Myogenic satellite cells are essential for postnatal muscle growth and the regeneration of muscle in response to injury. An understanding of how the extracellular matrix affects satellite cell activity, and the temporal and spatial expression of extracellular matrix macromolecules is largely unknown. In the avian genetic muscle weakness, low score normal (LSN), satellite cell proliferation and differentiation rates are significantly lower than that observed in normal chicken satellite cells, which may be attributed to a late embryonic increase in the expression of decorin. Satellite cell-derived morphological properties, collagen type I expression, and the spatial distribution of collagen type I were investigated during normal and LSN satellite cell proliferation and differentiation. These studies showed a decrease in LSN myotube length and the number of nuclei per myotube. Collagen type I expression was similar between the LSN and normal satellite cell cultures during the course of proliferation and differentiation. However, the spatial distribution of collagen type I was altered in the LSN cultures 48 h after the initiation of fusion. The LSN cultures exhibited a premature extracellular distribution of collagen type I compared to the normal satellite cells.