Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “GANGLION”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 361 records · Page 20Linked to original sources
PubMed1998

Anatomic considerations of C2 nerve root ganglion.

STUDY DESIGN: Dissection and observation of the dorsal root ganglion of the second cervical spinal nerve bilaterally. OBJECTIVES: To determine the position of the C2 dorsal root ganglion and the heights of the C2 ganglion and its corresponding foramen. SUMMARY OF BACKGROUND DATA: The dorsal root ganglion has been well studied in the middle and lower cervical spine and in the lumbar spine. In no previous study are the position and height of the C2 dorsal root ganglion and its corresponding foramen described. METHODS: Fifteen cadaveric cervical spines were exposed posteriorly. The C2 nerve roots and ganglia were dissected between the arch of the atlas and the lamina of the axis. The heights of the C2 ganglion and foramen were measured. The location of the C2 ganglion was also macroscopically observed. RESULTS: The heights of the C2 ganglion and foramen are 5.7 +/- 0.8 mm and 7.7 +/- 1.2 mm, respectively. The C2 ganglion occupies 76% of the foramen height. All C2 dorsal root ganglia are confined within foramens between the arch of the atlas and the lamina of the axis. CONCLUSIONS: The C2 dorsal dorsal root ganglia are all proximally placed and occupy most of the foramen height, which may render the C2 ganglion vulnerable to entrapment.

Cadaver↗
PubMed1975

Effects of divalent cations and of catecholamines on the late response of the superior cervical ganglion.

The characteristics of the late response of the superior cervical ganglion of dogs were studied by close-arterial injection of catecholamines and divalent cations to the ganglion. 2. Dopamine, noradrenaline and adrenaline inhibit the late response as well as ganglionic activity induced by other means. The effect of dopamine is brief but that of adrenaline is prolonged. 3. Cd2+, Co2+, Ni2+, Zn2+, Hg2+ and Fe2+ markedly potentiate the late response, whereas Mn2+, Ca2+ and Mg2+ inhibit it. 4. may potentiate ganglionic activity triggered by other ganglionic stimulants. The Cd-augmented activity may be blocked by a ganglion-blocker which is specific to the stimulant. 5. CdCl2 may exhibit a direct ganglion-stimulating action on a ganglion which shows prominent late responses and has been conditioned by tetanic preganglionic stimulation. 6. CdCl2 and MnCl2 may inhibit ganglionic transmission by suppressing acetylcholine release from presynaptic nerve terminals. 7. It is concluded that the late response represents the late discharges of ganglion cells, which are very sensitive to inhibition by CaCl2 and MnCl2 and may be potentiated by CdCl2.

Animals↗
PubMed1977

The reorganization of synaptic connexions in the rat submandibular ganglion during post-natal development.

1. The innervation of neurones in the submandibular ganglion of neonatal and adult rats has been studied with intracellular recording, and light and electron microscopy. 2. Intracellular recordings from neurones in isolated ganglia from adult animals showed that about 75% of the ganglion cells are innervated by a single preganglionic fibre. 3. However multiple steps in the post-synaptic potential (about five on average) were elicited in ganglion cells from neonatal animals by graded stimulation of the preganglionic nerve. The same result was obtained when the preganglionic fibres were stimulated at their emergence from the brainstem, indicating that neonatal neurones are innervated by several different preganglionic nerve cells. 4. The number of preganglionic fibres innervating individual ganglion cells gradually decreased during the first few weeks of life, and by about 5 weeks each ganglion cell was generally contacted by a single preganglionic axon. 5. Synapses were made on short protuberances in the immediate vicinity of the neuronal cell bodies in both neonatal and adult ganglia as shown by staining presynaptic boutons with the zinc-iodide osmium method, injection of horseradish peroxidase into ganglion cells, and electron microscopical examination. 6. Electron microscopical counts of synaptic profiles per ganglion cell perimeter showed that the number of synaptic contacts made on ganglion cells actually increased during the first few post-natal weeks, when the number of axons innervating each neurone was decreasing. 7. These results show that in the rat submandibular ganglion there is a reorganization of neuronal connexions during the first few weeks of life which results in a transition from multiple to generally single innervation of ganglion cells.

Action Potentials↗
PubMed1983

Neural units in the superior cervical ganglion of the guinea-pig.

The size and arrangement of the set of neurones innervated by individual preganglionic axons (the neural unit) has been investigated in the superior cervical ganglion of the guinea-pig. 1. Based on the ratio of preganglionic neurones to ganglion cells, and the average number of axons contacting each ganglion cell, we estimated that individual preganglionic axons innervate on the order of 50-200 superior cervical ganglion cells. 2. Of 562 pairs of ganglion cells examined with intracellular recording, forty-seven (8.4%) were innervated by one or more common axons. 3. Pairs of ganglion cells innervated by the same axon were not necessarily near each other. Although nearby cells were more likely to share innervation than neurones far apart, cells sharing innervation were often found several hundred micrometers apart, and were occasionally separated by the largest dimension of the ganglion (about 1-2 mm). 4. The incidence of cell pairs that shared innervation from more than one axon was greater than expected from the frequency of pairs sharing at least one axon. 5. Extracellular recordings from small fascicles of the cervical sympathetic trunk showed that preganglionic axons from different segmental levels intermingle extensively en route to the superior cervical ganglion. 6. Taken together, these findings support the view that sets of ganglion cells are innervated in common not because of any special topographic relationship within the ganglion, but because they share one or more properties that make them especially attractive to particular preganglionic axons.

Animals↗
PubMed1985

The selective innervation of guinea-pig superior cervical ganglion cells by sprouts from intact preganglionic axons.

If the guinea-pig superior cervical ganglion is partially denervated in a way which spares some preganglionic axons arising from each of the spinal cord segments which normally innervate this ganglion (C8-T7), sprouting of the intact preganglionic axons occurs without a loss of selective end-organ responses to stimulation of individual ventral roots (Maehlen & Njå, 1981). In the present work we examine the selective innervation of individual ganglion cells by ventral roots after sprouting and compare it to that in normal ganglia. After sprouting the pattern of ganglion cell innervation by the intact preganglionic axons shows some of the features typical of normal ganglia. Thus each ganglion cell is strongly innervated by one or two neighbouring spinal cord segments, with the adjacent segments contributing a synaptic influence which diminishes with distance from the dominant one. Acutely after the partial denervation there is a tendency for the rostral segments to innervate ganglion cells more strongly than do caudal segments, compared to the situation in normal ganglia. The same is true following sprouting. The pattern of ganglion cell innervation observed after sprouting can be explained if the affinities of ganglion cells for innervation from particular spinal levels are assumed to be unchanged and the shift in the relative availability of different preganglionic axons, caused by the partial denervation, is taken into account. This view was substantiated by statistical analysis based on a model of selective synapse formation in the guinea-pig superior cervical ganglion. We conclude that the ability of individual ganglion cells to distinguish preganglionic axons arising from different spinal levels is maintained during sprouting. Moreover, the way in which selective recognition and the availability of different preganglionic axons combine to produce particular patterns of innervation appears to be similar in normal development and after partial denervation in maturity.

Animals↗
PubMedDate not supplied

The insect frontal ganglion and stomatogastric pattern generator networks.

Insect neural networks have been widely and successfully employed as model systems in the study of the neural basis of behavior. The insect frontal ganglion is a principal part of the stomatogastric nervous system and is found in most insect orders. The frontal ganglion constitutes a major source of innervation to foregut muscles and plays a key role in the control of foregut movements. Following a brief description of the anatomy and development of the system in different insect groups, this review presents the current knowledge of the way neural networks in the insect frontal ganglion generate and control behavior. The frontal ganglion is instrumental in two distinct and fundamental insect behaviors: feeding and molting. Central pattern-generating circuit(s) within the frontal ganglion generates foregut rhythmic motor patterns. The frontal ganglion networks can be modulated in-vitro by several neuromodulators to generate a variety of motor outputs. Chemical modulation as well as sensory input from the gut and input from other neural centers enable the frontal ganglion to induce foregut rhythmic patterns under different physiological conditions. Frontal ganglion neurons themselves are also an important source of neurosecretion. The neurosecretory material from the frontal ganglion can control and modulate motor patterns of muscles of the alimentary canal. The current and potential future importance of the insect stomatogastric nervous system and frontal ganglion in the study of the neural mechanisms of behavior are discussed.

Animals↗
PubMed2000

Adrenergic influences on coeliac ganglion affect the release of progesterone from cycling ovaries: characterisation of an in vitro system.

The superior ovarian nerve (SON) arrives at the ovary through the suspensory ligament and innervates mainly the ovarian stroma. Most neurones from which the SON fibres originate are located in the complex coeliac and mesenteric ganglia. Taking into account that other ganglia have been shown to have alpha- and beta-adrenergic receptors, and that the coeliac ganglion receives adrenergic fibres from other sympathetic paravertebral and preaortic ganglia, we utilised adrenergic agonists and antagonists specific to the ganglion, to analyse the role of the alpha and beta receptors in ovarian physiology. To that end, it was necessary to develop and standardise an in vitro coeliac ganglion-SON-ovary (coeliac ganglion-SON-O) experimental system that would enable study of the release of steroids in the ovary in the absence of humoral factors. We investigated the effect of adrenergic agents on the liberation of progesterone in the different stages of the oestrous cycle. To this end we placed the coeliac ganglion and the ovary in different compartments, connected through the SON, to produce a system being studied as a whole. Combined neural and hormonal (luteinising hormone (LH)) effects were also examined. Non-specific stimulation with KCl in the ganglion compartment evoked different responses in terms of release of progesterone, depending on the physiological conditions of the cycle; this demonstrated the sensitivity and viability of the system. During pro-oestrus, stimulation of the ganglion compartment with adrenergic agents such as the agonist noradrenaline or the beta-adrenergic antagonist propranolol, did not modify the release of progesterone. In contrast, the alpha-adrenergic antagonist, phentolamine, induced a strong inhibitory response. During the oestrous stage, noradrenaline was inactive, but phentolamine and propranolol exerted a strong stimulus throughout the experiment. On dioestrus day 1 (D1), both noradrenaline and propranolol increased the release of ovarian progesterone, whereas phentolamine had the opposite effect. Finally, on dioestrus day 2 (D2), what was noteworthy was the pronounced inhibitory effect of noradrenaline, whereas phentolamine was inactive and propranolol showed its greatest stimulatory effect. In order to compare the combined neural and endocrine effects on the ovarian release of progesterone, the experiment was carried out during stages D1 and D2, when the corpora lutea are at their peak of activity. Adrenergic agents were added to the ganglion and LH in a final concentration of 50 ng/ml was added to the ovarian comparment. Different effects were observed indicating a differential response to these agents in stimulated and basal conditions. We conclude that the in vitro coeliac ganglion-SON-ovary system is a functional entity because it possesses its own autonomic tone. This is verified because different basal values of progesterone appear in the different stages of the oestrous cycle. In similar fashion, variations of progesterone induced via the neural pathway were observed under different experimental conditions. In contrast, on D2, noradrenaline added to the ganglion compartment had an inhibitory effect on the liberation of ovarian progesterone. This would indicate that, during this phase, noradrenaline may not be the neurotransmitter released in the ovarian compartment, but that other inhibitory molecules might participate in the observed effects. Finally, during D2, the neural input would condition the ovarian response to LH, facilitating the decrease in progesterone necessary to start a new cycle. The experimental scheme is, in our opinion, a valuable tool for the study of peripheral neural participation in ovarian physiology.

Adrenergic Agents↗
PubMed1981

Ganglion cell distribution in the retina of the mouse.

The distribution of ganglion cells in the mouse retina was studied with the use of Nissl criteria for distinguishing cell types in the ganglion cell layer. Retrograde filling with horseradish peroxidase (HRP) from the optic fiber tract helped to validate Nissl criteria and served to identify displaced ganglion cells. We estimated a total of 117,000 nonvascular cells in the ganglion cell layer; of these, 70,000 were probably ganglion cells, and 47,000 could not be classified. The density of the presumed ganglion cells was highest-more than 8000 cells/mm2-just temporal to the optic disk, and lowest-less than 2000 cells/mm2-in the most dorsal retina. The retinal region with highest ganglion cell density was slightly elongated in a nasotemporal direction. About 2% of all HRP-filled ganglion cells had their cell bodies in the inner nuclear layer. These displaced cells differed in topographical distribution from the normally positioned ganglion cells: although occurring throughout the retina, they were more common along the retinal periphery. Measurements of ganglion cell areas showed a tendency toward larger size with eccentricity. At no retinal location did cell-size histograms reveal clearly separate size classes.

Animals↗
PubMedDate not supplied

Two cases of ganglion cysts in the lumbar spinal canal.

Two cases of ganglion cysts in the lumbar spinal canal: MR findings. Ganglion cysts in the spinal canal are rare. To our knowledge, only 12 cases have been reported. In addition, ganglion cysts depicted by MR are extremely rare. We report the MR findings in two cases of ganglion cysts in the lumbar spinal canal. In both cases, the ganglion cysts were slightly higher in intensity than CSF on T2-weighted images. In addition, a thin band of low intensity was depicted around the ganglion in both cases. This finding may help to diagnose ganglion in the spinal canal. On T1-weighted images, the signal intensity of the ganglion was very similar to that of the intervertebral disc in both cases. In summary, although ganglion mimics disc hernia or sequestrated disc on both T2- and T1-weighted images, the possibility of a ganglion should be considered whenever an extradural mass showing high signal intensity surrounded by a thin band of low intensity is identified on T2-weighted images.

Adolescent↗
PubMedDate not supplied

Effects of gamma-aminobutyric acid on the compound action potential of the rat superior cervical ganglion.

The effects on the ganglionic transmission of gamma-aminobutyric acid (GABA) and related drugs were studied in the rat isolated superior cervical ganglion. The extracellularly recorded postganglionic compound action potential was used as an index for ganglionic transmission. GABA reversibly inhibited the ganglionic transmission by blocking the action potential. The effect of GABA is markedly antagonized by bicuculline (20 microM) or picrotoxin (200 microM). Furosemide (1 mM) was also effective in antagonizing the ganglionic effect of GABA. The antagonism by bicuculline was not affected in the presence of pentobarbital (50 microM). Baclofen inhibited the ganglionic transmission through an activation of GABAB receptors since it was markedly antagonized by phaclofen. Muscimol and isoguvacine were less effective than GABA in blocking the ganglionic transmission. The GABA uptake inhibitor isonipecotic acid blocked the ganglionic transmission, probably by activating GABAA receptors, because the effect was antagonized by bicuculline, but the GABA uptake inhibitor guvacine had no significant effect on the ganglionic transmission. These results suggest that GABA causes a ganglionic blockade by activation of both GABAA and GABAB receptor subtypes.

Action Potentials↗
PubMed2003

Retinal ganglion cell projections to the hamster suprachiasmatic nucleus, intergeniculate leaflet, and visual midbrain: bifurcation and melanopsin immunoreactivity.

The circadian clock in the suprachiasmatic nucleus (SCN) receives direct retinal input via the retinohypothalamic tract (RHT), and the retinal ganglion cells contributing to this projection may be specialized with respect to direct regulation of the circadian clock. However, some ganglion cells forming the RHT bifurcate, sending axon collaterals to the intergeniculate leaflet (IGL) through which light has secondary access to the circadian clock. The present studies provide a more extensive examination of ganglion cell bifurcation and evaluate whether ganglion cells projecting to several subcortical visual nuclei contain melanopsin, a putative ganglion cell photopigment. The results showed that retinal ganglion cells projecting to the SCN send collaterals to the IGL, olivary pretectal nucleus, and superior colliculus, among other places. Melanopsin-immunoreactive (IR) ganglion cells are present in the hamster retina, and some of these cells project to the SCN, IGL, olivary pretectal nucleus, or superior colliculus. Triple-label analysis showed that melanopsin-IR cells bifurcate and project bilaterally to each SCN, but not to the other visual nuclei evaluated. The melanopsin-IR cells have photoreceptive characteristics optimal for circadian rhythm regulation. However, the presence of moderately widespread bifurcation among ganglion cells projecting to the SCN, and projection by melanopsin-IR cells to locations distinct from the SCN and without known rhythm function, suggest that this ganglion cell type is generalized, rather than specialized, with respect to the conveyance of photic information to the brain.

Animals↗
PubMed1999

Nitric oxide mediates excitotoxic and anoxic damage in rat retinal ganglion cells cocultured with astroglia.

BACKGROUND: Nitric oxide has been implicated in the process of retinal ganglion cell death in glaucoma. OBJECTIVE: To investigate the role of nitric oxide in mediating retinal ganglion cell death in a culture system that models glial-neuronal interactions at the level of the optic nerve head. METHODS: Dissociated retinal ganglion cells from neonatal rats were plated on monolayers of astroglia and identified by retrograde labeling with the fluorescent marker 1.1-dioctadecyl-,3,3,3,tetramethylindocarbocyanineperchlorate. Two days after dissociation, cocultures of retinal ganglion cells and glia were treated with graded concentrations of the nitric oxide synthase inhibitor N-nitro-L-arginine (NNA), and exposed to either anoxia for 1 to 24 hours or excitatory amino acids for 6 hours. Surviving retinal ganglion cells were counted with fluorescence microscopy and expressed as a percentage of retinal ganglion cells surviving in control cultures. RESULTS: Cell survival after anoxia increased in a dose-dependent fashion with exposure to NNA. Mean +/- SD survival rate of retinal ganglion cells after 6 hours of anoxia was 57%+/-10% with NNA treatment compared with 31%+/-3% without treatment (P<.01). When treated with excitatory amino acids, cell survival was 31%+/-6% after administration of N-methyl D-aspartate, 500 micromol/L, and 27%+/-8% after administration of sodium glutamate, 500 micromol/L. Survival was increased in cultures with exposure to NNA, 100 micromol/L, to 53%+/-11% and 69%+/-11%, respectively (P<.01). CONCLUSION: In this coculture of retinal ganglion cells and astroglia, reduction of the glial source of nitric oxide through nitric oxide synthase inhibition provided partial but significant protection against the lethal effects of anoxia and excitatory amino acids on retinal ganglion cells. CLINICAL RELEVANCE: Neuroprotective agents may play a role in patients with glaucoma who have progressive visual field loss, despite satisfactory control of intraocular pressure. Inhibition of nitric oxide synthase at the level of the optic nerve head may contribute to a clinically significant level of neuroprotection.

Animals↗
PubMed2002

Involvement of cyclin-dependent kinases in axotomy-induced retinal ganglion cell death.

We have tested the role of cyclin-dependent kinases (CDKs) in the type 3B death of axotomized retinal ganglion cells, by injecting intraocularly olomoucine, roscovitine, or butyrolactone I. Each of these inhibits CDK1, CDK2, and CDK5; CDK1 and CDK2 are involved in cell proliferation, whereas CDK5 is involved in neuronal differentiation. The inhibitors partially protected ganglion cells against the effects of axotomy. These agents may affect the ganglion cells directly, because CDK1, its regulatory subunit cyclin B1, and CDK5 were identified immunohistochemically in the perikarya of ganglion cells, and this was confirmed for CDK1 and CDK5 in Western blots of the ganglion cell layer. These blots showed an axotomy-induced phosphorylation of CDK5 occurring remarkably quickly (within 6 hours of axotomy) but little if any change in the phosphorylation state of CDK1. In addition, we studied the expression of proliferation markers, including proliferating cell nuclear antigen (PCNA) and the synthesis of DNA, by immunohistochemical and autoradiographic methods. Normal or axotomized ganglion cells did not express PCNA and did not synthesize DNA. Although we cannot exclude the possibility that axotomized ganglion cells may leave their quiescent state, our data show that they did not progress beyond the G1 phase of the cell cycle. Finally, in contrast to inhibitors of CDKs, cell cycle blockers with different targets than CDKs did not protect ganglion cells. Globally, our results suggest that axotomy-induced death of ganglion cells involves the activation of CDK1, CDK2, or CDK5 (most probably CDK5) but not the full cell cycle machinery.

Animals↗
PubMed2003

Developmental relationship between cholinergic amacrine cell processes and ganglion cell dendrites of the mouse retina.

Ganglion cells of the mammalian retina undergo structural remodeling before their dendrites are confined to functionally distinct laminas within the inner plexiform layer. It has been proposed that cholinergic amacrine cells provide laminar cues that remodel ganglion cell dendrites, because their processes stratify before those of the ganglion cells. To address this possibility, it is necessary to know whether cholinergic cells contact all or only some classes of ganglion cells during development. We, therefore, used two-photon microscopy to simultaneously reconstruct the dendritic arbors of different classes of ganglion cells and terminal processes of cholinergic cells in neonatal mouse retina. We determined that, after birth, cholinergic cells contacted only a subset of ganglion cells. Large bistratified cells (LBCs), resembling direction selective ganglion cells in other species, had dendrites that fasciculated with the cholinergic plexuses. The LBCs received numerous presynaptic cholinergic contacts shortly after birth. In contrast, large monostratified cells (LMCs), ramifying outside the cholinergic plexuses at maturity, received few, if any, cholinergic contacts even at early stages when their dendrites overlapped with the cholinergic processes. These observations suggest that cholinergic cells provide laminar cues for only subsets of ganglion cells. They also indicate that the synaptic organization between amacrine and ganglion cells may be specified early in development.

Acetylcholine↗
PubMed2005

Morphological identification of ganglion cells expressing the alpha subunit of type II calmodulin-dependent protein kinase in the macaque retina.

Expression of the alpha subunit of type II calmodulin-dependent protein kinase (alphaCamKII) distinguishes the koniocellular neurons of the primate lateral geniculate nucleus (LGN) from the primary parvo- and magnocellular neurons, but whether the same neurochemical signature distinguishes the retinal ganglion cells providing them input is not known. We find that, in the retina, alphaCamKII expression also differentiates two primary groups of ganglion cell, both characterized by broad, sparsely branching dendritic trees and cell bodies intermediate in size between the parvo- and magnocellular-projecting ganglion cells. Cells in the first group have three or four primary dendrites, a thick axon, and a rounded cell body and likely are made up of multiple types. In contrast, ganglion cells in the second group demonstrate a highly regular morphology, with strictly two primary dendrites and a thinner axon emanating from a smaller, elliptical cell body. This cell resembles the "large sparse" ganglion cell identified by others in retrograde labeling from the LGN and represents about 2% of all ganglion cells. In the optic nerve, alphaCamKII+ axons are also intermediate in size and form a bimodal distribution, correlating with the axonal sizes of the two groups of ganglion cell. For the LGN, we describe a group of alphaCamKII+ axon terminals with morphology consistent with terminals from retinal ganglion cells. These terminals form long, filamentous contacts with alphaCamKII+ relay cells and increase in frequency from the dorsal to the ventral koniocellular regions. Our results indicate that ganglion cells expressing alphaCamKII represent multiple projections to the brain, at least one of which provides input to one or more koniocellular regions of the LGN.

Animals↗
PubMed2005

Connexin36 mediates gap junctional coupling of alpha-ganglion cells in mouse retina.

Alpha-ganglion cells are present in all vertebrate retinae and are subdivided into ON and OFF types according to their level of dendritic ramification within the inner plexiform layer. They have large dendritic fields and usually a good responsiveness to moving stimuli. They were the first ganglion cells in which tracer coupling was observed, suggesting the presence of gap junctions composed of unknown connexins. Here we show that ON-alpha-ganglion cells in the mouse retina are coupled to amacrine cells, whereas OFF-alpha-ganglion cells are coupled to other OFF-alpha-ganglion cells and to amacrine cells. These tracer coupling patterns were completely absent in mice deficient in connexin36 (Cx36). The expression of Cx36 protein in alpha-ganglion cells but not in coupled amacrine cells was confirmed in mice in which the Cx36 coding DNA was replaced by the lacZ reporter gene. The dendritic localization and the distribution pattern of Cx36 patches, analyzed in mice in which the enhanced green fluorescent protein (EGFP) was linked to the C-terminal region of the Cx36 protein, revealed a rather small number of fluorescent plaques and different patterns for ON- and OFF-alpha-ganglion cells. Furthermore, tracer coupling between OFF-alpha-ganglion cells could be inhibited by quinine, a gap junctional blocker with a slight preference for gap junctions formed by Cx36. These data strongly suggest that Cx36 gap junction channels are functional not only in interneurons but also in output neurons of the retina and are responsible for distinct coupling patterns of ganglion cells.

Amacrine Cells↗
PubMed1983

Developmental relationships between trigeminal ganglia and trigeminal motoneurons in chick embryos. I. Ganglion development is necessary for motoneuron migration.

The migration and early development of trigeminal (V) motoneurons were studied in chick embryos in which two different populations of primary trigeminal sensory neurons had been removed prior to the birthdate of the V motoneurons. Ablation of mesencephalic neural crest cells, which eliminates monosynaptic sensory input, did not affect the migration, early development, or later differentiation of the V motoneurons. However, when the anlagen of the V ganglion were removed, the V motor root did not exit from the brainstem and the V motor nucleus did not develop. Although the neurons of the V ganglion do not innervate adult V motoneurons, these populations are related developmentally. In those embryos in which the V ganglion did not develop, medial column cells, which are midline, postmitotic, premigratory V motoneurons, and a few medial, elongated cells (possibly migratory) were present until days 5-6, but these cells did not complete their lateral migration to form the lateral nucleus of V. In cases where the ganglion anlagen were not completely removed, the number of postmigratory V motoneurons was positively correlated to the size of the ganglion remnant. There also was a correlation between the axial position of the postmigratory V motoneurons and the ganglion remnants. If a caudal remnant developed, only caudal V motoneurons, whose axons reached the ganglion, migrated; if a rostral remnant developed, only rostral V motoneurons, with axons reaching this remnant, migrated. Additionally, if the central axons of the ganglion remnant entered the metencephalon in either dorsal or ventral ectopic positions, the V motor nucleus was located in a corresponding aberrant position. Thus, some characteristic of the V ganglion cells appears to guide the motor axons and somas to their final brainstem position.

Animals↗
PubMed1984

Retinal ganglion cells in two teleost species, Sebastiscus marmoratus and Navodon modestus.

Distribution patterns of ganglion cells in the retina were examined in Nissl-stained retinal whole mounts of Sebastiscus and Navodon. The existence of area centralis in the temporal retina in both species suggests binocular vision. In Navodon, another high density area was found in the nasal retina, and a dense band of ganglion cells was observed along the horizontal axis between the two high-density areas. There is an obvious trend for the ganglion cell size to increase as the density decreases. The total number of ganglion cells was estimated to be about 45 X 10(4) in Sebastiscus and 87 X 10(4) in Navodon, whereas the total number of optic nerve fibers was about 35 X 10(4) and 70 X 10(4), respectively. The retinal ganglion cells labeled with HRP were classified into six types according to such morphological characteristics as size, shape, and location of the soma as well as dendritic arborization pattern. Type I cells have a small round or oval soma in the ganglion cell layer and a small dendritic field in the inner plexiform layer. Type II cells are similar to type I cells, but the dendrites arborize more closely to the ganglion cell layer in the innermost region of the inner plexiform layer. Type III cells have a medium-sized round soma in the ganglion cell layer, and the dendrites extend in an extremely wide area in the inner plexiform layer with few branches. Type IV cells have a large soma which is located in the ganglion cell layer. Dendrites emanate from the soma in all directions, branching out several times within a rather small region in the innermost part of the inner plexiform layer. Type V cells have large somata of various shapes, usually dislocated to the inner plexiform or granular layer. The dendrites extend in every direction and occupy an extremely large area in the inner plexiform layer. Type VI cells have the largest somata, which are also dislocated to the inner plexiform or granular layer. Type VI cells have a characteristic triangular or fan-shaped dendritic field. Soma size and the axon diameter are intimately linked, that is, small somata of type I and II cells give off thin axons, and large somata of type V and VI give off thick axons.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗