer. Somatostatin‐like immunoreactive puncta were seen in the dentate molecular layer, stratum moleculare of the hippocampus, and in the subicular plexiform layer.

Neuropeptide Y‐like immunoreactive nerve cell bodies were less numerous than somatostatin‐like immunoreactive ones. They were mainly seen in the dentate granule cell layer and dentate hilus, stratum radiatum and stratum oriens of the hippocampus, and in the subicular cell layer. Intensely stained neuropeptide Y‐like immunoreactive fibers were numerous, and present in all areas examined. They formed fiber plexuses in the dentate molecular layer and dentate hilus, stratum moleculare of the hippocampal regio superior, and in the subicular plexiform layer. Neuropeptide Y‐like immunoreactive puncta were present in the dentate molecular layer, stratum moleculare of the hippocampus, and in the subicular plexiform layer.

Consistent and very characteristic variation in the distribution of somatostatin‐like and neuropeptide Y‐like immunoreactivity was found along the septotemporal axis of the hippocampus.

The distribution of somatostatin‐like and neuropeptide Y‐like neurons and terminals in the domestic pig displayed striking similarities with the basic pattern of organization of these neuropeptides in other species, although more subtle species‐specific characteristics were also observed in the pig. © 1992 Wiley‐Liss, Inc.
Cholinergic innervation of the human striatum, globus pallidus, subthalamic nucleus, substantia nigra, and red nucleus
Authors: Mesulam M.‐Marsel , Mash Deborah , Hersh Louis , Bothwell Mark , Geula Changiz
Published: January 2005

The anatomical organization of cholinergic markers such as acetylcholinesterase, choline acetyltransferase, and nerve growth factor receptors was investigated in the basal ganglia of the human brain. The distribution of choline acetyltransferase‐immunoreactive axons and varicosities and their relationship to regional perikarya showed that the caudate, putamen, nucleus accumbens, olfactory tubercle, globus pallidus, substantia nigra, red nucleus, and subthalamic nucleus of the human brain receive widespread cholinergic innervation. Components of the striatum (i.e., the putamen, caudate, olfactory tubercle, and nucleus accumbens) displayed the highest density of cholinergic varicosities. The next highest density of cholinergic innervation was detected in the red nucleus and subthalamic nucleus. The level of cholinergic innervation was of intermediate density in the globus pallidus and the ventral tegmental area and low in the pars compacta of the substantia nigra.

Immunoreactivity for nerve growth factor receptors (NGFr) was confined to the cholinergic neurons of the basal forebrain and their processes. Axonal immunoreactivity for NGFr was therefore used as a marker for cholinergic projections originating from the basal forebrain (Woolf et al., '89: Neuroscience 30:143–152). Although the vast majority of striatal cholinergic innervation was NGFr‐negative and, therefore, intrinsic, the striatum also contained NGFr‐positive axons, indicating the existence of an additional cholinergic input from the basal forebrain. This basal forebrain cholinergic innervation was more pronounced in the putamen than in the caudate. The distribution of NGFr‐positive axons suggested that the basal forebrain may also project to the globus pallidus but probably not to the subthalamic nucleus, substantia nigra, or red nucleus. The great majority of cholinergic innervation to these latter three structures and to parts of the globus pallidus appeared to come from cholinergic neurons outside the basal forebrain, most of which are probably located in the upper brainstem.

These observations indicate that cholinergic neurotransmission originating from multiple sources is likely to play an important role in the diverse motor and behavioral affiliations that have been attributed to the human basal ganglia. © 1992 Wiley‐Liss, Inc.
Growth properties of larval and adult locust neurons in primary cell culture
Authors: Kirchhof Barbara , Bicker Gerd
Published: January 2005

We developed a cell culture system for thoracic neurons of fifth instar or adult locusts (Locusta migratoria) in order to obtain maximum visualization of cellular morphology and direct access to neurons for electrophysiological analysis. The dissociated neurons regenerated new neurites in a serum‐free defined culture medium, in which they remained viable for up to 3 weeks. Viability of the cells was confirmed by intracellular recordings demonstrating active membrane properties and action potentials. While the morphology of the cultured neurons is distinct from their in vivo counterparts, they retained some cellular surface properties and markers related to transmitter metabolism.

Two factors influencing cellular morphology in vitro were identified in Locusta: (1)the presence of a primary neurite stump, and (2) membrane contacts between cells. Dissociated neurons of the locus species Schistocerca gregaria grown in a hemolymph‐enriched medium showed a marked reduction in branching patterns and a tenfold increase in neurite length compared to neurons growing in a medium without hemolymph. This culture system could prove useful for identifying the action of hemolymph‐derived growth factors. © 1992 Wiley‐Liss, Inc.
Photic regulation of Fos‐like immunoreactivity in the suprachiasmatic nucleus of the mouse
Authors: Colwell Christopher S. , Foster Russell G.
Published: January 2005

In mammals, the suprachiasmatic nucleus (SCN) of the hypothalamus functions as the primary pacemaker of the circadian system. Light has been shown to induce Fos‐like immunoreactivity (Fos‐LI) in the SCN of rats and hamsters. The purpose of the present study was to evaluate extensively the effect of light on Fos‐LI in the mouse SCN. Brief pulses of light administered to animals otherwise in constant darkness were found to induce Fos‐LI. This photic induction was unaffected by the rd mutation, which causes the profound loss of photoreceptors but fails to affect circadian responses to light. Light regulation of Fos‐LI was dependent upon the phase of the circadian cycle in which the light pulse was administered. Phases at which light causes phase shifts of the circadian system were permissive for Fos‐LI induction (CT 16 and 24), while phases in which light does not cause phase shifts were not permissive (CT 6 and 9). The time course of the induction at CT 16 was also described. In a light/dark cycle, Fos‐LI was found to be rhythmically expressed with Fos‐LI elevated soon after the lights came on but remaining low throughout the rest of the cycle. However, this rhythm is a direct consequence of the light because in constant darkness Fos‐LI was always low. These results have implications regarding the possible functional roles of Fos in the circadian system and add to our understanding of light regulation of circadian physiology in the mouse. © Wiley‐Liss, Inc.
Projections of the ventral premammillary nucleus
Authors: Canteras N. S. , Simerly R. B. , Swanson L. W.
Published: January 2005

The projections of the ventral premammillary nucleus (PMv) have been examined with the Phaseolus vulgaris leucoagglutinin (PHAL) method in adult male rats. The results indicate that the nucleus gives rise to two major ascending pathways and a smaller descending pathway. One large ascending pathway terminates densely in most regions of the periventricular zone of the hypothalamus, with the notable exception of the suprachiasmatic, suprachiasmatic preoptic, and median preoptic nuclei. This pathway is in a position to influence directly many cell groups known to regulate anterior pituitary function. The second large pathway ascends through the medial zone of the hypothalamus and densely innervates the ventrolateral part of the ventromedial nucleus and adjacent basal parts of the lateral hypothalamic area, medial preoptic nucleus, principal nucleus of the bed nuclei of the stria terminalis, ventral lateral septal nucleus, posterodorsal part of the medial nucleus of the amygdala, posterior nucleus, and immediately adjacent regions of the posterior cortical nucleus of the amygdala. It is already known that these regions are major components of the sexually dimorphic circuit, and interestingly, that they provide the major neural inputs to the PMv. The smaller descending projection from the PMv seems to innervate preferentially the posterior hypothalamic nucleus, although a small number of fibers appear to end in the tuberomammillary nucleus, supramammillary nucleus, specific regions of the medial mammillary nucleus, interfascicular nucleus, interpeduncular nucleus, periaqueductal gray, dorsal nucleus of the raphe, laterodorsal tegmental nucleus, Barrington's nucleus, and locus coeruleus. Relatively sparse terminal fields associated with ascending fibers were also observed in the dorsomedial nucleus of the hypothalamus; in the nucleus reuniens, parataenial nucleus, paraventricular nucleus of the thalamus, and mediodorsal nucleus; in the central nucleus of the amygdala, anterodorsal part of the medial nucleus of the amygdala, posterior part of the basomedial nucleus of the amygdala; and in the ventral subiculum and adjacent parts of hippocampal field CA1, and the infralimbic and prelimbic areas of the medial prefrontal cortex. Taken as a whole, the evidence suggests that the PMv receives two major inputs‐one from the sexually dimorphic circuit, and the other from the blood in the form of gonadal steroid hormones‐and gives rise to two major outputs: one (perhaps feed‐forward) to the neuroendocrine (periventricular) zone of the hypothalamus, and the other (perhaps feed‐back) to the sexually dimorphic circuit.© 1992 Wiley‐Liss, Inc.
Acetylcholinesterase reactivity in the frontal cortex of human and monkey: Contribution of AChE‐rich pyramidal neurons
Authors: Mrzljak Ladislav , Goldman‐Rakic Patricia S.
Published: January 2005

Light and electron microscopic histochemistry were used to analyze the distribution of the enzyme acetylcholinesterase (AChE) in the frontal cortex of macaque monkey and human. In prefrontal, premotor, prelimbic, and medial paralimbic areas, AChE reactivity showed a characteristic bilaminar appearance due to a combination of positive neuronal and fiber labeling in deep layer III and layer V. In addition, layer I contained dense AChE‐reactive fiber plexuses labeled throughout the frontal areas.

One of the major issues addressed in this study was whether pyramidal neurons in the nonhuman primate cortex express AChE reactivity, as has been reported for humans. Three different histochemical methods were applied to provide confidence in the reliability of the results. Light microscopic analysis revealed strongly reactive, intensely stained pyramidal neurons in monkey as well as in the human. Further, these AChE‐rich neurons exhibited the same pattern of laminar and regional variation in both species. In the prefrontal and premotor areas, AChE‐rich pyramidal neurons predominated in layer III. In the motor cortex, they were also concentrated in layer III, but numerous AChE‐rich pyramids were observed in layer V. In contrast, medial paralimbic areas had more AChE‐rich neurons in layer V than in layer III. Finally, at the electron microscopic level, the subcellular distribution of AChE histochemical product in pyramidal neurons was identical in both monkey and human. The only difference noted between the two species was that the density of AChE‐rich pyramidal neurons was greater in humans than in monkeys.

Since nonhuman primates possess a system of AChE‐reactive pyramidal neurons similar to human, they provide a potentially useful animal model for analyzing acetylcholinesterase neuronal systems in the cortex, which are compromised in various neuropathological diseases like Alzheimer's disease. © 1992 Wiley‐Liss, Inc.
Synaptic connections of the narrow‐field, bistratified rod amacrine cell (AII) in the rabbit retina
Authors: Strettoi Enrica , Raviola Elio , Dacheux Ramon F.
Published: January 2005

The synaptic connections of the narrow‐field, bistratified rod amacrine cell (All) in the inner plexiform layer (IPL) of the rabbit retina were reconstructed from electron micrographs of continuous series of thin sections. The All amacrine cell receives a large synaptic input from the axonal endings of rod bipolar cells in the most vitreal region of the IPL (sublamina b, S5) and a smaller input from axonal endings of cone bipolar cells in the scleral region of the IPL (sublamina a, S1–S2). Amacrine input, localized at multiple levels in the IPL, equals the total number of synapses received from bipolar cells.

The axonal endings of cone bipolar cells represent the major target for the chemical output of the All amacrine cell: these synapses are established by the lobular appendages in sublamina a (S1–S2). Ganglion cell dendrites represent only 4% of the output of the All amacrine and most of them are also postsynaptic to the cone bipolars which receive All input. The All amacrine is not presynaptic to other amacrine cells.

Finally, the AII amacrine makes gap junctions with the axonal arborizations of cone bipolars that stratify in sublamina b (S3–S4) as well as with other All amacrine cells in S5.

Therefore, in the rabbit retina 1) the rod pathway consists of five neurons arranged in series: rod → rod bipolar → AII amacrine → cone bipolar → ganglion cell; 2) it seems unlikely that a class of ganglion cells exists that is exclusively devoted to scotopic functions.

In ventral, midperipheral retina, about nine rod bipolar cells converge onto a single All amacrine, but one of them establishes a much higher proportion of synaptic contacts than the rest. Conversely, each rod bipolar cell diverges onto four All amacrine cells, but one of them receives the largest fraction of synapses. Thus, within the pattern of convergence and divergence suggested by population studies, preferential synaptic pathways are established. © 1992 Wiley‐Liss, Inc.
GAD‐ and GABA‐immunoreactivity in the ascending auditory pathway of horseshoe and mustached bats
Authors: Vater Marianne , Kössl Manfred , Horn Anja K. E.
Published: January 2005

A comparative study of the immunostain to antibodies directed against glutamic acid decarboxylase (GAD) and gamma‐aminobutyric acid (GABA) in the ascending auditory pathway was carried out in horseshoe bats (Rhinolophus rouxi) and mustached bats (Pteronotus parnellii).

In both species GAD/GABA‐positive puncta (presumed axonal boutons) and GAD/GABA‐positive cells were found in the cochlear nucleus, the superior olivary complex, the nuclei of the lateral lemsiscus, the inferior colliculus, and the medial geniculate body. General features of the immunostaining pattern in the auditory pathway agree with observations in other mammals, Quantitative analysis of puncta distribution shows that many auditory centers are characterized by subregional differences in puncta density and distribution. This indicates local differences in putatively inhibitory input related to connectivity and tonotopic organization.

The following species characteristic features were found: 1) The dorsal non‐laminated portion of the dorsal cochlear nucleus in horseshoe bats lacks the GAD/GABA‐immunoreactive cells typical for the ventral laminated portion and the dorsal cochlear nucleus of other species. Clearly, a cytoarchitectonic specialization is accompanied by a loss of putatively GABAergic local inhibitory circuits. 2) The ventral division of the medial geniculate body of the mustached bat lacks GAD/GABA‐immunopositive cells. Such cells are present in the horseshoe bat and other mammals. This finding implies functional differences in the organization of the medial geniculate body within the same mammalian order. © 1992 Wiley‐Liss, Inc.
Fine structure of rat septohippocampal neurons: I. Identification of septohippocampal projection neurons by retrograde tracing combined with electron microscopic immunocytochemistry and intracellular staining
Authors: Naumann Thomas , Linke Rüdiger , Frotscher Michael
Published: January 2005

In this report the normal dendritic organization and fine structure of identified Septohippocampal projection neurons is described as a prerequisite for a time course analysis of retrograde changes in these neurons following axotomy (see Naumann et al., J. Comp. Neurol. 325:219–242, 1992). Septohippocampal projection neurons were retrogradely labeled by injection of the fluorescent tracer Fluoro‐Gold into the hippocampus. Next, retrogradely labeled cells in Vibratome sections of the medial septum/diagonal band complex were intracellularly stained with the fluorescent dye Lucifer Yellow (LY). Photooxidation of LY resulted in a stable electron‐dense reaction product, which allowed us to study these double‐labeled neurons by electron microscopy. Another series of sections containing retrogradely labeled neurons were immunostained for choline acetyltransferase (ChAT) or paryalhumin (PARV). In this way the fine structure of two different chemically characterized subpopulations of Septohippocampal neurons could be compared with that of the LY‐injected neurons.

Intracellular filling of retrogradely labeled neurons with LY stained the cell body and the entire dendritic arbor. Essentially, three classes of neurons could be distinguished, i.e., bipolar cells, multipolar neurons, and an intermediate group. All these neurons displayed smooth, often varicose dendrites lacking spines. Mainly located close to the midline, there was a group of cells with only very few if any LY‐stained dendrites. In the electron microscope, the double‐labeled neurons were easily identified by numerous electron‐dense lysosomes associated with transported Fluoro‐Gold and the diffuse reaction product resulting from photooxidation. They displayed fine‐structural characteristics as previously described for cholinergic neurons. In fact, our fine‐structural analysis of ChAT‐positive Fluoro‐Gold‐labeled neurons, but also of backfilled PARV‐positive cells, gave very similar results. All these neurons had infolded nuclei, abundant cytoplasmic organelles, and a few axosomatic synapses. Thus, a plain electron microscopic study does not allow one to distinguish between subpopulations of Septohippocampal projection neurons. © 1992 Wiley‐Liss, Inc.
Fine structure of rat septohippocampal neurons: II. A time course analysis following axotomy
Authors: Naumann Thomas , Peterson Gary M. , Frotscher Michael
Published: January 2005

Previous light microscopic immunocytochemical studies with antibodies against transmitter‐synthesizing enzymes have suggested that septohippocampal neurons undergo retrograde degeneration following transection of their axons by cutting the fimbria‐fornix. However, a fine‐structural analysis of the degeneration process in these cells is lacking so far. Here we have identified septohippocampal neurons by retrograde tracing with Fluoro‐Gold. Thereafter, the fimbria‐fornix was transected bilaterally. Fine‐structural changes in prelabeled septohippocampal neurons were then studied after varying survival times up to 10 weeks.

Examination under the fluorescence microscope of Vibratome sections through the septal region revealed numerous retrogradely labeled cells after all survival times following axotomy. These neurons were then intracellularly injected with the fluorescent dye Lucifer Yellow in order to stain their dendritic arbor. Many cells were found after each survival time that displayed characteristics of septohippocampal neurons in control rats (see Naumann et al., J Comp Neurol 325:207–218, 1992). In addition, increasing with survival time, there were many shrunken neurons with a reduced dendritic arbor. Representative examples of both normal appearing and shrunken neurons were photoconverted for subsequent electron microscopic analysis, Relatively few signs of neuronal degeneration were found at each survival time analyzed. The majority of cells, including the heavily shrunken ones, displayed fine‐structural characteristics of normal neurons, However, a few degenerating neurons and reactive glial cells were present in all survival stages.

We conclude that axotomized septohippocampal projection neurons cease the expression of transmitter‐synthesizing enzymes and shrink, but many more cells survive for extended periods of time without target‐derived neurotrophic factor than was assumed in previous light microscopic studies. © 1992 Wiley‐Liss, Inc.
Neuroepithelial cells in the rat spinal cord express glutamate decarboxylase immunoreactivity in vivo and in vitro
Authors: Ma Wu , Behar Toby , Maric Dragan , Maric Irina , Barker Jeffery L.
Published: January 2005

It is unknown whether neuroepithelial cells in the mammalian central nervous system express neurotransmitter‐synthesizing enzymes. In this study, expression of glutamate decarboxylase (GAD), the γ‐aminobutyric acid (GABA)‐synthesizing enzyme, was examined in proliferative cells and postmitotic neuroblasts in embryonic rat spinal cord. Immunostaining coronal sections of the embryonic spinal cord with K2 antiserum, which recognizes GAD proteins encoded by the GAD67 gene, revealed intensely stained neuroepithelial cells in the basal plate at embryonic day (E) 13, in the intermediate plate between E 13–16, and last seen in the alar plate at E 16. Nissl counterstaining demonstrated that a small number of these GAD‐immunoreactive cells adjacent to the neural tube lumen were mitotic. The ventral‐to‐dorsal gradient of GAD expression in precursor cells and postmitotic neuroblasts correlates anatomically and temporally with the sequential generation of motoneurons, commissural neurons, and interneurons in the dorsal horn. Some of these GAD‐immunoreactive neuroepithelial cells may re‐enter the mitotic cycle, while others are postmitotic neuroblasts presumably migrating to the intermediate zone to differentiate into young neurons. Double‐immunostaining cells acutely dissociated from E 11–18 spinal cords with K2 and anti‐bromodeoxyuridine antisera, following a bromodeoxyuridine pulse in vivo, revealed considerable numbers of DNA‐synthesizing cells immunoreactive for GAD. The absolute number of double‐stained cells peaked during E 12–15, coinciding with terminal cell division in most spinal neurons. These observations suggest that spinal neuronal precursors can synthesize GAD‐related proteins prior to, or during, the terminal cell cycle. Although GAD immunoreactivity revealed by K2 antiserum was detected in proliferative cells and in migrating postmitotic neuroblasts, GABA immunoreactivity was never detectable in these cells. These early embryonic GAD‐immunoreactive neuroepithelial cells may either synthesize levels of GABA that cannot be detected immunocytochemically, and/or express enzymatically inactive GAD‐related proteins. © 1992 Wiley‐Liss, Inc.
Unique topographic separation of two spectral classes of cones in the mouse retina
Authors: Szél Á. , Röhlich P. , Gaffé A. R. , Juliusson B. , Aguirre G. , Van Veen T.
Published: January 2005

We have found two immunologically distinguishable cone types in the retina of the mouse, each localized to two opposite halves of the eye. One cone type was labelled by the monoclonal antibody COS‐1 specific to the middle‐to‐long wave sensitive visual pigment of the mammals, while the other type was stained by the shortwave‐specific monoclonal antibody (OS‐2). These results were confirmed with other antibodies directed against specific sequences of the visual pigments. As a result of the uneven distribution of the two cone types the mouse retina is divided into two fields separated by an oblique meridional line. The middlewave sensitive cones were present exclusively in the dorsal half of the mouse retina (M‐field). The overwhelming majority of the shortwave sensitive cones occupied the ventral half (S‐field), and only a small number was scattered among the middlewave sensitive cones in the dorsal retina. The ratio of the two cone types in the M‐field corresponds to what has been found in the retina of other mammals, including rodents such as the gerbil and the rat. The S‐field represents an entirely unique area with the unusually great number of shortwave sensitive cones and with the complete lack of the middlewave sensitive ones.

The present study provides the structural basis for dichromacy in a rodent species considered for a long time to be monochromat. In addition, it shows that the ventral retina, containing exclusively S‐cones in a relatively high density, is a unique retinal field not present in other mammalian species studied so far. © 1992 Wiley‐Liss, Inc.
Central projections and motor nuclei of the facial, glossopharyngeal, and vagus nerves in the mormyrid fish Gnathonemus petersii
Authors: Lazar G. , Szabo T. , Libouban S. , Ravaille‐veron M. , Toth P. , Brändle K.
Published: January 2005

Most of the information about the anatomy of the fish's cranial nerves was collected in the first two decades of this century. Experimental analysis of the VIIth, IXth, and Xth cranial nerves by modern tract tracing techniques started about 20 years ago. Several species have been investigated to date, including one species of Agnatha (Myxinoidea), two species of elasmo‐branchs, and species of some orders of Teleostei like Cyprinidae, Siluriformes, Perciformes, and Gadidae.

The Sensory and motor nuclei of the VIIth, IXth, and Xth cranial nerves of Gnathonemus petersii were studied by anterograde and retrograde axoplasmatic transport of horseradish peroxidase and cobaltous lysine complex. The sensory nuclei form a continuous column of cells in the brain stem extending caudal to the obex. The rostral one‐fourth of this column is occupied by the overlapping terminals of the VIIth and IXth nerves. The vagus nerve has 5 roots. The first 4 of these innervate the gills and the fifth supplies viscera. Afferents from the gills terminate ipsilaterally rostral to the obex in topographic order and their terminal fields overlap. Viscerosensory fibers terminate ipsilaterally in the obex region and bilaterally in the commissural nucleus of Cajal.

The facial motor nucleus is located rostral to the sensory nucleus. Facial motoneurons have pear‐shaped and multipolar perikarya. Their axons form a rostrally directed knee before leaving the brain. The motoneurons of the IXth and Xth nerves have a common cell column. The vagal motoneurons form a periventricular, a medial, and an intermediate cell group rostral to the obex. In the obex region and also caudal to it, a lateral and a caudal group can be distinguished. Vagal motoneurons show a topographic arrangement that is similar to that of the sensory vagal projections. The majority of motoneurons have pear‐shaped perikarya and ventrolaterally oriented dendrites. In the caudal nucleus the dendrites extend dorsally and overlap the terminals of sensory fibers. The axons form a dorsolaterally directed arch before joining the sensory roots.

Since G. petersii uses its electrosensory system primarily for detection of food, its gustatory system is less developed than in other fishes, which possess a large number of taste buds. © 1992 Wiley‐Liss, Inc.
Cytoarchitectonic organization and morphology of cells of the field L complex in male zebra finches (taenopygia guttata)
Authors: Fortune Eric S. , Margoliash Daniel
Published: January 2005

The organization of the field L complex, a thalamorecipient auditory region in the telencephalon of birds, was examined in Nissl and Golgi preparations of male zebra finches (Taenopygia guttata). The field L complex comprises five cytoarchitectonic subdivisions: L1, L2a, L2b, L3, and L, although the border between L and L2b is not distinct. L2a is a plate extending dorsocaudally from the dorsal medullary lamina in the caudal neostriatum. L1 lies on the anterodorsal border and L3 lies on the posteroventral border of L2a. L, the area designated “field L” by Rose (J. Psychol. Neurol., 1914, 2:278–352), forms the medial and posterior borders of the field L complex, L2b is a thick band that forms the dorsal and dorsolateral boundary of the field L complex and is continuous with L medially. Nucleus interface (NIf) is a nucleus that lies between L2a and L1 near the lateral edge of the complex.

The four types of Golgi stained neurons that occur in the zebra finch field L complex correspond to those described for the European starling (Sturnus vulgaris). Additionally, type 3 neurons are subdivided into “unoriented” neurons with spherical dendritic fields and “oriented” neurons with bipolar dendritic fields. NIf contains a distinct class of neurons that have large somata with both thick and thin spiny dendrites. The distribution of Golgi cell types between the subdivisions of the field L complex corresponds to the morphology of cells seen in Nissl material. Type 3 oriented cells are found almost exclusively within L2a. L3 has significantly greater numbers of the largest cells (type 1) and significantly smaller numbers of the smallest cells (type 4) than does LI. There are no significant differences in the distribution of Golgi stained cells between L2b and L. © 1992 Wiley‐Liss, Inc.
Design and control of the head retractor muscle in a turtle, Pseudemys (trachemys) scripta: II. Efferent innervation
Authors: Callister R. J. , Peterson E. H.
Published: January 2005

The head retractor muscle (RCCQ) of Pseudemys scripta is a useful model in which to study the mechanisms animals use to vary the force and timing of movement. Single fibers in this muscle differ significantly in attachments, length, diameter, taper characteristics, and histochemical properties, suggesting that they may be energetically and architecturally specialized for different roles in head movement. In the present paper, we report the peripheral and central efferent innervation of these diverse muscle cells, and we ask how the design of the neural apparatus is matched to the properties of its target muscle fibers.

Three out of four bellies in RCCQ are supplied by multiple segmental nerves. The territories of these nerves are separated rostrocaudally within the muscle belly; thus, long muscle fibers cross the territories of two or more segmental nerves. Motor terminals in RCCQ resemble those on frog twitch muscles. Their sizes (length, bouton number) are correlated with the diameters of their target muscle fibers. Each muscle fiber bears 2–14 terminals evenly spaced (approx. 5 mm apart) along its length. Thus, single muscle fibers in RCCQ are multiterminally, and long fibers are multisegmentally innervated. Control experiments indicate that the axons in each segmental nerve arise from different motor neuron populations. Thus, short, in‐series fibers are supplied by different motor neurons, and individual long fibers in RCCQ are polyneuronally innervated. These data help explain how long muscle fibers with relatively slow conduction speeds can generate rapid head movements, and they raise questions about the central mechanisms that coordinate the recruitment of RCCQ motor neurons. © 1992 Wiley‐Liss, Inc.
Development of commissural neurons in the embryonic rat spinal cord
Authors: Silos‐Santiago Inmaculada , Snider William D.
Published: January 2005

Little is known about the development of the various populations of interneurons in the mammalian spinal cord. We have utilized the lipid‐soluble tracer DiI in fixed tissue to study the migration and dendritic arborization of spinal neurons with axons in the ventral commissure in embryonic rats. Crystals of DiI were placed in various locations in the thoracic spinal cord in order to label commissural neurons within the dorsal horn, intermediate zone, and ventral horn at E13.5, E15, E17, and E19.

Seven different groups of commissural interneurons are present in the spinal cord by E13.5. Migration is relatively simple with groups occupying a position along the dorsoventral axis roughly corresponding to their position of origin along the neuroepithelium. By E15, commissural cells are near their final locations and exhibit characteristic morphology. One striking feature is the tendency of cells with similar morphology to cluster in distinct groups. By E19, at least 18 different types of commissural interneurons can be identified on morphological grounds. Although the situation is complex, some generalities about dendritic morphology are apparent. Commissural neurons located in the dorsal horn are small and have highly branched dendrites oriented along the dorsoventral axis. In more ventral regions, commissural neurons are larger and possess dendritic arbors oriented obliquely or parallel to the mediolateral axis with long dendrites extending toward the lateral and ventral funiculi. The number of primary dendrites of most groups is set by E15 and dendritic growth occurs in the transverse plane by lengthening and branching of these primary processes.

This study demonstrates that a large number of classes of commissural interneurons can be recognized on the basis of characteristic morphologies and locations within the dorsal horn, intermediate zone and ventral horn of the embryonic rat spinal cord. This finding is consistent with the fact that commissural neurons project to many different targets and mediate a variety of different functions. The demonstration that dendritic arbors of spinal interneurons with characteristic morphologies can be conveniently labelled with DiI should prove useful in future studies on the development of specific circuits in the mammalian spinal cord. © 1992 Wiley‐Liss, Inc.