Development of components of the extracellular matrix, basal lamina and sarcomere in chick quadriceps and pectoralis muscles

1. The purpose of this study was to investigate differences in the developm ent of components of the cell/matrix linkage in two functionally different muscle types: the pectoralis muscle, a major locomotory muscle in birds but not particularly functional in chickens, and the quadriceps muscle, a smal ler and more functionally active muscle in the chicken. 2. The development of the extracellular matrix, basal lamina and sarcomere in the pectoralis and quadriceps muscles in chick embryos was examined bioc hemically to determine differences in the rate of development between these two muscles. Samples of these muscle types were dissected out from chick e mbryos from embryonic day 10 until 8 weeks post hatch. 3. Using SDS-PAGE electrophoresis and western blotting with antibodies agai nst sarcomeric actin, laminin and collagens I,III and IV, it was apparent t hat muscle development begins earlier in the quadriceps muscle than in the pectoralis, and that late in the developmental process (d 18) both muscle t ypes were well differentiated. The final concentration of collagens in the mature muscle remained higher in the quadriceps than in the pectoralis musc le. 4. The onset of development of the extracellular matrix, basal lamina and s arcomere was earlier in the quadriceps than the pectoralis, which could hav e functional implications for these muscles as a whole.