“…Continued proliferation of the cells may be supported by mitogens such as fibroblast growth factor (FGF) and insulin-like growth factor (IGF), which are up-regulated in muscle after injury (Jennische and Olivecrona, 1987;Jennische, 1989;Guthridge et al, 1992). Most satellite cells in regenerating muscle proliferate within empty sleeves of basal lamina from the degenerating myofibers and this material is thought to play several important roles as: (1) mechanical scaffolding (Vracko and Benditt, 19721, (2) a reservoir of growth factors (Yamada et al, 1989), and (3) a substratum of macromolecules favorable for myogenesis (Ocalan, et al, 1988;von der Mark and Ocalan, 1989). Finally, re-establishment of vascular and neural connections within the regenerating muscle is essential for normal growth and function (Grounds, 1991).…”