Early changes in extrafusal and intrafusal muscle fibers following heterochronous isotransplantation

0142215 - FGU-C 20010274 RIV US eng J - Journal Article
Jirmanová, Isa - Soukup, Tomáš
Early changes in extrafusal and intrafusal muscle fibers following heterochronous isotransplantation.
Acta Neuropathologica. Roč. 102, č. 5 (2001), s. 473-484. ISSN 0001-6322. E-ISSN 1432-0533
R&D Projects: GA ČR GA304/00/1653
Institutional research plan: CEZ:AV0Z5011922
Keywords : muscle transplantation * degeneration and regeneration of muscle fibers * extrafusal and intrafusal fibers
Subject RIV: FH - Neurology
Impact factor: 2.165, year: 2001

The ultrastructure of regenerating intrafusal and extrafusal fibres was studied 18 hours to 30 days after heterochronous isotransplantation, when bupivacaine-treated EDL or soleus muscles from early postnatal rats were intramuscularly grafted into EDL muscles of adult inbred recipients. Similarly as in other models of mammalian muscle regeneration, surviving satellite cells gave rise to presumptive myoblasts multiplying within the preserved basal lamina tubes at day 4 after grafting, myoblasts fused to form myotubes with central myonuclei by day 6 after grafting. Extrafusal myotubes differentiated into thin muscle fibres by day 8, which progressively increased in diameter and their nuclei became localized subsarcolemmally from day 13 onwards. The basal laminae of some intrafusal fibres already contained one or more nascent myotubes by day 4 after grafting. Regenerated intrafusal fibres lacked the typical nuclear accumulations and their number varied from 1 to 8 fibres per spindle; additional fibres formed in the periaxial space or between layers of the capsule. Regenerated muscle spindles usually had a thinner outer capsule and a reduced inner capsule and periaxial space. The present study demonstrates that extrafusal and intrafusal muscle fibres degenerate and regenerate after heterochronous isotransplantation similarly as they do in standard grafts. However, the time course is slightly different. Degeneration was completed by day 5 after grafting as in free grafts, but the regeneration of extrafusal and intrafusal fibres started one or two days earlier, apparently because of the rapid and facilitated revascularization from the host muscle compared to that of standard grafts.
Permanent Link: http://hdl.handle.net/11104/0039922