Summary
Dorsal unpaired median (DUM) neurons are bilaterally symmetrical. A single primary neurite arises from the soma and runs anteriorly through the neuropil before dividing into two lateral neurites which pass to the nerve roots on each side of the ganglion. The primary neurite runs in one of two tracts, one of which lies further from the surface of the ganglion than the other. The primary neurites in the deeper tract belong to DUM1, DUM5 and DUM3,4,5 neurons, and those in the more superficial tract, to DUM3, DUM3,4 and DUM3,4,5 neurons. Previous studies have shown that in the developing embryonic nervous system the primary neurites of DUM neurons can also be observed to lie in one of two tracts, but these do not appear to correspond to those seen in the adult. The results described here differ further from those of other investigations of adult and embryonic locusts in that no DUM4,5 neurons were seen, but DUM3,4 neurons, not found in previous studies, were frequently stained. The secondary neurites of DUM neurons characteristically give rise to fine 0.2–0.5 μm diameter processes which may run for hundreds of microns through the neuropil with very little branching. The problems this may pose for signal transmission along such processes is discussed. Presynaptic processes of several types make inputs on to spines on the lateral neurites of DUM neurons and on to branches from secondary neurites. Output synapses were rarely observed and were found only on lateral neurite spines. It therefore appears unlikely that the DUM neurons examined play a major central role within the metathoracic ganglion. A novel structure, with the appearance of a presynaptic density but which was not associated with synaptic vesicles, was found in certain regions of the neurons.
Similar content being viewed by others
References
Altman, J. S. &Tyrer, N. M. (1977) Locust wing hinge stretch receptors.Journal of Comparative Neurology 172, 409–30.
Bacon, J. P. &Altman, J. S. (1977) A silver intensification method for cobalt-filled neurones in wholemount preparations.Brain Research 189, 359–63.
Bentley, D. R. (1973) Postembryonic development of insect motor systems. InDevelopmental Neurobiology of Arthropods (edited byYoung, D.), pp. 147–77. Cambridge: Cambridge University Press.
Bräunig, P. (1982) Peripheral and central nervous organisation of the locust coxo- trochanteral joint.Journal of Neurobiology 13, 413–34.
Bray, D. F. &Wagenaar, E. B. (1978) A double staining technique for improved contrast of thin sections from Spurr embedded tissue.Canadian Journal of Botany 56, 129–35.
Brogan, R. T. &Pitman, R. M. (1981) Axonal regeneration in an identified insect neurone.Journal of Physiology 319, 34–35P.
Burrows, M. (1973) The morphology of an elevator and a depressor mononeurone of the hind wing of a locust.Journal of Comparative Physiology 83, 165–78.
Casaday, G. B. &Camhi, J. M. (1976) Metamorphosis of flight motor neurones in the mothManduca sexta.Journal of Comparative Physiology 112, 143–58.
Ceccareli, B. &Hurlbutt, W. P. (1980) Vesicle hypothesis of the release of acetylcholine.Physiological Reviews 60, 396–441.
Clark, R. (1976) Structural and functional changes in an identified cricket neurone after separation from the soma. I: Structural changes.Journal of Comparative Neurology 170, 253–56.
Crossman, A. R., Kerkut, G. A., Pitman, R. M. &Walker, R. J. (1971a) Electrically excitable nerve cell bodies in the central ganglia of two insect speciesPeriplaneta americana andSchistocerca gregaria.Comparative Biochemistry and Physiology 40A, 594–97.
Crossman, A. R., Kerkut, G. A. &Walker, R. J. (1971b) Axon pathways of electrically excitable cell bodies in the insect nervous system.Journal of Physiology 218, 55–6.
Crossman, A. R., Kerkut, G. A. &Walker, R. J. (1972) Electrophysiological studies on the axon pathways of specified nerve cells in the central ganglia of two insect speciesPeriplaneta americana andSchistocerca gregaria.Comparative Biochemistry and Physiology 43A, 393–415.
Davis, N. T. (1977) Motor neurones of the indirect flight muscles ofDysdercus fulvoniger.Annals of the Entomological Society of America 70, 377–86.
Difiglia, M., Pasik, P. &Pasik, T. (1980) Early postnatal development of the monkey neostriatum: a golgi and ultrastructural study.Journal of Comparative Neurology 190, 303–31.
Dunn, R. A. &Morest, D. K. (1975) Receptor synapses without synaptic ribbons in the cochlea of the cat.Proceedings of the National Academy of Sciences USA 72, 3599–603.
Evans, P. D. (1981) Octopaminergic modulation of neuromuscular transmission in the locust. InAdvances in Physiological Science, Vol. 22,Neurotransmitters in Invertebrates (edited byRozsa, K. S.). Oxford: Pergamon Press; Budapest: Akademia Kiado.
Evans, P. D. (1982) Properties of modulatory octopamine receptors in the locust. InNeuropharmacology of Insects, Ciba Foundation Symposium 88, pp. 48–69. London: Pitman.
Evans, P. D. &O'Shea, M. (1977) The identification of an octopaminergic neurone which modulates neuromuscular transmission in the locust.Nature 270, 257–59.
Evans, P. D. &O'Shea, M. (1978) The identification of an octopaminergic neuron and the modulation of a myogenic rhythm in the locust.Journal of Experimental Biology 73, 235–60.
Evans, P. D. &Siegler, M. V. S. (1982) Octopamine mediated relaxation of maintained and catch tension in locust skeletal muscle.Journal of Physiology 324, 93–112.
Frölich, A. &Meinhertzhagen, I. A. (1982) Synaptogenesis in the first optic neuropile of the fly's visual system.Journal of Neurocytology 11, 159–80.
Goodman, C. S. (1982) Embryonic development of identified neurons in the grasshopper. InNeuronal Development (edited bySpitzer, N. C.). New York, London: Plenum Press.
Goodman, C. S., O'Shea, M., McCaman, R. &Spitzer, N. C. (1979) Embryonic development of identified neurones: Temporal pattern of morphological and biochemical differentiation.Science 204, 1219–22.
Goodman, C. S., Pearson, K. G. &Spitzer, N. C. (1980) Electrical excitability: A spectrum of properties in the progeny of a single embryonic neuroblast.Proceedings of the National Academy of Sciences USA 77, 1676–80.
Goodman, C. S. &Spitzer, N. C. (1979) Embryonic development of identified neurones: Differentiation from neuroblast to neurone.Nature 280, 208–14.
Govind, C. K., Meiss, D. E. &Pearce, J. (1982) Differentiation of identifiable lobster neuromuscular synapses during development.Journal of Neurocytology 11, 235–47.
Hoyle, G. (1974) A function for neurones (DUM) neurosecretory on skeletal muscle of insects.Journal of Experimental Zoology 189, 401–6.
Hoyle, G. (1978) The dorsal unpaired median neurons of the locust metathoracic ganglion.Journal of Neurobiology 9, 43–57.
Hoyle, G., Colquhoun, W. &Williams, M. (1980) Fine structure of an octopaminergic neurone and its terminals.Journal of Neurobiology 11, 103–26.
Hoyle, G. &Dagan, D. (1978) Physiological characteristics and reflex activation of DUM (octopaminergic) neurones of locust metathoracic ganglion.Journal of Neurobiology 9, 59–79.
Hoyle, G., Dagan, D., Moberley, B. &Colquhoun, W. (1974) Dorsal unpaired median insect neurones make neurosecretory endings on skeletal muscle.Journal of Experimental Zoology 187, 159–65.
Landmesser, L. &Pilar, G. (1972) The onset and development of transmission in the chick ciliary ganglion.Journal of Physiology 222, 691–713.
Lane, N. J. &Skaer, H. LeB. (1980) Intercellular junctions in insect tissues.Advances in Insect Physiology 15, 35–214.
Murphy, A. D. &Kater, S. B. (1980) Sprouting and functional regeneration of an identified neuron inHelisoma.Brain Research 186, 251–72.
Plotnikova, S. I. (1969) Effector neurones with several axons in the ventral nerve cord of the Asian grasshopper,Locusta migratoria.Journal of Evolutionary Biochemistry and Physiology 5, 276–78.
Rall, W. (1981) Functional aspects of neuronal geometry. InNeurones Without Impulses (edited byRoberts, A. andBush, B. M. H.), pp. 223–54. Cambridge: Cambridge University Press.
Tauc, L. (1982) Nonvesicular release of neurotransmitter.Physiological Reviews 62, 857–93.
Truman, J. W. &Riess, S. E. (1976) Dendritic reorganisation of an identified motoneuron during metamorphosis of the tobacco hornworm moth.Science 192, 477–79.
Tyrer, N. M. &Gregory, G. E. (1982) A guide to the neuroanatomy of locust suboesophageal and thoracic ganglia.Philosophical Transactions of the Royal Society B 297, 91–123.
Watson, A. H. D. &Burrows, M. (1981) Input and output synapses on identified motor neurones of a locust revealed by the intracellular injection of horseradish peroxidase.Cell and Tissue Research 215, 325–32.
Watson, A. H. D. &Burrows, M. (1982) The ultrastructure of identified locust motor neurones and their synaptic relationships.Journal of Comparative Neurology 205, 383–97.
Watson, A. H. D. &Burrows, M. (1983) The morphology, ultrastructure and distribution of synapses on an intersegmental interneurone of the locust.Journal of Comparative Neurology 214, 154–69.
Wood, M. R., Pfenninger, K. H. &Cohen, M. J. (1977) Two types of presynaptic configurations in insect central synapses.Brain Research 130, 25–45.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Watson, A.H.D. The dorsal unpaired median neurons of the locust metathoracic ganglion: neuronal structure and diversity, and synapse distribution. J Neurocytol 13, 303–327 (1984). https://doi.org/10.1007/BF01148121
Received:
Revised:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF01148121