Transformation of ultrastructural type of fast-twitch muscle fibres after cross-innervation by tetrodotoxin-blocked slow muscle nerve.

ABSTRACT It is shown in rats that cross-innervation of the fast-twitch muscle extensor digitorum longus (EDL) by the nerve of the slow-twitch muscle soleus (SOL) can cause a complete transformation of the Z-band width from the fast to the slow muscle fibre type within two weeks and that it can still induce such a transformation, though usually less completely, even when impulse activity is excluded by chronical tetrodotoxin (TTX) block of the nerve. This provides a piece of clear-cut evidence for the presence of some activity-independent trophic factor in the neural determination of skeletal muscle fibre type.

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    ABSTRACT: The purpose of the present study was to analyse the changes of macromolecular organizations in nonjunctional sarcolemmas of different types of skeletal muscle fibres after cross-innervation. In normal rats the mean density of square arrays (6 nm particles organized in orthogonal arrays) was 9.02 / μm2 for the nonjunctional sarcolemmas of fast-twitch extensor digitorum longus (control EDL, CE) muscle fibres and 0.34 / μm2 for the nonjunctional sarcolemmas of slow-twitch soleus (control SOL, CS) muscle fibres. After cross-innervation between the fast-twitch EDL and slow-twitch SOL muscle fibres by slow and fast muscle nerves respectively for three months, the mean density was 0.45/ μm2 for the nonjunctional sarcolemmas of the operated EDL (OE) and 8.3/ μm2 for the nonjunctional sarcolemmas of the operated SOL (OS), This indicates that the cross-innervation causes a reciprocal transformation of the number and distribution of such macromolecular organizations in the electrically excitable nonjunctional sarcolemmas.
    Cell Research 12/1995; 5(2):143-154. DOI:10.1038/cr.1995.14 · 11.98 Impact Factor
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    ABSTRACT: Incorporation of bowel into the bladder (enterocystoplasty) has been widely used to increase bladder capacity. It has been reported by others that the response of smooth muscle from the cystoplastic segment of the intestine shifts from that of the intestine (relaxation to alpha-agonists and ATP) to that of the bladder (contraction to alpha-agonists and ATP). This suggests a functional integration of the intestinal muscle into the bladder; the mechanisms are unknown. The aims of the present study were (1) to elucidate if there are signs of bladder nerves sprouting across the anastomosis into the intestinal segment, and (2) to study what happens with the intrinsic innervation of the intestinal segment. As a model, we used cecocystoplasty in rats. The bladder was opened and a patch of cecum with intact vascular supply was anastomosed to the bladder. After two to 11 months the rats were sacrificed and the bladders mounted as wholemounts and stained for acetylcholinesterase-containing nerves, or embedded in paraffin for histology. A pronounced degeneration of the myenteric plexus was found in the cecal segments. In some areas, this had proceeded to the extent that the ganglia were isolated ovoid lumps of cells with no apparent connection to other ganglia. Areas lacking ganglia and nerve trunks but still with muscle could be found in all specimens. Abundant axon bundles were demonstrated sprouting from the cut bladder nerves close to the anastomosis. The bundles spread out in a fan-like pattern or were organized as fewer thicker nerves. There were many nerve bundles entering the cecal segment where they branched and the diameter decreased till they no longer became visible. Some nerves reached surviving lumps of myenteric ganglion cells. The results show that the bladder nerves sprout into the anastomosed cecal segment. It is reasonable to assume that these nerves are responsible for the changes in receptor pharmacological properties of the cecal smooth muscle towards that of bladder muscle.
    Urological Research 01/2000; 27(6):476-82. DOI:10.1007/s002400050138 · 1.31 Impact Factor
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    ABSTRACT: An enzymatic method was developed to obtain intact seminiferous lobules from the testis of the dogfish (Scyliorhinus canicula L.). The freshly isolated lobules were then identified by use of a transillumination technique. Testes from mature dogfish were collected and transverse sections incubated with a mixture of collagenase (0.025%) + pronase (0.08%) at 4 C overnight. Dissociation of the tissue was achieved by mechanical agitation in a calcium and magnesium-free buffer (pH 7.8; 870 mOsm) at room temperature, for 30 min. Based on differences in light absorption and size as well as on comparison with the corresponding histological and ultrastructural cell composition, the seminiferous lobules were identified and classified according to the stages of spermatogenesis of Mellinger (1965). The characteristic changes take place in the size and surface of the lobules and are mainly due to differences in the arrangement of the germ cells, in their number, and in the light absorption characteristics of their nuclei. The combination of the procedures of isolation and transillumination of the dogfish seminiferous lobules, in native condition, offers an original method for the study of germ cell-Sertoli cell interactions in the non-mammalian vertebrate.
    Cell and Tissue Research 12/1988; 255(1):199-207. DOI:10.1007/BF00229082 · 3.33 Impact Factor