title: An electron microscopic study on the muscle cells and nerve fibres in the digestive gland of the snail Cryptomphallus aspersa.
abstract: This work is an electron microscopic study of the muscle cells and the nerve fibres which can be found between the connective tissue of the digestive gland of the gastropod mollusc Cryptomphallus aspersa. The muscle cells are smooth and are located immediately below the basal lamina of the secretory epithelium or in more central zones of the connective tissue of the gland. Two types of myofilaments can be found in the sarcoplasm: thin and thick. The thin ones have an approximate diameter of 5 nm, whereas the thick ones vary in diameter between 15 and 65 nm. The possibility exists that the myofilaments of 15 nm might belong to a third type. Nerve fibres can be found in central zones of the connective tissue of the digestive gland, at the base of the glandular tubules and within the secretory epithelium. In these fibres it is characteristic to find a large number of granules, of a diameter between 80 and 250 nm, surrounded by a membrane, the content of which varies in density. Small clear vesicles of 40 . . . 70 nm in diameter can also be observed. Occasionally granules, which fuse their membranes thus mixing their content, can be detected.
mesh_terms: D000818:Animals; D004702:Endocrine Glands / Q000648:ultrastructure*; D008854:Microscopy, Electron; D009132:Muscles / Q000648:ultrastructure*; D009412:Nerve Fibers / Q000648:ultrastructure*; D012908:Snails / Q000648:ultrastructure*