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PubMed1990

Comparison of central versus peripheral nerve pathways to the guinea pig inferior mesenteric ganglion determined electrophysiologically after chronic nerve section.

The contributions of central versus peripheral nerve pathways to neurons of the inferior mesenteric ganglion of guinea pigs were studied. Nerve trunks innervating neurons in the ganglion were surgically sectioned and intracellular electrical responses to nerve stimulation were measured 6-8 days after surgery. Guinea pigs were divided into two experimental groups: (1) those that had the lumbar sympathetic chain ganglia (LSG) L2 through L4 removed and (2) those that had the intermesenteric, lumbar colonic and hypogastric nerves sectioned leaving central connections intact. After 6-8 days fast excitatory postsynaptic potentials (EPSPs) and slow EPSPs were recorded intracellularly in randomly selected principal ganglionic neurons. The threshold stimulus voltage to elicit a fast EPSP, the amplitude of the slow EPSP and the number of neurons in which each type of synaptic potential occurred in response to stimulation of each of the nerve trunks was compared between surgically-sectioned animals and sham-operated controls. Neither section of preganglionic nerve trunks nor of postganglionic nerve trunks eliminated all synaptic input to neurons in the ganglion, indicating that neurons with cell bodies located central to the ganglion as well as in visceral target organs made synaptic connections in the ganglion. Both fast and slow synaptic potentials could be evoked by stimulation of postganglionic nerve trunks even after they were sectioned provided that preganglionic nerves were intact, indicating that axons of central origin which synapse in the ganglion may continue out into postganglionic nerve trunks. In like manner, evidence was obtained indicating that fibers from peripheral nerve trunks which initiate either fast or slow synaptic potentials in ganglionic neurons may continue out into the lumbar splanchnic nerves. These studies demonstrate that the synaptic potentials recorded in the inferior mesenteric ganglion arise not only from neurons with cell bodies central to the ganglion but also from neurons with cell bodies located in the visceral organs which this ganglion subserves.

Action Potentials↗
PubMed1987

[Met5]enkephalin-Arg6-Phe7- and [Met5]enkephalin-Arg6-Gly7-Leu8-immunoreactive nerve fibres and neurons in the superior cervical ganglion of the rat.

[Met5]enkephalin-Arg6-Phe7-(MEAP-) and [Met5]enkephalin-Arg6-Gly7-Leu8-(MEAGL-) immunoreactivity was studied by indirect immunohistochemistry in the superior cervical ganglion of the rat with specific antisera produced in rabbits against the corresponding synthetic opioid peptides. Several MEAP- and a few MEAGL-immunoreactive principal nerve cells were observed in the ganglion, while the small intensely fluorescent cells appeared as non-reactive. The superior cervical ganglion also contained dense networks of MEAP- and MEAGL-immunoreactive nerve fibres, which often formed basket-like structures around the principal nerve cells and small intensely fluorescent cells. After ligation of the preganglionic nerve trunk with simultaneous transection of the main postganglionic trunks, a distinct accumulation of both MEAP- and MEAGL-immunoreactivity was observed on both sides of the ligature. Ligation of the preganglionic nerve trunk caused a marked decrease in the number of both MEAP- and MEAGL-immunoreactive nerve fibres in the ganglion. Ligation of the main postganglionic nerve trunks with simultaneous preganglionic nerve division resulted in accumulation of MEAP- and MEAGL-immunoreactive material on the ganglionic side of the ligature in both the external and internal carotid nerve. After division of both the pre- and postganglionic nerve trunks, some immunoreactive nerve fibres and principal nerve cells were still observed in the ganglion. A few immunoreactive neurons and nerve fibres were also observed in the ganglion stellatum. A large number of MEAP- and MEAGL-immunoreactive nerve fibres was detected in the spinal cord at the levels C6-Th6. A few neurons in the intermediolateral cell column of the spinal cord at levels C8-Th1 showed MEAP- but not MEAGL-immunoreactivity. The cultured superior cervical ganglion contained a few MEAP-immunoreactive neurons, and the fibre outgrowth showed immunoreactivity both to MEAP and MEAGL. In electron microscopy, MEAGL-immunoreactivity in the superior cervical ganglion was localized in nerve fibres containing neurotubules and in principal nerve cells. The present results demonstrate that the rat superior cervical ganglion contains both extrinsic and intrinsic MEAP- and MEAGL-immunoreactive nerve fibres. Most of these fibres are of preganglionic origin. Both the principal nerve and small intensely fluorescent cells are often surrounded by MEAP- or MEAGL-immunoreactive nerve fibres and may receive innervation by these fibres. Several ganglionic neurons projecting to the sympathetic target tissues show MEAP- and/or MEAGL-immunoreactivity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2003

Macro- and microstructural organization of the rabbit's celiac-mesenteric ganglion complex (Oryctolagus cuniculus).

The macro- and microstructures of the rabbit celiac-mesenteric ganglion complex are described in 20 young animals. We found ten celiac ganglia, twenty-seven cranial mesenteric ganglia and eleven celiac-mesenteric ganglia. The celiac ganglia had a rectangular shape in nine cases (90%) and a circular one in one case (10%). The cranial mesenteric ganglia presented triangular (66.7%), rectangular (11.1%), L-shape (18.5%) and semi-lunar (3.7%) arrangements. The celiac-mesenteric ganglia were organized in three patterns: a single left celiac-mesenteric ganglion having a caudal portion (72.7%); celiac-mesenteric ganglia without a caudal portion (18.2%) and a single celiac-mesenteric ganglion with two portions: left and right (9.1%). The microstructure was investigated in nine celiac-mesenteric ganglia. The results showed that the celiac-mesenteric ganglion is actually a ganglion complex constituted of an agglomerate of ganglionic units separated by nerve fibers, capillaries and septa of connective tissue. Using the semi-thin section method we described the cellular organization of the celiac-mesenteric ganglion complex. Inside of each ganglionic unit, there were various cell types: principal ganglion neurons (PGN), glial cells (satellite cells) and SIF cells (small intensely fluorescent cells or small granular cells), which are the cytologic basis for each ganglionic unit of the rabbit's celiac-mesenteric ganglion complex.

Animals↗
PubMed1974

Synapse formation during embryogenesis on ganglion cells lacking a periphery.

1. The development of transmission was studied in chick ciliary ganglia that had been deprived of their periphery during early embryonic development.2. Peripherally deprived neurones in the ganglion differentiate in normal numbers and send functional axons into the post-ganglionic nerve.3. Ganglion cells lacking a periphery follow the normal developmental sequence sending out transient dendrites at the time ganglion cell synapses are formed, and later retracting them when calyces appear.4. Synapses, which appear functionally and ultrastructurally normal, form on all ganglion cells at the normal time and transmission is normal until Stage 34. Therefore information from the periphery is not required for ganglion cell synapse formation per se.5. From Stages 35 to 38 most cells die, so that only 8% of the original number of cells remain in the operated ganglion. Transmission fails in many cells during this same time, but precedes cell loss by only a short time, so that deafferentation probably does not contribute substantially to cell death.6. Both ciliary and choroid cells achieve full cytologic differentiation and are distinct from each other, indicating that the periphery is not required for the elaboration of the distinctive characteristics of these cells. Presynaptic fibres also differentiate into typical bouton as well as calyciform endings. Therefore, the type of preganglionic ending does not depend on ganglion cells establishing proper peripheral contacts.7. It has not been possible to ascertain whether ganglion cell specificity is affected by the periphery.8. Peripheral removal affects ganglion cell migration, so that two ganglia are formed. Approximately half of the cells migrate into the remnant optic cup forming a second misplaced ganglion. Ciliary and choroid cells occur in both ganglia and these cells go through the typical sequence of events described above.

Action Potentials↗
PubMed2001

Coeliac ganglion adrenergic activity modifies ovarian progesterone during pregnancy: its inter-relationship with LH.

Most of the fibres that constitute the superior ovarian nerve (SON) originate at the neuronal bodies of the coeliac ganglion and innervate rat ovarian stroma cells. The purpose of this work was to study the part played by innervation on ovarian release of progesterone on day 15 and at the end of pregnancy in an integrated in vitro system known as the coeliac ganglion-SON-ovary system. We also investigated, in the same system, whether there is some kind of inter-relationship between the effect of adrenergic agents and LH on progesterone release on day 15 of pregnancy. The coeliac ganglion and the ovary were incubated in separate compartments, linked by the SON. The ovary was immersed in 2 ml buffer solution (ovarian compartment) and the coeliac ganglion was immersed in 2 ml of a different buffer solution (ganglion compartment). Under these conditions, the accumulation of progesterone in the ovarian compartment medium was used as an endpoint. Conditions were standardised on day 15 of pregnancy, when the decrease in the release of ovarian progesterone caused by non-specific stimulation on the ganglion with KCl (56 mM) demonstrated the functional integrity of the system. Neural influence was evaluated by the addition of adrenergic agents at a concentration of 10(-6)M to the coeliac ganglion. On day 15 of pregnancy, noradrenaline and propranolol increased progesterone release while phentolamine diminished it. The existence of ganglionic tone was assessed by analysing progesterone basal levels at different stages of pregnancy. The highest secretion of progesterone was found to take place on day 15, diminishing as pregnancy advanced. In addition, adrenergic neural participation was studied during the physiological luteolysis occurring at the end of pregnancy. Major findings were that noradrenaline increased ovarian accumulation of progesterone on day 19 and decreased it on day 20, while propranolol and phentolamine diminished progesterone release on both days. In additional studies, some neuroendocrine aspects were investigated at a peripheral level. The addition of LH only to the ovarian compartment did not affect progesterone secretion. However, when LH in the ovarian compartment was accompanied by noradrenaline, propranolol or phentolamine in the ganglion compartment, the release of progesterone decreased. It can be concluded that modifications of the neural state of the coeliac ganglion affect ovarian progesterone secretion and the physiology of pregnancy via the SON. The results may confirm that the coeliac ganglion-SON-ovary system provides a direct link between the autonomic nervous system and physiological events during pregnancy.

Adrenergic Agents↗
PubMed1993

A study on the submandibular ganglion of the monkey with special reference to ultrastructural changes after lingual nerve sectioning.

This study describes normal light and electron microscopic features of the monkey submandibular ganglion. The intraglandular ganglion is composed of a collection of smaller ganglia distributed mainly at the hilum of the submandibular gland: one or two large ganglia were often found along with the main duct, while the smaller ones were located at the periphery. All ganglion cells were covered by satellite cells. Ultrastructurally, the ganglion cells showed the usual features of autonomic neurons, being round to oval with a prominent nucleus and nucleolus. Their cytoplasm contained numerous randomly distributed organelles. Occasional ganglion cells showed darkened dendrites. The majority of the synapses observed were of the axo-dendritic type, although the axo-somatic type was not uncommon. In the latter, the axon terminals were sometimes seen to deeply invaginate the soma of the ganglion cells forming synaptic contacts. Non-synaptic desmosome-like junctional complexes were common between the ganglion cells. Following the severance of the lingual nerve, the ganglion showed structural alterations beginning 1 day after the operation. The earliest sign of change was the increase in the number of macrophages surrounding the ganglion. Three and five days after the lingual nerve sectioning, the number of darkened dendrites considerably increased. Associated with this change were neuronal nuclei displaying irregular outlines. Other changes involved the disintegration of the preganglionic fibres and their axon terminals. The latter were observed to be engulfed by the infiltrated macrophages and Schwann cells. By 7 days after the preganglionic parasympathectomy, the ganglion cells resumed normal features, suggesting the acute and reversible nature of the transneuronal degeneration of the monkey submandibular ganglion cells. This is further supported by the absence of cell death during the period examined.

Animals↗
PubMed1986

Activation of DA1 receptors by dopamine or fenoldopam increases cyclic AMP levels in the renal artery but not in the superior cervical ganglion of the rat.

In the isolated superior cervical ganglion of the rat, activation of either DA1 or DA2 receptors leads to inhibition of ganglionic transmission. Using dopamine as well as relatively selective dopamine receptor agonists and antagonists we have performed electrophysiological as well as biochemical experiments to study the nature of dopamine receptors in this sympathetic ganglion. Fenoldopam, a selective DA1 receptor agonist caused marked inhibition of the compound postganglionic action potential evoked by stimulation of preganglionic nerve. The inhibitory effect of fenoldopam was antagonized by the DA1 receptor antagonist R-sulpiride but not by the DA2 receptor antagonist S-sulpiride. However, the more potent and selective DA1 receptor antagonist SCH-23390 failed to antagonize ganglion blocking effect of fenoldopam indicating that DA1 receptor in sympathetic ganglia is different from that in blood vessels. The superior cervical ganglion also contains DA2 receptors inasmuch as quinpirole, a DA2 receptor agonist, caused inhibition of ganglionic transmission which was antagonized by S-sulpiride but not by R-sulpiride. The existence of both subtypes of dopamine receptor in the superior cervical ganglion was ascertained further as dopamine itself caused inhibition of ganglionic transmission which was antagonized by either S- or R-sulpiride. Again, however, the DA1 receptor antagonist SCH-23390 failed to antagonize the ganglion blocking effect of dopamine. To characterize further the ganglionic DA1 receptor we sought to demonstrate whether or not ganglionic DA1 receptor is linked to the enzyme adenylate cyclase as is known to be the case for peripheral DA1 or central D1 dopamine receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1986

Stages in the structural differentiation of retinal ganglion cells.

Using a cultured wholemount technique we have studied the morphological differentiation of ganglion cells in the retina of the rat and cat, during normal development. In both species the differentiation of ganglion cells begins in embryonic life, before embryonic day (E) 17 in the rat and E36 in the cat. It is useful to describe the morphological differentiation of ganglion cells as occurring in three stages. In the first stage, each germinal cell becoming a ganglion cell extends an axon into the fibre layer of the retina and towards the optic disc, and the soma of the cell moves towards the ganglion cell layer. As the soma approaches the ganglion cell layer, the processes that attach its poles to the inner and outer surfaces of the retina are withdrawn. When the soma reaches the ganglion cell layer, a stage of active dendritic growth begins, which lasts until shortly before birth in the cat and until several days after birth in the rat. The cell extends stem dendrites that branch profusely and are commonly tipped by growth cones. The major morphological classes of ganglion cell become distinct in the latter part of stage 2, as do the centroperipheral gradients in ganglion cell size apparent in the cat. During the third stage, the dendritic trees of ganglion cells no longer branch or extend by means of active growth cones. Very considerable growth of all parameters of the cell (soma size, dendrite calibre and length, axon calibre) occurs nevertheless, presumably by interstitial addition of membrane throughout the cell.

Age Factors↗
PubMed1989

Monoamine-accumulating ganglion cell type of the cat's retina.

A monoamine-accumulating ganglion cell type has been identified in an in vitro preparation of the cat's retina by a catecholamine-like fluorescence that appears following intravitreal injections of dopamine and the indoleaminergic transmitter analog, 5,7-dihydroxytryptamine (5,7-DHT). A subpopulation of large, weakly fluorescing neurons were identified as composing a single, morphologically distinct ganglion cell type by intracellular injections of horseradish peroxidase (HRP). In a sample of 374 HRP-filled cells soma diameter ranged from 13-21 microns (mean +/- SD = 16.6 +/- 1.3). Dendritic field size increased with increasing retinal eccentricity from 150-200 microns diameter at 0.5 mm from the area centralis to 600-800 microns diameter in the far retinal periphery. Dendrites are thin (approximately 1 micron diameter), show a characteristic branching pattern, and are narrowly stratified at the outer border of the inner plexiform layer. The monoamine-accumulating ganglion cell and the outer (OFF-center) alpha cell occupy distinct strata within sublamina a of the inner plexiform layer separated by a gap of about 5 microns. The total number of monoamine-accumulating (MA) ganglion cells was estimated at 5,400, about 3.5% of the total ganglion cell population. Spatial density of the MA ganglion cells, calculated from cell counts made in vitro, ranges from 60 cells/mm2 near the area centralis to 5 cells/mm2 in the far retinal periphery. A coverage factor (density x dendritic field area) of 2.2 was maintained from central to peripheral retina. The nature of the dendritic overlap was observed directly by making HRP injections into several neighboring ganglion cells. Five to seven neighboring dendritic trees extensively overlapped a given cell's dendritic field. However the dendritic processes did not intersect randomly but tended to interdigitate such that a uniform interdendritic spacing and density of dendritic processes was constructed locally within the dendritic plexus. Rotation of individual dendritic trees from their normal orientation produced a dramatic 4-5-fold increase in the number of dendritic intersections, suggesting that an active, local mechanism operates in the precise placement of individual dendrites within the plexus. The monoamine-accumulating ganglion cell appears morphologically equivalent to the delta ganglion cell (Boycott and Wässle; J. Physiol. (Lond.) 240:397-419, '74; Kolb et al.; Vision Res. 21:1081-1114, '81) and to the recently recognized indoleamine-accumulating ganglion cell (Wässle et al: J. Neurosci. 7:1574-1585, '87).(ABSTRACT TRUNCATED AT 400 WORDS)

5,7-Dihydroxytryptamine↗
PubMed1991

Birthdates of trigeminal ganglion cells contributing axons to the infraorbital nerve and specific vibrissal follicles in the rat.

Prenatal labelling with [3H]-thymidine was combined with retrograde tracing techniques in adult rats to determine the birthdates of the trigeminal (V) ganglion cells that contributed axons to the infraorbital nerve (ION) and the generation of the subsets of ION cells that innervated specific vibrissae follicles (C-1 and C-5). The V ganglion cells contributing axons to the ION are born between embryonic (E-, E-0 = the day of conception) days 9.5 and 14.5. The percentages (normalized so that they total 100%) of the total V ganglion population born on E-9.5 through E-14.5 were 5.8, 25.7, 19.8, 23.4, 21.0, and 4.4%, respectively. The distribution of birthdates for the V ganglion cells that were retrogradely labelled from the ION closely matched that for the ganglion as a whole. All of these neurons were also born on E-9.5 through E-14.5, and the percentages born on each day were 6.3, 23.6, 18.1, 24.0, 23.6, and 4.4%. Finally, a similar distribution of birthdates was obtained for the V ganglion cells that were retrogradely labelled after injection of retrograde tracers into either the C-1 or C-5 vibrissae follicles. We were unable to detect any distinctive spatial distributions for either all V ganglion or ION cells born on a specific embryonic day. Furthermore, neurons with a given birthdate and that innervated a given follicle were distributed throughout the entire region containing all of the ganglion cells supplying the follicle in question. Therefore, it appears that the V ganglion cells contributing axons to the ION are born over the entire period of ganglion neurogenesis and further that the organization of the ION's innervation of the periphery is not a function of cell birthdate.

Animals↗
PubMed1992

New metrics for analysis of dendritic branching patterns demonstrating similarities and differences in ON and ON-OFF directionally selective retinal ganglion cells.

The morphology and dendritic branching patterns of retinal ganglion cells have been studied in Golgi-impregnated, whole-mount preparations of rabbit retina. Among a large number of morphological types identified, two have been found that correspond to the morphology of ON and ON-OFF directionally selective (DS) ganglion cells identified in other studies. These two kinds of DS ganglion cell are compared with each other, as well as with examples of class I, class II, and class III cells, defined here with reference to our previous studies. Cell body, dendritic field size and branching pattern are analyzed in this paper and levels of dendritic stratification are examined in the following paper. ON DS ganglion cells are about 10% larger in soma size and about 5 times the dendritic field area of ON-OFF DS ganglion cells, when compared at the same retinal location. These two morphological types of ganglion cell can be said to define the upper and lower bounds of an intermediate range of cell body and dendritic field sizes within the whole population of ganglion cells. Nevertheless, in previous physiological studies receptive field sizes of the two types were shown to be similar. This discrepancy between morphological and physiological evidence is considered in the Discussion in terms of a model of the excitatory receptive field of ON-OFF DS ganglion cells incorporating starburst amacrine cells. A new set of metrics is introduced here for the quantitative analysis and characterization of the branching pattern of neuronal arborizations. This method compares the lengths of terminal and preterminal dendritic branches (treated separately), as a function of the distances of their origins from the soma, viewed graphically in a two-dimensional scatter plot. These values are derived from computer-aided 3D logging of the dendritic trees, and distance from the soma is measured as the shortest distance tracked along the dendritic branches. From these metrics of the "branch length distributions," scale-independent branching statistics are derived. These make use of mean branch lengths and distances, slopes of lines fitted to the distributions, and elliptical indices of scatter in the distributions. By these measures, ON and ON-OFF DS ganglion cells have similar branching patterns, which they share to varying degrees with functionally unrelated class III.1 ganglion cells. The scale of the branching patterns of ON and ON-OFF DS cells and their degree of uniformity are different, however.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1995

Morphological classification of retinal ganglion cells in mice.

Mice have been used for extensive studies on optic nerves and retinal ganglion cells, but mouse retinal ganglion cells have not been classified morphologically. In the present study, normally placed retinal ganglion cells and displaced retinal ganglion cells in pigmented and albino mice were classified morphologically using horseradish peroxidase. These cells were classified into three types according to the sizes of the soma and the dendritic field: type I cells, large soma and large dendritic field; type II cells, small-to-medium soma and small dendritic field; and type III cells, small-to-medium soma and large dendritic field. Some ganglion cells had both symmetric and asymmetric cells. Each type was further subdivided according to the termination level of dendrites in the inner plexiform layer and the dendritic branching pattern. Except for type III displaced ganglion cells, dendrites of the normally placed ganglion cells and the displaced ganglion cells ramify in the outer two-fifths of the inner plexiform layer (sublamina a) or the inner three-fifths of the inner plexiform layer (sublamina b). Type III displaced ganglion cells ramify only in sublamina a. Dendrites of some normally placed type I ganglion cells ramify in both sublaminae. Displaced biplexiform cells were observed, the dendrites of which ramify in both the inner and the outer plexiform layers. All cell types were found in both mouse strains.

Animals↗
PubMed2000

[Effect of fibroblast growth factor-1 (FGF-1) on spiral ganglion cells of the mammalian cochlea].

Transient expression by hair cells, increasing levels of FGF-1 mRNA in neonatal rat spiral ganglion neurons and strong expression in adulthood, make FGF-1 a candidate to be associated with development and maintenance of the mammalian spiral ganglion. To test this hypothesis, dissociated spiral ganglion cells from 5 day old rats were cultured in the presence of FGF-1 at 100 ng/ml plus heparan sulfate proteoglycans (HSPG) at 500 ng/ml for 72 hours. Spiral ganglion cells incubated with FGF-1/HSPG achieved an average neurite length of 323 microns while control cells gained an average neurite length of 203 microns. The results of this study are consistent with our previous findings in whole spiral ganglion explants (3) where FGF-1 incubation significantly stimulated neurite outgrowth at about the same range. However, stimulation of neurite outgrowth in dissociated spiral ganglion cells suggests that FGF-1 directly binds to FGF receptors on the surface of spiral ganglion neurons and/or neurites instead of acting via intermediate cells such as glia. Since FGF receptor mRNA was found to be expressed only at very low levels in neonatal spiral ganglion neurons (7) it is possible that the receptors are highly localized, perhaps to neurite growth cones. Alternatively, an unknown FGF receptor or splice variant may be expressed in these cells. Adequate FGF-1 application to the human inner ear may stimulate spiral ganglion cell survival and neurite extension after hair cell loss in patients suitable for cochlear implant treatment. By creating a closer contact between spiral ganglion cells and the electrode, FGF-1 might also improve the efficacy of cochlear implants.

Animals↗
PubMed1995

The site of the inhibitory action of endogenous opioids in the superior cervical ganglion of the cat.

A low-frequency stimulus train to the preganglionic input inhibits synaptic transmission in the superior cervical ganglion (SCG) of the cat. The inhibition is blocked by naloxone as well as by selective antagonists at mu and delta opiate receptors, which suggests that the mediator is an endogenous opioid [27,29]. Exogenous opioid peptides, including methionine-enkephalin (Met-Enk), which is present in preganglionic axons of the SCG, inhibit ganglionic transmission by a naloxone-sensitive mechanism. In the present study we test, in the anesthetized cat, whether the naloxone-sensitive synaptic inhibition is mediated by a pre- and/or post-synaptic mechanism. As a test of presynaptic inhibition, we measured the acetylcholine (ACh) released by preganglionic stimulation into the venous effluent of the perfused SCG. As a test of post-synaptic inhibition, we measured the effect of a preganglionic conditioning train on the ganglion cell firing evoked by ganglion-stimulant drugs injected into the arterial supply of the ganglion. In presence of naloxone (3 microM), which blocked the synaptic inhibition, the amount of ACh released by stimulated preganglionic axons did not change. Thus, the endogenous opioid which mediates the naloxone-sensitive inhibition does not act by depressing ACh release. In contrast, the ganglion cell firing evoked by ganglion-stimulant drugs was markedly depressed by a conditioning train, and naloxone blocked the depression, which suggests that the endogenous mediator of the naloxone-sensitive inhibition acts postsynaptically to decrease the excitability of ganglion cells. Exogenous Met-Enk depressed both ACh release by preganglionic stimulation and the firing of ganglion cells evoked by ganglion-stimulant drugs.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia↗
PubMed1990

Retinal ganglion cell density and cortical magnification factor in the primate.

The question of whether the large area occupied by the primate fovea in the visual cortex (V1) is the result of a selective amplification of the central visual field, or whether it merely reflects the ganglion cell density of the retina, has been a subject of debate for many years. Measurements of the ganglion cell densities are made difficult by lateral displacements of cells around the fovea and the occurrence of amacrine cells in the ganglion cell layer. We have now identified and counted these amacrine cells by GABA immunocytochemistry and by retrograde degeneration of ganglion cells. By reconstructing the fovea from vertical and horizontal serial sections, we were able to measure the densities of cones, cone pedicles and ganglion cells within the same retina. We found 3-4 ganglion cells for every foveal cone. This ratio decreased to one ganglion cell per cone at an eccentricity of 15-20 deg (3-4 mm) and in peripheral retina there are more cones than ganglion cells. The ganglion cell density changes by a factor of 1000-4000 between peripheral and central retina. A comparable gradient has been reported for the representation of the peripheral and central visual field in V1. We suggest that ganglion cell density can fully account for the cortical magnification factor and there is no need to postulate a selective amplification of the foveal representation.

Animals↗
PubMed1991

Postnatal development of ganglion cells in the rabbit retina: characterizations with AB5 and GABA antibodies.

The use of cell-specific monoclonal antibodies provides a means by which the emergence, differentiation and maturation of retinal neurons can be studied. The present study investigates the labelling of ganglion cells in the developing rabbit retina by a ganglion cell-specific monoclonal antibody, AB5(12,13). AB5 labelling of ganglion cells was observed as early as day postnatal. By 6-8 days postnatal, AB5-labelled ganglion cells had begun differentiating into the various ganglion cell subtypes observed in the adult retina. This differentiation process appeared to continue throughout the first 3 weeks postnatal. The AB5 monoclonal antibody was also used in a double-label paradigm with an anti-gamma-aminobutyric acid (GABA) polyclonal antibody to differentiate the GABAergic ganglion cells from other GABAergic elements in the retina and to study their development. GABAergic ganglion cells were first observed at 3 days postnatal and by 6 days postnatal, it was possible to observe a wide variety of GABAergic ganglion cells ranging from small cells to large alpha-type cells. The appearance of AB5 labelling in ganglion cells at relatively early stages of development suggests that the AB5 monoclonal antibody may be a useful tool for studying the development of ganglion cell structure, distribution, synaptic relationships and neurochemical specificity.

Aging↗
PubMed1994

Ganglion cell neurogenesis, migration and early differentiation in the chick retina.

Neurogenesis, migration and maturation of ganglion cells in the posterior pole of chick retina have been studied using embryonic incorporation of [3H]thymidine, immunocytochemistry and retrograde labeling. Unlike previous studies, we have examined the neurogenesis of independently identified ganglion cells that have survived the period of naturally occurring cell death (embryonic days 11-16). Embryos were labeled with [3H]thymidine at different embryonic ages (embryonic days 3, 5 and 7). After the chicks hatched, ganglion cells were retrogradely labeled with rhodamine microspheres and the retinas were processed for autoradiography and fluorescent microscopy. The results indicate that 40% of the ganglion cells in the posterior pole undergo a final mitosis by embryonic day 3 and that more than 25% of the ganglion cells are born on or after embryonic day 7. These results also suggest that naturally occurring cell death does not preferentially affect ganglion cells born on specific embryonic days. Using immunocytochemistry with an antibody against neuron-specific beta-tubulin and retrograde labeling with the carbocyanine dye DiI we show that ganglion cells begin to differentiate before the completion of their migration to the presumptive ganglion cell layer. These results suggest the following developmental sequence. (1) Ganglion cells of the posterior pole undergo their final mitosis near the ventricular margin between embryonic days 2 and 8. (2) They maintain contacts with both retinal surfaces and their nuclei move toward the ganglion cell layer. At this time they start to differentiate, expressing a form of neuron-specific tubulin and growing axons that can reach the optic chiasm. (3) Once migration is completed dendritic development commences.

Animals↗
PubMed1996

Morphologic evidence for three cell types in the human spiral ganglion.

Although two types of spiral ganglion cells (large type I and smaller type II) have classically been described by anatomic studies in both animal and human spiral ganglion, there is physiologic and morphologic evidence for subtypes of the large type I ganglion cell. In addition, in the animal and human, a variety of morphologic differences based on cytoplasmic content, myelinization, immunostaining and morphometric analysis have suggested more than one variety of type I ganglion cell. Light and electron microscopic serial sections of the spiral ganglion in two human specimens in the basal, middle and upper middle turns were pooled for morphometric analysis of the cell area, nuclear area and axon diameter. Analysis of variance, bivariate scatter plots and multivariate cluster analysis provided evidence for 3 types of ganglion cells in the human spiral ganglion: large, intermediate and small, varying from each other significantly on the basis of cell area. It was suggested, based on the morphologic findings and prevalence of the cell types, that the large and intermediate cells were subtypes of the classic type I spiral ganglion cell, whereas the small ganglion cell was consistent with the classically described type II ganglion cell.

Adult↗