Myotube morphology, and expression and distribution of collagen type I during normal and low score normal avian satellite cell myogenesis

Myogenic satellite cells are essential for postnatal muscle growth and the regeneration of muscle in response to injury. An understanding of how the e xtracellular matrix affects satellite cell activity, and the temporal and s patial expression of extracellular matrix macromolecules is largely unknown . In the avian genetic muscle weakness, low score normal (LSN), satellite c ell proliferation and differentiation rates are significantly lower than th at observed in normal chicken satellite cells, which may be attributed to a late embryonic increase in the expression of decorin. Satellite cell-deriv ed morphological properties, collagen type I expression, and the spatial di stribution of collagen type I were investigated during normal and LSN satel lite cell proliferation and differentiation. These studies showed a decreas e in LSN myotube length and the number of nuclei per myotube. Collagen type I expression was similar between the LSN and normal satellite cell culture s during the course of proliferation and differentiation. However, the spat ial distribution of collagen type I was altered in the LSN cultures 48 h af ter the initiation of fusion. The LSN cultures exhibited a premature extrac ellular distribution of collagen type I compared to the normal satellite ce lls.