Structure of visual pathways in the nervous system of freshwater pulmonate molluscs

Central nervous system of freshwater pulmonate molluscs Lymnaea stagnalis and Planorbarius corneus was stained using retrograde transport of neurobiotin in the optic tract fibers. In both species, perikarya and fibers of the stained neurons are found in all ganglia except the buccal ones. Afferent fibers of the optic nerve form dense sensory neuropil located in relatively small volume of cerebral ganglia. Typical neuronal groups sending their processes into the optic nerves of ipsilateral and contralateral body halves are described. Among them, neurons of visceral and parietal ganglia innervating both eyes concurrently as well as sending projections into peripheral nerves are revealed. These neurons, supposedly, have a function to integrate sensory signals, which may be a basis for regulation of light sensitivity of retina and functioning of peripheral organs. Bilateral links of the molluscan eye with the pedal ganglia cells and statocysts are found, which is, likely, a structural basis of certain known behavioral patterns related to stimulation of visual inputs in the studied gastropod molluscs.     

Neurofilament phosphorylation in development. A sign of axonal maturation?

Monoclonal antibodies to the 200K neurofilament (NF) protein selectively decorated axons in tissue sections. Dilution of the antibodies in phosphate buffer and digestion with phosphatase abolished the stain. With conventional monoclonal and polyclonal NF antibodies, i.e. antibodies decorating NF regardless of their location (axons, perikarya and dendrites), the staining was not affected by this treatment. With all antibodies, axon-specific and conventional, the staining was abolished by trypsin digestion. Subsequent digestion with phosphatase did not restore the staining. Compared with conventional NF antibodies, staining with axon-specific anti-NF 200K was a late phenomenon in chick embryo development. NF 200K immunoreactivity was first observed in peripheral nerves and in the anterior columns of the spinal cord on day 10. Sensory ganglia and optic nerve fibers were negative. With conventional NF antibodies these structures were stained on days 4 and 5, respectively. In the following days of development the study was confined to the retina, optic nerves, cranial peripheral nerves and sensory ganglia. Up to day 16, bundles of thin peripheral nerve fibers, strongly decorated by conventional NF antibodies, did not stain with anti-NF 200K in double labelling experiments. Nerve bundles emerging from the ganglia were also negative, although some thick nerve fibers within the ganglia were stained. NF 200K immunoreactivity was first observed on day 17 in the optic nerve and in the layer of optic nerve fibers. At this time, staining was confined to the bundle emerging from the temporal side of the retina. In newborn chicken, only few fibers stained with anti-NF 200K in the nasal bundle, while the temporal bundle was well stained. It is suggested that the NF 200K antibodies reacted with a phosphorylated epitope in the axon, and that NF phosphorylation is a late event in ontogenesis probably related to axonal maturation.     

两种软体动物神经系统一氧化氮合酶的组织化学定位

运用一氧化氮合酶(NOS)组织化学方法研究了软体动物门双壳纲种类中国蛤蜊和腹足纲种类嫁Qi神经系统中NOS阳性细胞以及阳性纤维的分布。结果表明：在蛤蜊脑神经节腹内侧,每侧约有10-15个细胞呈强NOS阳性反应,其突起也呈强阳性反应,并经脑足神经节进入足神经节的中央纤维网中;足神经节内只有2个细胞呈弱阳性反应,其突起较短,进入足神经节中央纤维网中,但足神经节中,来自脑神经节阳性细胞和外周神经系统的纤维大多呈NOS阳性反应;脏神经节的前内侧部和后外侧部各有一个阳性细胞团,其突起分别进入后闭壳肌水管后外套膜神经和脑脏神经索。脏神经节背侧小细胞层以及联系两侧小细胞层的纤维也呈NOS阳性反应。嫁Qi中枢神经系统各神经节中没有发现NOS阳性胞体存在;脑神经节、足神经节、侧神经节以及脑—侧、脑—足、侧—脏连索中均有反应程度不同的NOS阳性纤维,这些纤维均源于外周神经。与已研究的软体动物比较,嫁Qi和前鳃亚纲其它种类一样,神经系统中NO作为信息分子可能主要存在于感觉神经。而中国蛤蜊的神经系统中一氧化氮作为信息分子则可能参与更广泛的神经调节过程。     

The stomatogastric nervous system of the house cricket Acheta domesticus L. I. The anatomy of the system and the innervation of the gut

The distribution of the ganglia and nerves of the stomatogastric nervous system and the innervation of the extrinsic and intrinsic muscles are described. Median unpaired frontal and hypocerebral ganglia and paired ingluvial ganglia are present. The anterior pharynx is innervated by branches of the frontal nerve and by the anterior and posterior pharyngeal nerves, originating from the frontal ganglion. The posterior pharyngeal nerves are linked to nerves innervating the posterior part of the pharynx which have their origin in the hypocerebral ganglion, the anterior portion of which has previously been regarded as part of the recurrent nerve. Paired esophageal nerves run the length of the esophagus and crop between the hypocerebral and and ingluvial ganglia, innervating the muscularis by serial side branches. From each ingluvial ganglion runs an ingluvial nerve which innervates the gizzard and a cecal nerve which innervates the midgut and its ceca. At the posterior end of the midgut there is a poorly developed nerve ring. Nerves running posteriorly from this nerve ring link the stomatogastric nervous system with the proctodeal innervation from the terminal abdominal ganglion. Multipolar peripheral neurons are present on the muscularis of the whole of the foregut, rather randomly distributed on the crop and gizzard but forming fairly definite groupings at some points on the pharynx. Though of varied appearance, these cells could not be divided into discrete morphological categories. Peripheral neurons on the midgut are of different and characteristic morphology, though a few cells of the same appearance as those of the foregut occur at the midgut-hindgut boundary. Nerve fibers on the gut almost invariably terminate on the fibers of the muscularis.     

Postembryonic development of leucokinin I-immunoreactive neurons innervating a neurohemal organ in the turnip moth Agrotis segetum

Summary In the abdominal ganglia of the turnip moth Agrotis segetum, an antibody against the cockroach neuropeptide leucokinin I recognizes neurons with varicose fibers and terminals innervating the perisympathetic neurohemal organs. In the larva, the abdominal perisympathetic organs consist of a segmental series of discrete neurohemal swellings on the dorsal unpaired nerve and the transverse nerves originating at its bifurcation. These neurohemal structures are innervated by varicose terminals of leucokinin I-immunoreactive (LKIR) fibers originating from neuronal cell bodies located in the preceding segment. In the adult, the abdominal segmental neurohemal units are more or less fused into a plexus that extends over almost the whole abdominal nerve cord. The adult plexus consists of peripheral nerve branches and superficial nerve fibers beneath the basal lamina of the neural sheath of the nerve cord. During metamorphosis, the LKIR fibers closely follow the restructuration of the perisympathetic organs. In both larvae and adults the LKIR fibers in the neurohemal structures originate from the same cell bodies, which are distributed as ventrolateral bilateral pairs in all abdominal ganglia. The transformation of the series of separated and relatively simple larval neurohemal organs into the larger, continuous and more complex adult neurohemal areas occurs during the first of the two weeks of pupal life. The efferent abdominal LKIR neurons of the moth Agrotis segetum thus belong to the class of larval neurons which persist into adult life with substantial peripheral reorganization occurring during metamorphosis.     

Changes in lectin binding of lumbar dorsal root ganglia neurons and peripheral axons after sciatic and spinal nerve injury in the rat

Summary The effects of chronic lesions of rat lumbar spinal or sciatic nerves on the binding of Glycine max (soybean) agglutinin to galacto-conjugates, in small-and medium-size primary sensory neurons of the L₄ and L₅ dorsal root ganglia, were examined over a 580-day period. Spinal nerve section resulted in a marked decrease in the population of stained neurons within 7 days. However, despite some retrograde morphological changes triggered by axonal injury, the proportion of stained nerve cells was normalized 180 days postoperatively. This temporary decrease in perikaryal lectin reactivity was initially associated with a marked accumulation of stained material in the nerve, proximal and distal to the site of section, with similar accumulations also being noticeable at each level of injury in sciatic nerves subjected to double ligature. This may reflect the presence of glycocompounds linked to the autolysis of nerve fibers during the phase of retrograde dying-back and Wallerian degeneration. At later stages, stained deposits could be seen scattered along central and peripheral axonal processes of the dorsal root ganglion neurons in the vicinity of the cell body. They may indicate a disturbance in the peripheral turnover of glycoproteins in chronically-transected nerves, with piling up of neuronal products. Sciatic nerve injury caused similar but less severe effects which, except for the L₄ ganglion cells, were rapidly reversible.     

化学损毁交感神经后大鼠心内神经节生长抑素的变化

应用免疫组织化学和原位杂交方法研究了大鼠心内神经节细胞中SS的分布及其mRNA表达。结果发现,大鼠心内神经节中有SS－IR阳性神经纤维和细胞,心内神经部分细胞浆中有SSmRNA表达,表明大鼠心内神经节细胞有SS合成和贮存。用小剂量6－OH－DA选择性损毁心内交感神经纤维后,心内神经节中SS－IR阳性神经纤维和细胞的积分光密度均有不同程度增强,反映了心内交感神经和付交感神经的相互抑制作用。     

The ultrastructure of the cardiac ganglion of the desert scorpion,Paruroctonus mesaensis (Scorpionida: Vaejovidae)

Light and electron microscopy of the pacemaker ganglion of the scorpion heart indicate that it is about 15 mm long and 50 μm in diameter and extends along the dorsal midline of the heart. The largest cell bodies (30–45 μm in diameter) occur in clusters along the length of the ganglion. The ganglion appears to be innervated with fibers from the subesophageal and first three abdominal ganglia. The cardiac ganglion is surrounded by a neurilemma and a membranous sheath. The latter is apparently derived from connective tissue cells seen outside the ganglion. Nerve fibers other than those in the neuropil areas are usually surrounded by membrane and cytoplasm of glial cells. Often there are several layers of glial membrane, forming a loose myelin. The cardiac nerves to the heart muscle are also surrounded by a neurilemma, and the axons are surrounded by glia. The motor nerves contain lucent vesicles 60–100 nm and opaque granules 120–180 nm in diameter. In the cardiac ganglion, some nerve cell bodies have complex invaginations of glial processes forming a peripheral trophospongium. In the neuropil areas, nerve cell processes are often in close apposition. The septilaminar configuration typical of gap junctions is common, with gap distances of 1–4 nm. In tissues stained with lanthanum phosphate during fixation, we found gaps with unstained connections (1–2 nm diameter) between nerve-nerve and glial-nerve cell processes. Annular or double-membrane vesicles in various stages of formation were also seen in some nerve fibers in ganglia stained with lanthanum phosphate. Nerve endings with electron-lucent vesicles 40–60 nm in diameter are abundant in the cardiac ganglion, suggesting that these contain the excitatory transmitter of intrinsic neurons of the ganglion. Less abundant are fibers with membrane-limited opaque granules, circular or oblong in shape and as much as 330 nm in their longest dimension. Also seen were some nerve endings with both vesicles and granules.     

青年猫和老年猫视神经超微结构观察比较

目的探讨青年猫和老年猫视神经年龄相关的形态学变化及可能造成的生理影响。方法取4只青年猫(2-3岁,2-2.5kg)和4只老年猫(10-13岁,2.5-3.5kg)颅内相对应部分视神经,制作横向半薄切片和超薄切片,半薄切片用甲苯胺蓝硼砂溶液染色,光镜观察、测量视神经的直径(不含外层神经膜);超薄切片标本用醋酸和柠檬酸铅染色,电镜观察、计数视神经纤维密度、测量视神经纤维外径D(含髓鞘)和内径d(不含髓鞘),按一定分级范围算出各种直径的纤维及各种d/D比值的纤维所占百分比,分别画出直方图,对实验结果进行统计学分析并绘制纤维直径谱。结果与青年猫相比,老年猫视神经直径显著增大(P0.05);纤维数量显著下降(P0.05)。纤维直径谱分析结果显示,青、老年猫纤维直径分布范围相似,但老年猫纤维的峰直径及纤维平均直径比青年猫的显著减小(P0.05),老年猫视神经纤维的d/D比值亦明显降低。另外,老年猫视神经中部分轴突肿胀,髓鞘疏松、结构紊乱,板层脱离、空泡化,有的轴索髓鞘溶解。结论在衰老过程中,老年猫视神经纤维丢失,纤维直径减小,d/D比值下降,以及纤维髓鞘的松散解体,这些变化均可能导致视神经纤维对视觉信息的传导速度减慢,是老年个体视觉分析速度下降的重要原因。     

Immunocytochemical localization of carbonic anhydrase in myelinated fibers in peripheral nerves of rat and mouse

Rat sciatic nerve, spinal root, and cranial nerve were immunostained with an antibody against rat brain carbonic anhydrase II (ca), to determine the localization of ca in the rat peripheral nervous system (PNS). Similar methods were applied to mouse nerves to see if that antigen could be detected in the PNS of this species. In rat nerves, intense immunostaining was observed in the axoplasm of many of the myelinated fibers, whereas others were stained less intensely or were negative. A heterogeneous pattern of immunostaining was also found in neuronal perikarya within the ganglia, and in some regions of the ganglia ca immunostaining was found in putative satellite cells and their processes. Ca in rat PNS therefore appears to occur at both neuronal and glial sites, whereas it is exclusively glial in the CNS. In longitudinal sections of some fibers within rat nerves, ca immunostaining could be detected at the inner boundaries of the myelin sheaths. In mouse nerves, axoplasmic staining was observed but it was fainter than in rat nerves. Interspecies differences were most obvious in the dorsal columns of the spinal cord. In rat, intensely stained axons proceeded through the roots into the gracilis or cuneate and often into the gray matter. In mouse, there was much less immunostaining of axons but more intense ca immunostaining in CNS myelin than in the CNS myelin in the rat cord. The implications concerning putative functions of ca in the rodent nervous system are discussed.     

Melanogenesis in cultures of peripheral nervous tissue: I. The origin and prospective fate of cells giving rise to melanocytes

Chick embryo spinal ganglia, peripheral nerves, and connective tissue usually associated with ganglia were cultured separately using several combinations of media and substrata. Melanocytes appear in cultures of both ganglia and peripheral nerves. The only cell type common to both the ganglion and peripheral nerve that could account for the observed pigment cells was the population of small cells with intensely staining nuclei that normally associates closely with nerve cell bodies and fibers. These cells could be distinguished morphologically from fibroblastic cells, which originated in the connective tissue capsule and did not undergo melanogenesis. We conclude that these small cells are supportive (Schwann, satellite, and perineurial) cell precursors and are one source of melanocytes in cultured peripheral nervous tissue.     

Control of leech swimming activity by the cephalic ganglia

We investigated the role played by the cephalic nervous system in the control of swimming activity in the leech, Hirudo medicinalis, by comparing swimming activity in isolated leech nerve cords that included the head ganglia (supra- and subesophageal ganglia) with swimming activity in nerve cords from which these ganglia were removed. We found that the presence of these cephalic ganglia had an inhibitory influence on the reliability with which stimulation of peripheral (DP) nerves and intracellular stimulation of swim-initiating neurons initiated and maintained swimming activity. In addition, swimming activity recorded from both oscillator and motor neurons in preparations that included head ganglia frequently exhibited irregular bursting patterns consisting of missed, weak, or sustained bursts. Removal of the two head ganglia as well as the first segmental ganglion eliminated this irregular activity pattern. We also identified a pair of rhythmically active interneurons, SRN1, in the subesophageal ganglion that, when depolarized, could reset the swimming rhythm. Thus the cephalic ganglia and first segmental ganglion of the leech nerve cord are capable of exerting a tonic inhibitory influence as well as a modulatory effect on swimming activity in the segmental nerve cord.     

猫视神经年龄相关的形态学变化

对4只青年猫(1-3龄)和4只老年猫(10-13龄)视神经进行形态计量比较研究。取两个年龄组的颅内相应部分视神经进行横向连续切片,H.E染色于光镜下观察其基本结构;相邻切片进行结晶紫染色显示胶质细胞;神经丝蛋白(NF)免疫染色显示视神经纤维,胶质纤维酸性蛋白(GFAP)免疫染色显示星形胶质细胞(AS),对实验结果进行统计学分析并绘制纤维直径谱。与青年猫相比,老年猫视神经外膜厚度、直径、面积均显著增加,视神经纤维的密度和数量显著下降,且以视神经中央部纤维密度下降最显著;纤维直径谱分析结果显示,青、老年猫纤维直径分布范围相似,但老年猫的峰直径及纤维平均直径比青年猫的显著减小;另外,老年猫视神经束中的星形胶质细胞明显膨大,胶质细胞密度以及星形胶质细胞占胶质细胞总数的百分比均显著增加。结果表明:在衰老过程中视神经纤维出现明显的丢失现象,纤维平均直径显著减小使其对视觉信息的传导速度减慢,这可能是导致老年个体视觉分析速度下降的重要原因;老年个体视神经束内胶质细胞活动增强可能对维持视神经纤维形态、功能或延缓视神经进一步衰老起保护作用     

The mapping of the neurons that participate in the innervation of the body wall of the edible snail]

In the paper are presented the results of the experiments with the retrograde staining of the left-side cutaneous nerves of the pedal ganglia of the snail Helix lucorum. The somata of neurons which sent processes forming the studied nerves were revealed with the help of nickel and cobalt ions precipitation by the rubeanic acid. A lot of nerve cells including some command neurons were found in all the ganglia excluding the buccal ones. Especially large amount of neurons was stained in the ipsilateral pedal, pleural, and parietal ganglia.     

A NOTE ON THE ACTION OF CURARE,ATROPINE, AND NICOTINE ON THE INVERTEBRATE HEART

1. The alkaloids (curare, atropine, and nicotine) in molluscs and arthropods stimulate and paralyze the central nervous system and peripheral (visceral) ganglia, but do not paralyze the motor nerve endings to skeletal or visceral muscle. 2. They stimulate and paralyze the denervated heart. 3. They paralyze or block the cardioinhibitory nerves, but not the cardioaccelerator nerves. 4. In the Limulus heart these drugs act primarily on the heart ganglion, not on the heart muscle or the intrinsic motor nerve fibers.     

Localization of Lom-AG-myotropin I-like substances in the male reproductive and nervous tissue of the locust,Locusta migratoria

Summary Lom-AG myotropin I (Lom-AG-MTI) was the first peptide to be isolated from the male accessory reproductive glands of the locust, Locust migratoria. It shows no sequence similarity to any of the peptides identified from vertebrate or invertebrate tissues. A polyclonal antiserum was used to localize Lom-AG-MTI-like material in the male reproductive system and nervous system of the locust. Immunoreactivity was found in two of the hyaline gland tubules. In the brain, cell bodies were detected in the proto- and deuterocerebrum as well as the frontal ganglion. Nerve fibers were stained in the neuropils of the brain and throughout the labial nerves into the recurrent nerve. Thoracic and last abdominal ganglia contained neurons which could be stained with Lom-AG-MTI antiserum. The pronounced reactivity in the central nervous system suggests a possible neuroregulatory function of the peptide.     

大鼠脊神经节内交感神经支配的荧光组织化学与HRP示踪观察

本研究应用乙醛酸诱发儿茶酚胺（ＣＡ）荧光技术观察大鼠肾上腺素（ＮＡ）能神经在脊神经节内的分布;并应用ＨＲＰ顺、逆行追踪技术对脊神经节内ＮＡ能神经纤维的起源及其与脊神经节神经元的关系进行了探讨。荧光组织化学观察发现、有些神经节神经元胞体周围分布有带膨体的ＮＡ能神经末梢;有的紧密围绕脊神经节细胞——卫星细胞复合体。颈上交感神经节内注射霍乱毒素Ｂ亚单位结合ＨＲＰ（ＣＢ┐ＨＲＰ）,在同侧Ｃ３～６节段脊神经节内可见标记的点状纤维末梢紧邻于节细胞旁。Ｔ１１～Ｌ２节段脊神经节内注射ＨＲＰ后,在同侧椎旁交感链（Ｔ９～Ｌ１）内可见标记的交感节后神经元胞体。上述实验结果表明,交感节后神经元发出节后纤维可直接到达脊神经节内,与节细胞发生接触。本研究提示、交感神经在脊神经节水平可能参与躯体初级传入信息的调制     

Neuronal organization of the left celiac ganglion in the cat

Unit responses of the isolated left celiac ganglion to stimulation of various nerves of the solar plexus were studied by intracellular microelectrode recording in cats before and after degeneration of the preganglionic fibers. The resting potential of the ganglionic neurons was ?62.2±2.9 mV and the amplitude of the spike potential 72.4±3.2 mV. The spike was followed by after-hyperpolarization with a mean amplitude of 24% of the spike amplitude and a duration of between 25 and 180 msec. A characteristic feature of the ganglion was the presence of orthodromic unit responses to stimulation of peripheral nerve fibers of the solar plexus. The higher threshold of activation of the neurons by peripheral fibers than by preganglionic fibers and the preservation of orthodromic unit responses to stimulation of peripheral nerves after degeneration of the preganglionic fibers are evidence that the peripheral reflex arc is closed in this ganglion. Neurons of the left celiac ganglion are divided into three groups. Only preganglionic fibers of the splanchnic nerve with different properties converge on the neurons of the first group (the most numerous); only afferent fibers of peripheral nerves converge on the neurons of the third group (the least numerous); both types of fibers terminate on neurons of the second group. This convergence may lie at the basis of the mechanism of the centrifugal and peripheral reflex interaction in the ganglion for coordinated visceral activity.     

Monoamines in the nervous system of the tube-wormChaetopterus variopedatus (Polychaeta): Biochemical detection and serotonin immunoreactivity

Summary The presence and distribution of biogenic monoamines in the tube-wormChaetopterus variopedatus were investigated by a radioenzymatic method and HPLC with electrochemical detection, and the cellular localization of serotonin by peroxidase-antiperoxidase (PAP) immunohistochemistry with an antibody against serotonin-formaldehyde-protein conjugate. Dopamine, norepinephrine, epinephrine, serotonin (5-HT) and some of their metabolites were detectable, dopamine and norepinephrine being present in substantially larger amounts than 5-HT and epinephrine. With few exceptions, the largest amounts of amines were localized in the most nerve-rich tissues such as tentacles, and those containing cerebral ganglia and the ventral nerve cord. Serotonin-immunoreactive unipolar neurons were widely distributed in the dorso-lateral cerebral ganglia, the neurosecretory pharyngeal ganglion and the segmental ganglia of the anterior (dorsolateral) and posterior (medioventral) nerve cords. Some nerve-fiber tracts stained in the cerebral ganglia, but the neuropiles of segmental ganglia were the most intensely reactive CNS structures. Numerous reactive fibers were also present in connectives, commissures and segmental nerves. All peripheral sensory structures included serotonin-immunoreactive cells and neurites, especially the parapodial cirri and the bristle receptors of the setae. Trunk and parapodial muscles contained reactive varicose fibers and neuronal somata. These results suggest that monoamines are abundant and widespread in these worms and that 5-HT appears to have a key sensory role.     

The distribution of putative nitric oxide releasing neurones in the locust abdominal nervous system: a comparison of NADPHd histochemistry and NOS-immunocytochemistry

Nitric oxide is well established as a signalling molecule in the nervous system of vertebrates and invertebrates. In this study we evaluate the usefulness of NADPHdiaphorase histochemistry and immunocytochemistry for detecting the presence of nitric oxide synthase in locusts. We describe the distribution of putative nitric oxide releasing neurones and stained neuropiles in the locust ventral nerve cord, in particular the abdominal ganglia and abdominal neuromeres. NADPHdiaphorase histochemistry revealed prominent staining in all neuropilar regions and a specific distribution pattern of stained cell bodies in all examined ganglia. Nitric oxide synthase immunocytochemistry, using a commercially available universal antibody, labelled cells in corresponding positions within the ganglia. This was confirmed by double labelling of alternate sections. Western blot analysis demonstrated that in locusts this universal NOS-antibody binds to a protein of similar size to nitric oxide synthase identified in other insect species. The antibody also labelled axons in most peripheral nerves of all examined ganglia, whereas NADPHdiaphorase histochemistry only revealed such stained fibres within peripheral nerves in some preparations, because they may have been masked by intense background staining. We therefore conclude that nitric oxide synthase-immunocytochemistry and NADPHd histochemistry are both good markers for the presence of nitric oxide synthase in the locust ventral nerve cord, and that nitric oxide may be used as a signalling molecule by efferent neurones in locusts.