The optic neuropiles and chiasmata of Crustacea

Summary On the basis of ontogeny and adult morphology, an interpretation of the arrangement of optic neuropiles and fibre connexions of the Crustacean compound eye is presented. In the embryo of phyllopods and decapods, the ommatidia, the lamina ganglionaris, and the medulla externa are developed synchronously from a common medial proliferation zone. As this zone persists in all investigated adult Crustacea that possess compound eyes, such a derivation of the mentioned structures is taken to be universal within the group. The direction of growth of the lamina ganglionaris is parallel with the row of ommatidia, the growth direction of the medulla externa is perpendicular to it and parallel with the long axis of the eyestalk. This arrangement is more or less retained in most adult non-Malacostracan Crustacea, and the axons of fully developed neurons pierce the optic neuropiles and leave and enter on the neuropile side. As a result, there is no chiasma in the non-Malacostracan groups.The Malacostraca have an extra neuropile, the medulla interna, derived from the medulla terminalis. Chiasmata occur between the lamina ganglionaris and the medulla externa, and between the medulla externa and the medulla interna. This difference from the non-Malacostracans depends on the course of the fibres. Those coming from the lamina ganglionaris leave the lamina on the neuropile side and enter medulla externa between the cell bodies in the perikaryon layer of the medulla externa neurons and the neuropile of the medulla. The fibres from the medulla externa to the lamina come from T-shaped neurons and emanate from the perikaryon layer side, entering the lamina on its neuropile side. The fibre relations between the medulla externa and the medulla interna are similar. Thus in both cases, chiasmata are present from the beginning, but they become obvious when the medulla externa rotates through part of a circle.The directed growth of the optic neuropiles and the course of the fibre connexions are consequently crucial to the understanding of the topographic relations between the neuropiles. A pattern with short neurons connecting neighbouring optic neuropiles and long neurons connecting the medulla externa with the central nervous system is common to all crustaceans.In memoriam Bertil Hanström.This work has been supported by a grant from the Swedish Natural Science Research Council 2760-3, 99-35.     

Postembryonic changes in the optic primordia and optic bud in the flesh fly Sarcophaga ruficornis fabr. (Diptera: Sarcophagidae)

Differentiation of the optic lobe anlagen begin in the brain of second instar. Each is an elongated disc of cortical cells placed on the dorsolateral border of each protocerebrum. In the late second instar the disc elongates and its two ends bend inwards which gradually separate from the central region, thus giving three imaginal discs. The protocerebral neuropile extends into these discs and medulla interna and externa are formed. The rudiments of compound eyes (cephalic complex) appear in the early laid larva. These are attached with the brain and pharyngeal wall separately. The posterior portion of cephalic complex (optic bud), after establishing a nervous association with the central optic lobe anlage (lamina ganglionaris), forms the compound eye. Ech optic bud is attached to the brain by a non-nervous stalk. The epiblast cells of the optic bud do not migrate into the brain and the lamina is formed by the proliferation of the central imaginal disc. The reorientation of the optic lobe anlagen starts in the late third instar and the medulla interna divides into two unequal lobes. In 2 day pupa the nerve fibres from the lamina travel into the optic stalk and the optic nerve is formed. The epiblast cells of the optic bud differentiate to form a peripheral epithelial layer which becomes pigmented and gets apposed to the lateral boundary of the brain. The central epiblast cells of the optic bud form several ommatidia. The optic nerve degenerates gradually and various components of the compound eye are formed by the epiblast cells. Chiasm internum is present but chiasm externum is absent.     

Corticotropin-releasing hormone-like immunoreactivity in the brain of the snake Bothrops jararaca

The distribution of corticotropin-releasing hormone in the brain of the snake Bothrops jararaca was studied immunohistochemically. Immunoreactive neurons were detected in telencephalic, diencephalic and mesencephalic areas such as dorsal cortex, subfornical organ, paraventricular nucleus, recessus infundibular nucleus, nucleus of the oculomotor nerve and nucleus of the trigeminal nerve. Immunoreactive fibres ran along the hypothalamo-hypophysial tract to end in the outer layer of the median eminence and the neural lobe of the hypophysis. In general, immunoreactive fibres occurred in the same places of immunoreactive neurons. In addition, immunoreactive fibres were observed in the septum, amygdala, lamina terminalis, supraoptic nucleus, nucleus of the paraventricular organ, ventromedial hypothalamic nucleus and interpeduncular nucleus. These results indicate that, as for other vertebrates, corticotropin-releasing hormone in B. jararaca brain, besides being a releasing hormone, may also act as a central neurotransmitter and/or neuromodulator.     

Serotonin immunoreactive neurons in the central nervous system of an insect (Periplaneta americana)

Serotonin-like immunoreactivity was mapped in the central nervous system (CNS) of the cockroach, Periplaneta americana. Immunoreactive staining occurred in every ganglion of the CNS. The largest numbers of immunoreactive somata were detected in the optic lobes and the brain, and lowest numbers in the first and second thoracic ganglia. Dense stained fibers, ramifications, and varicosities were found in all ganglia, and numerous axon like processes occurred in all interganglionic connectives. Immunoreactive processes were not, however, detected in most of the peripherally projecting nerve roots. Processes were found only in roots of the suboesophageal ganglion and the tritocerebral lobes of the brain. A comparison of the map for serotonin immunoreactivity with one generated for the pentapeptide transmitter proctolin suggests that the two systems overlap only in the suboesophageal ganglion and the tritocerebrum. The amine and peptide may co-occur in neurons in these regions. The serotonin immunoreactive system appeared significantly different from the octopaminergic system of the ventral nerve cord. Seventy-two potentially identifiable immunoreactive cells were located in the cockroach CNS. Some of these may be suitable for physiological study of the functional role of serotonin.     

Insect optic lobe neurons identifiable with monoclonal antibodies to GABA

Five monoclonal antibodies against GABA were tested on glutaraldehyde fixed sections of optic lobes of three insect species, blowflies, houseflies and worker bees. The specificity of these antibodies was analyzed in several tests and compared with commercially available anti-GABA antiserum. A very large number of GABA-like immunoreactive neurons innervate all the neuropil regions of these optic lobes. Immunoreactive processes are found in different layers of the neuropils. The immunoreactive neurons are amacrines and columnar or noncolumnar neurons connecting the optic lobe neuropils. In addition some large immunoreactive neurons connect the optic lobes with centers of the brain. Some neuron types could be matched with neurons previously identified with other methods. The connections of a few of these neuron types are partly known from electron microscopy or electrophysiology and a possible role of GABA in certain neural circuits can be discussed.     

Insect optic lobe neurons identifiable with monoclonal antibodies to GABA

Summary Five monoclonal antibodies aginst GABA were tested on glutaraldehyde fixed sections of optic lobes of three insect species, blowflies, houseflies and worker bees. The specificity of these antibodies was analyzed in several tests and compared with commercially available anti-GABA antiserum.A very large number of GABA-like immunoreactive neurons inncrvate all the neuropil regions of these optic lobes. Immunoreactive processes are found in different layers of the neuropils. The immunoreactive neurons are amacrines and columnar or noncolumnar neurons connecting the optic lobe neuropils. In addition some large immunoreactive neurons connect the optic lobes with centers of the brain.Some neuron types could be matched with neurons previously identified with other methods. The connections of a few of these neuron types are partly known from electron microscopy or electrophysiology and a possible role of GABA in certain neural circuits can be discussed.     

NPY-like peptides occur in the nervous system and midgut of the migratory locust, Locusta migratoria and in the brain of the grey fleshfly, Sarcophaga bullata

The distribution of the NPY-like substances in the nervous system and the midgut of the migratory locust, Locusta migratoria and in the brain of the grey fleshfly, Sarcophaga bullata was determined by immunocytochemistry using an antiserum directed against synthetic porcine NPY. The peroxidase-antiperoxidase procedure revealed that NPY immunoreactive cell bodies and nerve fibers were observed in the brain, optic lobes, corpora cardiaca, suboesophageal ganglion and ventral nerve cord of the locust and in the brain, optic lobes and suboesophageal ganglion of the fleshfly. In the locust midgut, numerous endocrine cells and nerve fibers penetrating the outer musculature contained NPY-like immunoreactivity. The concentrations of NPY immunoreactive material in acetic acid extracts of locust brain, optic lobes, thoracic ganglia, ovaries and midguts was measured using a specific radioimmunoassay technique. The dilution curves of the crude tissue extracts were parallel to the standard curve. The highest amount of NPY-like immunoreactivity was found in the locust ovary and midgut. Reverse-phase high-performance liquid chromatography (RP-HPLC) and radioimmunoassay were used to characterize the NPY-like substances in the locust brain and midgut. HPLC-analysis revealed that NPY-immunoreactivity in the locust brain eluted as three separate peaks. The major peak corresponded to a peptide less hydrophobic than synthetic porcine NPY. RP-HPLC analysis of midgut extracts revealed the presence of an additional NPY-immunoreactive peak which had a retention time similar to the porcine NPY standard. The present data show the existence of a widespread network of NPY immunoreactive neurons in the nervous system of the locust and the fleshfly. Characterization of the immunoreactive substances indicates that peptides similar but not identical to porcine NPY are present in the central nervous system and midgut of insects.     

Immunolocalization of allatostatin-like neuropeptides and their putative receptor in eyestalks of the tiger prawn, Penaeus monodon

Allatostatin (AST)-like immunoreactivity (IR) was localized in the eyestalk of Penaeus monodon by immunohistochemistry using four anti-AST antibodies. Depending on the antisera, AST-like immunoreactivity was detected in neuronal bodies of the lamina ganglionalis, cell bodies anterior to the medulla externa and cell bodies on the anterior and posterior of the medulla terminalis. Neuronal processes in neuropiles of the medulla externa, medulla terminalis, sinus gland and nerve fibers in the optic nerve were also recognized. No IR in cell bodies or in nerve fibers was found in the medulla interna. Strong AST-like immunoreactivity was found in hundreds of cells of the X organ. The localization of AST-like peptides suggests that they function as neurotransmitters and/or neuromodulators. Antiserum to the Drosophila AST receptor (Dar-2) recognized a single protein in P. monodon eyestalk protein extracts that was identical in size to that found in Drosophila protein extracts. Using this antiserum the putative P. monodon AST receptor was localized to the sinus gland in both juvenile and adult eyestalks. To our knowledge this is the first demonstration of a neuropeptide receptor localized to the crustacean sinus gland. This suggests that ASTs may function directly on the sinus gland as a neuromodulator. In juvenile eyestalks, the putative AST receptor was also localized to neuronal X organ cells of the medulla terminalis in males but not in females. The significance of this sex-specific receptor localization is unclear but emphasizes that ASTs function within the nervous system of the eyestalk.     

Distribution of GABA-like immunoreactive neurons in the optic lobes of Periplaneta americana

Summary Specific antisera against protein-conjugated -aminobutyric acid (GABA) were used in immunocytochemical staining procedures to study the distribution of the putative GABA-like immunoreactive neurons in the optic lobes of Periplaneta. GABA-like immunoreactive structures are evident in all three optic neuropil regions. Six different populations of GABAergic neurons, whose perikarya are grouped around the medulla, are found within the optic lobe. The number of these immunoreactive cells varies greatly and corresponds to the number of ommatidia of the eye. In the proximal part of the lamina, a coarse network of GABA-positive fibres is recognizable. These are the processes of large field tangential cells whose fibres pass through the distal surface of the medulla. A second fibre population of the lamina is made up of the processes of the centrifugal columnar neurons whose perikarya lie proximally to the medulla. The medulla contains 9 layers with GABAergic elements of variable immunoreactivity. Layers 1, 3, 5, 7 and 9 exhibit strong labelling, as a result of partial overlapping of the processes of centrifugal and centripetal columnar neurons, tangential fibres and/or lateral processes of perpendicular fibres and (possibly) processes of amacrines. A strong immunoreactivity is found in the proximal and distal layers of the lobula.     

白斑迷蛱蝶视觉系统中GABA和5-HT能神经元的分布

采用树脂石蜡(Colophony-Paraffin,CP)组织包埋切片技术和链霉菌抗生物素蛋白一过氧化物酶(Streptavidin—peroxidase,SP)免疫组织化学方法,首次报道了GABA和5-HT两种神经递质在白斑迷蛱蝶视觉系统(复眼及视叶)中的分布。与以往所报道的昆虫不同,白斑迷蛱蝶复眼中部分光感细胞对GABA和5-HT抗血清产生免疫反应。每侧视叶中约有2600多个GABA能阳性神经元,它们共分为6群。其中3群位于外髓附近(M1-3),另外三群位于内髓复合体边缘(LC1-3)。GABA能神经元发出的轴突在整个视叶的3个神经纤维网中都有分布。相比之下,视叶对5-HT抗血清的反应较弱,视叶神经纤维网中不存在代表5-HT阳性反应的粗大静脉曲张状纤维,只有一些排列规则的细小纤维。每侧视叶只有位于外髓附近的25个神经元呈现阳性反应,它们的分布位置与部分M3群的GABA能样神经元相同。本文还探讨了5-HT和GABA在调节视觉信息时可能发挥的作用[动物学报50(5)：770—777,2004]。     

Immunoreactive pancreatic polypeptide (PP) occurs in the central and peripheral nervous system: Preliminary immunocytochemical observations

Summary Pancreatic polypeptide (PP) is a candidate hormone of unknown physiological significance. It is produced by a population of endocrine cells in the pancreas. In the present study a PP-like peptide was found to occur in the mammalian and avian central and peripheral nervous systems. Immunoreactive nerve fibres and nerve cell bodies were widely distributed in the brain. Dense accumulations of nerve fibres occurred in the following areas: nucleus accumbens, interstitial nucleus of the stria terminalis, para- and periventricular hypothalamic nuclei, and medial preoptic area. In addition, nerve fibres were regularly seen in cortical areas. Immunoreactive perikarya were observed in the following regions: cortex, nucleus accumbens, neostriatum and septum. In the gut, immunoreactive nerve fibers were distributed in the myenteric plexus, in smooth muscle, around blood vessels, and in the core of the villi. Immunoreactive perikarya occurred in the submucosal and myenteric plexus, suggesting that PP immunoreactive nerves are intrinsic to the gut.In the species examined, the neuronal PP-like peptide could be demonstrated with an antiserum raised against avian PP, but not with those raised against bovine or human PP. Thus, neuronal PP is distinct from the PP that occurs in pancreatic endocrine cells.     

Immunocytochemical localization of CCAP,a novel crustacean cardioactive peptide,in the nervous system of the shore crab,Carcinus maenas L.

Summary Polyclonal antibodies were raised in rabbits against synthetic crustacean cardioactive peptide (CCAP) conjugated to bovine thyroglobulin, and were used to map CCAP-immunoreactive structures in the central nervous system of Carcinus maenas. As expected, the neurohemal pericardial organs (PO) displayed abundant immunoreactivity in nerve fibers and terminals. In addition, immunoreactive neurons were demonstrated in other parts of the nervous system. At least some of them do not appear to terminate in neurohemal structures and may have a non-endocrine, as yet unknown function. Immunoreactive perikarya with a diameter of 25–30 m occur in the brain. They project into the optic and antennary neuropil, and into the eyestalk. One cell was found in the medulla terminalis of the eyestalk and in the connective ganglion, respectively. From the latter, axonal branches could be traced into the brain and the thoracic ganglia (TG). In the TG, small-diameter perikarya give rise to extensive networks of varicose fibers. Some of the perikarya occur in a characteristic paired arrangement with larger CCAP-immunoreactive somata (diameter 40–50 m). These pairs of one small and one large cell occur in all mouthpart and leg segments of the TG, except the abdominal ganglia (AG), where only large cells were found. The main projections of the large neurons comprise one or more fibers in each of the seven segmental nerves (SN), leading to neurosecretory terminals in the PO. The fibers in the SN are joined by branches of an ascending axonal tract from the large perikarya in the AG. The large-type perikarya are considered to be the principal source of CCAP in the PO. The optic ganglia in the eyestalk, except the medulla terminalis, the neurohemal sinus gland and the stomatogastric nervous system are devoid of CCAP-immunoreactivity.In axon terminals of the PO, CCAP is not colocalized with other PO-neuropeptides, i.e. proctolin-, FMRFamide-like, and Leu-enkephalin-like immunoreactive materials. Electron-microscopic immunocytochemistry revealed a distinct CCAP-containing granule type in specific axon profiles and terminals in the PO.The architecture of CCAP-immunoreactive neurons is discussed with respect to previous morphological studies on the origin and pathways of fibers terminating in the PO.Dedicated to Professor K.E. Wohlfarth-Bottermann, Bonn, on the occasion of his 65^th birthday     

Seven novel FMRFamide-like neuropeptide sequences from the eyestalk of the giant tiger prawn Penaeus monodon

FMRFamide-like immunoreactivity (FLI) was localized in the eyestalk of Penaeus monodon by immunohistochemistry using a combination of three anti-FMRFamide-like peptide (FLPs) monoclonal antibodies. Approximately 3000 small neuronal cell bodies in the lamina ganglionalis; 100 medium to large size at the ganglion between the medulla interna and the medulla terminalis; and 250 medium size around the medulla terminalis were stained intensely. The neuronal processes in neuropils of the medulla externa, medulla interna, medulla terminalis, sinus gland and some nerve fibers in the optic nerve were also recognized. The small cell bodies, approximately 1500 cells, anterior to the medulla externa were stained inconsistently and the neuronal processes were not observed from these cells. Isolation of FLPs from 9000 eyestalks was performed using methanol/acetic/water (90:1:9) extraction. After the extract was partially purified using C18 cartridges, it was further purified by five to seven steps of RP-HPLC using three kinds of columns: C18; C8; and cyano, and three solvent systems: acetonitrile/trifluoro acetic acid; aceonitrile/heptafluoro butyric acid; and acetonitrile/triethyl ammonium acetate. Dot-ELISA using the combination of the same antibodies was used to monitor FLPs in the fractions during purification processes. Seven new sequences of FLPs were identified which can be divided into four subgroups according to the primary structure of the C-terminus: (1) GDRNFLRFamide; (2) AYSNLNYLRFamide; (3) AQPSMRLRFamide, SQPSMRLRFamide, SMPSLRLRFamide and DGRTPALRLRFamide; and (4) GYRKPPFNGSIFamide. These data indicate the high complexity of this peptide family in which multiple forms are usually exist.     

Four novel PYFs: members of NPY/PP peptide superfamily from the eyestalk of the giant tiger prawn Penaeus monodon

An immunocytochemical method was used for localization of pancreatic polypeptide (PP) immunoreactive substances in the eyestalk of Penaeus monodon using anti-C-terminal hexapeptide of PP (anti-PP6) antiserum. Approximately 200 neuronal cell bodies were recognized in the ganglia between the medulla interna (MI) and medulla terminalis (MT) and surrounding MT in conjunction with the neuronal processes in medulla externa (ME), MI, MT and sinus gland. About half of the PP immunoreactive neurons were also recognized by a combination of three monoclonal antibodies raised against FMRFamide-like peptides. Isolation of the PP immunoreactive substances from the eyestalk was performed using 7500 eyestalks extracted in methanol/acetic acid/water (90/1/9) followed by five to six steps of RP-HPLC separation. Dot-ELISA with anti-PP6 antiserum was used to monitor PP-like substances in various fractions during the purification processes. Four new sequences of one hexapeptide; RARPRFamide, and three nonapeptides; YSQVSRPRFamide, YAIAGRPRFamide and YSLRARPRFamide were identified, and named as Pem-PYF1-4 due to their structural similarity to the PYF found in squid Loligo vulgaris. Each of the new peptides shares four to seven common residues with the C-terminus of the squid PYF and with the NPFs found in other invertebrates. The NPY/PP superfamily as well as the FMRFamide peptide family may be present throughout vertebrates and invertebrates.     

Galanin-like immunoreactivity in the chicken brain

The anatomical distribution of neurons containing galanin has been studied in the central nervous system of the chicken by means of immunocytochemistry using antisera against rat galanin. Major populations of immunostained perikarya were detected in several brain areas. The majority of galanin-immunoreactive cell bodies was present in the hypothalamus and in the caudal brainstem. Extensive groups of labeled perikarya were found in the paraventricular, periventricular, dorsomedial and tuberal hypothalamic nuclei, and in the nucleus of the solitary tract in the medulla oblongata. In the telencephalon, immunoreactive perikarya were observed in the preoptic area, in the lateral septal nucleus and in the hippocampus. The mesencephalon contained only a few galanin-positive perikarya located in the interpeduncular nucleus. Immunoreactive nerve fibers of varying density were detected in all subdivisions of the brain. Dense accumulations of galanin-positive fibers were seen in the preoptic area, periventricular region of the diencephalon, the ventral hypothalamus, the median eminence, the central gray of the brainstem, and the dorsomedial caudal medulla. The distributional pattern of galanin-immunoreactive neurons suggests a possible involvement of a galanin-like peptide in several neuroregulatory mechanisms.     

Immunocytochemistry of histamine in the brain of the locust<Emphasis Type="Italic"> Schistocerca gregaria</Emphasis>

Histamine serves a neurotransmitter role in arthropod photoreceptor neurons, but is also present in a small number of interneurons throughout the nervous system. In search of a suitable model system for the analysis of histaminergic neurotransmission in insects, we mapped the distribution of histamine in the brain of the desert locust Schistocerca gregaria by immunocytochemistry. In the optic lobe, apparently all photoreceptor cells of the compound eye with projections to the lamina and medulla showed intense immunostaining. Photoreceptors of the dorsal rim area of the eye had particularly large fiber diameters and gave rise to uniform varicose immunostaining throughout dorsal rim areas of the lamina and medulla. In the locust midbrain 21 bilateral pairs of histamine-immunoreactive interneurons were found, and 13 of these were reconstructed in detail. While most neuropil areas contained a dense meshwork of immunoreactive processes, immunostaining in the antennal lobe and in the calyces of the mushroom body was sparse and no staining occurred in the pedunculus and lobes of the mushroom body, in the protocerebral bridge, and in the lower division of the central body. A prominent group of four immunostained neurons had large cell bodies near the median ocellar nerve root and descending axonal fibers. These neurons are probably identical to previously identified primary commissure pioneer neurons of the locust brain. The apparent lack in the desert locust of certain histamine-immunoreactive neurons which were reported in the migratory locust may be responsible for differences in the physiological role of histamine between both species.The study was supported by the Deutsche Forschungsgemeinschaft, grants Ho 950/13 and 950/14     

Localization of substance P-like,leucine-enkephalin-like,methionine-enkephalin-like,and FMRFamide-like immunoreactivity in the eyestalk of the fiddler crab,Uca pugilator

Summary The occurrence and distribution of substance P (SP)-like, methionine-(Met)- and leucine-(Leu)-enkephalinlike, and FMRFamide-like immunoreactivities were determined in the neuroendocrine complex of the eyestalk of the fiddler crab, Uca pugilator, by immunocytochemistry. SP-like immunoreactivity was found in the optic peduncle, sinus gland, medulla externa, medulla interna, lamina ganglionaris, and retinular cells. Met-enkephalin-like and Leuenkephalin-like immunoreactivity was observed in most of the retinular cells, optic peduncle, sinus gland, medulla terminalis, and lamina ganglionaris. However, Met-enkephalin-like, but no Leu-enkephalin-like, immunoreactivity was seen in the medulla terminalis X-organ. FMRFamide-like immunoreactivity could be seen in all parts of the eyestalk except in the sinus gland, lamina ganglionaris, and retinular cells. FMRF-amide-like activity was especially strong in the three chiasmatic regions connecting the optic ganglia. The possibility that these four peptides may function as neuroregulators in the fiddler crab is discussed.This investigation was supported in part by Grant No. PCM-8300064 from the National Science Foundation to MF and Biomedical Research Support Grant No. 2 SO7RRO5373 SUB from the University of Kansas Medical Center to LLV     

FMRFamide-like immunoreactivity in the brain and pituitary of the teleost. Eigenmannia lineata (Gymnotiformes)

The distribution of cells immunoreactive for the molluscan tetrapeptide FMRFamide in the brain and the pituitary of Eigenmannia was investigated immunohistochemically by the use of the peroxidase-antiperoxidase (PAP) technique and unlabelled antibodies. FMRFi neurons were located in the ganglion of the nervus terminalis at the rostroventral side of the bulbus olfactorius. FMRFi perikarya were also found in a dorsomedial diencephalic nucleus, in the nucleus ventromedialis, in some liquor-contacting neurons of the nucleus lateralis tuberis and of the nucleus recessus lateralis and posterior. The perikarya of the midbrain pre-pacemaker nucleus were only weakly immunoreactive for FMRFamide while large FMRFi neurons (T-cells) occurred in lamina VI of the torus semicircularis, in the brain stem, in dorsal and medial layers of the lobus lineae lateralis posterior (LLLp) and in the medullary electric organ pacemaker nucleus (pm). FMRFi fibers and nerve endings were found in the bulbus olfactorius, in medial areas of the telencephalon, and rather densely in the rostral diencephalon. Ventrocaudally to most of the hypothalamic nuclei the occurrence of immunoreactive fibres increased; many coursed to the pituitary through the pituitary stalk. FMRFi fibres also appeared in the deep layers of the tectum opticum, in the torus semicircularis, in the medial and lateral medulla and below the pacemaker nucleus. Wherever FMRFamide-immunoreactivity occurred fibres and nerve endings could be found in close contact with blood vessels.     

Immunocytochemical demonstration of octopamine-immunoreactive cells in the nervous system of Locusta migratoria and Schistocerca gregaria

Summary The distribution of octopamine in the metathoracic ganglion, brain and corpus cardiacum of Locusta migratoria and Schistocerca gregaria was investigated by means of immunocytochemistry with an antiserum against octopamine. The dorsal unpaired median (DUM) cells of the metathoracic ganglion were found to be strongly octopamine-immunoreactive. In the rostroventral part of the protocerebrum a group of seven immunopositive cells was demonstrated. Stained nerve fibres of these cells run into three directions: circumoesophageal connectives, midbrain, and optic lobes. As far as the protocerebrum is concerned, immunoreactive fibres were found in the central body, the protocerebral bridge, and in other neuropile areas. In the optic lobe a dense plexus of immunopositive fibres was found in the lobula and in the medulla. In the brain one other immunopositive cell was demonstrated, situated at the lateral border of the tritocerebrum. Octopamine could not be shown to occur either in the globuli cells of the mushroom bodies or in the dorsolateral part of the protocerebrum, where the perikarya of the secretomotor neurones are located that innervate the glandular cells of the corpus cardiacum. In the nervi corporis cardiaci II, which contain the axons of the neurones that extend into the glandular part of the corpus cardiacum, and in the corpus cardiacum proper no specific octopamine immunoreactivity could be found.     

Structure and metamorphic changes in the brain of the lemon butterfly Papilio demoleus L. (Lepidoptera: Papilionidae)

The morphology of the larval and adult brain of Papilio demoleus, and changes in the cell population and neuropile morphology during the pupal period have been described. The larval brain has more simple fibre areas than that of the adult. Dividing neuroblasts have been found which form the adult neurones. The larval brain contains the three neuromeres (proto-, deuto-, and tritocerebrum). The protocerebrum has well developed corpora pedunculata, a central body, a pons cerebralis and developing optic centres. The corpora ventralia are joined with each other by paired ventral commissures (single in adult). The deutocerebrum is simple and small, the antennal centres are small and simple (ef. adult). The glomerular tritocerebrum is posteroventral to the deutocerebrum, and fibres from the former travel to the crura cerebri. The cortex of the brain consists of four types of glial cells and of association cells, and large and medium sized motor neurones. The number of mitoses is greatest in the larval and prepupal stages; in the pupa it decreases gradually and in late stages it does not occur. Histolysis and pyknosis begin in the prepupa and decrease considerably in the late pupa. The entire neural lamella is broken down in the early pupa. Numerous haemocytes penetrate the laminae of the neural lambella and envelop the entire brain. In the adult, behind the well-developed central body is an ellipsoid body. The medulla interna is divided into two smaller lobes and the deutocerebral lobes are differentiated into cortical and medullary zones. Chiasmata between optic centres are also formed during the pupal period.