An active principle from the corpora cardiaca,corpora allata and suboesophageal ganglion of the locust,inducing egg diapause in Bombyx mori

The activity of the substance(s) which are contained in the cephalic endocrine organs of the locust which induce egg diapause in Bombyx mori was examined by implantation and injection of saline extracts of these organs. Extracts from the median and lateral neurosecretory parts of the locust brain were not effective in inducing egg diapause. Extracts of the corpora cardiaca, corpora allata, and suboesophageal ganglion of the locust induced diapause eggs in Bombyx pharate adults from which the suboesophageal ganglion had been removed. The first two extracts could induce egg diapause even in isolated abdomens of pharate adults of Bombyx. In the locust corpora cardiaca, the activity was present only in the glandular lobe and not in the nervous region. This activity decreased when the nervi corporis cardiaci I and II and of nervi corporis allati I were cut. Allatectomy also brought about a decrease in the activity in the glandular lobe which could not be restored by the injection of juvenile hormone. The activity in the corpora allata was enhanced slightly by the disconnection though not significantly.From these results, it is assumed that the corpora cardiaca, corpora allata and suboesophageal ganglion of the locust contain and active principle(s) capable of inducing egg diapause in Bombyx mori. The nervous connections between the brain, corpora cardiaca, and corpora allata are essential for the accumulation of the active substance(s) in the glandular lobes of the corpora cardiaca.     

Synthesis, transport, and release of a neurohormone by cultured neuroendocrine glands from the cockroach, Leucophaea maderae

A hindgut-stimulating neurohormone synthesized in vitro by the neurosecretory cells of cultured brains of Leucophaea maderae passes through the nervi corporis cardiaci I into the corpora cardiaca and is released into the culture medium. As much as 90 per cent of the hormone breaks down in the medium during a 3-day incubation period, and the amount recovered represents only a small fraction of the amount actually released.     

Ultrastructural Analysis of the Neuroendocrine Apparatus of Oncopeltus fasciatus (Heteroptera)

• 1 In Oncopeltus fasciatus, the A-cells of the pars intercerebralis and their tracts are stainable in situ with the performic acid-victoria blue (PAVB) method. The axons from these cells, after traversing the corpus cardiacum, terminate in the anterior part of the aorta which thus serves as the neurohemal organ.
• 2 Ultrastructurally, four types of secretory neurons are distinguishable in the pars intercerebralis region: pic-I with granules measuring 1000–3000 Å in diameter; pic-II with granules of irregular size and shape, the elongate ones showing mean dimensions of 2400 × 1400 Å; pic-III with less electron-dense granules measuring 1000–2700 Å in diameter; pic-IV, present not only in the pars intercerebralis but also in adjacent regions of the brain, with variable proportions of granules measuring 700–1800 A and dense-cored vesicles measuring 1000–2400 Å.
• 3 The nervi corporis cardiaci contain at least three types of neurosecretory axons, based on granule content, presumably representing pic-I, pic-II and pic-III neurons.
• 4 The wall of the aorta contains endings of at least three distinct types, again representing pic-I, pic-II and pic-III neurons, and thus provides the neurohemal site for these three types of protocerebral neurosecretory cells. Axons of pic-IV neurons appear to enter the cerebral neuropil.
• 5 The corpus cardiacum is composed of two types of parenchymal secretory cells, with electron-dense granules measuring 1300–3000 Å and 1000–2300 Å in diameter, respectively. The corpus cardiacum also contains interstitial cells and some axons of extrinsic origin, with and without granules.
• 6 The corpus allatum may be paired or median, and receives a small number of at least two types of axons. The corpora allata of some reproducing females show a large number of PAVB-stainable inclusions which appear to be modified cytoplasmic organelles, but are definitely not neurosecretory material.
• 7 The hypocerebral ganglion is composed of two types of secretory-appearing neurons and glial cells. The two neuronal types contain secretory granules, 1000–3000 Å and 900–2100 Å in diameter, respectively. Axons of the recurrent nerve also may contain occasional granules.
• 8 In this heteropteran insect, the two principal functions of the corpus cardiacum appear to be spatially separated: the neurohemal function is subserved by the aortic wall, which permits release of material into both the aortic lumen and the hemocoel, and the intrinsic endocrine function is possessed by the parenchymal cells.

     

Contribution à l'étude infrastructurale du système neurosécréteur rétrocérébral chez Locusta migratoria migratorioides (R. et F.)

Résumé L'étude infrastructurale des nerfs cardiaques afférents et des nerfs allato-cardiaques qui entrent dans la constitution du système neurosécréteur rétrocérébral de Locusta migratoria migratorioides (R. et F.) révèle l'existence des trois types de fibres neurosécrétrices définis dans les corpora cardiaca. Une quatrième catégorie de fibres caractérisées par la présence de vésicules claires existe dans les nerfs allato-cardiaques et dans les corpora allata. L'origine des fibres et l'évolution des grains de neurosécrétion au cours de leur transit sont envisagées.

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Ultrastructural study of the retrocerebral neurosecretory system in Locusta migratoria migratorioides (R. et F.)II. Neurosecretory pathways

Summary An ultrastructural study of the nervi corporis cardiaci and nervi corporis allati, which are part of the retrocerebral neurosecretory system of Locusta migratoria migratorioides, reveals the existence of three neurosecretory fiber types. A fourth neurosecretory fibertype with electron lucent vesicles is also present in the nervi corporis allati and in the corpora allata. The fibers are characterized by differences in the size and electron opacity of the neurosecretory granules. The origin of the various neurosecretory fiber types and the evolution of the neurosecretory granules are discussed.

     

Brain-derived neurotrophic factor-like neuropeptide is secreted as a neurohormone from specific brain neurons into the corpus allatum in the silkworm Bombyx mori

The aim of this study was to investigate the secretion of brain‐derived neurotrophic factor (BDNF)‐like neuropeptide in the silkworm, Bombyx mori , by using immunocytochemical techniques on the brain and retrocerebral complex of fifth instar larvae. In the brain, four pairs of median neurosecretory cell (MNC) bodies and six pairs of lateral neurosecretory cell (LNC) bodies had distinct immunoreactivities to this peptide, suggesting that this peptide is produced from two types of brain neuron. These reactivities were much stronger in the MNC than in the LNC. Labeled MNC projected their axons into the contralateral corpora allata, to which axons of labeled MNC were eventually innervated, through decussation in the median region, contralateral nerve corporis cardiaci I and nerve corpora allata I. Labeled LNC extended their axons into the ipsilateral corpora allata to be innervated through the ipsilateral nerve corporis cardiaci II and nerve corpora allata I. These results suggest that BDNF is secreted as a neurohormone from MNC and LNC of the brain into the corpora allata.     

Histology of the neurosecretory system and the retrocerebral endocrine glands of the adult migratory grasshopper, Melanoplus sanguinipes (Fab.) (Orthoptera: Acrididae)

Neurosecretory cells of only one type (A, sub type A₂) are seen in adult Melanoplus. Two groups of about 400 cells each are located dorsally in the pars intercerebralis medialis; four cells are located deep within the protocerebrum. We found no neurosecretory cells in other parts of the central or sympathetic nervous systems. In about 10% of the specimens, there was marked asymmetry in the location of the dorsal cell groups, with both of these groups and their axons located in one lobe of the protocerebrum. The nervi corporis cardiaci 1 cross-over in the corpus cardiacum, with the result that material produced by neurosecretory cells on one side of the brain is transported along axons that undergo two chiasmata to the corpus cardiacum of the same side. Stainable secretory material could be traced clearly from the cerebral cells to the corpus cardiacum, and even into the oesophageal nerves from the hypocerebral ganglion. However, stainable neurosecretory material is never present in the corpus allatum or along any of the nerves to this gland.     

Studies on the neurosecretory system and retrocerebral endocrine glands of Nezara viridula Linn. (Heteroptera: Pentatomidae)

The neurosecretory system and retrocerebral endocrine glands of Nezara viridula Linn. have been described on the basis of in situ preparations and histological sections employing the paraldehyde fuchsin (PF) and performic acid-victoria blue (PAVB) techniques. In the brain of N. viridula, there are two medial groups–each consisting of five neurosecretory cells which belong to A-type. The lateral neurosecretory cells are absent. The axons of the two groups of medial neurosecretory cells (MNC) compose the two bundles of neurosecretory pathways (NSP) that decussate in the anterodorsal part of the protocerebrum. The two pathways, after the cross-over, run deep into the protocerebrum and deutocerebrum and emerge as NCC-I from the tritocerebrum. The nervi corporis cardiaci-I (NCC-I) of each side which are heavily loaded with NSM terminate in the aorta wall. Thus, the neurosecretory material (NSM), elaborated in the medial neurosecretory cells of the brain, is stored in the aortic wall and nervi corporis cardiaci-I (NCC-I). The NCC-II are very short nerves that originate from the tritocerebrum and terminate in the corpora cardiaca (CC) of their side. Below the aorta, but dorsal to the oesophagus, lie two oval or spherical corpora cardiaca. A corpus allatum (CA) lies posterior to the corpora cardiaca (CC). The corpora cardiaca do not contain NSM; only the intrinsic secretion of their cells has been occasionally observed which stains orange or green with PF staining method. The corpus allatum sometimes exhibits PF positive granules of cerebral origin. A new connection between the corpus allatum and aorta has been recorded. The suboesophageal ganglion contains two neurosecretory cells of A-type which, in structure and staining behaviour, are similar to the medial neurosecretory cells of the brain. The course and termination of axons of suboesophageal ganglion neurosecretory cells, and the storage organ for the secretion of these cells have been reported. It is suggested that the aortic wall and NCC-I axons function as neurohaemal organ for cerebral and suboesophageal secretions.     

Ultrastructure of the corpus cardiacum and corpus allatum of the house cricket Acheta domesticus

Summary The ultrastructure of the corpus cardiacum (CC) and corpus allatum (CA) of the house cricket, Acheta domesticus, is described. Axon profiles within the CC contain neurosecretory granules 160–350 nm in diameter which are indistinguishable from those found in type I neurosecretory cells of the pars intercerebralis and in the nervus corporis cardiaci I. The CC itself contains two cell types: intrinsic neurosecretory cells and glial cells. Intrinsic NSC cytoplasm contains Golgi bodies and electron dense neurosecretory granules 160–350 nm in diameter. Synaptoid configurations with 20–50 nm diameter electron lucent vesicles were observed within axon profiles of the CC. The structure of the CA is relatively uniform with one cell type predominating. Typical CA cells possess large nucleoli, active Golgi complexes, numerous mitochondria, and occassional microtubules. Groups of dark staining cells scattered throughout the CA of some animals were interpreted as evidence of cellular death.This work was done while JTB was supported by USPHS Training Grant HD-0266 from NICHDI wish to express my thanks to Dr. Richard A. Cloney for sharing his expertise in electron microscopy     

Neurosecretory system of the earwig Labedura riparia, and the rôle of the aorta as a neurohaemal organ

The neurosecretory system of Labedura riparia has been described from sections and whole mounts using a variety of techniques. The pars intercerebralis contains two clusters of medial neurosecretory cells (MNC), each cluster consisting of 8 to 10 A-cells and occasional B-cells. The lateral sides of the brain have a few B-cells. The axons of the median neurosecretory cells terminate in the cephalic aorta (AO), whereas the axons of the lateral neurosecretory cells (LNC) terminate in the corpora cardiaca (CC). It appears that the neurosecretory material (NSM) elaborated in the MNC is stored in the cephalic aorta and that elaborated in the LNC is stored in the corpora cardiaca, which are two oval or elongate bodies composed of large chromophobe and small chromophil cells. Posteriorly there is the oval or elongate corpus allatum (CA) attached to the CC by thick nerves. The CA consists of one cell type only. Both CC and CA contain no A-cell neurosecretory material. It has been suggested that the neurosecretory system of L. riparia is composed of two complexes. One is formed by the medial neurosecretory cells for which the aorta functions as a neurohaemal organ, and the other is formed by lateral neurosecretory cells-lateral neurosecretory pathways-nervi corporis cardiaci-II in which the corpora cardiaca function as a neurohaemal organ.     

Identification of neurosecretory reservoirs in the mayfly Ephemera danica Müll. (ephemeroptera: ephemeridae) (author's transl)]

Neurosecretory reservoirs were found in the head of Ephemera danica. In the region where the nervus corporis cardiaci 1 is leaving the brain, the diameter of this nerve increases considerably. Different types of axons were observed, filled with great amounts of electron opaque secretory granules with mean diameters of 170 nm and 110 nm, respectively. Another neurosecretory reservoir is situated in the rostral part of the corpus cardiacum containing a secretory material of a different kind. Most of the granules have diameters of about 90 nm, and are electron opaque. A relatively small number of axons contains nearly electron lucent vesicles with the same mean diameter.     

THE NEUROENDOCRINE SYSTEM AND STOMATOGASTRIC NERVOUS SYSTEM OF THE ADULT TSETSE FLY GLOSSINA MORSITANS

The brain of Glossina morsitans Westwood contains four groups of neurosecretory cells which are stainable with chrome haematozylin and phloxin. The axons of these cells form a pair of nervi corporis cardiaci which pass posteriorly from the brain and innervate the corpora cardiaca and corpus allatum before uniting with a small ganglion posterior to the corpora cardiaca. This ganglion is considered to represent the fusion of the fusion of the hypocerebral and ventricular ganglia which remain separate in other insects.
There is no frontal ganglion in the adult Glossina and the recurrent nerve fuses with one of the nervi corporis cardiaci immediately behind the brain. The oesophageal nerves arising from the fused hypocerebral and ventricular ganglia innervate the oesophagus in the anterior part of the thorax, the proventriculus and the posterior extension of the oesophagus close to the crop. These nerves possess both sensory and motor nerve endings. The differences which exist between Glossina and other cyclorrhaphous Diptera with respect to their neuroendocrine/stomatogastric system are noted and considered in terms of the control of neuroendocrine function.     

The release of a pheromonotropic neuropeptide, PBAN, in the turnip moth Agrotis segetum, exhibits a circadian rhythm

In the female turnip moth, Agrotis segetum, a pheromone biosynthesis activating neuropeptide (PBAN) stimulates sex pheromone biosynthesis which exhibits a daily rhythm. Here we show data supporting a circadian rhythm in PBAN release from the corpora cardiaca, which we propose regulates the endogenous rhythm in sex pheromone biosynthesis. This conclusion is drawn as the observed daily rhythm in PBAN-like immunoreactivity in the hemolymph is persistent in constant darkness and is phase-shifted by an advanced light:dark cycle. PBAN-like immunoreactivity was found in the brain, the optic lobe, the suboesophageal ganglion and in the retrocerebral complex. In each hemisphere ca. 10 immunopositive neurons were observed in the pars intercerebralis and a pair of stained somata in the dorso-lateral protocerebrum. A cluster of cells containing PBAN-like immunoreactive material was found in the tritocerebrum and three clusters of such cells were found in the SOG. Their processes reach the corpora cardiaca via nervi corporis cardiaci and the dorsal surface of the corpora allata via the nervi corporis allati.     

Localization of octopaminergic neurones in insects

This paper reviews data on the localization of octopaminergic neurones revealed by immunocytochemistry in insects, primarily the locusts Schistocerca gregaria and Locusta migratoria, cricket Gryllus bimaculatus, and cockroach Periplaneta americana. Supporting evidence for their octopaminergic nature is mentioned where available. In orthopteran ventral ganglia, the major classes of octopamine-like immunoreactive (-LI) neurones include: (1) efferent dorsal and ventral unpaired median (DUM, VUM) neurones; (2) several intersegmentally projecting DUM interneurones in the suboesophageal ganglion; other DUM interneurones are probably GABAergic; (3) a pair of anterior median cells in the prothoracic ganglion; (4) a single pair of ventral cells in most thoracic and some other ganglia; these appear to be plurisegmentally projecting interneurones. Eight categories of octopamine-LI neurones occur in the orthopteran brain. The basic projections of three types are described here: one class project to the optic lobes to form wide field projections. Another type descends to cross into the tritocerebral commissure and may invade the contralateral brain hemisphere. A further class is the median neurosecretory cells with axons in the nervi corpori cardiaci I. Available data for the honey bee Apis mellifera and moth Manduca sexta indicate that the octopamine-LI cell types found in orthopterans also occur in holometabolous insects. Immunocytochemical evidence suggests that some octopaminergic DUM cells contain an FMRFamide-related peptide and the amino acid taurine as putative cotransmitters.     

The neurosecretory system of the adult Melanogryllus desertus pall. (Orthoptera,Gryllidae)

Summary The cerebral neurohemal area of Melanogryllus desertus is located posteriorly among the neurons of nervus corporis cardiaci I (NCCI) on the ventral median surface of the protocerebrum where axons penetrate the neural lamella and terminate on its outer surface. Numerous neurosecretory fibers containing three different types of granule occur within and on the outer surface of the neural lamella.The release of neurosecretory granules is accomplished by exocytosis and the formation of synaptoids. It can also take place as a mass release of granules into the stroma.     

Histology, histochemistry, and ultrastructure of neurosecretory cells in the optic lobe of the cockroach, Periplaneta americana

In the region of the distal optic chiasma of each optic lobe of Periplaneta americana, there is a group of about 120 monopolar neurosecretory cells. These cells do not stain with paraldehyde fuchsin but remain acidophilic after oxidation. They stain red or sometimes indigo with the azan technique. Histochemically, the neurosecretory material is positive for protein and the amino acids tryptophan and arginine but negative for 1, 2-glycols and strongly acidic groups. At the ultrastructural level, the cytoplasm of the cells contain many elementary neurosecretory granules 100 to 170 nm in dia. The cells also contain well-developed Golgi bodies and endoplasmic retieulum. The axons from these cells run toward the interior of the optic lobe. In this region, axons containing dense granules (mean diameter 70 nm) and synaptic vesicles synapse onto the axons from the neurosecretory cells. The neurosecretory axons then cross over to the anterior side of the optic lobe and run towards the brain. The function of these neurosecretory cells is unknown, but they may be involved with photoperiodically controlled activity rhythms.     

Three-dimensional architecture of identified cerebral neurosecretory cells in an insect

The organization of identified neurosecretory cell groups in the larval brain of the tobacco hornworm, Manduca sexta, was investigated immunocytologically. Computer-assisted three-dimensional reconstruction was used to examine the architecture of the neurosecretory cell groups. The group III lateral neurosecretory cells (L-NSC-III) which produce the prothoracicotropic hormone are located dorsolaterally in the protocerebrum and extend axons medially that decussate to the contralateral lobe prior to exiting the brain through the nervi corporis cardiaci I + II. The group IIa2 medial neurosecretory cells (M-NSC IIa2) are located anteriorly in the medial dorsal protocerebrum. The axons of these cells also exit the brain via the contralateral nervi corporis cardiaci I + II. However, their axons traverse a different pathway through the brain from that of the L-NSC III axons. Each of the cell groups possesses elaborate dendrites with terminal varicosities. The dendrites can be classified into specific fields based upon their location and projection pattern within the brain. The dendrites for these two neurosecretory cell groups overlap in specific regions of the protocerebral neuropil. After the axons of these neurosecretory cells exit the brain through the retrocerebral nerve, they innervate the corpus allatum where they arborize to form neurohemal terminals in strikingly different patterns. The L-NSC III penetrate throughout the glandular structure and the M-NSC IIa2 terminals are restricted to the external sheath. A third group of cerebral neurosecretory cells, the ventromedial neurons (VM) which stain with the monoclonal antibody to prothoracicotropic hormone in Manduca, are located anteriorly in the medial region of the brain. The axons of these cells do not exit the brain to the retrocerebral complex, but rather pass through the circumesophageal connectives and ventral nerve cord. These neurons appear to be the same VM neurons that produce eclosion hormone. One dendritic field of the L-NSC III terminates in close apposition to the VM neurons. The distinct morphologies of these neurosecretory cell groups in relation to other cell groups and the distribution of neuropeptides within the neurons suggest that insect neurosecretory cells, like their vertebrate counterparts, may have multiple regulatory roles.     

Immunological evidence for an allatostatin-like neuropeptide in the central nervous system of Schistocerca gregaria,Locusta migratoria and Neobellieria bullata

Methanolic brain extracts of Locusta migratoria inhibit in vitro juvenile hormone biosynthesis in both the locust L. migratoria and the cockroach Diploptera punctata. A polyclonal antibody against allatostatin-5 (AST-5) (dipstatin-2) of this cockroach was used to immunolocalize allatostatin-5-like peptides in the central nervous system of the locusts Schistocerca gregaria and L. migratoria and of the fleshfly Neobellieria bullata. In both locust species, immunoreactivity was found in many cells and axons of the brain-retrocerebral complex, the thoracic and the abdominal ganglia. Strongly immunoreactive cells were stained in the pars lateralis of the brain with axons (NCC II and NCA I) extending to and arborizing in the corpus cardiacum and the corpora allata. Although many neurosecretory cells of the pars intercerebralis project into the corpus cardiacum, only 12 of them were immunoreactive and the nervi corporis cardiaci I (NCC I) and fibers in the nervi corporis allati II (NCA II) connecting the corpora allata to the suboesophageal ganglion remained unstained. S. gregaria and L. migratoria seem to have an allatostatin-like neuropeptide present in axons of the NCC II and the NCA I leading to the corpus cardiacum and the corpora allata. All these data suggest that in locusts allatostatin-like neuropeptides might be involved in controlling the production of juvenile hormone by the corpora allata and, perhaps, some aspects of the functioning of the corpus cardiacum as well. However, when tested in a L. migratoria in-vitro juvenile hormone-biosynthesis assay, allatostatin-5 did not yield an inhibitory or stimulatory effect. There is abundant AST-5 immunoreactivity in cell bodies of the fleshfly N. bullata, but none in the CA-CC complexes. Apparently, factors that are immunologically related to AST-5 do occur in locusts and fleshflies but, the active protion of the peptide required to inhibit JH biosynthesis in locusts is probably different from that of AST-5.     

A comparative ultrastructural and physiological study on melanophores of wild-type and periodic albino mutants of Xenopus laevis

Summary The central and visceral nervous systems of the cockroach Periplaneta americana were studied by means of the peroxidase-antiperoxidase immunocytochemical method, with the use of antibody to bovine pancreatic polypeptide (PP). PP-like immunoreactive neuron somata are most numerous in the brain; at least 6 pairs of cell groups occur in clearly defined regions. Three pairs of cells each are also present in the suboesophageal ganglion and the thoracic ganglia, one pair of a single cell each in the first abdominal and the frontal ganglia, and 4 to 6 pairs of single cells in the terminal ganglion. No reactive cells were found in the retrocerebral complex and the second to the fifth abdominal ganglia. The axons containing PP-like immunoreactivity issue many branches that are distributed in the entire brain-retrocerebral complex, ventral cord, and visceral nervous system. PP-like immunoreactive material produced in the brain seems to be transported by three routes: protocerebrum to corpora cardiaca (-allata) through the nervi corporis cardiaci, tritocerebrum to visceral nervous system through frontal commissures, and to ventral cord through circumoesophageal connectives.A possible homology between the mammalian brain-GEP (gastro-enteropancreatic) system and the brain-midgut system of this insect is discussed.     

The innervation of the corpus cardiacum of Locusta migratoria: A neuroanatomical study with the use of Lucifer yellow

Summary Neural connections of the corpus cardiacum (CC) in the African locust, Locusta migratoria, were labelled with the fluorescent tracer Lucifer yellow. (1) Unilateral anterograde labelling of the nervus corporis cardiaci I revealed fluorescent fibres in the storage lobe of the CC (CCS). Some fluorescent fibres in the CCS closely approached the ipsilateral border of the glandular lobes of the CC (CCG). Fluorescent fibres also projected into the neuropile of the hypocerebral ganglion via the ipsilateral nervi cardiostomatogastrici I and II, and from there into the oesophageal nerves. (2) Unilateral anterograde labelling of the nervus corporis cardiaci II revealed fluorescent fibres in the CCS and in the ipsilateral CCG. Fluorescent fibres also projected via the ipsilateral nervus corporis allati I into the corpus allatum. (3) Unilateral retrograde labelling of the nervus corporis allati I revealed a distinct fluorescent nerve tract that runs through the CCS and into the nervus corporis cardiaci II. The tract arises from about eight cell bodies in the brain at the rostroventral side of the ipsilateral calyx of the mushroom body. (4) Labelling of the recurrent nerve revealed fluorescent fibres and some fluorescent cell bodies in the hypocerebral ganglion and, via the nervi cardiostomatogastrici I and II, also in the CCS. Fluorescent fibres were also present in the oesophageal nerves.     

New features of the brain-retrocerebral neuroendocrine complex of the locust Schistocerca vaga (scudder)

Summary The techniques of axonal iontophoresis and cobalt sulfide precipitation were used to elucidate the relationships of the brain's neurosecretory cell groups and the retrocerebral complex of the locust Schistocerca vaga. The axons of the nervi corporis cardiaci I (NCC I) arise (1) from the medial neurosecretory cells of the protocerebrum, showing only limited branching, looping or spiraling; and (2) from a cell group previously undescribed for this species, located in the tritocerebrum. The axons project into the neurohemal and the glandular portions of the corpora cardiaca and into the hypocerebral ganglion, but not into the corpora allata. Axons of the NCC II arise from the lateral neurosecretory cells of the protocerebrum and project into the center of the corpora allata via the nervi corporis allati I (NCA I), as well as into the neurohemal and glandular portions of the corpora cardiaca. Axons of the NCC III arise from another newly described cell group in the tritocerebrum and end in both the corpora cardiaca and corpora allata. Axons of the NCA II arise from cells in the subesophageal ganglion and also end in the corpora allata.Supported by NIH Predoctoral Fellowship No. 5 F 01 GM 43816-03, NSF Grant GB-23033 and NIH Grant CA-05045 to H. A. Bern and USPHS Grant 1 R 01 NS09404 to C.H.F. Rowell.I wish to express my gratitude to Professors H.A. Bern and C.H.F. Rowell for unending encouragement and advice. I am indebted to Dr. Mick O'Shea for instruction in the cobalt/axonal iontophoresis method, and to Ms. Bea Bacher for excellent technical assistance.