Summary
The ultrastructural characteristics of the neuromuscular junctions were studied in oesophageal (visceral) muscle and in four skeletal muscles of the head and trunk in Sagitta.
Three types of neuromuscular junctions were encountered. The first is made up of nerve terminals which synapse with the surface of the muscle fiber, in a deep or in a slight depression. The second is characterized by muscle fiber protrusions that cross the connective tissue and form synapses with nerve endings; in this type, numerous post-junctional membrane folds are noted. In the third type, the synaptic cleft is very large (> 0.2 μm) and contains bundles of connective fibers.
Nerve endings are partially ensheathed in glial cells; they contain mostly clear synaptic vesicles, though some densecored vesicles are noted. In many muscle fibers post-junctional membrane thickenings are also observed. All observed neuromuscular junctions resemble chemical synapses.
Chaetognaths thus show a great variety of neuromuscular junction ultrastructure as do for instance Arthropods.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Auber J, Couteaux R (1963) Ultrastructure de la strie Z dans des muscles de Diptères. J Microsc 2:309–324
Bullock TH, Horridge GA (1965) Structure and function in the nervous systems of invertebrates. W.H. Freeman and Company, San Francisco London. I. & II
Burfield ST (1927) Sagitta. Liverpool marine biol. Comm Memoirs 28:1–104
Burnstock G (1970) Structure of smooth muscle and its innervation. In: Bülbring E, Brading AF, Jones AW, Tomita T (eds) Smooth muscle. Edward Arnold Ltd, London, pp 1–69
Coob JLS, Laverack MS (1967) Neuromuscular systems in Echinoderms. Symp Zool Soc London 20:25–51
Couteaux R (1973) Motor end-plate structure. In: Bourne GH (ed) The structure and function of muscle. Acad Press, New York London II:483–530
Crabtree RL, Sherman RG (1981) Ultrastructural characterization of superficial and deep flexor muscles in the crayfish thorax. Can J Zool 59:357–363
De Beauchamp P (1960) Classe des Chétognathes (Chaetognatha). In: Grasse PP (ed) Traité de zoologie. Masson & Cie, Paris V:1500–1520
De Bell JT (1965) A long look at neuromuscular junctions in nematodes. Q Rev Biol 40:233–251
Duvert M (1969) Ultrastructure des myofibrilles dans les muscles longitudinaux de Sagitta setosa (Chaetognathes). CR Acad Sci Paris 268:2452–2454
Duvert M, Salat C (1979) Fine structure of muscle and other components of the trunk of Sagitta setosa (Chaetognatha). Tissue Cell 1:217–230
Duvert M, Salat C (1980) The primary body-wall musculature in the arrow-worm Sagitta setosa (Chaetognatha): an ultrastructural study. Tissue Cell 12:723–738
Duvert M, Gros D, Salat C (1980) Ultrastructural studies of the junctional complex in the musculature of the arrow-worm, Sagitta setosa (Chaetognatha). Tissue Cell 12:1–11
Elder HY (1975) Muscle structure. In: Usherwood PNR (ed) Insect muscle. Acad Press, New York, San Francisco: 1–74
Emschermann (1982) Les Kamptozoaires. Etat actuel de nos connaissances sur leur anatomie, leur développement, leur biologie et leur position phylogénétique. Bull Soc Zool France 107:317–344
Flood PR (1966) A peculiar mode of muscle innervation in Amphioxus. Light and electron microscopic studies of the so-called ventral roots. J Comp Neurol 126:181–218
Flood PR (1970) The connection between spinal cord and notochord in Amphioxus (Branchiostoma lanceolatum). Z Zellforsch 103:115–128
Grassi B (1883) Die Chaetognathen. Fauna and Flora des Golfes von Neapel. V:1–126
Grimstone AV (1959) Cytology, homology and phylogeny, a note on “organic design”. Am Nat XCII:273–282
Gupta BL, Little C (1970) Studies on Pogonophora. 4. Fine structure of the cuticle and epidermis. Tissue Cell 2:637–696
Gupta BL, Little C (1975) Ultrastructure, phylogeny and Pogonophora. Z Zool Syst Evolut Forsch 45–63
Hertwig O (1880) Die Chaetognathen; ihre Anatomie, Systematik und Entwicklungsgeschichte, eine Monographie. Gustav Fischer, Jena, 111 p Vitafel
Huddart H (1975) The comparative structure and function of muscle. International series of monographs in pure and applied biology. Zool Division 53:397
Hyman LH (1959) Phylum Chaetognatha. In: The invertebrates. Mc Graw-Hill, New York 5:1–71
Karnovsky MJ (1965) A formaldehyde-glutaraldehyde fixative of high osmolality for use in electron microscopy. J Cell Biol 27:137 A
Lang F (1972) Ultrastructure of neuromuscular junctions in limulus heart. Z Zellforsch 130:481–488
Mill PJ, Knapp MF (1970) Neuromuscular junctions in the body wall muscles of the earth worm, Lumbricus terrestris Linn. J Cell Sci 7:263–271
Osborne MP (1975) The ultrastructure of nerve-muscle synapses. In: Usherwood PNR (ed) Insect muscle. Acad Press, New York San Francisco, pp 151–205
Pappas GD (1975) Ultrastructural basis of synaptic transmission in the nervous system. DB Tower I:19–30
Silva MT, Santos Mota JM, Melo JVC, Carvalho Guerra F (1971) Uranyl salts as fixatives for electron microscopy. Study of the membrane ultrastructure and phospholipid loss in bacilli. Biochem Biophys Acta 233:513–520
Smith DS, Del Castillo J, Anderson M (1973) Fine structure and innervation of an annelid muscle with the longest recorded sarcomere. Tissue Cell 5:281–302
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Duvert, M., Barets, A.L. Ultrastructural studies of neuromuscular junctions in visceral and skeletal muscles of the chaetognath Sagitta setosa . Cell Tissue Res. 233, 657–669 (1983). https://doi.org/10.1007/BF00212233
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00212233