Temporal Expression of Myogenic Regulatory Genes in Different Chicken Breeds during Embryonic Development.

The basic units of skeletal muscle in all vertebrates are multinucleate myofibers, which are formed from the fusion of mononuclear myoblasts during the embryonic period. In order to understand the regulation of embryonic muscle development, we selected four chicken breeds, namely, Cornish (CN), White Plymouth Rock (WPR), White Leghorn (WL), and Beijing-You Chicken (BYC), for evaluation of their temporal expression patterns of known key regulatory genes (, , and ) during pectoral muscle (PM) and thigh muscle (TM) development. The highest expression level of occurred from embryonic days E13 to E15 for all breeds, indicating that it was the crucial stage of myoblast fusion. Interestingly, the fast-growing CN showed the highest gene expression level of during the crucial stage. The gene expression at D1 was much higher, implying that might have an important role after hatching. Histomorphology of PM and TM suggested that the myofibers was largely complete at E17, which was speculated to have occurred because of the expression increase in and the expression decrease in . Our research contributes to lay a foundation for the study of myofiber development during the embryonic period in different chicken breeds.