The distribution of pheromone-biosynthesis-activating neuropeptide (PBAN) immunoreactivity in the central nervous system of the corn earworm moth,Helicoverpa zea

Summary Production of sex pheromone in several species of moths has been shown to be under the control of a neuropeptide termed pheromone-biosynthesis-activating neuropeptide (PBAN). We have produced an antiserum to PBAN from Helicoverpa zea (Lepidoptera: Noctuidae) and used it to investigate the distribution of immunoreactive peptide in the brain-suboesophageal ganglion complex and its associated neurohemal structures, and the segmental ganglia of the ventral nerve cord. Immunocytochemical methods reveal three clusters of cells along the ventral midline in the suboesophageal ganglion (SOG), one cluster each in the presumptive mandibular (4 cells), maxillary (12–14 cells), and labial neuromeres (4 cells). The proximal neurites of these cells are similar in their dorsal and lateral patterns of projection, indicating a serial homology among the three clusters. Members of the mandibular and maxillary clusters have axons projecting into the maxillary nerve, while two additional pairs of axons from the maxillary cluster project into the ventral nerve cord. Members of the labial cluster project to the retrocerebral complex (corpora cardiaca and cephalic aorta) via the nervus corpus cardiaci III (NCC III). The axons projecting into the ventral nerve cord appear to arborize principally in the dorsolateral region of each segmental ganglion; the terminal abdominal ganglion is distinct in containing an additional ventromedial arborization in the posterior third of the ganglion. Quantification of the extractable immunoreactive peptide in the retrocerebral complex by ELISA indicates that PBAN is gradually depleted during the scotophase, then restored to maximal levels in the photophase. Taken together, our findings provide anatomical evidence for both neurohormonal release of PBAN as well as axonal transport via the ventral nerve cord to release sites within the segmental ganglia.Abbreviations A aorta - Br-SOG brain-suboesophageal ganglion complex - CC corpus cardiacum - PBS phosphate-buffered saline - PLI PBAN-like immunoreactivity - TAG terminal abdominal ganglion - VNC ventral nerve cord     

Neural control of rhythmic pheromone gland exposure in Utetheisa ornatrix (Lepidoptera: Arctiidae)

The rhythmic exposure of the sex pheromone gland during calling in female Utetheisa ornatrix (L.) (Lepidoptera: Arctiidae) is under neural control. Two lines of evidence support this conclusion. (1) Bisection of the ventral nerve cord of adult females prevented calling while sham-operations had little effect. (2) Brief electrical stimulation of the ventral nerve cord in isolated abdomens elicited extended trains of regularly spaced gland exposures indistinguishable from normal calling behaviour. The coordination of calling behaviour is localized in the terminal abdominal ganglion and the peripheral structures that it innervates. Removal of the corpora allata and corpora cardiaca, neurohaemal organs previously implicated in calling control, did not affect calling behaviour.     

FMRfamide-like immunoreactivity in the ventral nerve cord of the larval eastern spruce budworm,Choristoneura fumiferana (clemens) (Lepidoptera : Tortricidae)

Distribution of FMRFamide-like immunoreactivity was examined in the larval ventral nerve cord of the eastern spruce budworm, Choristoneura fumiferana (Lepidoptera : Tortricidae). Indirect immunofluorescent methods revealed the existence of 3 groups of FLI neurons in each ganglion. The neurons are distributed in a bilaterally symmetrical fashion at the anterodorsal, midlateral and posteroventral regions of the ganglia. There are 4 FMRFamide-like immunoreactive fiber tracts on the dorsal surface of the ganglia to which the anterodorsal FLI neurons project ipsilaterally, while the midlateral pair projects both ipsi-, and contralaterally. The last abdominal ganglion (AG8) has 4 additional pairs of FLI neurons; and axons from some of these extend into the median abdominal nerve, which suggests some role for this neuropeptide in the control of posterior structures of the larva.     

Immunocytochemical study of tyrosine hydroxylase and dopamine β-hydroxylase immunoreactivities in the rat pancreas

An immunohistochemical and immunoelectron microscopic study was used to demonstrate tyrosine hydroxylase (TH) and dopamine -hydroxylase (DBH) immunoreactivities in the rat pancreas. Small TH immunoreactive cells were found in close contact with large TH immunonegative ganglion cells among the exocrine glands and were occasionally found in some islets. Some of these TH immunoreactive cells were also DBH immunopositive. The immunoreaction product was seen diffusely in the cytoplasm and in the granule cores of TH immunoreactive cells. All intra-pancreatic ganglion cells were immunoreactive for DBH, but not for TH. The TH immunoreactive cells were identified as small intensely fluorescent (SIF) cells due to their localization and morphological characteristics and showed no insulin, glucagon, somatostatin or pancreatic polypeptide immunoreactivities. These results indicate that SIF cells may release dopamine or noradrenaline to adequate stimuli while the intra-pancreatic ganglion cells with only DBH may not synthesize catecholamines in a normal biosynthetic pathway. TH immunoreactive nerve bundles without varicosities and fibers with varicosities, associated or unassociated with blood vessels, were found in both the exocrine and endocrine pancreas. Close apposition of TH immunoreactive nerve fibers to the smooth muscle and endothelial cells of the blood vessels was observed. A close apposition between TH immunoreactive nerve fibers and exocrine acinar cells and islet endocrine cells was sometimes found in the pancreas. The immunoreaction product was seen diffusely in the axoplasm and in the granular vesicles of the immunoreactive nerve fibers. Since no TH immunoreactive ganglion cells were present in the rat pancreas, the present study suggests that noradrenergic nerve fibers in the pancreas may be extrinsic in origin, and may exert an effect on the regulation of blood flow and on the secretory acitivity of the acinar cells, duct cells and endocrine cells.     

Structure of allotransplanted ganglia and regenerated neuromuscular connections in crayfish

In adult crayfish, Procambarus clarkii, motoneurons to a denervated abdominal superficial flexor muscle regenerate long-lasting and highly specific synaptic connections as seen from recordings of excitatory postsynaptic potentials, even when they arise from the ganglion of another crayfish. To confirm the morphological origins of these physiological connections we examined the fine structure of the allotransplanted tissue that consisted of the third abdominal ganglion and the nerve to the superficial flexor muscle (the fourth ganglion and the connecting ventral nerve cord were also included). Although there is considerable degeneration, the allotransplanted ganglia display intact areas of axon tracts, neuropil, and somata. Thus in both short (6–8 weeks) and long (24–30 weeks) term transplants approximately 20 healthy somata are present and this is more than the five axons regenerated to the host muscle. The principal neurite and dendrites of these somata receive both excitatory and inhibitory synaptic inputs, and these types of synaptic contacts also occur among the dendritic profiles of the neuropil. Axon tracts in the allotransplanted ganglia and ventral nerve cord consist largely of small diameter axons; most of the large axons including the medial and lateral giant axons are lost. The transplanted ganglia have many blood vessels and blood lacunae ensuring long-term survival. The transplanted superficial flexor nerve regenerates from the ventral to the dorsal surface of the muscle where it has five axons, each consisting of many profiles rather than a single profile. This indicates sprouting of the individual axons and accounts for the enlarged size of the regenerated nerve. The regenerated axons give rise to normal-looking synaptic terminals with well-defined synaptic contacts and presynaptic dense bars or active zones. Some of these synaptic terminals lie in close proximity to degenerating terminals, suggesting that they may inhabit old sites and in this way ensure target specificity. The presence of intact somata, neuropil, and axon tracts are factors that would contribute to the spontaneous firing of the transplanted motoneurons. © 1996 John Wiley & Sons, Inc.     

Neurological influences on pheromone release and calling behaviour in the gypsy moth, Lymantria dispar

ABSTRACT. Surgical removal of the brain or disconnection of the last abdominal ganglion from the ventral nerve cord prevented sex pheromone release in female Lymantria dispar (L.) (Lymantriidae), as assayed by the male wing-fanning response. The calling behaviour continued to occur in individuals whose terminal abdominal ganglion had been thus isolated, however, indicating that the neural mechanisms controlling calling function independently in the last abdominal ganglion.     

Distribution of SchistoFLRFamide-like immunoreactivity in the adult ventral nervous system of the locust,Schistocerca gregaria

SchistoFLRFamide (PDVDHVFLRF-NH₂) is one of the major endogenous neuropeptides of the FMRF-amide family found in the nervous system of the locust,Schistocerca gregaria. To gain insights into the potential physiological roles of this neuropeptide we have examined the distribution of SchistoFLRFamide-like immunoreactivity in the ventral nervous system of adult locusts by use of a newly developed N-terminally specific antibody. SchistoFLRFamide-like immunoreactivity in the ventral nerve cord is found in a subgroup of the neurones that are immunoreactive to an antiserum raised against bovine pancreatic polypeptide (BPP). In the suboesophageal ganglion three groups of cells stain, including one pair of large posterior ventral cells. These cells are the same size, in the same location in the ganglion and have the same branching pattern as a pair of BPP immunoreactive cells known to innervate the heart and retrocerebral glandular complex of the locust. In the thoracic and abdominal ganglia two and three sets of cells, respectively, stain with both the SchistoFLRFamide and BPP antisera. In the abdominal ganglia the immunoreactive cells project via the median nerves to the intensely immunoreactive neurohaemal organs.     

Embryology of the thoracic and abdominal ganglia of the large milkweed bug, Oncopeltus fasciatus (Dallas), (Hemiptera, Lygaeidae)

In this study, the condensation of the three thoracic and 11 abdominal segmental ganglia to form a prothoracic and central nerve mass during embryogenesis is described. During katatrepsis, many changes occur in the organization of these ganglia; this study suggests that some of these changes are caused by mechanical forces acting on the ventral nerve cord at this time. The ventral nerve cord begins its anterior migration and coalescence ten hours after katatrepsis and is completed 63 hours later. The central ganglion is made up of the meso- and metathoracic ganglia and seven abdominal ganglia. Intrasegmental median cord nuclei are shown to form glial elements in the median sagittal plane of the neuropile and in the longitudinal connectives. Intersegmental median cord neuroblasts migrate into the posterior gangliomeres but, apparently, degenerate soon after katatrepsis. Lateral cord cells bordering on the neuropile form a glial investment that surrounds this fiber tract region. Peripheral lateral cord cells are shown to form the cells of the outer ganglionic sheath, the perineurium.     

Regulation of sex pheromone biosynthesis in two noctuid species,S. littoralis and M. brassicae,may involve both PBAN and the ventral nerve cord

In order to understand better the mechanism of regulation of pheromone production in moth species, we performed ELISA analyses to detect and follow pheromone biosynthesis activating neuropeptide-like immunoreactivity (PBAN-IR) in different tissues of the two noctuidae species, Spodoptera littoralis and Mamestra brassicae. Male S. littoralis and both male and female M. brassicae brain-subesophageal ganglion (Br-SEG), corpora cardiaca-corpora allata complex, and terminal abdominal ganglion extracts showed the presence of PBAN-IR during both the photophase and the scotophase. However, PBAN-IR was found only in scotophase in female hemolymph. Analysis of extracts of Br-SEG, terminal abdominal ganglion, and hemolymph after HPLC fractionation showed that the most immunoreactive fraction in all the extracts exhibited the same retention time as Hez-PBAN, suggesting that similar PBAN-like material is present in all these tissues. In vivo studies demonstrated that severing the ventral nerve cord in M. brassicae anterior to the terminal abdominal ganglion impaired normal sex pheromone production by third-scotophase females, as was previously shown in S. littoralis. Additionally, PBAN-IR levels were lower in hemolymph samples obtained at the peak of pheromone production in both S. littoralis and M. brassicae females that had the ventral nerve cord severed compared with sham operated animals. These results, along with earlier reported data, indicate that control of pheromone production in both species may involve both PBAN (or PBAN-like peptides) and the ventral nerve cord and support the hypothesis that a neural input from the ventral nerve cord triggers the release of the pheromonotropic peptide(s) into the hemolymph, which then acts directly on the pheromone gland to stimulate pheromone biosynthesis. Arch. Insect Biochem. Physiol. 37:295–304, 1998. © 1998 Wiley-Liss, Inc.

1 We thank Germán Lázaro for insect rearing.

     

Localization of pigment-dispersing hormone (PDH) immunoreactivity in the central nervous system of Carcinus maenas and Orconectes limosus (Crustacea), with reference to FMRFamide immunoreactivity in O. limosus

Summary By use of antisera raised against synthetic pigment-dispersing hormone (PDH) of Uca pugilator and FMRFamide, the distribution of immunoreactive structures in the central nervous system (CNS) of Carcinus maenas and Orconectes limosus was studied by light microscopy. In both species, a total of 10–12 PDH-positive perikarya occur amongst the anterior medial, dorsal lateral and angular somata of the cerebral ganglion (CG). In C. maenas, one PDH-perikaryon was found in each commissural ganglion (COG) and several more in the thoracic ganglion. In O. limosus, only four immunopositive perikarya could be demonstrated in the ventral nerve cord, i.e., two somata in the anterior and two in the posterior region of the suboesophageal ganglion (SOG). PDH-immunoreactive tracts and fiber plexuses were present in all central ganglia of both species, and individual axons were observed in the connectives. FMRFamide-immunoreactivity was studied in O. limosus only. Neurons of different morphological types were found throughout the entire CNS, including numerous perikarya in the anterior medial, anterior olfactory, dorsal lateral and posterior cell groups of the CG. Four perikarya were found in the COG, six large and numerous smaller ones in the SOG, and up to eight cells in each of the thoracic and abdominal ganglia. In each ganglion, the perikarya form fiber plexuses. Axons from neurons belonging to the CG could be traced into the ventral nerve cord; nerve fibers arising from perikarya in the SOG appeared to project to the posterior ganglia. In none of the structures examined colocalization of PDH- and FMRF-amide-immunoreactivity was observed.Dedicated to Prof. K.-E. Wohlfarth-Bottermann on the occasion of his 65th birthday     

Organization of the larval pre-ecdysis motor pattern in the tobacco hornworm,Manduca sexta

The tobacco hornworm, Manduca sexta, undergoes several larval molts before transforming into a pupa and then an adult moth. Each molt culminates in ecdysis, when the old cuticle is shed. Prior to each larval ecdysis, the old cuticle is loosened by pre-ecdysis behavior, which consists of rhythmic compressions that are synchronous along the abdomen and on both body sides, and rhythmic retractions of the abdominal prolegs. Both pre-ecdysis and ecdysis behaviors are triggered by a peptide, eclosion hormone. The aim of the present study was to investigate the neural circuitry underlying larval preecdysis behavior. The pre-ecdysis motor pattern was recorded in isolated nerve cords from eclosion hormone-treated larvae, and the effects of connective transections and ionic manipulations were tested. Our results suggest that the larval pre-ecdysis compression motor pattern is coordinated and maintained by interneurons in the terminal abdominal ganglion that ascend the nerve cord without chemical synaptic relays; these interneurons make bilateral, probably monosynaptic, excitatory connections with identified pre-ecdysis motor neurons throughout the abdominal nerve cord. This model of the organization of the larval pre-ecdysis motor pattern should facilitate identification of the relevant interneurons, allowing future investigation of the neural basis of the developmental weakening of the pre-ecdysis motor pattern that accompanies the larval-pupal transformation.Abbreviations A3, A4... abdominal ganglia 3, 4... - AT terminal abdominal ganglion - ALE anterior lateral external muscle - DN dorsal nerve - DN_A anterior branch of the dorsal nerve - DN_L lateral branch of the dorsal nerve - DN_P posterior branch of the dorsal nerve - EH eclosion hormone - TP tergopleural muscle - VN ventral nerve - VN_A anterior branch of the ventral nerve - VN_L lateral branch of the ventral nerve - VN_P posterior branch of the ventral nerve     

Abdominal distention terminates subsequent host-seeking behaviour of Aedes aegypti following a blood meal

The failure of Aedes aegypti females to engage in host-seeking behaviour following a replete blood meal was investigated. Abdominal distention appears to be responsible for this immediate inhibition after feeding. Large enemas of saline had the same effect as blood in terminating host-seeking; this was not due merely to the presence of large amounts of fluid, but rather to the distention produced by these liquids. Since transection of the ventral nerve cord anterior to the 2nd abdominal ganglion did not release the inhibition in blood-fed females, we restricted the degree of distention of abdominal segments with wax. Distention of the abdomen anteriorly by a blood meal more effectively inhibited host-seeking than did distention posteriorly, suggesting that stretch receptors in the anterior portion of the abdomen regulate the response towards a host.     

Properties of descending dorsal unpaired median (DUM) neurons of the locust suboesophageal ganglion

A group of six dorsal unpaired median (DUM) neurons of the suboesophageal ganglion (SOG) of locusts was studied with neuroanatomical and electrophysiological techniques. The neurons are located posteriorly in the SOG and have axons that descend into the ganglia of the ventral nerve cord, some as far as the terminal abdominal ganglion. Within thoracic ganglia the neurons have profuse dendritic ramifications in many neuropiles, including ventral sensory neuropiles. Based on their projection patterns three different morphological types of neurons can be distinguished. These neurons receive excitatory inputs through sensory pathways that ascend from the thoracic ganglia and are activated by limb movements. They may be involved in the modulation of synaptic transmission in thoracic ganglia.     

Signal transmission in the photosensitive pineal organ of the rainbow trout: Modulation of ganglion cell activity by intrinsic dopamine

The photosensitive pineal organ of the rainbow trout (Oncorhynchus mykiss) transduces photic information into nycthemeral neuronal signals. To investigate origin, cellular localization, and functional significance of pineal catecholamines, we performed HPLC-analysis of catecholamines and tyrosine hydroxylase (TH) activity, as well as immunocytochemical and electrophysiological studies. In biochemical and immunocytochemical investigations, pineal cells were found to contain endogenous TH. Using HPLC-analysis, the presence of a catecholamine precursor ( -dopa), catecholamines (dopamine, norepinephrine, epinephrine), and a metabolite (DOPAC) was demonstrated. The release of -dopa, dopamine and DOPAC from isolated pineal organs was shown by superfusion experiments. Extracellular recordings were used to monitor the action of dopaminergic drugs on electrical activity of ganglion cells. Dopamine increased the discharge activity of action potentials, whereas dopamine receptor antagonists resulted in a reduction of ganglion cell activity. Our data provide evidence for establishing dopamine as an intrinsic neurotransmitter or neuromodulator in the photosensitive pineal organ of the rainbow trout.     

The vasopressin-like immunoreactive (VPLI) neurons of the locust,Locusta migratoria. I. Anatomy

Summary Antiserum to arginine-vasopressin has been used to characterise the pair of vasopressin-like immunoreactive (VPLI) neurons in the locust. These neurons have cell bodies in the suboesophageal ganglion, each with a bifurcating dorsal lateral axon which gives rise to predominantly dorsal neuropilar branching in every ganglion of the ventral nerve cord. There are extensive beaded fibre plexuses in most peripheral nerves of thoracic and abdominal ganglia, but in the brain, the peripheral plexuses are reduced while neuropilar branching is more extensive, although it generally remains superficial. An array of fibres runs centripetally through the laminamedulla chiasma in the optic lobes. Lucifer Yellow or cobalt intracellular staining of single VPLI cells in the adult suboesophageal ganglion shows that all immunoreactive processes emanate from these two neurons, but an additional midline arborisation (that was only partially revealed by immunostaining) was also observed. Intracellularly staining VPLI cells in smaller larval instars, which permits dye to reach the thoracic ganglia, confirms that there is no similar region of poorly-immunoreactive midline arborisation in these ganglia. It has been previously suggested that the immunoreactive superficial fibres and peripheral plexuses in ventral cord ganglia serve a neurohaemal function, releasing the locust vasopressin-like diuretic hormone, F₂. We suggest that the other major region of VPLI arborisation, the poorly immunoreactive midline fibres in the suboesophageal ganglion, could be a region where VPLI cells receive synaptic input. The function of the centripetal array of fibres within the optic lobe is still unclear.Abbreviations AVP arginine vasopressin - DIT dorsal intermediate tract - FLRF Phe-Leu-Arg-Phe - FMRF-amide Phe-Met-Arg-Phe-amide - LDT lateral dorsal tract - LVP lysine vasopressin - MDT median dorsal tract - MVT median ventral tract - SEM scanning electron microscopy - SOG suboesophageal ganglion - VIT ventral intermediate tract - VNC ventral nerve cord - VPLI vasopressin-like immunoreactive     

绿盲蝽腹神经节的解剖结构

【目的】揭示绿盲蝽Apolygus lucorum腹神经节的组成结构。【方法】采用免疫组织化学染色方法,利用突触蛋白抗体对绿盲蝽成虫的腹神经节进行免疫标记,激光共聚焦扫描显微镜扫描照相获得原始数据,用图像分析软件进行标记,构建三维结构模型。【结果】绿盲蝽成虫腹神经节位于腹神经索的末端,与其前方的后胸神经节和中胸神经节紧密融合,形成后部神经节。与脑和胸神经节类似,腹神经节由周围的细胞体和内部的神经髓构成。腹神经节的神经纤维束主要包括位于腹侧的两条纵向神经连索和向两侧发出的9束神经纤维。9束神经纤维连接着9个神经原节,即富含突触联系的神经髓。这些神经原节紧密融合,无明显的边界,最后两节形成膨大的末端腹神经节。两侧的神经原节由横向的神经连锁连接起来。腹神经节外周的细胞体数量较多,排列紧密,大小一致,仅在前端背侧中间和后端腹侧中间位置分别有2个和5个体积较大的细胞体。【结论】本研究结果明确了绿盲蝽腹神经节的结构,为进一步研究昆虫的行为调控及神经系统发育和演化奠定一定的形态学基础。     

Respiratory nervous activity in the isolated nerve cord of the larval dragonfly, and location of the respiratory oscillator

ABSTRACT. Rhythmic respiratory nerve activity was recorded in the dragonfly larvae, Anax parthenope Julius Brauer (Anisoptera). Alternating expiratory and inspiratory bursts of spikes occurred in abdominal nerve cords isolated from all peripheral connections. These bursts are similar to the activity recorded in semi-intact preparations, suggesting that the respiratory rhythm can be generated without peripheral sensory feedback. Expiratory bursts started and ended at the same time in different segments of semi-intact preparations. When connectives were severed, the nerve cord separated from the last abdominal ganglion did not normally show rhythmic bursts; the last ganglion alone and the nerve cord connected to the last ganglion exhibited the rhythmic bursts. However, in a few cases the nerve cord separated from the last ganglion exhibited the rhythm. The results suggest that the last ganglion contains the main oscillator, but that other weak oscillators occur elsewhere.     

Crustacean cardioactive peptide in the nervous system of the locust,Locusta migratoria: an immunocytochemical study on the ventral nerve cord and peripheral innervation

Summary Crustacean cardioactive peptide-immunoreactive neurons occur in the entire central nervous system of Locusta migratoria. The present paper focuses on mapping studies in the ventral nerve cord and on peripheral projection sites. Two types of contralaterally projecting neurons occur in all neuromers from the subesophageal to the seventh abdominal ganglia. One type forms terminals at the surface of the thoracic nerves 6 and 1, the distal perisympathetic organs, the lateral heart nerves, and on ventral and dorsal diaphragm muscles. Two large neurons in the anterior part and several neurons of a different type in the posterior part of the terminal ganglion project into the last tergal nerves. In the abdominal neuromers 1–7, two types of ipsilaterally projecting neurons occur, one of which gives rise to neurosecretory terminals in the distal perisympathetic organs, in peripheral areas of the transverse, stigmata and lateral heart nerves. Four subesophageal neurons have putative terminals in the neurilemma of the nervus corporis allati II, and in the corpora allata and cardiaca. In addition, several immunoreactive putative interneurons and other neurons were mapped in the ventral nerve cord. A new in situ whole-mount technique was essential for elucidation of the peripheral pathways and targets of the identified neurons, which suggest a role of the peptide in the control of heartbeat, abdominal ventilatory and visceral muscle activity.Abbreviations AG abdominal ganglia - AM alary muscle - AMN alary muscle nerve - CA corpus allatum - CC corpus cardiacum - dPSO distal perisympathetic organ - LHN lateral heart nerve - LT CCAP-immunoreactive lateral tract - NCA nervus corporis allati - NCC nervus corporis cardiaci - NM neuromer - PMN paramedian nerve - PSO perisympathetic organ - SOG subesophageal ganglion - VDM ventral diaphragm muscles - VNC ventral nerve cord     

Differentiation of noradrenergic traits in the principal neurons and small intensely fluorescent cells of the parasympathetic sphenopalatine ganglion of the rat

Catecholamine synthetic enzymes are found in many cranial parasympathetic principal neurons, and in the small intensely fluorescent (SIF) cells that populate parasympathetic as well as sympathetic ganglia. While there is evidence that the acquisition of noradrenergic properties in sympathetic neuron precursors depends on factors that these cells encounter in the trunk environment, the mechanisms that direct the development of noradrenergic traits in cranial parasympathetic neurons and SIF cells are not understood. The present study examines the time course of appearance of tyrosine hydroxylase (TH) immunoreactivity in the principal neurons and SIF cells of the rat sphenopalatine ganglion. We show that the sphenopalatine ganglion of normal adult rats contains both a small population of TH-immunoreactive principal neurons and many SIF cells. The TH-immunoreactive principal neurons do not synthesize or store detectable catecholamines, even though the majority of sphenopalatine ganglion neurons do contain 1-amino acid decarboxylase catalytic activity. Sphenopalatine ganglion principal neurons do not accumulate detectable levels of exogenous catecholamines. This observation suggests that they lack a high affinity norepinephrine uptake system. In contrast to what has been observed previously for sympathetic neurons, the appearance of TH immunoreactivity in sphenopalatine neurons is not temporally correlated with the cessation of neural crest cell migration. The first TH-immunoreactive neurons do not appear in the sphenopalatine ganglion until Embryonic Day 16.5, 2 days after the ganglion has condensed and process outgrowth has begun. The number of sphenopalatine neurons that express TH immunoreactivity increases dramatically between Embryonic Day 18.5 and Postnatal Day 1, but then decreases. In fact, the percentage of sphenopalatine neurons that express TH immunoreactivity is almost fivefold higher in newborn than in adult rats. SIF cells cannot be definitively identified in the sphenopalatine ganglion until after Embryonic Day 18.5. The time course of appearance of TH immunoreactivity in sphenopalatine ganglion cells raises the possibility that TH expression is stimulated in these cells by factors encountered either at their condensation site or at their target, such as glucocorticoids or nerve growth factor. The relatively late appearance of SIF cells in the sphenopalatine ganglion argues against the hypothesis that SIF cells are the precursors of all autonomic neurons.     

Fine Structural Analysis of the Central Nervous System in the Spider, Achaearanea tepidariorum (Theridiidae: Araneae)

ABSTRACT Central nervous system (CNS) of arachnids is still mysterious and has a rich unexplored field compare to what is known in insects or crustaceans. The CNS of the spider, Achaearanea tepidariorum, consists of a dorsal brain or supraesophageal ganglion and circumesophageal connectives joining it to the subesophageal mass. As the segmentation of the arachnid brain is still under discussion, we classify the brain as a protocerebral and tritocerebral ganglion depending on the evidences which generally accepted. The subesophageal nerve mass underneath the brain is the foremost part of the ventral nerve cord. All of this nerve mass is totally fused together, and forming subesophageal ganglia in this spider. In the brain, the nerve cells are packed in the frontal, dorsal and lateral areas, but are not absent from the posterior and ventral regions. In addition, the nerve cells of the subesophageal and abdominal ganglia are only restricted to the ventral and ventolateral regions. The CNS of the spider, Achaearanea tepidariorum is similar in feature to the Family Araneidae.