bluuebunny/crossref_metadata_2025 huggingface dataset:
Time of origin of neurons in the murine enteric nervous system: Sequence in relation to phenotype
Authors: Pham Tuan D. , Gershon Michael D. , Rothman Taube P.
Published: January 2005

The hypothesis was tested that developing enteric neurons withdraw from the cell cycle in a sequence related to their phenotype. The birthdays of immunocytochemically identified myenteric and submucosal neurons were determined in the murine duodenum and jejunum. [3H]thymidine ([3H]TdR) was injected into timed pregnant mice or pups at 4–8 hour intervals over a 24 hour period. Pups were killed on postnatal day 30 (P30). [3H]TdR incorporation was detected by radioautography in enteric neurons, which were phenotypically identified by the simultaneous detection of the immunoreactivities of 5‐hydroxytryptamine (5‐HT), choline acetyl transferase (ChAT), neuropeptide Y (NPY), enkephalin (ENK), calcitonin gene‐related peptide (CGRP), and vasoactive intestinal peptide (VIP). The dates of the earliest withdrawal from the cell cycle of neurons containing these markers were determined, as well as the length of time during which the identified neurons continued to be born, and the date on which their rate of birth was maximal. The birthdates of myenteric neurons that contained 5‐HT (E8–E14, peak at E10) or ChAT (E8–E15, peak at E12) tended to be earlier than those that contained ENK (E10–E18, peak at E14), NPY (E10–E18, peak at E15), VIP (E10–P5, peak at E15), or CGRP (E10–P3, peak at E17). For any given immunocytochemically defined neuronal phenotype, submucosal neurons tended to be born later than their myenteric counterparts and submucosal neurons that contained neuropeptides were born later than those that contained only ChAT immunoreactivity. The day (E8) on which the first 5‐HT‐ and ChAT‐immunoreactive neurons became postmitotic is earlier than the day (E9) on which the colonization of the bowel by crest‐derived cells has been detected. The population of neural precursors that colonizes the gut, therefore, is heterogeneous; many cells are proliferating, but a specific subset, which will ultimately give rise to serotoninergic or cholinergic neurons, is already postmitotic. Neurons continued to be born throughout fetal life and even after birth. Consequently, terminally differentiated neurons coexist in the developing enteric nervous system with dividing neural precursor cells. This observation is consistent with the idea that early developing neurons could affect the development of enteric neural precursors; moreover, they also demonstrate that it is possible to add neurons to the enteric plexuses even after the neural circuits on which the bowel depends have become functional.
Octopamine immunoreactive cell populations in the locust thoracic‐abdominal nervous system
Authors: Stevenson P. A. , Pflüger H.‐J. , Eckert M. , Rapus J.
Published: January 2005

We describe octopamine‐immunoreactive somata and their projections in the pro‐ meso‐, meta‐ and pregenital abdominal‐ganglia of locusts. Immunoreactive midline somata were identified as dorsal‐ and ventral‐ unpaired median (DUM‐ and VUM‐, respectively) neurones due to their: characteristic large size and positions of somata, primary neurites in DUM‐tracts giving rise to T‐junctions, and bilaterally projecting axons. In the prothoracic ganglion there are most likely 8 such cells; in the meso‐ and metathoracic, some 20 each; and in each individual pregenital abdominal ganglion, typically 3. All appear to project to peripheral nerves and their numbers correspond to the number of peripherally projecting DUM‐cells identified to date in each ganglion. We suggest that probably all peripherally projecting DUM‐cells are octopaminergic in the examined ganglia. Presumptive DUM‐interneurones are not octopamine‐immunoreactive, but, confirming other studies, are shown to label with an antiserum to γ‐amino butyric acid (GABA).

Other octopamine‐immunoreactive neurones include a pair of midline, prothoracic, anterior medial cells, not necessarily DUM‐cells, and a pair of ventral lateral somata in each thoracic‐ and the first abdominal ganglion. The latter project intersegmentally in ventral tracts. Intersegmentally projecting octopamine‐immunoreactive fibers in dorsal tracts probably arise from a prothoracic DUM‐cell, which leaves through suboesophageal nerves, or descending suboesophageal DUM‐cells. Thus, the octopamine‐immunoreactive system of thoracic and pregenital abdominal ganglia in locust comprises all peripherally projecting DUM‐cells and a plurisegmental network.
Nitric oxide synthetase (NOS)‐containing sympathoadrenal cholinergic neurons of the rat IML‐cell column: Evidence from histochemistry, immunohistochemistry, and retrograde labeling
Authors: Blottner Dieter , Baumgarten Hans‐Georg
Published: January 2005

Nitric oxide synthetase (NOS) can be selectively stained in neurons by either NADPH‐diaphorase (i.e., NOS)‐histochemistry or immunohistochemistry with antibodies raised against NOS, which apparently label identical reactive sites (Hope, B.T., G.J. Michael, K.M. Knigge, and S.R. Vincent, Proc. Natl. Acad. Sci. USA 88:2811–2814, '91). We provide histochemical evidence for the existence of a neuron‐specific NOS‐activity in autonomic neurons of the thoracic spinal cord. Among the four main preganglionic cell clusters investigated at mid‐thoracic levels, Th7–10, the intermediolateral (IML)‐cell column was the most prominently stained cell group. The histochemical staining was absent in other spinal cord neurons and non‐neuronal cells, e.g., GFAP‐positive glial cells. Staining was completely blocked by Nω‐nitro‐L‐arginine (L‐NNA), a potent NOS‐inhibitor for brain and peripheral autonomic neurons, but was still observed in the presence of another NOS‐inhibitor, Nω‐monomethyl‐L‐arginine (MeArg). The NOS‐activity co‐localized with nearly half of the ChAT‐immunostained neurons located in the mid‐thoracic IML‐cell column as quantified by cell counts in single and double‐stained tissue sections. We conclude that NOS‐activity‐containing neurons represent a distinct group among cholinergic IML‐neurons, which suggests a more general function of this newly defined subpopulation of the spinal cord autonomic system. In vivo Fast blue retrograde labeling combined with histochemical staining and immunostaining revealed that sympathoad‐renal projection neurons belong to the distinct NOS and ChAT‐positive IML‐cell group. The results are consistent with the idea of a crucial role of NOS and the related L‐arginine‐dependent nitric oxide biosynthesis for adrenomedullary innervation and autonomic control of adrenal gland function.
Claustrum in the hedgehog (Erinaceus europaeus) brain: Cytoarchitecture and connections with cortical and subcortical structures
Authors: Dinopoulos A. , Papadopoulos G. C. , Michaloudi H. , Parnavelas J. G. , Uylings H. B. M. , Karamanlidis A. N.
Published: January 2005

The Cytoarchitecture of the claustrum in the hedgehog (Erinaceus europaeus) brain, the morphology of its neurons, and the efferent connections with cortical and subcortical structures were studied with the Nissl and Klüver‐Barrera, the Golgi, and the horseradish peroxidase methods. It was found that the claustrum is a well developed nucleus in the hedgehog telencephalon and, as in other mammals, is divided into dorsal and ventral parts. In Golgi‐stained sections, spiny multipolar cells are the predominant neurons of both the dorsal and the ventral claustrum and are projection neurons. Aspiny multipolar neurons with fewer, often beaded, dendrites constitute a minority in both divisions and are interneurons.

Injections of wheat germ agglutinin‐horseradish peroxidase (WGA‐HRP) in the prefrontal, motor, somatosensory, auditory and visual areas, and HRP or WGA‐HRP injections in the thalamus showed that: (1) the claustroneocortical projections originate in the dorsal claustrum and are distributed to the entire neocortex; these projections are mainly ipsilateral but some also originate contralaterally; (2) the claustroneocortical projections show a rough topographic organization; there exists a substantial degree of overlap; and (3) the claustrothalamic projection, arising throughout the dorsal claustrum, is strictly ipsilateral. No evidence of a thalamoclaustral projection was found.

The present results suggest that, although the hedgehog has been referred to as a “paleocortical mammal” owing to the great development of its rhinencephalic structures in comparison with its small neocortex, the dorsal claustrum is well developed and is connected with all neocortical areas as well as with the thalamus, establishing it as a key structure in the hedgehog forebrain.
Topographical organization and relationship with ventral striatal compartments of prefrontal corticostriatal projections in the rat
Authors: Berendse Henk W. , Graaf Yvonne Galis‐De , Groenewegen Henk J.
Published: January 2005

The anterograde tracer Phaseolus vulgaris‐leucoagglutinin was used to examine the topographical organization of the projections to the striatum arising from the various cytoarchitectonic subdivisions of the prefrontal cortex in the rat. The relationship of the prefrontal cortical fibres with the compartmental organization of the ventral striatum was assessed by combining PHA‐L tracing and enkephalin‐immunohistochemistry.

The prefrontal cortex projects bilaterally with an ipsilateral predominance to the striatum, sparing only the lateral part of the caudate‐putamen complex. Each of the cytoarchitectonic subfields of the prefrontal cortex has a longitudinally oriented striatal terminal field that overlaps slightly with those of adjacent prefrontal areas. The projections of the medial subdivision of the prefrontal cortex distribute to rostral and medial parts of the striatum, whereas the lateral prefrontal subdivision projects to more caudal and lateral striatal areas. The terminal fields of the orbital prefrontal areas involve midventral and ventromedial parts of the caudate‐putamen complex. The projection of the ventral orbital area overlaps with that of the prelimbic area in the ventromedial part of the caudate‐putamen.

In the “shell” region of the nucleus accumbens, fibres arising from the prelimbic area concentrate in areas of high cell density that are weakly enkephalin‐immunoreactive, whereas fibres from the infralimbic area avoid such areas. Rostrolaterally in the “core” region of the nucleus accumbens, fibres from deep layer V and layer VI of the dorsal part of the prelimbic area avoid the enkephalin‐positive areas surrounding the anterior commissure and distribute in an inhomogeneous way over the intervening moderately enkephalin‐immunoreactive compartment. The other prefrontal afferents show only a preference for, but are not restricted to, the latter compartment, In the border region between the nucleus accumbens and the ventromedial part of the caudate‐putamen complex, patches of strong enkephalin immunoreactivity receive prefrontal cortical input from deep layer V and layer VI, whereas fibres from more superficial cortical layers project to the surrounding matrix.

Individual cytoarchitectonic subfields of the prefrontal cortex thus have circumscribed terminal domains in the striatum. In combination with data on the organization of the midline and intralaminar thalamostriatal and thalamoprefrontal projections, the present results establish that the projections of the prefrontal cortical subfields converge in the striatum with those of their midline and intralaminar afferent nuclei. The present findings further demonstrate that the relationship of the prefrontal corticostriatal fibres with the neurochemical compartments of the ventral striatum can be influenced by both the areal and the laminar origin of the cortical afferents, depending on the particular ventral striatal region under consideration.
Differential projections of the anterior and posterior regions of the medial amygdaloid nucleus in the syrian hamster
Authors: Gomez Diana M. , Newman Sarah Winans
Published: January 2005

The medial nucleus of the amygdala is important for the neural control of reproductive behavior in the adult male Syrian hamster. Two types of signals are essential for this behavior, chemosensory stimuli and gonadal steroids; these signals appear to be received in different parts of the medial nucleus. The anterior region receives input from olfactory and vomeronasal systems, both of which are required for this behavior, whereas the posterior region receives gonadal hormone inputs. Behavioral studies have also suggested a functional differentiation of these two areas; electrolytic lesions of the anterior, but not the posterior, part eliminates normal sexual behavior. In this study, the efferent projections of the anterior and posterior divisions of the medial nucleus of the amygdala in the Syrian hamster were analyzed throughout the forebrain after injections of the anterograde neuronal tracer, Phaseolus vulgaris‐leucoagglutinin. Neurons of the anterior, but not the posterior, medial nucleus, were found to project to numerous olfactory bulb projection areas and to the ventral striatopallidal complex. Within areas of the chemosensory circuitry that control reproductive behavior, the anterior region of the medial nucleus projects to the intermediate part of the posterior bed nucleus of the stria terminalis and the lateral part of the medial preoptic area, whereas the posterior region of the medial nucleus projects to the medial parts of these areas. Differences in targets were also observed in the ventromedial nucleus of the hypothalamus where the anterior region projects to the core while the posterior part projects to the shell of this nucleus. Furthermore, reciprocal projections between the anterior and posterior regions of the medial nucleus were observed. Taken together, these studies support the hypothesis that the anterior and posterior regions of the medial amygdaloid nucleus provide substantially different contributions to the control of reproductive behaviors.
Immunohistochemical localization of nicotinic acetylcholine receptor subunits in the mesencephalon and diencephalon of the chick (Gallus gallus)
Authors: Britto Luiz R. G. , Keyser Kent T. , Lindstrom Jon M. , Karten Harvey J.
Published: January 2005

Monoclonal antibodies against two α‐bungarotoxin‐binding subunits (α7 and α8) of the nicotinic acetylcholine receptors (nAChRs) were used as immunohistochemical probes to map their distribution in the chick diencephalon and mesencephalon. The distribution of the α7 and α8 nAChR subunits was compared to the distribution of immunoreactivity produced by a monoclonal antibody against the β2 structural subunit of the nAChRs.

Structures that contained high numbers of α7‐like immunoreactive (LI) somata included the intergeniculate leaflet, nucleus intercalatus thalami, nucleus ovoidalis, organum paraventricularis, nucleus rotundus, isthmic nuclei, nucleus trochlearis, oculomotor complex, nucleus interstitio‐pretecto‐subpretectalis, stratum griseum centrale of the optic tectum, and nucleus semilunaris. Neuropil staining for α7‐LI was intense in the nucleus dorsomedialis hypothalami, nucleus geniculatus lateralis ventralis, griseum tecti, isthmic nuclei, nucleus lentiformis mesencephali, nucleus of the basal optic root, and stratum griseum et fibrosum superficiale of the tectum. High numbers of α8‐LI somata were found in the stratum griseum et fibrosum superficiale of the tectum and the nucleus interstitio‐pretecto‐subpretectalis, and intense neuropil staining for α8‐LI was found in the dorsal thalamus, nucleus geniculatus lateralis ventralis, lateral hypothalamus, griseum tecti, nucleus lentiformis mesencephali, nucleus interpeduncularis, and stratum griseum et fibrosum superficiale of the tectum. High numbers of β2‐LI somata were found only in the nucleus spiriformis lateralis, whereas neuropil staining for β2‐LI was intense in the nucleus geniculatus lateralis ventralis, nucleus suprachiasmaticus, nucleus lateralis anterior, nucleus habenularis lateralis, area pretectalis, griseum tecti, nucleus lentiformis‐mesencephali, nucleus externus, and nucleus interpeduncularis, and in the stratum griseum centrale, stratum griseum et fibrosum superficiale, and stratum opticum of the tectum.

These results indicate that there are major disparities in the localization of the α‐bungarotoxin‐binding α7 and α8 nAChR subunits and the β2 structural nAChR subunit in the chick diencephalon and mesencephalon. These nAChR subunits appear, however, to coexist in several regions of the chick brain.
Observations on the early development of the optic nerve and tract of the mouse
Authors: Colello R. J. , Guillery R. W.
Published: January 2005

The early development of the retinofugal pathway of mice has been studied by light and electron microscopic methods in order to define the spatial distribution and the structure of the growth cones as they advance from the eye to the brain. We have studied the relationships of the growth cones to each other, to the glia and, in the older individuals, to the nerve fibers that are already terminating in the brain. We have looked at the rate of advance of the growth cones and have paid particular attention to the changing relationships of the growth cones as they approach the optic chiasm. We have also looked to see whether, at early stages, it is possible to recognise any characteristic features distinguishing the fibers destined to be the thickest in the adult, which come from ganglion cells that are generated among the earliest ganglion cells.

In transverse sections through the optic stalk about 50–100 μm behind the eye, the first bundles of fibers are seen on embryonic day 12.5 (E12.5) as a mixture of thin (< 0.5 μm) axons, thicker growth cones, and fine filopodial and foliopodial extensions. During the next two days, as these bundles in the intraorbital nerve increase in size and number, growth cones can be seen in all of the bundles and in all parts of the bundles. They show only a slight preference for one part of the nerve relative to another, and our material provides no evidence for the view that axons are particularly inclined to follow pre‐existing bundles.

The structure of the pathway changes significantly as it is traced towards the chiasm, and no section or small stretch of sections can be regarded as representative of the nerve as a whole. As the fibers approach the optic chiasm the growth cones come to lie predominantly close to the pial surface, with the deeper regions occupied almost entirely by fine axons. The change occurs in a region where the glial environment also changes, and where a characteristic neural tube‐like organization first becomes recognizable. Here the glial cells lie in a periventricular position and send slender radial processes out towards the subpial surface.

The newly invading axons in the early optic nerve taper from a broad growth cone back to an extremely slender axon, less than 0.5 μm in diameter. The tapered region is of the order of 100–300 μm in length and advances through the nerve at approximately 60 μm per hour. During days 13–19 about 20,000 fibers are added to the nerve each day and by the end of this period almost all of the growth cones have advanced beyond the nerve and tract. All of the axons now have a remarkably uniform, fine caliber, and in the tract there is no indication of the differences that later characterize axons in the different parts of the tract. The fibers destined to be the thickest as yet have no features that distinguish them from the others.
Ultrastructure of hyaline, border, and vacuole cells in chick inner ear
Authors: Oesterle Elizabeth C. , Cunningham Dale E. , Rubel Edwin W
Published: January 2005

The sense organ for hearing in birds, the basilar papilla, is capable of replacing lost or damaged hair cells and supporting cells through regeneration. Potential candidates for precursor‐cell populations include cells within the auditory receptor epithelium and nonsensory cells inferior to the sensory epithelium. Ultrastructural characteristics of hyaline cells, border cells, and vacuole cells, nonsensory cells which border or lie inferior to the receptor epithelium proper, were studied with transmission electron microscopy. Data were obtained from normal neonatal and adult chickens.

Several rows of epithelial cells separate hyaline cells from inferiorly located organ supporting cells and hair cells. Ultrastructural characteristics and location of these epithelial cells differentiate them from organ supporting cells and hyaline cells; consequently, we have termed them „border cells”︁. Synaptic specializations are observed between neural elements and border cells, and gap junctions are found between adjacent border cells, between border cells and neighboring organ supporting cells, and between juxtaposed border and hyaline cells.

Hyaline cells, in contrast to border cells, are highly specialized. Dense bundles of filaments are present in hyaline cells from the basal one‐half of the papilla, and an unusual structure, a rough tubular aggregate, is present in hyaline‐cell cytoplasm. Pre‐ and postsynaptic specializations are observed between neural elements and hyaline cells, and gap‐junctional complexes link neighboring hyaline cells.

Vacuole cells lie inferior to the hyaline cells and rest on the inferior fibrocartilaginous plate. They are unspecialized morphologically. Their only remarkable morphological feature is the abundance of spherical vacuoles within their cytoplasmic matrix.
Analysis of neuritic outgrowth from severed giant axons inLumbricus terrestris
Authors: Lyckman A. W. , Heidelbaugh S. M. , Bittner G. D.
Published: January 2005

This study analyzes the detailed morphometric pattern at various postoperative times of neuritic outgrowths from the proximal and distal stumps of two uniquely identifiable axons. Morphological patterns of neuritic outgrowths from stumps of severed axons were compared for medial and lateral giant axons in the central nervous system of the earthwormLumbricus terrestris.Outgrowths from proximal and distal stumps were labeled by injection of fluorescent dye into axonal stumps and assessed according to morphometric parameters. Outgrowths from axonal stumps of severed giant axons were statistically indistinguishable for most morphometric measures of neuritic quantity, shape, direction, and location. There were two exceptions to this general rule: 1) proximal stumps of medial giant axons produced significantly more neurites than distal stumps of medial giant axons, and 2) proximal stumps of lateral giant axons produced significantly longer neurites than proximal stumps of medial giant axons. No measure of neuritic outgrowth showed a significant change from the second through seventh postoperative week, suggesting that most outgrowth occurred in the first two postoperative weeks and that neuritic morphology remained stable through the seventh postoperative week. Neurites grew across the lesion site in relatively straight trajectories parallel to the longitudinal axis of the ventral nerve cord and often grew alongside the appropriate axonal stump across the lesion site. The length of neurites growing in close apposition to appropriate axonal stumps or giant axons was much greater than expected, had outgrowth been randomly directed. These data provide a basis for future investigations of the mechanisms that regulate neuritic outgrowth.
Somatic sensory responses in the rostral sector of the posterior group (POm) and in the ventral posterior medial nucleus (VPM) of the rat thalamus
Authors: Diamond Mathew E. , Armstrong‐James Michael , Ebner Ford F.
Published: January 2005

The rodent barrel field cortex integrates somatosensory information from two separate thalamic nuclei, the ventral posterior medial nucleus (VPM) and the rostral sector of the posterior complex (POm). This paper compares the sensory responses of POm and VPM cells in urethane‐anesthetized rats as a first step in determining how cortex integrates multiple sensory pathways.

A complete representation of the contralateral body surface was identified in POm. Trigeminal receptive fields (RFs) of POm and VPM cells were mapped by computer‐controlled displacement of individual whiskers; responses were quantified by using peristimulus time histograms. Average RF size was similar in POm (5.1 whiskers) and VPM (4.4 whiskers), but evoked responses in the two nuclei differed significantly according to all other measures. VPM cells were maximally responsive to one single whisker‐the „center RF.”︁ Stimulating this whisker evoked, on average, a response of 1.4 spikes/stimulus at a latency of 7 ms; surrounding whiskers evoked responses of < 1 spike/stimulus at latencies of > 8 ms. In contrast, POm cells were nearly equally responsive to several whiskers. Quantitative criteria allowed us to designate a single whisker as the „center RF”︁ and stimulating this whisker evoked, on average, a response of 0.5 spikes/stimulus at a latency of 19 ms. VPM cells, but not POm cells, were able to „follow”︁ repeated whisker deflection at > 5 Hz.

We conclude that, when a single whisker is deflected, VPM activates the related cortical barrel‐column at short latency— before the onset of activity in POm. The timing of activation could allow POm cells to modulate the spread of activity between cortical columns.
Evaluation of neural fold fusion and coincident initiation of spinal cord occlusion in the chick embryo
Authors: Desmond Mary E. , Field Marcia C.
Published: January 2005

Although it is known that rapid expansion of the vertebrate brain begins near the time that the spinal neurocoel is occluded, it still remains unknown when occlusion occurs in relation to neurulation. Since both morphogenetic events are critical for normal brain growth, it is important to decipher the temporal relationship between the two processes. This study assessed the temporal relationship of the two events with the rationale that if it could be demonstrated that occlusion occurs coincident with the completion of neurulation, then it could be argued that factors shown to direct neurulation could also initiate occlusion. Nearly 600 chick embryos (stages 9− through 12+) were cultured atop egg‐agar, the caudal extent of neurulation determined, the cranial five pairs of somites removed and the neurocoels assessed for occlusion. In stage 9− through 10− chicks, neurulation of the spinal cord is incomplete. Stages 10 through 12+ exhibit neurulation and occlusion from the 8th to 19th somites. When lateral tissues were removed in embryos 8 through 10−, the neural folds became dysraphic whereas in embryos stage 10 and older, the folds remained fused dorsomedially and occluded. The only surgical manipulation that was found to prevent occlusion was elimination of the lateral tissues responsible for elevation and closure of the neural folds. Analysis of particular components of the lateral tissues essential for convergence, by treating embryos (n = 75) with chemicals known to degrade tissue‐tissue bonds or specific components of the perineural matrix, indicated that more than 75% of the embryos treated with EDTA, EDTA plus Ca2+, trypsin, collagenase, or hyaluronidase exhibited little or no effect on convergence, dorsomedial fusion, and concomitant occlusion. © 1992 Wiley‐Liss, Inc.
Nerve growth factor receptor immunoreactivity in neurons of the normal adult rat spinal cord and its modulation after peripheral nerve lesions
Authors: Rende Mario , Hagg Theo , Manthorpe Marston , Varon Silvio
Published: January 2005

Motoneurons of the rat spinal cord express low‐affinity nerve growth factor receptor (LNGFR) and corresponding mRNA during development, and re‐express it after their axotomy by peripheral nerve injury. The present study establishes the anatomical and quantitative baseline of LNGFR immunoreactive (LNGFR‐IR) neurons of the entire normal adult female rat and then investigates the temporal course for the re‐expression of LNGFR‐IR in lumbar motoneurons after either a crush lesion (which is followed by regeneration and reconnection to the muscle) or a cut lesion with removal of the distal stump (where a neuroma but no reconnection is formed). In the normal adult spinal cord, two types of LNGFR‐IR neurons were recognized: (1) small populations of large motoneurons located in the ventral horn mainly in correspondence to the regions of the phrenic, cremasteric and dorsolateral nuclei, and (2) a more numerous and more dorsally located population of small neurons. With a sciatic cut lesion, the number of LNGFR‐IR motoneurons at spinal levels L4–L6 rapidly and dramatically increased to a maximum between post‐lesion days 1 and 7, apparently involving most axotomized motoneurons of the region, and returned to the baseline level by day 30. With a crush lesion, similar numbers and virtually the same time‐course of LNGFR‐IR appearance were seen, but the onset of progressive disappearance of LNGFR‐IR neurons was delayed by one week, so that at 30 days, the most caudal motoneurons (which are last to reach their target) were still LNGFR‐IR. Comparison of these two time courses gives clues to the kind of signals that may be involved in initiating and/or maintaining the LNGFR response. © 1992 Wiley‐Liss, Inc.
Intrinsic and commissural connections of the rat inferior colliculus
Authors: Saldaña Enrique , Merchań Miguel A.
Published: January 2005

This study analyzes the distribution of the intrinsic and commissural fiber plexuses originating in the central nucleus of the inferior colliculus in the rat. The anterograde tracer Phaseolus vulgaris‐leucoagglutinin (PHA‐L) was injected iontophoretically at different places along the tonotopic axis of the central nucleus and visualized immunohistochemically. In coronal sections the terminal fields of axons originating at each injection site are seen to create four well‐defined bands across the rostrocaudal extent of the inferior colliculus, two in the ipsilateral and two in the contralateral side. The “ipsilateral main band” extends dorsomedially and ventrolaterally from the injection site, in register with the known isofrequency contours of the central nucleus, spanning this nucleus and extending into the dorsal cortex of the inferior colliculus. The “ipsilateral external band” is located in the external cortex, where it is oriented dorsoventrally, slightly oblique to the pial surface. In caudal sections, the ventral portion of these two bands appear to join. The two bands in the contralateral inferior colliculus occupy a symmetric position to those of the ipsilateral side, forming a mirror‐like image. The position of the four bands changes as the position of the injection site is varied along the frequency gradient axis of the central nucleus. After ventromedial (high frequency area) injections, the main band is ventral and medial, and the external band ventral and lateral. After more dorsolateral (lower frequency) injections, the main band is more dorsal and lateral, whereas the external band is more dorsal but more medial. Thus, the change in the position of the external band is separate and opposite to that of the main band. We suggest that the main bands represent isofrequency contours. Since the projection from the central nucleus to the external cortex of the inferior colliculus also appears to be tonotopic, we also propose a tonotopic organization for the external cortex. The main bands overlap the terminal field of the lemniscal fibers in the central nucleus; thus, it is concluded that the intracollicular fibers contribute to the formation of the known fibrodendritic laminae of the central nucleus.

A possible role in preservation of frequency information and integration of other different acoustic parameters is proposed for the main bands. The external bands could participate in polysensory integration, and the commissural connections could be involved in hitherto unknown stages of binaural processing of sound.

Based on our results, several modifications are proposed for delineating the subdivisions of the inferior colliculus. © 1992 Wiley‐Liss, Inc.
Embryonic development of a population of spiking local interneurones in the locust (Schistocerca gregaria)
Authors: Shepherd David , Laurent Gilles
Published: January 2005

We examined the embryonic development of an identified group of thoracic spiking local interneurones in the locust. These interneurones are primary integrators of mechanosensory information from the legs and make inhibitory output connections with motor neurones, nonspiking local interneurones, and intersegmental interneurones. Using intracellular dye injection, we traced the origins of these interneurones and described their morphological development. All of the interneurones in this population are produced by neuroblast NB4‐1. The interneurones are produced during the latter stages of the neuroblast lineage and could not be identified before 55% development. Their growth could be divided into three distinct phases: first, a period of initial outgrowth (55–70%) during which the basic skeleton of major neurites is formed; second, a shorter period of rapid growth (70–80%) during which the basic skeleton is elaborated by the addition of many side branches; and third, a period of maturation (80–95%) during which the branches formed during earlier growth appear to be pruned. The possible implications of these results for neural development and synaptogenesis are discussed. © 1992 Wiley‐Liss, Inc.
Anatomical organization of the brainstem octavolateralis area of the oyster toadfish, Opsanus tau
Authors: Highstein Stephen M. , Kitch Rusty , Carey John , Baker Robert
Published: January 2005

Anatomical studies were undertaken to analyze the brainstem organization of the auditory, vestibular, and lateral line nuclei in a teleost, the oyster toadfish, Opsanus tau. Neuronal cytoarchitectonics and horseradish peroxidase label of cranial nerves were utilized to delineate the borders of the five octavus and two lateralis brainstem nuclei. Each of the eight octavolateralis nerves were labeled individually to compare and contrast their central projections. Projections of the three semicircular canals were found to be largely overlapping. Terminal fields were observed within the eminentia granularis and in each of the octavus nuclei. The nucleus anterior octavus was reciprocally innervated by the semicircular canals and the saccule. The canals terminated heavily in the ventral portions of the anterior octavus, whereas the saccule terminated extensively in the dorsal nuclear portions. The saccule also distributed terminals throughout the octavus cell column, including a light terminal field within the dorsal, medial, and anterior portions of the descending octavus nucleus, a region densely innervated by this end‐organ in other species. These results suggest that the anterior octavus nucleus may have a dual function. The dorsal portions may be an auditory relay nucleus, whereas the ventral portions may subserve vestibular function. Utriclar and lagenar afferents also terminated throughout the octavus cell column. Afferents of the anterior and posterior lateral lines ended within the eminentia granularis and the lateral line nuclei. Semicircular canal afferents and lateral line afferents appeared completely segregated within the eminentia. The above results are useful as an aid in the understanding of an ongoing, comprehensive functional analysis of auditory and vestibular mechanisms in toadfish and complement previous work on the efferent vestibular and sound‐producing motor systems. Examination of toadfish contributes to a more general and complete overview of the octavolateralis area of teleosts and the eventual identification of primitive and derived patterns of octaval organization. Additionally, this work may permit the further demonstration of species‐typical characters that may indicate adaptations to particular behavioral repertoires.
The calcium binding proteins parvalbumin and calbindin‐D 28K form complementary patterns in the cat superior colliculus
Authors: Mize R. Ranney , Luo Qian , Butler Grace , Jeon Chang‐Jin , Nabors Burt
Published: January 2005

Parvalbumin (PV) and calbindin‐D 28K (CaBP) are calcium binding proteins involved in calcium regulation in the brain. In some regions they coexist in the same neuron, while in other regions they are found in different cell types. We have studied the distribution and morphology of PV labeled neurons in the cat superior colliculus (SC) with antibody immunocytochemistry and compared this labeling to that of CaBP. PV neurons were concentrated in a dense tier within the deep superficial gray and upper optic layers. Scattered PV neurons also were found within the deep layers of SC. By contrast, CaBP neurons were concentrated in three tiers: one within the zonal and upper superficial gray layers, a second within the deep optic and upper intermediate gray layers (IGL), and a third within the deep gray layer. The distribution of PV neurons is thus complementary to that of CaBP neurons, with the CaBP cell tiers bordering the dense tier of PV neurons.

PV neurons varied in size and morphology. The average diameter of labeled cells was 20 μm, almost twice the size of CaBP neurons. The cells were predominantly round, vertical fusiform, or stellate, and included the very large neurons found scattered in the IGL. Horseradish peroxidase injections into the lateral geniculate nucleus, the lateral posterior nucleus, the opposite superior colliculus, the dorsal lateral pontine gray nucleus, and two descending pathways—the crossed predorsal bundle and the tecto‐ponto‐bulbar tracts—each labeled SC neurons that were also labeled by PV. A large percentage (84%) of projection neurons contained PV. This result also differs from CaBP neurons in SC, most of which are interneurons. Two antigen double‐label experiments did not produce any cells that contained both PV and CaBP. The two calcium binding proteins thus reveal a unique sublaminar organization in SC that consists of alternating small cell interneuron groups and large cell projection neuron groups.
Changes of chemoarchitectural organization of the rat spinal cord following ventral and dorsal root transection
Authors: Hirakawa Makoto , Kawata Mitsuhiro
Published: January 2005

Time‐related changes in the distribution of chemical messengers in the rat spinal cord following the transection of dorsal and ventral roots were observed by using immunohistochemistry for the following antigens: microtubule‐associated protein 2 (MAP2), calcitonin gene‐related peptide (CGRP), substance P (SP), galanin (Gal), Met‐enkephalin (Enk), neuropeptide Y (NPY), and serotonin (5‐HT). To investigate dendrocytoarchitectonic organizational changes, morphometric analyses were performed on both the gray and the white matter of tissue samples stained with MAP2 antiserum. A significant reduction in the area of gray matter on the lesioned side was seen from 1 to 24 weeks postoperation, and progressive changes in the shape of the gray matter were also observed. CGRP‐immunoreactive fibers were reduced in number in the posterior horn after root transection, except in the lateral part of lamina I. In contrast, CGRP immunoreactivity in the anterior horn cells of the ipsilateral side was increased early after transection, but later it progressively decreased. Root transection also caused significant reduction in the number of SP‐immunoreactive fibers in the posterior horn, but no changes were seen in the anterior horn. Gal immunoreactivity was also affected by root transection, and it changed in a similar way to CGRP immunoreactivity. 5‐HT‐immunoreactive fibers were increased in the posterior horn after transection, and later decreased. In the anterior horn, there were no changes in the intensity or distribution pattern of 5‐HT‐immunoreactive nerve fibers following root transection. Enk and NPY immunoreactivity in the anterior and posterior horns was not affected by root transection up to 24 weeks postoperative. These results show that spinal root transection caused significant changes in the chemoarchitectural organization of nerve fibers containing certain types of chemical messengers, such as CGRP, SP, Gal, and 5‐HT, in addition to altering dendritic geometry in the spinal cord.
Effects of prenatal ethanol exposure on the development of Bergmann glia and astrocytes in the rat cerebellum: An immunohistochemical study
Authors: Shetty Ashok K. , Phillips Dwight E.
Published: January 2005

The consequences of prenatal ethanol exposure on the postnatal development of Bergmann glia and astrocytes in the rat cerebellum were investigated by using glial fibrillary acidic protein (GFAP) immunolabeling. Pregnant rats were either fed with an ethanol containing liquid diet (6.7% v/v) or pair‐fed with an isocaloric diet throughout gestation. On postnatal day (PD) 15 and 22, parasagittal sections of the cerebellar vermis from female offspring were processed for GFAP immunohistochemistry to assess the development of Bergmann glia and astrocytes in lobules I, VII, and X and astrocytes in the central core of white matter. On PD 15, compared to control animals, ethanol exposed animals had fewer GFAP positive Bergmann glial fibers per unit length of molecular layer; a significantly greater percentage of morphologically immature Bergmann fibers; a significantly greater GFAP positive astrocytic area per unit area of internal granular layer and central white matter; and the astrocytic processes were wider and more closely packed. These glial changes were associated with significantly thicker external granular layer in all 3 lobules. However, no significant differences were seen between the ethanol exposed and control animals on PD 22, indicating “catch‐up growth” in the ethanol exposed animals during the third postnatal week. These results suggest that prenatal ethanol exposure causes (1) delayed maturation of Bergmann glia, which in turn contributes to the delayed migration of granule cells; and (2) alterations in the normal postnatal development of astrocytes. © 1992 Wiley‐Liss, Inc.
NADPH diaphorase in the spinal cord of rats
Authors: Valtschanoff Juli G. , Weinberg Richard J. , Rustioni Aldo
Published: January 2005

To identify spinal neurons that may synthesize nitric oxide, cells and fibres histochemically stained for NADPH diaphorase (a nitric oxide synthase) were studied in the spinal cord of rats. The histochemical reaction gave an image similar to the best Golgi impregnations, staining cells down to their finest processes. Transverse, horizontal, and parasagittal 50 and 100 μ sections were used to follow dendritic and axonal arborizations of stained neurons. Major cell groups were identified in the superficial dorsal horn and around the central canal (at all spinal levels), and in the intermediolateral cell column (at thoracic and sacral levels). Scattered positive cells were also found in deeper dorsal horn, ventral horn, and white matter. In some cases, axons of cells in the dorsal horn could be traced into the white matter; many of these cells resembled neurons projecting to various supraspinal targets. Stained cells in the intermediolateral column, which sent their axons into the ventral root, were presumed to be preganglionic autonomic neurons. Dense plexes of fiberes were stained in laminae I and II and in the intermediolateral column.

A large number of NADPH diaphorase‐positive neurons in the spinal cord appear to be involved in visceral regulation. Fibers of the intermediolateral system had a special relationship with vasculature, suggesting that nitric oxide may help to couple neural activity with regional blood flow in the spinal cord. The abundance of NADPH diaphorase‐positive neurons and fibres in the superficial dorsal horn suggests that nitric oxide may also be involved in spinal sensory processing. © 1992 Wiley‐Liss, Inc.
Afferent projections to the mammillary complex of the rat, with special reference to those from surrounding hypothalamic regions
Authors: Gonzalo‐Ruiz A. , Alonso A. , Sanz J. M. , Llinás R. R.
Published: January 2005

To better understand the functional organization of the mammillary nuclei, we investigated the afferents to this nuclear complex in the rat with iontophoretically injected wheat germ agglutinin conjugated to horseradish peroxidase. Particular attention was paid to tracing local hypothalamic afferents to these nuclei.

Injections into the medial mammillary nucleus (MMN) revealed strong projections from the subicular region, and weaker projections from the prefrontal cortex, medial septum, and the nucleus of the diagonal band of Broca. Other descending subcortical projections to the MMN arise from the anterior and the lateral hypothalamic area, the medial preoptic area, and the bed nucleus of the stria terminalis. Ascending afferents to the MMN were found to originate in the raphe and various tegmental nuclei.

Following all injections into the MMN, labelled neurons were found in nuclei surrounding the mammillary body. The lateral and posterior subdivisions of the tuberomammillary nucleus projected mainly to the pars medianus and pars medialis of the MMN. The dorsal and ventral premammillary nuclei projected to the pars lateralis of the MMN. The supramammillary nucleus at rostral level had a small projection to the pars medialis and lateralis of the MMN. However, the most obvious projection from this nucleus was to the pars posterior of the MMN, chiefly from the lateral part of the caudal supramammillary nucleus.

Injections into the lateral mammillary nucleus revealed inputs from the presubiculum, parasubiculum, septal region, dorsal tegmental nucleus, dorsal raphe nucleus, and periaqueductal gray. In addition, the lateral mammillary nucleus was found to receive a moderate projection from the medial part of the supramammillary nucleus and stronger projections from the lateral part of the caudal supramammillary nucleus. A very light projection was also seen from the lateral and posterior subdivisions of the tuberomammillary nucleus.

These findings add to our knowledge of the extensive and complex connectivity of the mammillary nuclei. In particular, the local connections we have demonstrated with the supramammillary and tuberomammillary nuclei indicate the existence of significant local circuits as well as circuits involving more distant brain regions such as the septal nuclei, subiculum, prefrontal cortex, and brain stem tegmentum. © 1992 Wiley‐Liss, Inc.
Immunocytochemistry of dopamine in the brain of the locust Schistocerca gregaria
Authors: Wendt Beatrice , Homberg Uwe
Published: January 2005

Catecholamine‐induced histofluorescence studies have suggested a rich innervation of the locust brain by dopamine‐containing neurons. To provide a basis for future studies on dopamine action in this insect, the location and morphology of neurons reacting with antisera against dopamine were investigated in the supraoesophageal ganglion of the locust, Schistocerca gregaria. In each brain hemisphere, about 100 interneurons in the midbrain and approximately 3,000 cells in the optic lobe show dopamine‐like immunoreactivity. All major areas of the brain except the calyces of the mushroom body, the antennal lobe, large parts of the lobula, and some areas in the inferior lateral protocerebrum contain immunoreactive neuronal processes. The arborization patterns of most dopamine‐immunoreactive cell types could be identified through detailed reconstructions.

The central body exhibits the most intense immunostaining. It is innervated by at least 40 pairs of dopamine‐immunoreactive neurons belonging to three different cell types. Additional arborizations of these neurons are in the superior protocerebrum and in the lateral accessory lobes. A group of 4 immunoreactive neurons with ramifications in the antennal mechanosensory and motor center gives rise to a dense meshwork of varicose fibers in the pedunculus and parts of the α‐ and β‐lobes of the mushroom body. Other cell types innervate the ventrolateral protocerebrum, the inferior protocerebrum and the posterior optic tubercles. Three descending neurons originating in the tritocerebrum exhibit dopamine‐like immunoreactivity. In the optic lobe, about 3,000 columnar intrinsic neurons of the medulla and a group of centrifugal tangential cells with arborizations in the medulla and lamina are dopamine‐immunoreactive. The study extends previous histofluorescent investigations on the distribution of catecholamines in the locust brain and suggests homologies among dopamine‐immunoreactive cell groups in locusts, bees, and flies. © 1992 Wiley‐Liss, Inc.