In this study, the leg muscles and breast muscles from E12 to E18 of fast growth yellow chicken, silky fowl, dwarf yellow chicken and Xinghua chicken were used as experimental materials. The diameter and cross-sectional area of skeletal muscle fiber were observed and measured to compare the differences of leg muscle and breast muscle between different breeds in the development of chicken embryo. The results showed that the development of chicken embryonic skeletal muscle were different between the four breeds （P〈0.05）. The larger and fast growth chickens could fuse a complete outline of the muscle fibers at earlier age than the smaller and slow growth chickens （P〈0.05）. However, the muscle fiber diameter had no significant difference between varieties in the late embryonic period （P〉0.05）. Leg muscle development was faster than the breast muscle in the four breeds （P〈0.05）, and the leg muscle fiber diameter was greater than the breast muscle during every embryonic ages （P〈0.05）. This study could provide a theoretical basis for revealing the growth characteristics of muscle fiber and the difference of meat quality in various chicken breeds.
skeletal muscle development
muscle fiber diameter
cross-sectional area of muscle fiber