Neural determination of muscle fibre numbers in embryonic rat lumbrical muscles

• DOI: 10.1242/dev.100.3.395
• Publication Date: 2021-04-26T00:35:23Z
• Authors: J. J. Ross; M. J. Duxson; A. J. Harris
• Keywords: Semitendinosus muscle; Hindlimb

The generation and development of muscle cells in the IVth hindlimb lumbrical rat was studied following total or partial denervation. Denervation carried out by injection beta-bungarotoxin (beta-BTX), a neurotoxin which binds to destroys peripheral nerves. Primary myotubes were generated denervated muscles reached their normal stable number on embryonic day 17 (E17). This not maintained examined E19 E21 contained many degenerating primary myotubes. Embryos injected with (beta-BTX) E12 E13 suffered loss motoneurones, resulting reduced axons L4 ventral root (the is supplied L4, L5 L6 roots) numbers nerve terminals intrinsic hindfoot. Twitch tension measurements showed that all partly innervated contracted response stimulation. formed at innervation throughout development, but diminished secondary E21. latter correlated reduction mononucleate within muscles. If beta-BTX E18 denervate after myotube formation complete, embryo After E19, begin form, possessed In both cases, had stopped about 1 greatly reduced, indicating cessation most probably due exhaustion supply competent myoblasts. We conclude regulate stimulating mitosis nerve-dependent population myoblasts activation these requires physical presence as well contraction