Summary
The fine structure of the terminal sensilla on the maxillary palps of Schistocerca gregaria has been investigated. Most organules include six neurons with dendrites extending to the tip of the cuticular peg, the opening of which is controlled so that the dendrites are not always exposed. The neurons are isolated from each other by a neurilemma cell and two other glial cells, while typical epidermal cells containing dense bundles of microtubules support the whole group of cells. At the poles of the neurons are specialised areas in which the cytoplasm is differentiated from that elsewhere. It contains a large number of mitochondria and small helical structures, while close to it are characteristic spheres of membranes, termed onion bodies, in various stages of development.
It is suggested that the fluid bathing the distal parts of the dendrites and exuding from the tip of the peg has a number of specialised functions. It is probably concerned in forcing open the tip of the peg by hydrostatic pressure, it prevents the exposed tips of the dendrites from desiccating and it acts as a transmitter in which chemicals on the surfaces touched by the sensillum must dissolve before reaching the dendrites. This fluid may be produced by the neurilemma cell or by the neurons themselves. Closure of the pegs does not seem to produce any material reduction in the overall loss of water by the insect.
Each neuron sends an axon to the brain; there is no peripheral fusion of axons. Possibly one neuron has a mechanoreceptor function, although no specialised terminal at the base of the peg has been observed. The concentration of mitochondria at either end of the neuron may be concerned in the production of action potentials, while the cavity of the peg and tormogen cell perhaps has a role in the conduction of the receptor potential to the perikaryon. Intercellular connections are such as to give mechanical stability to the cells of the organule and permit transport between the cells. Extracellular tubules extending from the wall of the peg into the cell complex may serve to anchor the peg during the moulting process.
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References
Adams, J. R., P. E. Holbert, and A. J. Forgash: Electron microscopy of the contact chemoreceptors of the stable fly, Stomoxys calcitrans (Diptera: Muscidae). Ann. ent. Soc. Amer. 58, 909–917 (1965).
Alexander, N. J., and W. H. Fahrenbach: Fine structure of endocrine hindgut cells of a lepidopteran, Ostrinia nubilalis (Hübn.). Z. Zellforsch. 94, 337–345 (1969).
Al-Lami, F., and R. G. Murray: Fine structure of the carotid body of normal and anoxic cats. Anat. Rec. 160, 697–717 (1968).
Aziz, S. A.: Probable hygroreceptors in the desert locust, Schistocerca gregaria Forsk. (Orthoptera: Acrididae). Indian J. Ent. 19, 164–170 (1958).
Behnke, O.: Helical arrangement of ribosomes in the cytoplasm of differentiating cells of the small intestine of rat foetuses. Exp. Cell Res. 30, 597–598 (1963).
Blaney, W. M., and R. F. Chapman: The anatomy and histology of the maxillary palp of Schistocerca gregaria (Orthoptera, Acrididae). J. Zool. (Lond.) 157, 509–535 (1969).
Duncan, C. J.: The molecular properties and evolution of excitable cells. Oxford: Pergamon Press 1967.
Edney, E. B.: The water relations of terrestrial arthropods. Cambridge: Cambridge University Press 1957.
Guthrie, D. M.: The function and fine structure of the cephalic airflow receptor in Schistocerca gregaria. J. Cell Sci. 1, 463–470 (1966).
Hydén, H.: The neuron. In: J. Brachet and A. E. Mirsky (eds.), The cell. Biochemistry, physiology, morphology, vol. 4. New York: Academic Press 1960.
Karlsson, U.: Three dimensional studies of neurons in the lateral geniculate nucleus of the rat 1. Organelle organization in the perikaryon and its proximal branches. J. Ultrastruct. Res. 16, 429–481 (1966).
Lai-Fook, J.: The structure of developing muscle insertions in insects. J. Morph. 123, 503–528 (1967).
Larsen, J. R.: The fine structure of the labellar chemosensory hairs of the blowfly, Phormia regina Meig. J. Insect Physiol. 8, 683–691 (1962).
Lawrence, P. A.: Development and determination of hairs and bristles in the milkweed bug, Oncopeltus fasciatus (Lygaeidae) (Hemiptera). J. Cell Sci. 1, 475–498 (1966).
Le Berre, J.-R., Y. Sinoir et C. Boulay: Étude de l'équipement sensoriel de l'article distal des palpes chez la larve de Locusta migratoria migratorioides (R. & F.). C. R. Acad. Sci. (Paris) 265, 1717–1720 (1967).
Locke, M.: Pore canals and related structures in insect cuticle. J. biophys. biochem. Cytol. 10, 589–618 (1961).
—: The structure of septate desmosomes. J. Cell Biol. 25, 166–169 (1965).
—: What every epidermal cell knows. In: J. W. L. Beament and J. E. Treherne (eds.), Insects and physiology. London: Oliver & Boyd 1967.
Lowenstein, W. R., and Y. Kanno: Studies on an epithelial (gland) cell junction I. Modifications of surface membrane permeability. J. Cell Biol. 22, 565–586 (1964).
Moulins, M.: Les cellules sensorielles de l'organe hypopharyngien de Blabera craniifer Burm. (Insecta, Dictyoptera). Étude du segment ciliaire et des structures associées. C. R. Acad. Sci. (Paris) 265, 44–47 (1967).
—: Les sensilles de l'organe hypopharyngien de Blabera craniifer Burm. (Insecta, Dictyoptera). J. Ultrastruct. Res. 2, 474–513 (1968).
Murray, R. G., and A. Murray: The fine structure of the taste buds of rhesus and cynomolgus monkeys. Anat. Rec. 138, 211–233 (1960).
Nicklaus, R., P.-G. Lunquist u. J. Wersäll: Elektronmikroskopie am sensorischen Apparat der Fadenhaare auf den Cerci der Schabe Periplaneta americana. Z. vergl. Physiol. 56, 412–415 (1967).
Noble-Nesbitt, J.: The cuticle and associated structures of Podura aquatica at the moult. Quart. J. micr. Sci. 104, 369–392 (1963).
Palay, S. L., and G. E. Palade: The fine structure of neurons. J. biophys. biochem. Cytol. 1, 69–88 (1955).
Rees, C. J. C.: Transmission of receptor potential in dipteran chemoreceptors. Nature (Lond.) 215, 301–302 (1967).
Rudall, K. M.: The chitin/protein complexes of insect cuticles. Adv. Ins. Physiol. 1, 257–314 (1963).
Schneider, D.: Chemical sense communication in insects. Symp. Soc. exp. Biol. 20, 273–297 (1966).
Slifer, E. H., J. J. Prestage, and H. W. Beams: The chemoreceptors and other sense organs on the antennal flagellum of the grasshopper (Orthoptera; Acrididae). J. Morph. 105, 145–191 (1959).
Smith, D. S., and J. E. Treherne: Functional aspects of the organisation of the insect nervous system. Adv. Ins. Physiol. 1, 401–484 (1963).
Steinbrecht, R. A.: On the question of nervous syncytia: lack of axon fusion in two insect sensory nerves. J. Cell Sci. 4, 39–53 (1969).
Stürckow, B.: Ein Beitrag zur Morphologie der labellaren Marginalborste der Fliegen Calliphora und Phormia. Z. Zellforsch. 57, 627–647 (1962).
Tateda, H., and H. Morita: Initiation of spike potentials in contact chemosensory hairs of insects I. The generation site of the recorded spike potentials. J. cell. comp. Physiol. 54, 171–176 (1959).
Thurm, U.: An insect mechanoreceptor. Part I: Fine structure and adequate stimulus. Cold Spr. Harb. Symp. quant. Biol. 30, 75–82 (1965).
Uvarov, B. P.: Grasshoppers and locusts. Cambridge: Cambridge University Press 1966.
Venable, J. H., and R. Coggeshall: A simplified lead citrate stain for use in electron microscopy. J. Cell Biol. 25, 407–408 (1965).
Waddington, C. H., and M. M. Perry: Helical arrangement of ribosomes in differentiating muscle cells. Exp. Cell Res. 30, 599–600 (1963).
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We are grateful to the Royal Society for a grant for the purchase of an ultramicrotome, to the Anti-Locust Research Centre for supplying the locusts, and to various colleagues for assistance and advice. We are also indebted to the Cambridge Instrument Company Ltd. for permission to publish Figs. 2 and 3.
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Blaney, W.M., Chapman, R.F. The fine structure of the terminal sensilla on the maxillary palps of Schistocerca gregaria (Forskål) (Orthoptera, Acrididae). Z. Zellforsch. 99, 74–97 (1969). https://doi.org/10.1007/BF00338799
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DOI: https://doi.org/10.1007/BF00338799